STRONGBACK DISCUSSION etc. [Archive] - Pearson Ariel Association Forums

Tony G

10-17-2003, 06:52 AM

Robin,
Think of the two plates as splints if you like, but the plates and bolts are really operating as a lever. You know how you can lift a heavy object rather easily by using a long board with something 'jammed' underneath it close to the object your lifting. Well, you can also stop heavy things from moving using the same priciple. In this case the heavy object is the load of the mast step and we want to stop it. The plates work in conjunction with the bolts to form levers and fulcrum.
I don't have the manual memorized yet so I can't recall if it asks you to relax the standing rigging slightly before jacking. But if the mast has been stepped and unstepped several times and if the standing rigging has been adjusted or tensioned in accordance with the changing (lower) mast step you may have to relax it before jacking. I, personally, would jack the beam before starting to work on it. It's not realistic to think you can take all of the sag out of the beam by jacking it up. However, restoring the cabin top to its original shape or very close to it would be very desirable for an afternoon's work. Without a doubt, jacking up the beam against fully tensioned standing rigging or lifting the cabin top beyond its original position would not be good.
The three bolts allready there? No idea. As sencondary and tertiary owners we sometimes run across some strange @*&#!
Careful on removing that laminate! That's exactly how our redo got started. If your heart's set on it try removing all the trim that's necessary first then lay a piece flat metal stock (like a framing square) on the cabinet top or face to protect it and provide a straight edge. Then score the laminate repeatedly with a utility knife. Instead of going for broke in one pass with the knife try eight or nine consistent passes. Heat the laminate with a heat gun or one furious hair dryer and slide a 6" putty knife behind the laminate to work it loose. Then try to 'snap' it off along the score. Work in straight lines. I, more than others, understand the need to snoop but keep in mind you'll need to put something back. Know when to say when! Most of all really study what you find. For what it's worth, Tony G

Scott Galloway

07-30-2004, 12:55 AM

Thanks to Bill for your continuing efforts and to Dave (marymandara) for your efforts to discover and or produce masthead replacements and rudder shoes etc. Rather than respond on that thread in the "General - Off Topic" forum, I am asking for this new one on the topic of "Strengthening the mast support, strongbacks etc." in this "Technical forum"

My big technical problem right now is serious structural damage to the mast support area and strong back caused by a recent accident, and also a damaged mast head fitting. I have looked at the Association Manual and various threads on this site in regard to reinforcing or augmenting the strongback, and finding the necessary parts. The information seems to be spread all over, but the available information is incomplete.

I have found and reviewed photos of the main salon side of stainless steel plates added to the strongbacks in Sirroco and Orinoco Flow, but would be interested in shots of those installations from the forward cabin and also photos and text descriptions of approaches taken by others to deal with mast compression and mast support issues.

I had no personal issues in this area whatsoever, until two days ago, but in a harbor tabernacle-related accident on July 28th, my mast was driven downward and aft into the deck thus cracking the laminate or solid section under the mast clear through to the cabin liner. A previous owner unstepped the mast and modified the deck section with epoxy in time past in a manner which will not be clear to me until destructive testing has been initiated. I imagine that I may have my hands full shortly.

I have not been able to determine the extent of damage to the masthead fitting. It took the brunt of th eimpact, but transferred much of the force down the mast into the deck.

Just knowing that new mast head fittings may be available soon is very helpful to me.

I fear that the repairs may be both expensive and costly time-wise.

It would be nice to have all of this information in one thread on this forum. So if you all see fit, I could use some photos and words of advice in this area.

ebb

07-30-2004, 08:03 AM

Scott,
Perhaps a shorter winded person than me for this........but if you do wade back and weed thru the compression beam and/or bulkhead posts there is a wealth of info.

You have to remove the mast to access damage to the mast base area. And you do have to forensic what the DFO did there. It would indeed take enormous forces to do structural damage IMCO because the compression bulkhead and framing distributes the loads.

You separate out what the new accident caused, what the DFO caused (ie what his repairs were,) and what time has caused to the area by shrinkage of interior structure and the constant pushing of the mast down by the rigging. And decay that might be present in the composite (balsa core) and the beam. Then you figure what it will take to fix it - and what level of repair. If you a DIY then why not run it by the 'workers' on this forum?

I found, anyway, that the cabin top returned to its natural curve with the mast and the mast step removed, or nearly so, you can assume the cabin top was a fair curve befor the mast was set there. Then probe and assess the actual damage. Take photos!!!

[It is kind of like talking in your hat when you can't see what you are talking about. Descriptions sometimes take too long in words to form a mental image in the reader. Assuming the damage is extensive and the rise of the cabin aft f the mast was what the mast was forced into.... the drill is the same: ie remove the rigging and the mast. An actual crack in the molding of the cabin HAS to be posted here. The curves and radiuses make it immensely strong. Please post pics of the damage. I'm imagining something like a mortar shell If the pieces can be coaxed back to their former position then repair is really a piece of cake. A logical series of steps. Even a hole there would be easy to fix..]

Bill

07-30-2004, 02:00 PM

Here is a view of the strongback reinforcement plate on the forecabin side. Unpolished ss . . . :)

Bill

07-30-2004, 02:01 PM

Prettier on the maincabin side :D

Tony G

07-30-2004, 05:56 PM

Scott,
I'm very sorry to read of your mishap. It sounds frustrating and painful. Ebb's right, some pics would help flesh-out story on the repair. Once you have the mast off it should be pretty straight forward. As far as FRP goes, if previous work was done in the step area you'll probably need to enlarge the 'reconstruction' to include that work. At least that way you'll know exactly what was done and it be done to your standards. The beam can be handled a number of different ways and all acceptable. Someone once pointed out here that the original design worked fine on these boats for many years. You could simply replace the old with an exact copy. Or, a sandwichedly enhanced version that many Ariels have in them these days. One could even be as unconventional as Ebb:D and laminate a new stronger beam. He is radical.
Unfortunately this all takes time. But as you know, there is something emensly gratifying about nursing or mending a boat and making her right again.
Hope any of this helps. Tony G

willie

08-01-2004, 10:46 AM

When i had the mast unstepped, there was about 1/4'' gap between cabin top and beam, so filled with epoxy, and then added this 2'' alum. angle iron, through bolted. Bolted new hinge down through the beam and angle. Will now have two nuts for a nut head gouger, but couldn't figure out any other way to make it stout. The hinge has to rip out the whole piece of 2'' angle now, which ought to make as big a mess as you have someday! Here's a shot of the angle, and the hinge.

willie

08-01-2004, 10:50 AM

used 3/8 bolts. had to make relief holes for heads in top plate. used origional holes of bronze screws, and origional wood step.

Scott Galloway

08-01-2004, 05:07 PM

Thanks everyone for the helpful suggestions and the great photos and thanks Ebb, I did search the site for all of the words that I could conceive might lead me to photos of this area. I will now search through the compression beam and bulkhead posts. This accident is not something that I can discuss at this point since it involves other people and a clam that I may have to file.

I can say a couple of things. I think that when my boat was tabernacled, the previous owner found some delamination beneath the old mast step. He told me that he had added epoxy to the area, and based on other work done on the main deck, I assume that he probably drilled a few holes and pumped epoxy into the voids. That would make more or less a solid section beneath the mast, and strengthen the support of the mast, but of course epoxy does not compress like balsa wood, so a severe shock load (such as one placed squarely in the very center of the mast head fitting, such as running your mast into a concrete bridge member while it is partially lowered in a forward direction) for example would tend to transfer considerable force both downward and aftward, and this might (for example) send offset lateral transverse fiberglass cracks across the deck surface, force the mast step mounting blots through the cabin liner, causing the liner to buckle, and possibly crack the strong back, depress the top of the door frame and separate the door posts and other support members below deck from their intended secure bonds etc. (for example).

So I am very well aware that removal of the mast and destructive testing of the various elements of the support system will be required beffore repairs can be initiated. The extent of the damage will dictate whether a complete new support system will be installed, or whether the stainless steel brace approach will suffice. I am interested in handing to my surveyor some examples of the fine work that members of this forum have done to deal with cumulative trauma to the strong back so that we might consider them for the accident repair task ahead. The photos that you have posted will greatly assist me in this effort. The more photos, the merrier. And yes, I will be posting some photos by and by.

marymandara

08-02-2004, 12:09 PM

I can't comment too directly on an Ariel mast beam/strongback, as the last time I was in actual physical proximity to one I was about 5 or 6 years old...and my Commander was a Commander...

All the same, from the photos I have seen it looks awfully similar to the Triton mast beam/compression posts/diagonal braces...which, FWIW, come out completely with relative ease and are pretty simple parts to replicate. I'd be moved to just dig out the old ones and replace.

Dave

John

08-02-2004, 08:20 PM

The top plate/fitting for my compression post seems to be crushing as though the plate that is the bottom is being driven up into the fitting. Pictures when I get to the boat later this week.

I read the sections on compression posts but I am still not clear what I am dealing with in terms of removing/replacing what I have. I know that plate that the mast sits on was replaced by the former owner with one he had fabricated from a phenolic material similar to what has been use for blocks.

Oh well, all can't be bad. I put the first coat of varnish on my stripped and filled grabrails, and the Red Sox won behind Tim Wakefield on his birthday. This is Boston after all.;)

epiphany

08-16-2006, 03:09 PM

Senor Ebb -

Par for your course, the work is excellent and shows much thought and even more labor! The 1/2 solid dodger - great idea, will have to ponder that one. I have been planning to build (make?) a firehose-frame dodger, a la Yves Gelinas on "Jean-du-Sud" (http://www.capehorn.com/sections/30%20ans/30ansAng.htm) . Combining the two ideas deserves some consideration...

Anywho, I've begun (de)construction belowdecks. After dropping the mast this past Sunday, I decided to go ahead with the strongback modification while it is down, and before I put it back up.

The past couple of days I've been battling a head cold, but today I got fed up with just lying around feeling ill, and took out my aggression on the strongback and bulkhead. The strongback is now lying on the cockpit seat, and the bulkhead is cut away to within 2" of the top of the standard locker countertops. The "main cabin" is now open to the v-berth, and it really makes a difference in how the interior "feels"!!! I love it, it's like the boat is bigger already. Hopefully by the end of the week/early next, I'll begin reconstruction of the structural components I've removed. I'll be posting pics in my Gallery thread soon...

So anyway, I have a question for you concerning your strongback -

Basically - What are it's dimensions? That's to say: How many inches thick is it in its vertical and horizontal cross section? I'm trying to get an idea of what I'm seeing back on page 1 of this thread, and in the latest pics...

I've decided to go with a wide, low-profile design for the strongback, about 2" 'thick', and 8" wide (or more - I'll be removing some of the headliner to do this). Reasoning: keep the interior as visually open as possible, while making sure that my non-engineered solution is far and away stronger than what was in this boat for 40 years (which was surprisingly slapdash, once I could see it upon tearing it apart). I think it'll be all composite, glass and foam, mostly glass.

I drew a line onto the bulkhead and s/b before tearing it apart, to get an idea of how much space that was, and I think it'll be sufficient for getting the material I need in there. Yours looks to be about the same size as the strongback which was original - is this so? Thanks!

ebb

08-16-2006, 10:59 PM

Hey Kurt, excellent!
Did I miss what wood you will use for the compression beam?
Depends on where the struts, the verticals are going. All the way to the cabin side (as 338) or are you keeping the forward stateroom, and will have a doorway?

Could guess that if you were going with the doorway 2 X 8 would be OK. In white oak. Wider apart and deflection could be a factor. I would go to 2 1/2" And I might think to lag in a piece of 5/16" steel on edge - cut exactly to the arc of the cabin roof - as insurance. There is a problem with this if you are laminating: your lags are going into the lams which spoils their integrity.

There is good reason why beams are usually deeper rather than flat. You know you'd have a superior beam if you put the 8" on edge. I think 338's is like 2 3/4 X 5. With smaller section plain whiteoak struts on the sides, at the ends of the beam.

Maybe you could weld up a 2 X 8 s.s. arc as a 'C' channel. That might work good. No wood, just steel. Very good, if you through bolted across the cabin top the whole length.
Don't think I'd do away with some kind of verticals going down to the berths.
Theoretically any arch can't deflect if its ends cannot move. On the Triton site at least one guy assured his cabin arc by fabricating a curved athwartship mast base - thrubolted with the beam, no doubt.

At the end of the cabinsole where the V-berth deck rises -right there at the doorway in the bulkhead - I've glued in at 2'' thick mahogany 'floor'* (crosspiece) and I will be doubling that (and maybe a bit more) thinking that I may have to put a compression pole in because the beam is not adequate. They naturally end where the original settees rise. With a pad on them and the pieces fitting well andthe remaining pieces of the old bulkhead tabbed in solid they may spread the load of the mast over the keel well enough. I've heard that poles are great to grab onto below. Imagine a well rehearsed two handed 180 swing from a crouch to a 360 landing on the Airhead...

White oak is not a wood for gluing. Tannins mean the resorcinol won't work. Can't remember about brown glue (the powdered stuff} but white oak? don't think so. There are enough complaints about Gorilla urethane glue to keep me off it. No 'soft' glue will hold stress lamination. And epoxy requires a glue line. Might talk with Smith & Co. about their epoxy AllWoodGlue.

If the beam appeared to be molded into the cabin, not featured, but was disappeared, nicely rounded, into the cabin painting scheme, I bet you could go deeper on the beam scantling and be positive (almost) that the mast would stay out of the accommodation. Incorporating a number of fastenings thru the lamination might insure the mast won't crack it and delaminate. Be cool if you could carve the beam out of a curved branch. Indeed, if you rounded the bottom, curved it like a branch you'd gain more strength without it being obvious.

Interesting problem.

Epoxy has to have a glue line. In curved lams prebending by steaming would allow gluing without force. If your lams are thin and easy to bend (1/8"), and if you have the time: gluing up a few at a time, letting them get hard, and continuing with a few more, etc could work. Gluing a bundle of wood together under stress is not correct anyway. The piece will want to straighten itself out (flatten) which is not what we want to happen - so why build it in?
Wide lams may be difficult to set up a jig and to clamp. But the beam is pretty small. Gluing the beam to the boat would add strength and solidity.
Screws could be used to hold lams together while gluing and backed out after set. I have a bunch of 1/4" luan 1 1/2" squares with a hole in the middle. Drive them in with a grabber to tighten up pieces, get a bulge out.

I think you have to give attention to supporting the full width of the 8" beam with 8" wide verticals. Gotta support the beam!

Go for it!

__________________________________________________ ________________________________
*floors connect ribs together over the keel in traditional wood boats. Each pair of ribs, port and starboard, would have a floor, each floor fastened to the keel. Snobby using a term like that in a lit'l ole plastic Ariel. oh well... ;)

epiphany

08-17-2006, 06:07 AM

Included is a quicky graphic* I did up to illustrate my current thinking. I'm with you on the stiffener thinking: Since the vertical component of an I-beam is what makes it resistant to downward bending, I have been trying to figure the best way to incorporate that into a 2" thick structure which could resist the compression forces put on it by the mast. I've ruled out wood, because I think that in what I'm going to do it will only add extra weight, w/out adding any extra strength. I'll be relying on glass for strength. Too bad, I like the look of wood! But it will be elsewhere in the cabin, so... :)

In a nutshell, to build the beam: Lay up the glass onto a sheet of 3/4" thick foam (one side at a time), putting a total of 1/8" thickness glass on each side of the foam. This can be done with the foam in a horizontal position, making it easy to control wetting out, and to control alignment of the glass fibers in the cloth to achieve maximum strength in the finished beam. Once both sides are glassed and cured, carefully cut the 1" thick individual "slices" of the beam to a template taken directly from the hull, then bond the 'slices' to each other. After the slices are assembled into a unit, glass on the outer layers (top and bottom skins of beam).

When this entire beam assembly is cured, it gets bonded into/under the deck, bedded in glass and "ebb's mishmash" ;), drawn up into place with screws and/or bolts until cured. Use more mishmash to filet the edges of the beam to the deck for smooth transitions, and then, last, laminate on a final overskin of glass.

I plan to put 2 vertical stainless poles in place where the old doorframe verts were, they should give additional support and handholds. I 'mocked this up' yesterday to see how they would look visually, and they don't detract from the 'open' feeling the cabin has with most of the bulkhead removed (which I am loving!). At the bottom, they will tie in to reinforced floors similar to what you have done.

Whatcha think? :)

*(((As I was just making the graphic, the thought came to mind: "Hey, there's also the space between deck skins which could be incorporated!". Hmmm - doing so would give structure which would not protrude down into cabin space (good!), but it would involve much more work - remove outer deck skin once new beam was in place, build structure in where the current balsa core is, then replace deck skin. An idea which deserves further thought, and which someone else might be able to use at some point, so I've included it...)))

frank durant

08-17-2006, 06:11 AM

note to all 'beam' builders out there....Plywood is VERY strong when on edge (vertically).4 layers of 3/8th ply would give GREAT strength as long as the bottom edge was 'trimmed' out with wood so as to keep it from deflecting for/aft under load. I know little about boatbuilding,but in home building we often use plywood as an additional laminate when building a beam to increase the compression strength. WAY stronger than conventional wood.

epiphany

08-17-2006, 06:36 AM

Frank -

I assume that is so because the wood fibers run in different directions in a ply? (as opposed to the same direction in a normal piece of wood.)

I'd considered using plywood in this manner, but thought I might get a stiffer vertical with the glass 'ribs' like in the graphic.

So - I could do the beam then with 14-16 'slices' of 1/2' ply, bonded together with a couple layers of 6 oz cloth between each, make it 1 3/4" thick in the vertical dimension, and cap it with 1/4" of glass...? All this would get the same final treatment - completely encapsulated and bonded to the underside of the deck, as noted above.

It might be quicker to do that way. One thing I liked about all-composite, though, was no worries about water penetration. Could take care of that with much care in sealing things up I guess...

ebb

08-17-2006, 08:00 AM

Indeed. I do like the multiple I-Beam composite, great graphic. It's an engineering challenge! EG how thick do you make the webs? The more you think about it the more feasible it becomes.

The verticle supports inside, two placed about where the original doorway is, should do it. Could also buildup wide pads on the beam to spread the 'point load' of the supports.

Mike Goodwin introduced us to maranti "Aquaply" and "Hydroply" which are superior in every way to American fir - that stuff would make a good arch - ala Frank's post. Thanks, buddy! 3/8" of maranti equals 3/4" american fir. I would not use FinnPly. Would caution that cutting the 2" wide curved pieces out and gluing those together side to side to get your width is not such a good idea. There still will be flex don't you think? Could you put it on the floor and jump on it??? Even with the extra wide width I think there is not enuf 'meat' in 2 inches. Would like to debate this. I'd be happier with 2 1/2". Plus the two columns inside. As you know it's imco. Frank, though, of course meant bending 1/4" over a form and gluing up a 2, er, 2 1/2" stack! Only with meranti.

A composit structure composed of two skins separated by foam, endgrain balsa, honeycomb -essentially a nonstructural filler - will be stiffer than a solid lay up. Also lighter of course. But we can't forget that the load on the beam is concentrated in one place. Spreading out that point load is very important. Correct?

What we learned about an unrestored Ariel with a flattened cabin-crown under the mast is that the original Pearson structure (beam, strut braces and bulkhead) while funky was still working and in good shape. (On 338 anyway.) The structure had probably 'settled' or shrunk over the decades allowing the rigging to pull down on the mast. That is, it was more of a result of aging materials rather than the weight of the mast, or rot. After the two screws that hold the round wood maststep to the beam inside were removed, the composite cabin top popped back up to it's original crown!! Or pretty close to it - how about that?? That's the challenge confronting the renovator. We need to make some structure that will not move over time. This time. Or one that can be adjusted up when needed. I'll take the immovable, with some redundancy built in. And everything GLUED IN. We live in the age of incredible glue.

If one had the time, testing various structural ideas would be revealing. We'd need the various arcs and a carjack and some sort of meter. But doing this in the imagination is a good alternative. One can 'see' the various ideas and how they might be expected to react to a carjack (or an unmetered jumping attack by a twohundredfifty pounder wearing Redwings!) trying to straighten them out.

I'm oldfashioned and think solid heavy oak will do. But a well thought out composit of carbon fiber and the best epoxy would be much lighter and more in keeping with the technologic advances of this era......... :rolleyes: Would be a curious jig to come up with! Vacuum bagging, anyone?

The load on the compression beam is constant - and no doubt there'll be times when sailing that the load exceeds the norm, would be constant AND 'pumping.'

Gotta go to work :eek:

__________________________________________________ ______________________________
(Supposed to be working...) How about bent square (rectangular) steel tube? Easy to get the arc done. Get the best curve, weld four of them togther side to side. Fill the odd angles and spaces up top with epoxy mix using the beam with a film release. Take it down. Then glue it back up with rubber. No?

Might get a clear span out of that one. And however the supports go, they also could be the same tube all welded together. There's that old problem of what the finish will be: chromium oxide? Wait a dang minit... Use the best quatity iron (the other steel) tube and get it galvanized. No stinkun chromium oxide and no sticky epoxy!!!

epiphany

08-18-2006, 08:00 AM

Been thinking on this, and will be until I start doing something about it... :)

I took Franks post to mean that the ply - used as a stiffener - would be *on edge* (its laminates placed in a vertical orientation, like end-grain balsa). Each individual layer of wood being, in effect, the vertical component of an "I" beam. The fibers of the wood in the ply would be more-or-less vertical if it were installed that way. Laminated together flat the fibers would be horizontal, and function more like a leaf spring, right? Seems like that would be so...

Point loading: Exactly - I'm thinking "wide" in order to spread the point load of the mast base out.

The mast base pad on Katie measures a bit over 7.5" in diameter, but this sat on only a total (strongback + bulkhead edge) of 3.5" of structural support from belowdecks. (Not to mention that someone at the factory neglected to install the diagonal braces on this particular Ariel...) By making the beam 8" wide, I should see a lot more support from below.

I saw a different reaction than what you did when the deck was relieved of the mast burden. Mine has remained in the same slightly depressed shape, it didn't spring back up like yours did. I likely had more compression, due to my missing diagonal braces, though. In fact, I see evidence under the side decks that they flexed to a point which caused minor cracking - zoiks! So I am very much interested in spreading the load as far and as wide as I can, so that more of the deck/hull structure shares the burden.

I've given a lot of thought to different metal tubings as a brace. The ultimate would be 2" aluminum round tube, bent and welded in a shape just like that of the underdeck and hull shape, clear down and around. It would be as light as possible, very stiff and structurally strong, I think you could even do away with the entire bulkhead if you wanted, and it would look nicely "techno". It would not be cheap, however - I'd have to sell both CrewDogs and at least 1 kidney to be able to afford that! :) I think that if you welded up several square tubes, bent to fit the underdeck curve, you wouldn't need to fill them with anything other than some type of anticorrosive agent. But that would be complex, probably not cheap, and probably heavier than a wood or composite beam. Perhaps an I-beam made of flat plate, the top of it curved to mate the underdeck would work well, and be fairly easy and cheapest for a welder to make up. Maybe a wide box-shape, something like that. I don't weld, though, so someone else will have to pursue that route...

---------------------------

This weekend, I am going to take some scrap ply that I have - it's 1/2" or 5/8" - and rip it into 2" wide strips, then screw them together to make a 6-8" wide "test beam" - no curve, just a flat piece as long as the strongback will be. I'll put it up on some bricks or something, and jump up and down on it, maybe jack up my Toyota and set it down on it, see if I can destructively test it to get an idea of how strong such a construct might be. Kinda like that TV show. :D

If it proves strong enough, then next week I'll make one to fit the boat, tab it in similar to how the original strongback was tabbed (quick and easy), and then get some galvy pipe to support it with from belowdecks. At that point I'll be able to put the mast back up for some testing. It won't be hard to remove if it:

a) either doesn't work, or

b)works great, and just needs to be put it in properly - bedded in mishmash and glassed all over.

ebb

08-18-2006, 08:18 AM

Hmmmm, sounds like fun.
338 miraculously (knock on wood) has its balsa in decent shape. There was not much deterioration under the mast step. It may be that the balsa inside yours is tuna fish. If that is so the repair is easy (I did it!). Just cut the top off over the whole area where the mast sits and replace it with solid lams of xmatt. Gain a little strength there.......oh, and weight!

It's a toss up on the weight of a structure, tho some are a lot lighter, like carbon fiber. Even glass and foam can get heavy. I know, I keep creating that problem.

It's gonna be what you 'see' is right. It's already been done exactly as imagined. Just hasn't been installed yet. My vast :rolleyes: experience has been that it nearly always is the first vision you had to solve the problem. Then you embroider or doubt it. Notwithstanding Edison's 10,000 trys at inventing the lightbulb.
Later.......

frank durant

08-18-2006, 12:37 PM

Kurt...Quick note on the plywood thing. By 'on end' or 'vertically' ...I mean..as if you were putting the sheets on a wall,not a floor. Multiple layers 'on a wall' so to speak are extremely strong. Just incase I was confusing. OK OK..I know I'm confusing...

ebb

08-18-2006, 01:38 PM

OK, so if you do jigsaw the 2 inchers out of ply and glue them up face to face - you will end up with a lot of short grain. Even more short grain in cut curves. Couldn't agrue that that plywood structure is particularly strong at all. Nix that. Plus it's too much work - and wastes expensive ply.

Plywood bent flat, two inches built up of 8 layers of 1/4" marine ply wil be about twenty times stronger than that on edge stuff. A 2X8" made like this might not flex at all. But what are the loads? You will be cancelling any flex with interior supports. In 1/4" you might prebend the 8" strips - taking some stress out of the lamination. A little hot water, a hot day, and a black tarp.
Maybe prebend DRY it in the form for a few days. but overbend it, ie a smaller radius so that they might relax back to the curve of the form.

Could glue up 6 pieces of ply, let it set up hard, cut out the center, put it back in the form, layin some pvc foam with epoxy gel in the hole and glue on a top and bottom of 1/4". Don't think it would act exactly like a composit - it might be stiffer - but it would be lighter. Don'i know that the saving would be worth it.

What's the matter with overbuilding the compression beam anyway???

frank durant

08-18-2006, 04:52 PM

Ain't nothing wrong with overbuilding !! I know that in 'i-beam',floor joists or roof rafters that 7/16th OSB on edge with a 2x3 top/bottom holding it, go WAY farther on spans than I figure it should/would....but the engineers say yep.On your big arch I can see where it would be too much waste etc....but the average guy supporting his 'stock' under mast support would find great additional strength by simply laminating a nice piece of mahogany 3/8th ply to each (for/aft) side. Way easier than the steel bolt on in the manual and looks better too.

tha3rdman

08-19-2006, 06:50 AM

I dout there would be much waste, the arch wouldn't have to be continuos per ply, just dont pile up the joints in line with each other, the glue is stronger then the wood anyhow. If I were to do it I'd likely do it in 1/3 - 1/2 - 1/3 . . . plys put em in a vac bag, and wala. If you wanted to over kill the joints, scarf them.

Edit: As Frank mentioned the Tj's (the osb capped by dim lumber) can and do span further and hold more weight on the longer span then their relitively sized solid wood joists.

ebb

08-19-2006, 07:49 AM

Thing is Epiph wants a 2" deep beam that is 8" wide. The width is a valiant attempt to gain some mass, so that the unusual shallow beam will not want to bend. As I understand it, the original concept is to create a number of mini verticals inside the 2X8 to get that on edge stiffness in the width of the proposed bridge.

The problem is to create a non-flexing structure in a 2" X 8" parameter.

I'm absolutely sure that you cannot cut 2" wide vertical arcs out of ply and glue them side to side to make a 2" X 8" curved beam. You can ofcourse, but the resulting pieces are essentially 85% SHORT grain. And the finished piece no matter how much epoxy glue will not be very strong The only way to get the full benefit of ply is to glue it up in a short stack conventionally.

A solid 2" X 8" glued up mahogany plywood beam wouldn't weigh much more than the 8# of the original white oak one. The beam is less than 4' long. There isn't very much to bend here.

But it might bend.

But it WILL NOT BEND if the 2" X 8" beam is supported at the ends AND WITH
ONE OR TWO COLUMNS. A well constructed strut that has a very solid base.

You could put a compression pole right under the mast down to the keel and get away with no beam at all. Done all the time.

The original beam is 4 1/4" in the middle tapering to 2 1/2" on the ends. It is 2 3/4" wide. It is a very efficient, nice looking piece as designed. In no way could it be bent by the mast. Unless it rotted.

The only way the cabin top flattens (and it is really minimal: 1/2" maybe a bit more, limited experience here) is that the wood structures in the boat settled (and/or the balsacore in the composit cabintop rots) - with help from above. The beam remains unchanged. The bulkhead, beam and vertical struts were all carpentered DRY into place by the factory. Designed to move in time!!!

Dry means no glue was used (in 338). When anybody renovates in 2006, you want to glue in a monolithic composit solid mast support. No fooling around this time.

Can we get Epiph's 2" minimum??? No problem! ;)

epiphany

08-28-2006, 08:53 AM

Again, the materials used in late-model "Katie Marie" prove to be different than that used in earlier boats...

Of course, she had no diagonal braces, so I am sure that that had an effect on what I see with her OEM strongback. Although it is *not* rotted, it *has* cracked (see pics, cracks are evident). Without diagonals, it was under more stress, I'm sure. Additionally, it is a solid 1/2" less in the vertical dimension than what ebb measured on his strongback (3.75" vs ebb's 4.25"), and only 1 3/4" wide (1" less than ebb's!) - so it is a significantly smaller beam. Yet she still sailed on for 40 years almost...

One thing I noticed, and mentioned before IIRC - the flexation (is that a word? it is now... :)) of the side decks, forward of the bulkhead, which resulted in some cracking of the inner deck skin there. I see no evidence of this cracking on the after side of the bulkhead. It is because of this evidence of force transmittal that I decided to go with the wider beam. I think it was point loading which was responsible for the cracking - the deck was trying to bend around the bulkhead. (!!!) So, to clarify what I think may be a misconception because I didn't clearly state it before: The width of my upcoming beam is only in the smaller part an attempt to make up for its reduced thickness; primarily, in my addled mind, the increased width is to spread loads across the structure while stiffening it to alleviate/cancel any torsional loads. Do dat make sense? :)

By way of explanation: I know that the beam will flex downward, even if only incrementally, when the boat is under strain of full sail and pounding into seas. Said bending will transfer the load out to the cabin trunk sides. Visualization: hold your hands, halfway cupped, fingertips touching at the top of a small arc, to simulate the arch shape of the inside of the cabin trunk. The mast sits on your fingertips. Imagine it pushing down, simulate it with your hands, you can see that it transfers that force out to the sides. End result: the cracking I see. A wide beam will spread that load across more surface area, which translates into more strength, and less of a load at any one point. Right? It will serve in a similar manner to do what the diagonals Katie never had would have done, had they been there.

*That's* why I want the width. Spreading the love... ;)

I'm not counting on the entirety of the strongback to support the mast, just a small part of it. I'll be supporting the mast in the vertical with 2 metal poles I will put roughly in place of the former doorway frame. The poles will contact the strongback beam and cabin sole on wide bases. Up top, under the mast, center-to-center of these bases will only be about 16", so the span which needs to be strong enough to resist the crushing force of the mast will be unsupported for less than 14".

I am still designing it in my mind, haven't yet settled on that which feels "right". I've been thinking 2" thick on the beam because I think that done properly it will be strong enough, as well as a being visually nice. I haven't ruled out a thicker spot in the beam under this area, tapered into the rest of the beam for visual flow and load-spreading. I suppose I also could go with a metal plate in this span area, and go even thinner on the beam, since it will be poles doing most of the work.

Last, I'd assemble the beam of vertically-aligned plywood pieces with resin *and* glass cloth between the layers of ply, like in my "boxes" drawing, not just resin or glue. By using plywood instead of foam for the core material, I think it should add strength/stiffness.

bill@ariel231

08-28-2006, 06:26 PM

Kurt

just a voice of caution: I recommend you take a look at Brian Toss' book on rigging or a couple of web sites...

http://www.sponbergyachtdesign.com/ArticlesEngineering.htm

or

http://www.classicmarine.co.uk/Articles/rigging_loads.htm

(there are others)

from the sponberg site a rule of thumb is:

(mast_compression) = ((weight of boat) * (righting moment from CM to CB)) / (distance mast to chain plates)

rough numbers (eye-balling the boat at 30 degrees of heel)....

mast_compression = ((5200 lbs) * (1.0 to 1.5 feet)) / (4 feet) = (1300 to 1950) lbs

This number is higher than some other more detailed models. doubtlessly, Moderator Bill has some better numbers for weights & moments, but the point is there will be a large point load under the mast and you are looking at a large span.

before you commit to a radical change, you may want to build a full size model and load it with a jack or hydraulic press.

Maybe I have misread the article.. I'm just a software guy.

cheers,
bill

ebb

08-28-2006, 06:59 PM

Kurt,
the end result of your mast beam project will be zero flex of any sort.

As to the deck flexing, I believe it has to be rotton core. Right? Like 338 you may have a composit whose inner layer is damn thin. In the past I questioned whether a recore could be done from the top because the inside had little or no integrity. I found a single layer each (on the inside of the composite) of cloth and mat under the mast. Easily moved with the fingers. I've just assumed that later number boats were skimped on, but it may be individual ones.

I believe now when doing a radical coresectomy that the foredeck area should be carefully supported from inside with boards and battens or even an inflated bag or two. Cutting the deck out in small sections at a time so as not to loose the camber of the deck.

No bulkhead or knee was built-in to the underside of the deck/cabin roof in 338. Seems to be the way it was done back then. I would make sure they are well tabbed in this time so that the deck becomes part of the system, not a symptom of something wrong. How this can best be done is obviously open for discussion. The forward knees for the lowers ought to be able to support the deck. Wide tabbing and healthy core would take care of any flex in this area. No?
{The widest part of the foredeck and the rounded nose of the cabin is unsupported from inside - except by its monocque shape and the sides of the hull. Flex in this area would be strange - unless it was contributed by weakened deck.
The mast is supported by the whole top of the cabin and indeed by the whole top of the molded deck. Imco it's possible that some of the downward force of the mast could be translated into that cabin-nose/wide foredeck area. Loss of camber would be an indicator. Long straight-edge would show it.}

I managed to get glue under the liner port and starboard sides and carjack the sags and openings 338 had there up flat to the roof - I felt very uncomfortable messing with the liner so I opted for monolithic knees off the hull. I may go back and tab them in to the top. (But I might also remove them because my chainplates are going on the hull.) The liner as you know does not extend all the way out to the hull under the side decks so there is actually some prime attachment for part of the top of the aft knees (aft lowers) and the main bulkhead (or what remains of it under the decks.) Would not tab onto the liner. The knees tabbed in solid must contribute a good deal of stiff to the hull and deck in way of the shrouds what ever method of chainplate attachment.

IMHO, NOTHING should be able to move in the shroud/mast/deck/cabin/beam area. That is, nothing of the boat itself (the plastic) should move at all. The rig depends on it. The shrouds in big water can't suddenly get loose because of 'oilcanning' of hull or deck and not support the mast, both sides. Sudden loose shrouds could be a cause of the mast breaking in a knock down, doncherthink?

It does seem far fetched: but if the weight of the boat is supported by the mast (ala Sponberg) then two tons of concentrated force could do some strange distorting of plastic laminate! Would have to see it to believe it - like in frame by frame time lapse. Monocque structures can be crushed, I'd think they can be twisted on an axis, and relative flat thin planes can be oil-canned. Generally '60s plastic lams were substantial and made from excellent ingredients. That's what we gather, anyway. But composits with cores must have been fairly new and simple back then - now we know that the opposing skins must be equal in strength/thickness. David Pascoe, our favorite online marine surveyor talks about this on
http://www.yachtsurvey.com/HiTech.htm

I feel that the mast bulkhead along the hull from the deck down to the keel has to be very strong WITH WIDE TABBING. - and ideally the bulkhead should be connected across the keel, so that mast forces are shared on both sides of the boat. As above, so below. The circle must remain unbroken...in the bote, load, in the bote :rolleyes: ....

epiphany

08-30-2006, 05:06 AM

Bill - Thx for the suggestion, I have Toss' tome on the subject, will have to reread the pertinent chapters. The websites you posted are most informative, and give much food for thought. Once I decide on *something*, I will indeed make a test piece first, and do what I can to see that it will be up to the job!

Ebb - I don't see any obvious signs of core rot in the area, but do plan on making danged sure of it before wrapping it up. Eventually I'll be going with external plates, and the areas around the bulkhead and chainplate attachment points will recieve much strengthening and stiffening in the process. Like you, I don't want it to move at all, oilcanning is for powerboat engine rooms only. :)

The circle shall remain unbroken. :D

epiphany

09-03-2006, 04:35 PM

I took a good look at an Alberg-designed Cape Dory 26 (http://www.capedory.org/specs/cd26.htm) yesterday, checking out how the strongback was engineered in a very similar boat to ours, 20 some years after our boats were in production.

The CD26 has a center-pole support for the mast, with port-offset access to the v-berth. The mast support is apparently a solid wood, 2.5-3" square pole. Interestingly, the pole is offset from centerline *to starboard*, about 1.5". There is some sort of arched structure up against the overhead which the half-bulkhead attaches to (mechanically, no tabbing that I could see), but it is small, and hidden by the cabin liner. It is an upside-down triangle in shape, approx 3" wide against the overhead, and 3" to the apex of that triangle. The corners of the triangle are radiused about 1/4".

The wide piece of wood on the bulkhead against the overhead you can see in this pic is simply trim, it didn't appear to serve any structural function. Also note the seeming lack of cabin trunk side support on the port side at the bulkhead station.

From tapping against the overhead, it was evident that the deck construction in that area - forward of the bulkhead at least as far as the forward edge of the mast base - was more solid than in other areas of the overhead.

Last, and somewhat unrelated, the size of the standing rigging was obviously smaller than that which we have on our boats.

Interesting. :)

Bill

09-03-2006, 06:17 PM

Last, and somewhat unrelated, the size of the standing rigging was obviously smaller than that which we have on our boats. Interesting. :)

The Ariel used the same rigging and mast (cross section) as the Triton. Sort of explains why these are such a tough little yacht.

ebb

09-03-2006, 10:57 PM

Very shallow beam, (don't really see it!) - no side supports at the cabin sides.

Lots of similarity to the Ariel of 20 years earlier - looks like heavier buttocks, to keep her from squatting. But the beamless interior is very interesting. Did you knock on the sides? They'd have to be solid, wouldn't you say? Otherwise typical Alberg. I have to wonder how it is done? maybe a single post really can act like a keel stepped mast. Do the shroud-plates come thru the deck?

Numbers say only 78 of these were built.

Hard to imagine any boat near the size of an Ariel with less than 3/16" wire.
Wonder how the general construction quality compares between the two?

epiphany

09-04-2006, 04:47 AM

Bill - Right on, that was one of the attractions of the Ariel, for me. :) The guy with the CD26 said he is going to be staying at our marina, so I'll have to take a turnbuckle or something over, take a pic of the two for a comparison to post here on the site, it's so evident.

As an aside, I look at every boat in this size range which comes through the marina, none have the strong rigs we have... In fact, most late vintage boats (Ben-ter-lina's, primarily) have even smaller scantlings on boats which are 3-4' longer than ours. Not that I'd expect different there... :rolleyes:

Ebb - I looked all over for an interior shot of the CD25D which illustrates how the mast/bulkhead/strongB is set up on that model, couldn't find one... wah. Looking at the line drawings I could find, it is obvious that the mast sits well *aft* of the forward bulkhead location, so it would be interesting to see if there is any kind of evident internal reinforcement on those boats...

I didn't knock on the trunk sides of the 26, but shall. It would seem that the sides must primarily be under compression from the mast, if they need no reinforcement from other structure... Still, I will build mine up a bit. Tapping on them just now, they seem to have more of a solid sound than the deck. I don't think there is coring in there, is there? Have you seen any during your (de)construction?

The sidedecks on the 26 are obviously strengthened against compressive forces from the mast/rig by some sort of side-strongback, you can see it in the pics. That fits in with my plan to have my eventualbeam wrap down around and under the sidedecks...

The chainplates on the 26 are through-deck, connected to knees on the hull, just like the Ariel.

CD's have a reputation as generally well-found boats. Judging from what I could see, it seemed put together with at least as much care as an Ariel, or perhaps a bit more.

ebb

09-04-2006, 07:20 AM

Looking at the CD25 Sadler, the beam build-down is also slight. What is obviously the compression AREA is bracketed by wooden structures creating alcoves where lockers and heads are usually put. Haven't researched this at all, But the s/v Allia (with a good inside shot) has a #738 on her sail. That is a surprising difference in numbers of boats between the two designers if that is indicative.

If there has never been a problem with the CD25D mast, it is very worthy of study. And inspiration. We know that Alberg was a tyrant when it came to messing with his designs - the 'engineering' inside under the mast must be well thought out.

It's fantastic you have two live models to draw from.

I would like to see a cross-section and a diagram of this CD25D mastbeam puzzle. Maybe not, because I would be hard put not to change what 338 has now!

A bunch of luck with the project! :cool:

hawkinsp

02-11-2007, 09:45 PM

I was admiring the work that you did in reconstructing your strongback (view below) and that gave me ideas for mine. I would like to open up the inside much as you have done, but being very new to this and rather ignorant besides, I was wondering if you left that space open or if you reinforced and closed the bulkhead back to its original format? Would it be possible to leave it open like that? Could you include pictures of your finished product? I know I would enjoy seeing that.

ebb

02-12-2007, 05:31 AM

Peter,
We are outa luck here.
TonyG and Kurt are also opening up their interiors simularly.
Can't remember right now if any Ariels are sailing with this idea put to the test.

The span is less than 4'. Even less with the legs holding it up. My replacement for the original is laminated white oak of slightly larger section.
With a select piece of airdry, I'm certain a similar arch could be bandsawed out of timber just like the original with NO loss in strength. In 338 the strongback is epoxied to the bulkhead across the top (which supplies zero strength) and the white oak legs are lapped with the beam and epoxied to the bulkhead going down to the V-berth top (which supplies some strength and a lot of stability. imco)

AND no deflection. It is impossible to imagine any load that would deflect the arch. Any push down by the mast and rig to straighten the arch would have to push the sides out. Can't see that happening. The legs coming down from the ends of the strongback, imco, have to distribute the load to the hull, another strong curved structure. The V'berth structure at the remaining bulkhead is considerably beefed up in 338. I think I stacked at least two more 'ends' of 3/4" plywood inside the V'berth spaces under the struts to support them AND to distribute the load to the hull. So it's about 3" thick there now. The struts are well supported. Theory.

What the Factory has there to support the mast these 40 year has been discussed here. I have my theorys about the problems we have and what a solution is.

On pg16 #234, I asked whether a compass arch would be even stronger. I was looking for more side room for bunking. And decided that the arch showed there would intrude into our limited space. But noone could have an arguement against the shape for strength. A smaller compass radius strongback that would fit up into the trunk and bear on a point directly under the mast would be the strongest possible. Kurt has a definite arguement with that. I did not make a doorply model for that shape but it would be interesting to see how it relates to that opening into the V-berth. It's been done with other small boats and sometimes makes a pleasing keyhole shape.

I've continued the bulkhead across the bottom of what used to be that doorway, creating a 'floor' or load bearing area across the keel. Lot of stuff going on here in 338 -the cabin sole ends, super-gooped pvc pipe scuppers go thru on way to bilge, the step up into the V-berth stateroom, and the bilge tank ends there. It's pretty solid by extending the V-berth sole 3 or 4 inches onto the cabin sole with solidwood floors under the mast above.
and JUST IN CASE, a center pole support can now be installed to take the rigging load directly to the keel from the strongback.

Sorry about no action or photos. Wish I was CRUISING!!!:o

epiphany

05-04-2007, 04:12 AM

Ian Nicolson describes a great and very affordable way to do a compression post in his book titled "Build Your Own Sailboat". The post would be easily removable, if you wanted, so you could keep that lovely span, Ebb.

Take two pieces of angle iron, same length, make holes a few inches apart in them as if you were going to bolt them together on one side. These will be set onto the floors under the mast running fore and aft, wide enough apart to accomodate the post. With the post in place, bolts are slipped in ahead of and behind the post, and wooden chocks are used to take up any space between the bolts and the post (My thoughts: one could easily make the holes just far enough apart to obviate the need for the wooden chock blocks, and or have a piece made custom to fit the bottom of the post that wouldn't allow it any movement).

On the upper end of the post are threads, and a cap which screws down onto the post. The cap has 3 holes drilled into it; 2 directly across from each other near the end, and one slightly below the other two which is threaded to take a bolt.

Put the post into place, stick a rod or screwdriver into the two cap holes and use it as a lever with which to screw the cap up to the underside of the mast foot/pad/deck. Once it is adjusted properly, put a bolt into the threaded hole and tighten it to prevent the cap from screwing down accidentally (loosening the post).

Simple, effective, affordable, and easily doable with common pipe and fittings, I believe. The pipe could be blasted and painted w/a tough epoxy paint, or a sleeve could be made out of the same cloth as the interior finishings, and zipped around the pipe to make it esthetically pleasing.

I've been trying to think of drawbacks, but none have come to mind as yet.

One other thing I can see in the above picture which I would not have noticed if I hadn't seen the same on Craig's "Faith" just a few days ago - the longitudinal stringers on both your boat and Craigs are mounted much lower than the ones on my Ariel. From the pic, yours are about midway up the opening in the forward bulkhead, where mine are approx 2/3 the way up. I will put a measurer on mine and see where they lie exactly in relation to the deck, but a ballpark guess would put them 3-4" higher up the hull than are yours and Craigs. Since my boat was made near the end of production (#422), and information about these boats is mostly lost in the mists of time, I'll always wonder if this was a Carl-specified change, or just something which came about due to the decision of some laborer in the factory... Remember that mine was also missing diagonal supports on the main bulkhead, much to the chagrin of my compression beam. :)

And another edit: Your stringers run forward of the fore bulkhead all the way to the bow it looks like, where mine start/stop just aft of it.

ebb

05-04-2007, 07:53 PM

Kurt, Ian's tip is a good one, too.

Critique. Caps and pipe threading, not many turns. A coupling might provide a bit more length. Maybe threads could be deepened with more turns of thread doing the work of holding the roof up. The opposing thread of the coupling could be cut off. IE the coupling cut in half.
The coupling has a 'flat' top. You'd have to have a plate on top to take the rim when you are tightening against the wooden beam. And this plate could have a stud or some washers welded on it to hold the coupling and the pipe exactly in place when it's screwed up in compression.

Imagine the torque that post would take with a human swinging around on it.

The bottom of the post could be handled in the same way. The plate on the Ariel might turn out to be a convenient piece of larger angle supported over the keel and cut to fit the angle of the hull sides like a floor. I would hold it back from the hull a little. The horizontal flange would have the post connect ie the pipe inserted over some welded on washers. The vertical face of the angle could be for the bolts holding it in place. No bolt heads or angle iron on top. The post would appear to be floating.

I would probably cheat the compression post in place by jacking the beam with a bottle jack. You know, just put everything eggzactly where you want it while the jack has the pressure. Do again to get it purrfec. I'd see if you even need a coupling extension with the bottlejack. Tremendous pressure can be achieved with a jack. Might just cut all the parts to fit and slip em in place.

Galvanizing is the best coating you can put on steel. Galvanizing is cheap and sometimes they will take pity on the poor sailor bringing in his precious handmade stuff and put it in a bucket with another job. You'd also be galvanizing your new compression post INSIDE as well.
__________________________________________________ _____________________________________________
Interesting observation on the stringers. Location may be a trick of camera angles. The stringers in 338 were what the shelves rested on. Guess that their place on the Ariel hull is pretty much similar. Couple inches up or down?
338's stringers appeared to be jammed into place and slapped on with matt. They are for the most part crooked and not even parallel with the sheer as they could be.
I just decided to let them be. But added more stringer completely to the bow and all the way to the end of the cockpit. Added to make them appear like they came factory. Think the stringer going toward the bow sloped up some because it looked better.
The stringers, of course, are not level with the waterline.

My feeling at the time was to even the loads on the hull and I didn't feel that the stringers should just stop where it was convenient for Everett. What you see are stringers going clear to the bow. While they are stiffening members they are also stress points, so I have also radiused the corners with fillets. Argueable if any of this is really necessary, but I feel better that the boat is more symetrical, if that is the word.

I see settees and berths and other tabbed-in furniture providing longitudinal strength like the stringers. More so, because they are web frames providing immense stiffning.
I feel that these lines should be extended wherever possible in a remodel to elimnate hard points.

ebb

05-04-2007, 08:54 PM

About this compression post thing.
I think the post should be designed as a single (welded) piece that is bolted thru well fitted flanges to the beam and the floor. There should be no way that it could come apart.

There could a scenario where the boat is thrown on its side and the compression post be popped out of its seats. Pipe over flat washers as in the example previously. Possible. Could think that the compression post is holding the cabin up as well as holding it together.

Maybe this is a simpler solution: If the overhead beam is wide enough for an actual pipe flange (so named) which is a common pipe threaded fitting usually with chamfered holes for screws already drilled, one of those at each end of the pipe to widen the point load and hold it in place. They come threaded for pipe or unthreaded like tube fittings. Various collar heights and amount of thread. You use the cheap threaded ones, using that bottle jack to positively hold open the distance between beam and floor, the pipe would be micro fitted by tightening or loosening the flanges. Then welded to set the length of the post and close the seams and lock-in the flanges. Making it a single piece. Then galvanized, have to zinc the threads and fill the crevises.

Have to decided for yerself if the screws you put thru the flanges into wood are enough. The post is going to get yanked on, screws in sheer, so it's probably good. imco

This structure is simple - allowing positive fastening - and easy removal.;)
Careful cranking on that jack. Don't want to distort anything. It's an extra hand.

epiphany

05-05-2007, 04:39 AM

Ahh - I see what you mean about using a pice of angle as a floor - good idea. Maybe of Titanium, so no corrosion worries. ;D Seriously tho - galvanized, bedded in and coated with epoxy - the galvy finish wouldn't ever need replacing, right? So sealed it wouldn't corrode, couldn't wear off, and would be good basically forever - or am I missing something?

Whaddabout you put the coupling in the *middle* of the post, and lengthen/adjust the post just like you do a turnbuckle? :)

Ian's book mentions having a socket for the top of the pole to sit in - like you, I would want that plenty deep enough to know it isn't going to pop out of place if everything was going crazy. Especially if everything was going crazy...

Question for you, since you've done it already: Regarding evening up the gap twixt the house and the liner @ portlights - I was looking thru McMasterCarr website, wondering if some of their pre-made FRP slab could be put into place with epoxy to make it a uniform thickness. Would doing so maybe be easier/quicker than the method you used with thick paste? If so, what thickness would be needed, IYO? Thx. :)

epiphany

05-05-2007, 04:42 AM

Slow wireless... my apologies...

kendall

09-30-2008, 11:51 AM

The beam in 198 has a very slight bow in it, barely noticeable when eyeballed, and less than an eighth inch at the corners when measured with a straight edge, is that enough to worry about or should I do some refurb on it?

Did search, but while info on swapping and re-enforcing it was abundant, I couldn't find anything to indicate what was acceptable.

Also, are replacement lenses available for the stern light? mine has everything but the lense itself, looked at the other lights, and it's the same style (hemisphere about 1-1.25" diameter) the light's in good shape except for the missing lense so would prefer finding a lense if possible.

Thanks
Ken.

Bill

09-30-2008, 01:38 PM

Search on "strongback" for answers. Manual has complete discussion.

Sea Dog makes 1" replacement globes that fit the Pearson hardware. Plastic, however, not glass. Cheap, so you can purchase extras . . . :rolleyes:

ebb

09-30-2008, 02:21 PM

Hope that 'Bill Ariel 231' will post here. He is more practical and less wordy than I.

The support beam has a bow in it, of course, that more or less conforms to the curve of the coach roof. The support beam supports the composite fiberglass/balsa laminate that the mast step and mast sits on.

I believe that over time there is natural settling and shrinking that happens even though the wood of the beam is still in good condition. If you have opening across the top it may merely be a condition of age. Even bad original fitting that has opened even more.

Test the beam for soft spots especially in the center. If you have rot, that is a more complicated problem. It's another diagnosis. A repair such as described below cannot be fudged on a rotton beam. Replacement.
Check the curve of the roof outside to see if the mast rigging has pulled the mast into the roof any. Flattened it.
Because the navigation wires (used to) go into the interior through a hole under the hollow of the mast, rain water may have rotted the balsa under the mast-step in the composite. Check the roof if there is a slightly more localized depression. Needs to be fixed.
The coach roof should have a fair curve to it. Anything else requires a change in plan.

If you are lucky to have the mast sitting on a nice round cabin roof without any flattening (you may be the first!) then you can go about finding a way to fill the narrow space between the beam and the coach roof inside.

When you decide to go full monte on this fix, you remove the deck mast step by taking out the two 1/4" (#16) bronze flat-head lags that clamp it to the beam inside. Could be problem. When mine came out on 338 the cabin roof nearly returned to its original molded curve. And the narrow space inside opened up considerably more.

Pearson fudged the fit when assembling the Ariel as they used the mast support beam to clamp in the forward end of the cabin liner. That means that any fix cannot be attempted from the cabin - but from the V-berth area. It also supposes that the beam didn't fit quite as snug as it was supposed to. The beam may be tight against the liner on plywood bulkhead side but not quite so tight on the V-berth side.

You cannot fix the space problem with the mast rigged and pushing down on the roof. You can fix it when you RETURN THE COACH ROOF TO ITS ORIGINAL MOLDED CURVE by temporarily relieving all the pressures on it. The mast has to be taken down.

The coach roof has some rounded dimensions that isn't really compatible with flat carpentry.
Look at the problem with a few options in mind. You could for example bandsaw and shape to fit a single piece of wood that you glue into the space. That's the best way.

One uncommon way to consider.
Clean, scrape and remove paint, silicone snot, fillers that are in and around the space. You are working from the V-berth side. And you are deciding what you can do that will keep the roof totally supported.

I have had success using wood filler pieces and epoxy mishmash (laminating epoxy, fumed silica as thickener, and 1/4" chopped fiberglass strand) a kind of hairy pudding.
Wet the inside area with plain mixed epoxy and wipe it up best you can. Use terry toweling pieces stapled to thin battens. Get this 'primer/bond coat' dry as you can after wetting so that your mishmash won't mix with it and loosen and sag out of the joint.
Slide your wood filler pieces in slathered with gobs of pudding. You will have done a dry run so you know they fit good and where. The more wood, the less expensive glue. Longer pieces might even add a little strength to the beam.
Make sure you are stuffing the cavity all across the top.* You may be using some shim/wedges to get a tired coach roof to curve back properly - no forcing - you don't want to put anything under tension here - it will pull apart later - just enough.
I would shim the coach up using the beam in the center if necessary. Or prop the coach roof fair next to the beam with some 1X2 or 2X2 from the berth or sole. They'll be in the way, tho.
You might have a special shim or two that can be left epoxied in there. Use durable woods like fir and mahogany. Don't leave anything sticking out.
Once it's gooped and filled, take paper towels and remove any squeeze out and runs.
Clean up with alcohol so that there is minimal sanding prep for the next step.
This is a quick and dirty fix that allows the carpentry to be kept in place. It will only work if your diagnoses was correct.
Assumes that your beam and bulkhead are in good shape. That the composite under the mast is also OK. And the mast step itself.
It can be done this way, but I don't really recommend it. I would do a classic reconstruction if warrented - and do it right.
__________________________________________________ ________________________________________
* To control the extent of epoxy being pushed into and through the joint (the juices may run down the cabin side of the beam and bond the cabin door trim )- use cheap polyethylene foam 'backer rod' from your concrete store in the back of the space (seen from the V-berth). It isn't hard rod, it's soft yet firm foam you can stuff into tight places to create a dam. When you push in the wood filler pieces, you want the epoxy pudding to kind of billow out. There's going to be a little waste.
__________________________________________________ ________________________________________

BUT it's hard to know exactly what you got there without some photos. Good luck.

bill@ariel231

09-30-2008, 05:15 PM

Ken

I agree photos would help here. It sounds like a couple things may be going on here. I recommend a through check of the beam, the columns that support it and the deck core directly below the mast step.

Beam: is the beam compressed in the middle where it has been drilled out for fasteners and wiring? (mine was) Is it compressed where it crosses the columns at the passageway? It is supported by roughly a 2x2 at that point. Are there any tell tale fractures across the grain in either area? The only way to tell is to grind off the paint to see. If the beam has a small depression where it meets the column (or none), and there are no cracks and no rot then Ebb’s epoxy fix will work just fine.

If there are cracks or signs of Rot… reach for the Sawzall. The Beam is held in place with 3 to 4 wood screws (port and stbd) installed from the cabin side (hidden by the formica). I elected to cut them flush on the vee berth side. Making a new beam is easy if you have a band saw, not much harder with a recip saw and an angle grinder. If there is any doubt about the beam, it is worth the piece of mind to change it. Although the deck beam doesn’t look like it can take it, the design load for the mast step is often a high fraction of the boat’s displacement. (refer to Brian Toss’ book for the test case at 45 degrees heel on a boat’s standing rigging). In Periwinkle’s case (A-231) the beam had both rot and a fracture in the middle of the beam. The replacement was a white oak beam glued up from two planks, rough cut to a paper template of the old beam and trimmed to fit with a grinder. My replacement beam is now screwed in place with wood screws thru the bulkhead at the original factory location. Installation of the beam followed Ebb’s suggestion with the beam buttered in thickened epoxy before final assembly. One alteration I made from the factory install was to relocate the mast wiring to a tube on the stbd side of the mast mast step. After fabricating a new mast beam I couldn’t bring myself to drill a big hole in the middle of it for a wire chase.

Columns: Compression at the top is possible, but I haven’t seen it or any photo’s of pearson tritons and ariels with that symptom. See if there is any rot top or bottom that might indicate the column and the bulkhead moving down. This would be bad but again there is easy access on the vee-berth side to affect a repair.

Deck: While you are there, make sure the deck under the mast step doesn’t need to be recored. I’ve pulled my mast step twice. Once for the restoration and again when the deck core under the mast step failed. I believe the deck directly under the mast step should be solid ‘glass (or at least plywood). The original Balsa on mine was both crushed and wet when I opened the deck after 4 years of service. No issues since replacing the core with glass for a couple inches around the mast step. I recommend checking the deck core while all of this work is in progress because this is an easy extra step while the mast step is out.

Good luck
bill@ariel231
:)

ebb

10-01-2008, 06:48 AM

Right on Bill!

Shouldn't have to add anything except to emphasize this: Remember, there are four things that could be happening to the support beam.

1) It could have contracted rot through the electric wire hole and can no longer hold its curved shape. (338's beam was bandsawn white oak and showed no rot.) White oak doesn't like to rot.

2) The composite sandwich of the molded roof could be deteriorating because the core balsa is rotting from water entering the same wire hole. It compresses under the mast when there is no support inside.

3) The wood parts all together may have 'settled' and moved a little over the decades.
[This was 338's main problem when first tackled. I thought the beam had gone bad - but when taken out was perfectly OK] The composite core had some deterioration but imco the actual problem was the mast's irresistible force down on the beam and the beam not able to keep its original position.
Forensics conclude that since NONE of the parts (beam, angled braces that terminate on the V-berth tops, doorway framing) were glued to the plywood bulkhead but just mechanically screwed on... it all over time had gotten tired making it easy for the mast to compress it. While the mast contributes constant pressure, I'd guess that sailing the boat compounds the downward pressures.
The bulkhead upon which the strongback system is dependent is only 3/4" exterior fir plywood* that is tabbed to the boat ONLY at the hull under the deck. The whole top with the significant doorway cutout is free to move.
(With the exception of the two lags that hold the step in place that go through the deck into the top of the beam. And maybe the uppers' chain plates held by the deck!)

4) Constant downward pressure of the mast and step on the coach roof causes the beam to deflect, or to appear to deflect. The white oak beam is only 4 feet long - and if it's healthy no way in hell or high water will it flex. You might find deterioration of the fir plywood right next to it but the beam will be fine. (This is a guess -ANYTHING is possible.)
The round wood laminated step outside might also be deteriorating.
338's is still going strong.

Problems seen at the beam inside (the trim of the doorway sagging is common) could be one or a combination of these symptoms. Examine the parts and with what other Ariel skippers have found figure out what might be going on.

Imco if you are going to really fix this common aging problem you have to make sure that the coach roof under the mast can never deflect, never flatten, and always keep its original molded shape.
As Bill suggests all the interior structure under the mast should be renovated into a monocoque, a glued and screwed structure with the bulkhead tabbed everywhere, all round, to the boat. (Naturally, you won't tab onto the cabin liner!)
The upper shrouds thru-deck chainplates would also benefit from a more secure bulkhead. The ply where the uppers' chainplates come thru the deck no doubt is also deteriorating from water leaking in. Check this also.

__________________________________________________ __________________________________________
DOUBLE BULKHEAD idea for the traditional interior.
* A better structure would be to add another 3/4" ply bulkhead to the V-berth side of the beam and braces. Make it into a kind of a boxed truss. The all important 'compression' beam would then be supported on both sides and transformed into a true bridge.
Instead of it all cantilevered off the one wall - which is the problem.

Movement of all structural pieces would be locked forever between the bulkheads and all downward force from the mast taken evenly to the hull by both bulkheads. NOTHING COULD MOVE. The mast load would have a wider 'point load' spread on the hull - where a single loaded bulkhead often deforms a glass hull. It's the hull that takes all of the mast load.
Could scroll openings into the new bulkhead (maybe now even both) to gain back some lost space and keep closed areas ventilated.

This begs the question: why go to the trouble adding a whole bulkhead when a large one piece GUSSET that spans the whole doorway on the V-berth side MIGHT get the stiffness and immobility needed?
The original Pearson SO-CALLED bulkhead that the compression beam is sort of attached to is actually in THREE pieces: the two major pieces on either side of the doorway and a FILLER piece over the door that the door trim hides.**

(This is another unacceptable (imco) cheat on the part of Pearson because it don't add a MODICUM of support for the mast beam.)
It would have been much more shippy if the doorway had been top rounded like the Brits did in the Contessa 26 creating more truss and panel support for the beam. But then the carpentry trim and the door would have been beyond the capabilities of Pearson carpenters - would have had to be out-sourced and added another $200 to the price of an Ariel.

Instead of a complete second bulkhead:
Adding a crosspiece that goes completely across & down a little ways ( or even to the V-berths) is something to consider. Especially if you are racing your Ariel. Also if the bulkhead is being redone by, say, the removal of the disgusting imitation wood formica on the accommodation side - a cross TIE of plywood or mahogany across the top could be added on this side as well that would provide extra support for the beam. Glue and screw.

After the space above the beam has been addressed and filled or shimmed, adding a one piece gusset over the door in the V-berth that fits the coach-roof curve AND a side to side cross-tie in the cabin would stabilize the compression problem imco.

[It's my opinion that a metal strap across the top of the doorway does not fully solve the compression beam sagging problem.]
Point is
there are any number of fixes possible.

Even for a completely altered interior:
1) Water intrusion HAS to be fixed.
2) Rot has to be removed and fixed. Especially in the composite. It's pretty easy. 338 now is solid stitched mat and epoxy instead of balsa.
3) Coachroof must be full rounded, fully restored or fully upgraded.
It gets tremendous strength by being a true arch. If flattened, stress is concentrated right under the mast instead of the point load being spread to the curve of the arch. The beam inside is meant to preserve the coach-roof arc. The mast load should be held by the whole beam - not just the middle.
Wires should probably exit the side of the mast a half a foot or more above the deck and enter the interior thru one or more thru-deck glands near the mast. Thru-holes from the mast interior should be sealed off. It's no place for a hole because there is no access to a problem there.
OK, got carried away again!!!!! Apologies:o

I AM just throwing logs on the fire for discussion.
Wouldn't it be great if a concensus could be reached here?
that would provide an easy, satisfying and strong fix that ANYBODY with a new Ariel could use to repair the MAST SUPPORT BEAM PROBLEM./././
__________________________________________________ ___________________________________________
**This major fumble was left out of Everett's biography.:rolleyes:

Bill

10-01-2008, 09:16 AM

This thread will be merged with the strongback thread tonight.

kendall

10-01-2008, 09:28 AM

Appreciate the info, I'll get some pics today.
The bow is a very slight downward bend, not to the curvature of the roof. No space above it, it sits flat against the coachroof, also can't detect any rot, and the wiring comes up on deck beside the mast, not through the beam.

I'm in construction and do a lot of post and beam building and reconstruction, Kept wanting to call it a lintel, but knew that wasn't the nautical term.....

Ken.

kendall

10-06-2008, 05:15 PM

Good news, the downward bow was all in some trim he had wrapped the strongback in, spent an afternoon peeling the trim off, Put the square up while it was out and found it was nearly perfect.

bill@ariel231

10-06-2008, 06:28 PM

that is good news... on to the next project :)

commanderpete

10-07-2008, 05:43 AM

I found out the Sea Dog clear replacement lens (model 4000121-1) does NOT fit. Too big.

http://www.defender.com/product.jsp?path=-1|17|295769|320403&id=64846

This guy is supposed to sell replacement fixtures and globes. Not in the catalog. I haven't called him yet

http://www.bronzeblocks.com/

Commander227

12-09-2008, 11:04 AM

The Commander has a compression post under the mast that transfers the load right to the keel. Only a knuckle head would want to change a strong and fool proof design like that!

I'm kinda a knuckle head.

In an attempt to create a roomy, private head with easy access I want to remove the compression post and put in a strongback, full bulkheads and a door like the Ariel. looking at the Ariel drawings I don't see how the load is carried to the keel. It appears that the bulkhead is relied on to carry and disperse the load. It looks like there is a vertical support on either side of the doorway, but I don't see anything under it. does it just terminate at the sole?
The manual (pg 23)shows diagonal supports, but does not show how they terminate on the lower end. Is there any additional structure not pictured in the drawings?

ebb

12-09-2008, 12:25 PM

C'227,
Nice to see those two compared in drawings with each other like that. Thanks.

You are correct on all points.
I've gone on about this subject adnauseum elsewhere. But suffice to say that in the Ariel the bulkhead is part of the mast support system. There are the two posts that define the doorway - they go down to the hull above the turn of the bilge (screwed to the plywood bulkhead.)
There are two cross braces on the Vberth side also screwed to the bulkhead that terminate on the Vberth plywood tops. And two more vertical braces that support the end of compression beam at the coachroof sides - also terminating on the Vberth. Across the top the compression beam is also screwed to the bulkhead. And held in place thru the top by two bronze #14s or #16s coming thru the mast pad, thru the composite deck, and into the beam.* All structural wood was white oak.

The plywood bulkhead in A338 is really two halves with a filler across the top of the doorway and a filler across at the step up into the V-berth stateroom. There is no work done by either of these fillers. (FYI A338 has since been remodeled to remove the doorway.)

The plywood "bulkhead" is tabbed to the hull ONLY
and not to the under deck or the coachroof sides or overhead.
Only the hull. And not across where one might expect a 'floor' to be in a wood boat - per your question.
Originally the space between the bulkhead and the liner was stuffed with a factory supplied fabric covered foam tape.

The compression beam load is ultimately taken to the hull via the half bulkheads (let's call them) on either side of the doorway. The compression beam is not supported in the center between the door posts. The door posts therefore are dual compression posts if you look at it that way. But they bear on the hull incidentally. In an upgrade a wider bearing pad would be cut in under these posts.
__________________________________________________ ____________________________________
*ANY upgrade or remodel imco, if you are working from the original Pearson model,
should have all dimensional wood members GLUED and screwed to the plywood at the very least.
But the Pearson model is very flawed.

bill@ariel231

12-09-2008, 01:54 PM

A couple of points from an A-231 perspective:

"The manual (pg 23)shows diagonal supports, but does not show how they terminate on the lower end. Is there any additional structure not pictured in the drawings? "

Construction detail from A-231: A-231's diagonals terminate at the surface of the vee berth.

"The plywood "bulkhead" is tabbed to the hull ONLY and not to the under deck or the coachroof sides or overhead."

Construction detail from A-231: the original mast beam was buttered to the overhead with thicked polyester (the ubiquitous blue stuff). I did the same with thickened epoxy when i replaced the beam.

Scott Galloway

05-25-2009, 10:19 PM

As a result of a bridge vs. mast accident resulting from a crew malfunction related to tabernacle operations in 2004 I needed to do some repairs to my mast base support system on my 1965 Pearson Ariel. For a more detailed discussion of this repair with photo documentation, please see my Ariel web page:

http://www.solopublications.com/sailarir.htm

Although like many other Ariel owners, I wanted my main bulkhead to be a strong as possible, it is worthy of note that after forty years of successive owners riding a Pearson Ariel hard and putting it away wet caused no visible deformation of the strong back as of the autumn of 2004.

I removed the Formica on the aft side of the strong back and sanded both sides of the strongback. I chased a few cracks and voids, but those led led me to workmanship and assembly issues that resulted during construction forty years ago when my boat was built.

I filled a few voids and strengthened a few areas. The bulkhead and strong back have served three owners well over the years. My somewhat destructive examination continued to show virtually no bulkhead damage Both professionals with whom I consulted did not feel that through bolting steel plates on either side of the strong back would be the best solution to strengthening the mast support system. In my boat there was no evidence of sagging in the strong back.

Once the teak doorframe was removed, it was apparent that the horizontal beam above the door was level. One of the vertical frame members was actually vertical, but the other is not, so that the door opening is a lopsided trapezoid. Since the plywood opening is cut this way and there is no separation from the hull on either side or underneath, I must conclude that this “as built”, rather than “as failed”.

Although the Main-salon-side plywood bulkhead panel was not glassed to the cabin liner, I could see over this panel to what appears to be a glassed seam between the strong back and the deck. This seam was solid and there was no indication of sagging or separation. The area above the plywood on the Main Salon side of the bulkhead looked fresh and solid. I came to the same conclusion by looking at the seam between the strong back and the underside of the deck from the V Berth side. Removal of the paint from the strong back confirmed that conclusion.

The cracks that I chased and the voids that I discovered were probably left by the builders (the failure to wet out tabs holding key braces in place, voids in the fiberglass, (the use of AC plywood with significant internal voids, etc.). So I would have to say that my boat might have been both hastily built, but it was also overbuilt. The Pearson Ariel is sort of like a Sherman tank built by the low bidder. This is one strong boat, albeit one built somewhat strangely in places.

Because it is conventional wisdom to strengthen the strong back, I contracted for reinforcement by a professional. My contractor installed unidirectional cloth and triaxial cloth. This was glassed onto the bulkhead and strong back in a sufficient number of layers to reinforce the strong back/bulkhead without drilling holes through it or installing steel reinforcement plates as have been used on some Ariels. This solution provided for the strong back to be glassed to the underside of the deck forward of the bulkhead and to the cabin liner aft of the bulkhead. When repairing the top deck, the new top laminate, bottom laminate, core, and cabin liner were reconstructed as an integral unit. Thus the strong back, cabin liner and deck now function as an integral unit. Thus there is no longer a void above the plywood section of the main bulkhead on the main salon side. This void was originally filled by that strange foamy wire-reinforced trim piece. That piece was glued into the void above the plywood. Those little wires are sharp and hard to remove.

The longer bolts in the mast base that had been inserted in the foreword two holes were seriously bent as a result of the mast vs. bridge accident. The bolt holes for these bolt were directly above and ran through the stong back. They penetrated the strong back directly above the doorframe. Their securing nuts were captive inside the beam. Inspection holes were provided by the manufacturer in the bottom of the beam. Those holes were drilled completely through the teak door fame as well. The beam prevented the lower portion of the bolts from bending. In the accident, the bolts were pulled upward. The bends in the bolts occurred at the very top of the bolts. The angle of the force of the impact pulled the longer forward bolts upward, and the shorter aft bolts downward as the mast step plate rotated aftwards into the deck upon impact with the bridge. This effectively crushed the deck beneath the mast step. This entire area was rebuilt as an integral unit, and the forward boltholes were relocated.

The cabin liner in the main salon was obviously distressed as can be seen in the images on my above referenced web page. Less severe distress was evident in the forward salon, but some cracking in the lower laminate occurred.

The shorter bolts were driven down through the cabin liner causing the liner to crack and shatter.

The cracks in the bottom laminate were removed by grinding, as was the paint on the central section of the strong back.

Multiple layers of vinyl ester resin and fabric were added to the damaged area and to the strong back to tie the deck section to and reinforce the strong back. Again there was no damage to the strong back due either to the accident or to cumulative stress to this area.

The application of glass to both sides of the strong back and to the deck sections forward and aft of the strong back created a very strong integral structure to support the mast.

The strong back area (both sides and bottom) was reinforced with multiple layers of vinyl ester saturated fabric including unidirectional cloth and x mat.

The lamination extending from the cabin liner aft of the bulkhead around the strong back to the lower deck laminate in the V Berth area is continuous and seamless. The seam between the remaining Formica and the original gelcoat cabin liner and deck section was sealed with 3M 5200 and topped with a bead of 3M 5200.

I know that all of the above is counter to the prevailing discussion on this page. My point in adding this post is to indicate to those who may be interested that solutions are available other than the removal of their strong backs or installing often unsightly and always conspicuous steel plates on the bulkhead. The choice is a matter of approach to solving a real or assumed need to strengthen the mast support system. Regardless of what is done to this area, the cored deck section beneath the mast as installed is a vulnerable area for compression. Creating an integral unit (deck, cabin liner, and strongback) in my opinion solves this problem.

ebb

05-26-2009, 07:30 AM

GREAT forensics, Scott.
Love this kind of attention we give the ole girls.

Those extra laminations sound like a real good solution to making the whole strongback/bulkhead and mastload area as rigid and immovable as possible.

Think of you as in the restoration camp of Ariel upgrades. You are careful to honor the original intent of the designer/architect....whot's his name?

Many owners will want to see photos of your work. I know I'd like to see how the glassing went.
And the final result!

[Ebb has his caveats:
All rain water intrusions from the deck thru the repair area have to be completely sealed, ie bolts, screws, chainplates, electrical holes.
There should be no standing fresh water possible inside the mast. Don't want any water getting inside the new skin.

It sounds like you had the beam incorporated into the new interior skin reinforcement.
If you have an original oak strongback and it is now covered you might get away with it because of its age.
New oak won't accept regular polyester imco. I haven't worked with epoxy modified polyester.
But, as you know, if you laminated over everything (ply bulkhead - strongback - overhead) you are now getting the whole area into sharing the support of the mast load.

For DIYs: Styrene is a dangerous volatile component of vinylester. You ought to wear an appropriate canister mask for interior work and keep the boat clear of heavier-than-air fumes with forced air.
Imco vinylester should only be used by pros.
The right epoxy is much more user friendly and does a better job of gluing dissimilar materials together.

It must have been a difficult job of work - especially the prep and overhead work - and all the corners that had to be turned with wet Xmatt - would like a peek.]

Scott Galloway

05-26-2009, 03:13 PM

Ebb,

Thanks for the comments. I am definately in the restoration camp, but I am also in the "publish all approaches to commonly shared problems" camp. A multiplicity of approaches is what keeps this site interesting. Fortunately Ariel owners tend to stay that way for awhile, so we can all check back in later to see how some of these innovative ideas and retrofit solutions work and whether or not they hold up over time. I am eager to see your boat splash down. You have incorporated a number of innovative features in your Ariel. I look forward to reading about your sea trials, etc.

Peeks are easy. Just come down to Santa Cruz for a sail. As for photos of the repair, I referred above to my Ariel Structural retrofit page:

http://www.solopublications.com/sailarir.htm

There are photos aplenty there of this specific issue and other retrofit work I did in 2004. Most of what I did was restoration-oriented rather than redesign-oriented. One thing I didn't do that I would do if I had the mast off the boat again (and I am not eager to do that again) would be to put a tricolor LED light at the masthead. I didn't want the weight of a traditional tricolor light and weight of the requisite traditional wiring that high up the mast.

As to the hard work of building an integral void-less structural unit from my existing (undamaged) oak strong back, the deck, and the cabin liner beneath the mast step, the design and execution of that task was done under contract in my slip here in Santa Cruz by a professional who used vinyl ester resin and all sorts of modern glass fabric as described above to complete the job. So no polyester resin was used. Epoxy has its merits, and I have used it on other projects, but gelcoat doesn't stick to epoxy.

I was fortunate to have insurance coverage to cover the repair of the accident damage in this case and a skilled professional friend who was willing to take on the repair job on my little boat. This repair and new standing rigging were provided under contract. In the end I believe that my boat is now stronger than it was when it was built, and certainly it is stronger than it was before the accident. All other work on the restoration of my Ariel both in and out of water I did personally over the period 2001 to 2004.

And in the spirit of innovation, I have also documented my development of a sheet-to-tiller self-steering system for my Ariel on the following web page:

http://www.solopublications.com/sailariq.htm

That page, completed in 2005, has full documentation of the concept, design and execution with many photos of the self-steering gears working under sail. The design and application of the self steering gears on that page are based on the pioneering work of John Letcher as documented in his book, Self Steering for Sailing Craft International Marine Publishing Company, 1974; and some sketches and suggestions included in Tony Heisel's book, A Manual of Single Handed Sailing Arco Publishing Inc., 1981. I also relied heavily on the on-line resources including the pages produced by John Ward and Al Gunther.

I single hand a lot, and the Ariel Self-steering gears that I developed have greatly increased my range and endurance under sail. Certainly they have increased my enjoyment and comfort.

ebb

05-26-2009, 04:12 PM

Scott,
By the way GELCOAT does stick to EPOXY.

The epoxy must be carefully measured and mixed. Must be fully cured. Must be NO BLUSH.
My specs would say: 100% solids - 1 to 1 or 1 to 2 parts premium epoxy, so that there is no solvent out gassing to mess with the polyester.
Then it should be sanded with 60 grit.

Gelcoat will stick to epoxy.
But why would you want to use gelcoat over perfectly good epoxy?:rolleyes:

Scott Galloway

05-26-2009, 09:22 PM

Well you must mix up a better batch of epoxy that I ever have. Also my recollection is that I have read in some marine publication that the bond between epoxy and gelcoat is not a secure one. Can't say that I recall where I read that exactly. The previous owner of my boat drilled a few holes and filled them with epoxy. Gelcoat stuck to that for awhile. I removed a spinnaker pole holder and filled those holes with epoxy as well and ditto for the failure of those bonds in time.

I mixed my batches of epoxy as per the West System's instructions. All of the epoxy that I have covered with gelcoat was cured and sanded before the application of the gelcoat, but I have no idea at this point what the ratio of resin to catalyst was, since that was a number of years ago. The epoxied areas were very small in relation to the areas to which I applied the gelcoat. If it works for you, that's cool, but my few experiences with gelcoat to epoxy bonds have not been 100% positive.

The reason that I use gelcoat is that my boat has, as did all Ariels, a gelcoat skin on top of the fiberglass deck molding. I applied a new coat of gelcoat in several areas where the original coat was worn or where holes had been drilled and filled, or where stress or impact cracks were evident. I like gelcoat. It's pretty stuff if you apply it correctly, and it looks and lasts better than LPU. As to epoxy being a safe product to use, the safety of all marine products in my opinion is a matter of mythology, unless of course you are applying steamed white rice to nori, in which case only the raw fish that you apply afterwards is potentially toxic.

ebb

05-27-2009, 07:18 AM

It's a bit of a trick. When a polyester/glass boat gets laminated they spray gelcoat into the female mold and after partial set continue with the layers of glass and plastic. Can be said that the gelcoat in this case has a CHEMICAL bond with the laminate.

In the case of most repair, restoration, or new added work, gelcoat is the last layer. Most will distinguish this type of layering as MECHANICAL. And the gelcoat is going on as a coating. That's why a DIY looks for the most versatile product that is made for the job. I have heard that cured polyester can be 'softened' with styrene or acetone to help get a 'chemical' bond with a new polyester layer. That would include polyester gelcoat, I guess. Who wants to get into that!!??

We can think of ANY layer or coating as only achieving 'mechanical' bond - like a primer coat or finish paint. These days the most common and probably the best primer/sealers are epoxy based: single or two part, solvent or waterborne. A modern gelcoat product no doubt takes that into account. Paints and coatings can be almost any formulation these days including polyester. The epoxy undercoat usually sticks better and seals and neutralizes surfaces better.

Used on the exterior: gelcoat will protect UV sensitive epoxy. Gelcoat won't stick as good as epoxy, so prep is important.
These days every coating is modified one way or another: powder coating is done with modified polyester that produces good adhesion as a long lasting baked-on coating - usually on metal.

carl291

05-28-2009, 03:43 PM

Sometimes I wonder if making one area super stiff (strong back area) is wise in a vessel that is constantly flexing and subject to so many outside forces.
My judgment is based on a tractor trailer truck that I had lenghtened the frame 30 " to install a larger sleeper. The frame rails cross members were C shaped steel, in my wisdom for improvement I used square tubing for extra support. This move stiffened the frame but after a period the truck suffered from cracked frame rails before and after the square cross members. After two attempts at repair that failed, I decided to go back and use the C shaped crossmembers, at this point I never had another frame fracture. What I learned from this was every componet has to work (move) together. Granted frame rails are parallell and the curvature of a hull and deck by nature spreads out a loading force
After 50 years of sailing, these boats are still floating, I don't thnk there has been any reports of a mast pushing through the deck on an Ariel or a Commander mast pushing through the keel.
I may be ignorant on boat construction but I would think short of total interior reconstruction (ie. Ebb) repairing water damage and worker screw ups and short cuts, the Alberg design is pretty sound, even when confronting bridges.
Hey, I'm just saying:D

ebb

05-29-2009, 07:54 AM

Carl, this is a great point for discussion.
On boats I think naval architects and engineers are still out to lunch on the subject. Look at the constant breakdowns of the sleds in the Volvo Ocean Race and the repairs modern frp boats have to their hulls and decks.

I think FLEX came down to us from wooden boats, which are but bundles of mechanically connected pieces. Might say that the massively built clipper ships were very flexible - and while that may have saved them in heavy going - it may also have numbered their days.

I see the mighty oak vs the flexible sapling metaphor - but not sure how that relates to our A/Cs. Anything I propose comes from observation and reading, no formal training.

BUT, I think our boats have survived BECAUSE they were overbuilt and because they are STIFF.
We have exceptionally full and fair curves in the hull with no flats. The deck/cockpit mold also has curves in the flat appearing sections. As you know Ariels and Commanders have a pasted together BUTT JOINED DECK TO HULL SEAM. I don't know about other Pearson's of the time, but we might be the only class of boat that was put together this way. Lighter buillt engineered (chinsy) boats have serious problems with their hull to deck join - even if flanged, glued and screwed together.

And yet this seam which was pierced with screws from the s.s half round trim has never had an issue of actually coming apart. And I think that is because the boat AS A TORSION BEAM does not twist much. Given imco the seemingly casual way the bulkheads were put in this is pretty amazing.
I could be very wrong obviously. Somebody with a sailing Ariel can check this out by tying two lengths of string in an X from corner to corner in the cabin. If the tension is about even you might test any twist to the boat when close hauled by observing if one string or the other sags on a point sail.

Assuming this is a valid test, right? The boat might get more bent punching through heavy seas.

Because our four decade old boats began life in the beginning of the FIBERGLASS revolution Pearson got away with things modern boats have learned not to do. Engineers still push the envelope - usually for speed, and they don't ever think longevity.
While modern boats still manage to forget: stringers should never just stop but continue to the bow and stern. (Not done in the Ariel.)
Bulkheads (which are what helps keep a glass boat from twisting) should be attached to the hull and deck top-bottom-sides. (Not done in the Ariel.)
Bulkheads should not bear on the hull or deck without spreading the point load with wide fillets and tabbing. Thinner hulled modern boats float bulkheads
and attach them only from the sides - like a C-channel.

Carl, is your arguement that the funky way our boats were put together actually is the reason they lasted so long?

Even the A/C "over-built" hull showed the stress points. I know I found them when I faired the topsides prior to painting. The brown fairing compound in minor depressions on the old white gelcoat made a topo map of interior structures influencing the hull laminate.

I believe it is the nature of monocque construction to attain its integrity from having a stiff skin. Except maybe for ferro and steel the concept in fiberglass has its problems. Maybe a talented designer like C.A. takes that into account so that flex is factored into a plastic sailboat. The interior structure would take that into account.
But for the tabbing in of the accommodation settees and berths, I don't see that either the designer or manufacturer paid particular attention to hull-flex in my Ariel.

Ebb is certainly on record here concerning the support system under the mast.
I believe any flex here was due to corner-cutting and selling price. There cannot be flex here!

Don't know really to what extent the pros went to inside Scott's Ariel to tie the compression beam to the deck and to the bulkhead. In my mind's eye I see what I would have done. I believe the mast foundation should not move, ever. Any flex should certainly be in the rig. And setting up tensions in the rig would benefit hugely from an immovable base. We are talking about this single bulkhead. To spread the mast point load the cabin arch it stands on cannot be compromised. So arguably preserving that arch by almost any means is the right thing to do.

Now, Ebb, doing what he did: taking out most of this extremely important bearing and anti-torsion bulkhead, may be really asking for trouble. I'm depending on the overbuilt hull (which turns out in this later built hull, A338, is not so over-built) to stay out of trouble. Taking out the bulkhead and introducing FLEX could be my monkey. I'm tabbing in ALL my furniture, and call these panels: web frames. I feel that enough of them will nearly cancel out the torsion flex of the hull. Could be wrong. Like you say, Carl, trying to cancel out the natural flex of a fiberglass boat could be not only wrong but impossible.

On this score, I believe the lead ballast should be immobilized in the keel. That amount of weight concentrated in that one area in a relatively thin skinned vessel could out flex the innate stiffness of the monoque concept.

I've witnessed a couple earthquakes here in California.
I sat through one with a cup of tea in hand, actually enjoying the time of day and the landscape. I saw EVERYTHING in or on the landscape turn into waves: the solid ground, the porch I was sitting on, the house, the trees. Everything became plastic or liquid. Can't recall if the cup in my hand had the wave going through it.

Why couldn't a similar thing happen to a sailboat. Who's to say unknown vibrations can't happen to a vessel in water? So engineering gibberish and web frames will mean nothing when the boat turns to rubber. And it all becomes a wave form, including the skipper.

carl291

05-29-2009, 12:59 PM

Carl, is your argument that the funky way our boats were put together actually is the reason they lasted so long?

I hadn't thought of it in that manner, but, yes to a degree. In my introductory work on 259, I find no part of the boat where the workmanship stands out as skilled joinery. The balsa under the mast step was a mistake but look how long that lasted! The cabin door is missing on 259 ,may have started to drag and was removed. When I check the squareness of the opening, it was still square.
Creating a super stiff section with no flex I don't think lessens the force, I would think it transfers the force and maybe even multiplys it to the weaker non-reinforced area, at least in the case of the truck frame.
Not having bulkheads fit perfectly to the hull and glued solidly helped to eliminate hard spots in the hull.
To look at any part of the construction of these great boats and say not done good enough really has been proved wrong by time. IMHO
Can you think of anything built in the 60's that has been used, abused and neglected and still be brought back to as good or better than new for less than the original purchase without adjusting for inflation?;)

kendall

05-29-2009, 01:21 PM

I think a lot of the reason the doors are removed is because they make the interior feel smaller.
When I first looked at my triton, both doors were open and it felt pretty spacious, after cleaning it out enough to close the doors, it just seemed to feel a lot smaller.

198 doesn't have the door either, so I don't have any real experience. Though when I was working inside, I moved everything into the v-berth, and draped a sheet over the doorway, which made it feel much smaller.
What I'd like to do is open the doorway up a bit, which I feel would make it seem larger.
To do that though I think I'd have to go with a more robust strongback, and after having both my son in laws stand and bounce on the deck above the strongback,(400+lbs) with no detectable deformation, it seems sturdy enough that I don't want to mess with it just for cosmetics.

Ken.

ebb

09-12-2009, 07:17 AM

Been trying to see some progress in the A338 interior. (hopefully some pics in the Gallery soon)
So the anti-compression beam/struts and old ply glued in some time ago came into focus again.
What remaining of the original ply bulkhead: the pieces across the top that match the section of the beam and the skinnied down struts that terminate on the V-berth with the skinny remains of old ply have finally been mechanically connected with 24 #14 s.s. phillipshead screws. These are 316 flathead sheetmetal screws - meaning that the shank of the screw is like a straight lag - not tapered like wood screws. These 1/4" screws are indeed lags. (McMasterCarr.)

Worked out great. Since I was screwing into oak the pilothole could be tweeked a little wider so that the fastening was driven (with the Hitachi hammer drill) without fear of breaking. I'm wondering what kind of sheetmetal these screws would normally be used for?
BTW, would never use 316 screws in an exposed situation. Only bronze or monel should be used in oak. Wet oak eats iron for breakfast.

As back up for the laminated oak beam I choose 3/8" silicon bronze carriage bolts (Jamestown) with the bolthead inside and the nut buried in the deck composite. Drilled in 7 of these bolts along the length.

Began with a 1/4" hole drilled completely through.
Used a 1 3/4" holesaw to cut through the top into the balsa. The little lid popped off easy enough exposing the dry tunafish.
A 1/2" chisel quickly (almost TOO easily!!!) evacuated the wood. Used the same chisel to undercut the surrounding balsa. Put a tiny chunk of 1/4" dowel in the hole.
Then dumped two-part epoxy into the holes. Gratified to see very little liquid get absorbed and mopped it out with papertowels.
Refilled the holes with mishmash and came back later with the little PorterCable beltsander and knocked the hockypucks flat.
Then redrill the 1/4" hole.
Took a Bosch 1 1/8" flat bit with a large screw pilot. This sort of thing will want to take charge and pull the bit into the work. But I was using the screw thingy to center the bit in the hole - and bored down into the new puck enough to take a washer and a jamnut - together only 1/4" in depth. Plus a skoch for the fill to cover.

I'm going down today to the boat where I will drill the hole out to 3/8". I think I will prepare the square recess in the oak, knock the bolt thru, screw on the nut and see if the Fein tool* can pare the end of the bolt off right on top of the nut.
I'll refill the remaining hole with mishmash. let it set (hope the epoxy makes up for the skinny nut), dish it out a bit with the grinder and top it with a little circle of 6oz glass.
Then fair. Should be relatively seamless and never show up in the future.:o

The main reason for the bolts is that I don't trust epoxy used to laminate the beam. The bolts are not parallel to each other as each was drilled in perpendicular to the curve of the beam. In itself that's pretty strong - even if fastening through the deck, as described, is questionable.

Seems like the structure is locked.
Pity the poor sap what has to take this apart in the future!
If there is ever any question about the beam, it certainly seems possible to add an aluminum plate to the V-berth side of the beam. The plate would be cut to the exact shape of the beam and the coachroof.. Since the load is at right angle to any fastening, they could copy the same 'sheetmetal' screw as above with the plate also glued on with rubber adhesive, isolating the screws as well.
Driving screws into the thin oak laminations, therefore keep the screws relatively short.
If I were doing this again I would cut the beam out of solid white oak like the original. Could vertically laminate together thinner planks and thru-bolt.

AND as FRANK DURANT sez the beam could be vertically cut out of MERANTI HYDROTEC BS-1088 sheet and glued together (TiteBond III?). Could be curve laminated also, I guess. Since solid oak has no short grain like the cross layers in ply, I would definitely make the cross section of a meranti glue-up heftier than the oak dimensions.
BTW, only this plywood - NO OTHER, NO FIR, NO BIRCH - can be used for this purpose. imco

Hope this is useful.
__________________________________________________ _________________________________________
*Fein tool not so fine. Did nothing on the bolt ends. You can take a Fein to metal, but you can't make it cut.
I got a rant on this tool we'll save for later. Put a little flex cutoff blade in the Makita grinder and cut the bronze bolt ends like it was banana.

Commander 147

01-26-2010, 06:02 AM

I have been a woodworker for a long time and one of the magazines I like the best is Fine Woodworking. When I started doing my research for the correct glue to use on white oak I naturally went to Fine Woodworking to see what they had to say. Thought the article I found would possibly be of interest here so here is the link.

http://www.titebond.com/Download/pdf/HowStrongisYourGlue_FWW.pdf

ebb

01-26-2010, 07:39 AM

BUT FOR DISCUSSION let me throw in some things that imco have to be taken into account for woodwork on a boat.

NEVER USE AN "INTERIOR GLUE" ON A BOAT.

White Oak in lamination cannot be glued with any glue used in the Fine Woodworking test.
Titebond 3 so far as I know has not been tested for white oak bent laminations glued up under tension. Nor in a wet/dry cyclic boat environment.
I have HEARD for years that boatbuilders ("conventional wisdom") will not use any yellow glue because it will eventually creep because it is hygroscopic in the damp. The FW test is primarily for wood joints that will live in a fine moisture controlled frufru situation.
A glaring omission from the FW test is water resistant plastic resin glue you catalyzed with water. It has a long open time, requires clamping, and has almost no glue line. Commercial tillers use it.

Titebond 3 (not yellow but grey) seems to be a different animal, but will need testing for veneer laminations and other wood-to-wood gluing in damp.
The conventional test for glues used for wood-to-wood bonding is a four hour boil test!
There is only one glue that survives this test 100% and that is Resorcinol. This glue requires milled surfaces and pressure clamping, no gap filling, THAT I have always taken to mean very light sanding to deglaze surfaces.
Gorilla Glue has no place on a boat. I have witnessed a number of failures used for furniture. While epoxy is a glue, polyurethane* is not!

I have had my own failure with T-88, and wrote extensively here about my experience with it. My conclusion is that the best off the shelf 2-part STRUCTURAL EPOXY ("tropical wood") is made by Smith & Co.
I have used this glue for white oak laminations (untested) and noticed some starved joints. Imco it is very difficult to squeeze this product out of a clamped joint, BUT it seems to be possible and therefor is not used for bent in form lams.
I have some suggestions which have been reiterated elsewhere. Imco no trustworthy lamination can be made with ANY glue on white oak. Except Resorcinol.
And it may be that the oak must be pre-treated/de-natured to remove tannins.

I epoxy-laminated a white oak beam for A338. I put an epoxy saturated layer of fiberglass between each piece of oak in an attempt to not starve the joints. I also attempted to remove tannin oils with solvent and roughly scoured the faces with 40grit. Years now later I see some tiny separations appearing and decided to bolt the whole damn thing together - which I've described in the Gallery.
I'll always worry about it. Wood will ALWAYS move in a cyclic environment. In my case I have isolated the wood pieces with a hard non-moving material. Doesn't really work. So you see what happens using Resorcinol - there is NO glue joint. Can only describe the phenomenon as a chemical bond - rather than a secondary mechanical bond provided by ALL the other stickums.
WITHOUT QUESTION, it would be much better to bandsaw a new strongback out of solid white oak timber!!!

Ultimately, the best bond/attachment is always made with bolts and screws.
Maybe we should see glue as only in a support role for metal fastenings and as a caulk to keep moisture out of seams.

For wood-to-wood furniture work on the boat my gut feeling is that Titebond 3 can be used.
It is easy to use, there's no mixing, it's water cleanup, and hardly a glue line. Mahogany and fir and plywood, conventional joints like the open joints used in the FW test. Only an assumption.
Would like to see anecdotal evidence on this. [EG, what did Larry Pardey use for the extensive interior woodwork in Tallesin?]

For attaching wood to fiberglass there is also no 'boil test' guarantee that you will get bonding. Therefor fillets and tabbing must be used. And that has to be done with epoxy. Could say this method is an attempt to OVERPOWER the wood.:D
__________________________________________________ _______________________________
*Polyurethane tube rubber is another discussion.

Ariel 109

01-26-2010, 12:22 PM

If a wood joint stood a chance of being exposed to constant dampness I don't think I would use anything but an epoxy or resorcinol, as much as I like Tite-Bond III. But cycling between wet and dry states will ultimately destroy any joint, regardless of the glue. We all know that maintaining the varnish or paint helps things last.

Resorcinol has a funny taste if I remember.

ebb

01-26-2010, 01:19 PM

Resorcinol has the track record and is the only glue that will take extremes of wet and dry, heat and cold.
Epoxy has very limited exposure outside and has been known to disintegrate even if maintained. See the renovations that had to be done to all those traditional finished cruisers from 20/30 years ago - especially anchor platforms and bowsprits.
Epoxy glue is an interior glue! It can't take heat (it softens) and can't take cycling because it doesn't move. If you seriously have to keep exposed wood together, there's definitely 5200.

Tony G

01-26-2010, 02:21 PM

So, er, uh, what are you guys sayin' here? My mast beam is going to fall apart? I haven't noticed anything coming undone voluntarily yet. Is 'yet' the operative word in the works here? Crimony! I guess Ebb's lead in holding the beam together is a fix I could apply easy enough, but, I'd rather think it wasn't necessary...crud. Oh well, one step forward and you know the rest.

Ariel 109

01-26-2010, 03:12 PM

Resorcinol's rap is that of being harder to work with than epoxy. You can be sloppier with epoxy. Garden variety epoxies may have some trouble with UV and high temperatures but are tested as being stronger than resorcinol. And there are epoxies that perform well at higher temperatures. What are they making the new Boeing 787 from?

I agree that the best strong back is a band-sawed piece of solid white oak. Preferably from an old gnarly hanging tree.

Ben

ebb

01-27-2010, 08:46 AM

Well,
Resorcinol is a wood specific 'bonder'.
If you were gluing exterior mahogany rails up from strips and scarf joints there is no other glue. When you glue coaming blocks and winch islands up with epoxy you will have separation at some point. And as I just said if you have an epoxy glue-up like a bowsprit and/or teak anchor roller they are guaranteed to come apart. I don't know how long it'll take, but the more heat and wet/dry cycles they experience the sooner they will come apart.

I'm talking about pieces of wood brought together into a structure.
Epoxy IS definitely more versatile. You can glue wood together and seal it with the same epoxy. You can fill gaps and fillet, you can laminate fiberglass onto wood and foam panels with the same stuff. You could probably do a barrier coat on the hull with it. But, by definition, you only achieve a mechanical bond.
I hesitate to use that term here as the adhesion is mechanical but not a BOND. There is no comparing here with Resorcinol which can only glue flat pieces of wood together FOREVER. It has a bad rap because of its short open time and need for high clamping and controlled temp.

If I had been more comfortable with Resorcinol I might have done A-338's strongback lamination with it. I felt I couldn't do it within the short open time required.

It is entirely possible to put together a new rudder for the Ariel/Commander with foam and glass OR plywood and glass using good epoxy. There is always the chance that the epoxy can separate from the wood or the foam.
You have to take this into account when designing the rudder. But this is not gluing wood-to-wood. The whole intent is to encapsulate the wood - and it sometimes doesn't work. Exposed, varnished wood swells and shrinks. Epoxy glue-line is more or less non-shrink and hard. Wood wins.

If you had to glue wood-to-wood together for underwater use (like the original non-encapsulated rudder) Nobody would spec epoxy. It's possible to butcher-block and pre-bond pieces together into 'planks' with Resorcinol for cutting the shape and use polyurethane or polyether for gluing/caulking edge to edge planks. Most people these days would then SEAL the wood with a thinned epoxy, then attempt to waterproof with a polyurethane coating (or whatever new comes down the everchanging chemical pike.) Or go right to bottom paint. Imco that's conventional wisdom.

In every case epoxy must be protected with another coating. Even a novolac needs UV protection. Pigmented epoxy coatings/paints will chalk and breakdown. There is no comparison with LPU coatings Even polyester coatings will outlast epoxy coatings. On those winch islands use a clear coating with the highest UV rating you can find. That'll help some.

The chemistry keeps changing. There are new combinations appearing: epoxy polyesters. epoxy urethanes and resorcinol epoxies, and ETC for both adhesives and coatings. Quite amazing.
But at the moment everyday epoxies that we buy really have limited use on the exterior of a cruising sailboat.

Please, I work with these assumptions on my Areil. If there are developments or stuff I've forgotten (more likely every day), please clue me and the boat in! We both depend on it.
The limited info about glues and coatings that I work with IS ALL conventional.
__________________________________________________ _____________________________________________
google>
Laminating white oak w/ Resorcinol - The WoodenBoat Forum
__________________________________________________ _____________________________________________
For unstressed gluing somebody by now must have tried using CLEAR polyether or a silyl-urethane. !NOT SILICONE! Also sold as Hybrid Sealant/adhesive.
This is a one-part, low odor, 100% solids, long life, moisture cured, always flexible synthetic rubber in a gun tube.
Worth experimenting - like gluing a stack of mahogany blocks together and boiling them for awhile!!!

Ariel 109

01-27-2010, 01:15 PM

Ebb

I really appreciate the time you put into your responses. The epoxy vs. resorcinol question is new to me. I understand what you're getting at. And I'll be sure to put 10 coats of Eplfanes on those blocks.

I think many people including myself get involved with these old boats thinking that with a little repair effort you can have some fun sailing for a few seasons before everything wears out. Of course once you get started and develop attachments to the project you want the dam thing to work right and last.

Ben

Commander 147

01-27-2010, 01:47 PM

It is REAL easy to get really attached to these boats and want to do the absolute best job you can bringing them up to better than new condition.

Furniture I've built since I could reach the top of a tablesaw. But doing the job right on a boat is a whole new learning curve. And thanks to this place I'm getting an education.

ebb

01-29-2010, 07:46 AM

google> Have epoxy adhesives improved recently - Sailing with Lin and Larry ...
www.landlpardey.com/Tips/2007/April.html

You can also find discussions on The WoodenBoat Forum
and the boat design forum.
The second site seems to be sat on by guys like me who dog onto every new post and subject. I have a problem with them because what they say, often with something off color, is hearsay and somebody else's opinion - not even their own. They're comedians. And always NOT funny. I don't go there anymore.
The WoodenBoat Forum seems more sane. Inquiries are often by first timers so the experts who answer are likely to be basic and simple.

On the designforum you will find those who put Larry down - for whatever reason.
Larry at one point took at least one epoxy manufacturer to task for making false claims about the product. You no longer will find data sheets that say the epoxy is waterproof. Or stable in a cruising environment.

Lin and Larry have built their own sailboats and taken them around the world. Larry is an amazing observer. With tens of thousands of cruising miles in wooden boats I'll take his prejudice on glues for gospel. They have received recognition and awards (for their convictions and courage I expect.)
I listen to them and ignore the jealous marina rats who can only put them down.

Both Resorcinol and epoxy have their limitations.
The first because it is a technical glue.
And epoxy because its versatility lulls people into ignoring its limits.
__________________________________________________ ____________________________________
We all labor with what we know - what we think we know - what we would like to know - with modern chemistry and with traditional ways of thinking and working, I don't believe any thread with prejudices and opinion is convincing.

So try this one on for size and follow it through to the end. It's on the www.woodenboat.com forum. And this is a "flog the dead horse" subject for many of these guys. This thread has a bunch of boat builders and amateurs talking about this subject. Not all the bases are covered but the thread is revealing and will help you come to an understanding of the problem.
google: White Oak glued with Epoxy, PL, Gorilla Glue, Resorcinal The....
(incluide the resorcinal (sic) misspelling.)
The thread begins with "few 3" post

Commander 147

01-29-2010, 07:59 AM

My resorcinal will show up here Monday from Jamestown. ;)

jan nikolajsen

03-29-2010, 08:58 PM

The mast beam on my soon paid for A-273 shows no immediate signs of deterioration, but I thought a fun project on an otherwise quiet late afternoon would be to make a door way arch to further strengthen an already strong little ship. This contraption will be bolted on to the vertical members of the doorway, with the ends resting on cut-off pieces of trim. It will also be jacked up snug against the beam, with just a short bronze rod to index it.

It is made of ash, 17 laminations, and measures 1 5/8 square. Should have been one more layer, but when it was all clamped up I saw number 18 lying over in the firewood pile.. It will lower the headroom in the doorway, but at 6'3" I'm already crawling around in there.

So, what's the glue? The big question, right? Subject of many discussions here and elsewhere. Well, contrary to other folks experiences (friends and internet experts) I used Gorilla Glue. Why? Wanted to do this thing right now and besides epoxy it was all I had. Living 65 miles from the nearest city limits your spontaneity.

Since it is strictly not necessary it can acts as an experiment for Gorilla glue without dire consequences.

It will be shellac'ed.

My son did the tops'l schooner (at least that's what he calls it) when he was 9.

http://www.fivenineclimber.com/images/boats/ariel/arch.jpg

Tony G

03-30-2010, 07:46 AM

Jan

Nice arc! That will look 'shippy' in place. Heck, looks nice just sitting there. Do you have any other plans fro changes aboard?

Commander 147

07-11-2010, 10:54 AM

As I have mentioned before I plan to remove my commander compression post and replace it with a strongback. So today I started reading some of the prior posts to determine the demensions I should aim for on the strongback. Then I started measuring my commander and it seems that there are some differances between the the two boats in the amount of curvature of the deck unless I'm missing something else.

The drawing on page 23 of the manual shows the bottom of the strongback as a straight line from one side of the cabin to the other (or so I assume since the full width is not shown).

ebb said that his original strongback was 4-1/4" tall in the middle and tapering to 2-1/2" tall at the ends and 2-3/4" thick. If ebb's original was straight accross the bottom, that would indicate there was only 1-3/4" of camber from the edge of the cabin to the center.

ephifany said his original was only 3-3/4" tall in the middle but from the picture his does not look like it was flat on the bottom. So I may be making an assumption I should not.

In any case, I have 4" of camber in my deck. I placed a straight edge accross the cabin touching the bottom of the deck on each end and in the middle I had a rise of 4". So I will not be making my strongback straight across the bottom. If I want to end up someplace in the 2" thick area on the ends that means it would extend down 6" in the center. That is a bit much IMHO.

Below is a sketch of the approx. layout I'm looking to do. I plan to make it from 3ea. 4/4 boards of white oak laminated together vertically with resorcinol which will give me approx 2-3/4" thickness. I will butter the top of the strongback prior to putting it in place with thickened epoxy and then tab it to the deck and the bulkhead supporting it which will also be tabbed to the hull and deck. And of course I will have white oak bracing on the v-birth side which will be covered with 1/4' mahogany plywood as will the aft side of the bulkhead.

Any suggestions or comments about the plan?

ebb

07-12-2010, 07:19 AM

Jerry, Just took another look at the old strongback that came out of A338.
It isn't straight across on the bottom as you might think because of the doorway to the forward stateroom. The original door was cased.
In fact the top liner of the opening is often the first indication that something is going on under the mast.

So the strong back definitely looks curved top and bottom - until I sighted along the bottom and saw that the mid part had been flattened (looks like with an AX) obviouisly to square the doorway.

I laminated my 'upgrade' and later decided that it would have been BETTER and SIMPLER to bandsaw the beam out of white oak. And so easy to make the slight chamfer along the top to snug the cabin top.

Commander's have a COMPRESSION POST.
My guess is that the fiberglass of the cabintop can be kept honest with a plain curved beam top and bottom. In other words I think you can skinny the beam depth as long as you still support the center with a post. I might make the beam a little WIDER - to make up for the cheat.

The beam on the Ariel is 4' long.
Not much to get bent even with a point load in the center.
In fact, bet there never has been an actual bent beam in any of our boats.
Yesterday's Alberg Assoc breakfast there was talk of the Triton's beam getting pressed down and the cabin sides getting pushed out!!! Could see the bulging! That just wouldn't happen with our cabins.

Making sure our shortie is married to the cabin top will imco cancel the remotest possibility of that happening in a Commander.

I'd make certain the center post cannot move.
Actually you could scroll into the beam a PAD in the center over the post, to fatten the beam there if you want to skinny it down. You'd do this all at the bandsaw, right? no gluing in anything extra.
That would remove any tendency to bend. In other words, leave the beam deep in the center but scroll out the sides to remove head bangers. Really round the edges, someone's going to head the beam anyway!

In a modern 'engineered' mast compression POST set up they'd probably just have a disk of some material under the mast - with no beam at all!!!!

Commander 147

07-12-2010, 07:50 AM

ebb thanks for the feedback. I'm always interested to hear what you have to say.

So the bottoms were curved also. That explains a lot about the dimensions.

ebb, you may have missed that my whole reason for doing the mast beam is to eliminate the compression post. The unsupported portion of the beam in the center will actually be less than 2 foot wide when my mod is complete.

BTW the Precison line of sailboats made here in Florida are current production models with mast support beams that are made with plywood laminated together and then glassed to the bottom side of the deck. They have only a small portion of the beams ends supported by a plywood bulkhead that is just screwed to the beam. You can see it a little bit in the picture of my old Precision 18.

ebb

07-12-2010, 08:27 AM

Sorry Jerry,
assume is the mother of all foul ups.
The key still is we can have nothing move under the mast.
And each of us has our own unique solution it seems when we stray from the box.

I love the sweet lines of the Commander.
The curve of the cabin roof is particularly pleasing.

Maybe, maybe it's possible to design a kind of 'break water across the cabin under the mast.
Have the beam outside.
If it wasn't a breakwater but a rounded slope sided and gel-coated mound it might just disappear and not mess with the lines.

c_amos

06-23-2014, 04:48 AM

In discussing sailing Ariel Spirt, one of the possibilities was the idea of sailing her to Puerto Rico. As I considered what I would want to do before undertaking such a journey, the thing that came to mind first was to address the strong back.

I like the idea of the stainless plate sandwich, but getting the stainless bar and having it polished before getting underway was not going to work. I like the earlier post about using large aluminum angle, but hate hitting my head on the doorframe.

Add to that Ariel Spirit has the original bright work trim around the door, which I would not want to mess with that.

Used 5, 5/16" stainless carriage bolts with the smooth sides and stainless fender washers on the cabin side. Not a bad look, and very strong.

I like the angle because the extra angle will prevent the bar from trying to twist. The difference in what I did was that I put the "extra" bit on top. I a very pleased with the way it came out, will post a couple pictures later.

Just learned the person in NC that was buying the boat is going in another direction, so I am getting underway in a bit to sail the ~140 nm across the big bend... Glad to have addressed this before heading off shore.

c_amos

06-23-2014, 04:56 AM

View from the cabin side;
http://i124.photobucket.com/albums/p23/SailingFaith/f91c1deb11d0ca9248f40fe4636a79ee_zpsbd5aea23.jpg
(Also visible is the replacement plate from Bristol bronze).

View from the V-berth...

http://i124.photobucket.com/albums/p23/SailingFaith/2a243cf04a327d47c8afb36d4f766d1d_zps108aed0a.jpg

ebb

06-23-2014, 07:04 AM

Craig, Looks right on, the AL angle, great idea.

Don't forget the cabin laminate has a balsa core on top.
Ended up cutting something like a 1'X1' square of A338's cabin top out and replacing it with solid layup of glass.
The original mast electrics hole had invited rain water in which caused balsa rot. Balsa did not rot in the '60s.
Whose idea was it to put balsa under the mast?:rolleyes:

Discovered this with the mast removed and springing a batton over the top. Could see the top was flattened.
But also, later discovered that the damaged composit had sprung back almost to its original curve.
The cabin top was crushed mostly just under the maststep where the core had rotted.
Inside, could see that the strongback had a space over its top - with the mast removed - and the composite returning to its original curve.

Found that all Pearson support framing on the bulkhead was only screwed together.
My theory was, and still is, that, along with the shrouds pulling the mast into the boat over time,
the factory support framing (which was NOT glued in) also had settled, SHRUNK, if you will, over time.
The white oak beam I took out of A338 was in original condition....NO ROT....STILL CURVED....NOT FLATTENED in any way.
And I still have it somewhere in the garage to prove it.

Pearson used the strongback also to squeeze and hold the forward part of the cabin liner in place.
So on the V-berth side of the beam there was wider space between it and the cabin laminate because no liner inside.
And Pearson, had slipped in some sort of funky shim pieces to make up the difference. Not wedging, just filler.
But, like I say, the beam had air along the top. The 4' beam is also bandsawed square, while the cabin top is angled.
They had also, in A338, misalined the liner when assembling, and the interface was a really wierd mess to look at.
Not really knowing what was going on when trying to figure it out the first time - too funky to believe.
Have to conclude the assembly was never tight to begin with.
But over time Ariel has proven to be forgiving, anyway!

Think everything in the beginning was loose as a goose. But cinched up bent out of shape by the shrouds over decades.
Cabin top is thick laminate and a pronounced curve. Not easy to flatten.
Most A/C's are only sailed seasonally and on weekends, sit unused in marinas, they rest alot, and don't see much bluewater.
I found nothing positive with the B-grade plywood bulkhead*-oak beam-and fir framing stuff to keep the mast from flattening the cabin.
If the core is not rotten, then, perhaps all that is needed are well shaped shimes or wedges tapped in along the top of the strongback.
*the plywood 'bulkheading' across the doorway was a separate piece, a space filler doing no work.

CONSIDER THIS....If I remember, the vertical 2X framing at the V-berth doorway - SEEMS to support the strongback beam - but stops on top of the V-berths.
Just the mahogany trim goes down to the step......
Could say the V-berths themselves (some cleats & plywood tabbed on one side to the hull) and a few wood screws are really what is holding the mast up.
In fact, that's what Pearson did in A338.
So again. in my opinion, quick-n-dirty mechanical construction...... just settling over time.
[Admit I've gotten bent out of shape with Pearson's half-way measures.... on what they sent out from the factory as a coastal cruiser.]

Imco, the aluminum angle will help stabilize the inward pressure of the mast.
But you still may find the shrouds loosening with passage sailing. Hopefully not!
.................................................. .................................................. .................................................. ........................................

Sorry for the repetition of 'my thing' - found in many earlier posts. For me,
MORC (Pearson designated: Midget Ocean Racer Cruiser) sounds more like a goblin... than a pretty Alberg sloop.

ebb

09-10-2021, 09:39 AM

9/10/2021
A couple of observations from the future. Please excuse repetitions!

In short, my laminated beam across the cabin has no other support
except for the overbuilt gussets at the chainplates at the center shroud.
I laid in a substantial floor (Cross piece timber) at the step up into the
front cabin. Which in Litlgull no longer exists because the bulkhead
is removed (forward as a 'crash bulkhead').

I recorded the height from the floor timber to the bottom of the
laminated beam. But then I read that the tanins in white oak may react
with the resorcinol.. So I thru-bolted the whole thing to the cabin top
with bronze carriage bolts. Measured the height with mast and rig and
found barely 1/8" less. Seems OK. The unitized laminate, bolted and
glued up-graded deck (balsa replaced with solid frp), immovably supports
the mast with all its active downward pressure. We'll see! And, just in
case, a compression post, like the Commander's, could easily slip in
between the cross-floor and the cross-beam.
Someone here pointed out a pole in the middle of the accommodation
isn't a bad thing -- you use it to swing around or just as a steady-hold in
an often very active little ship..

That's A338. Our discussion here finds that the problem with the strong
back is not rot but the settling of the dry fitted pieces under rig pressure
over time.

For those skippers restoring their Ariels, I would suggest removing the
main bulkhead. Put in a substantial floor across the bottom at and as the
step up. Block the crossbeam into its final position if it's in good shape.*
Might GLUE it to the cabin top with rubber cement (4200). Then reframe
the passage way with substantial posts to support the venerable beam.
Thus we have the hull and cross-floor supporting the strongback. Finish
the bulkhead in an interesting plywood of your choice. Doorway can be
kept open with a privacy curtain for air circulation.
*May have to return the mast-DECK to its original curve with a jack -- and
repair any balsa-rot. If I remember the balsa is 3/8". Remove the deck
laminate carefully. Replace rot with glass mat and glue the deck back on.

Hope this still holds true: You cannot find a better marine plywood to
sheathe the bulkhead than BS1088 Meranti. It is made with phillipine-like
mahoganies and bonded under high pressure with phenolic glue. The
veneers are knotless thruout, panel is flawless and deadflat. Could get
by with the 6mm but 9mm will allow left overs for shelves and such. Easy
to varnish or paint.

This will provide all necessary support for the beam and rig overhead
forever. IMCO