Keel base dimensions

[Frenna]

In modifying a trailer to accept my new Commander, I need to figure out what the minimum width is that the keel will be able to sit in. I am planning to install a steel channel under it, and I want it to be able to offer some lateral support/keep the boat centered.

So if any of you have your boats out of the water and at hand, I would be very appreciative of the following information:

If we are talking about a channel with, say 3" high sides, what is the narrowest width that the keel will drop into. From my research it seems like the keel narrows down to about 9" at the widest point, but I cannot tell if the curvature at the base allows it to be even narrower, or if there is a flat area that is close to that entire width. I may add a bit to allow for adjustment and cushioning, but steel channel in the 8 inch range is readily available as scrap, wider such as 11" or 12" will be more challenging.

A good close up photo of the underside of the keel would also be great.

Thanks

[ebb]

Over the years working on the boat and referring to DRAWINGS in the Manual, I've come across many inaccuracies.
To start you off, port to starboard scale measure is 10 1/2" - presumably at the widest. The keel has very rounded section in the drawing, almost semi-circular. That makes the side radius about 5" along the bottom.
Don't remember that that is exactly the case.
From the drawing, there is 64" of horizontal (waterline) flat to the keel measured from the keel-post. (IE the cockpit seats and the settee inside are level with the bottom of the keel) Then the profile starts moving 'up' to become the front of the well rounded keel. Imco this area that is not quite flat should be included in the keel bottom 'cradle' Because that is where the fore-and-aft balance point of the boat is.

Perhaps using the most comfortable channel with 3" sides you could custom wood wedges so that when the boat is seated you'd get the keel snug. Not sure what would keep the wedges in place - maybe lagging in from the side of the channel, or a narrow ledge welded along the top of the sides would help keep the wedges in place.

I will be going down to the boat today or tomorrow I'll make up L-shaped pieces of cardboard and use them as a caliper to get that width. If I find the widest width point I'll measure it up from the keel-post.
It also computes that in the C channel strips could be welded in at the appropriate angles to the curve of the keel bottom. Some carpet would make it a very nice cradle. Could conceivably get a shallow dish-like shape that the keel would sit in so that it would not want to shift.
You'd have to lift the boat into it.
Or it could be a piece of channel that would be shifted into position then bolted into place through the trailer frame after the boat is where you want it and in jacks.
OR.....maybe padded rt angle pieces (instead of channel) could be arranged along the frame on either side so that they could be snugged to the keel and then bolted. That way you could adjust the boat to find the 'sweet spot' on the rig.


Just jabbering.....

[Rico]

Frenna,
Both C-155 and C-187 (and a couple other Ariels & Commanders I've seen) have a curved section at the bottom of the keel. There is not much of a flat brearing surface at the bottom.

The thickest part of the bottom of the keel (at the Bow) is around 9". I'm sure it varies a little from boat to boat. I made a PDF document that is downloadable listing a bunch of hull dimensions. See post #11 on the Mephisto Cat thread to download this document which is helpful in building / modifying a trailer or cradle. There are also some trailer pictures around that post.

The link to the thread follows:

http://www.pearsonariel.org/discussion/showthread.php?t=1552

You mention wanting to use a channel as a bearing surface, AND as a way to provide lateral stability. I would suggest that you use the channel UPSIDE DOWN which will give you a smooth a bearing surface (Small legs pointing downwards) with a piece of carpet covered lumber as a softer / higher friction surface. If I remember correctly, I used an 8" channel as described above.

You can use an alternate method of providing lateral stability to avoid chancing damage to the bottom of the keel. I have some lateral support pads on each side of the keel on my trailer for this purpose, but I've typically left them quite loose - 6"+ from actually touching the boat.

Having said this, I have never seen any movement at all of the boat in any direction... And I believe that If the boat did start moving, you'll likely have much bigger issues to worry about!

If the channel is narrow enough to actually provide lateral stability via the short 'legs', it will be tricky to load / unload the boat and a possible landing of the whole weight of the boat on the relatively sharp channel edge will damage the glass surrounding the keel. Such an arrangement also will force you to have a very precise pick onto the trailer, and it will be expensive in terms of travel-lift time. You already have a precision requirement regarding the ahead/astern position of the boat on the trailer in order to achieve the appropriate tongue weight...

[Frenna]

Thanks for all the info.

The channel upside down idea sounds good, but I have a lateral support just about under the center of balance of the boat, so I would have to cut the verticals to notch around it.

In my fantasy world the channel helps distribute a small amount of the dead weight to the laterals that are forward and aft of the balance one. (There are a total of 3 laterals on the trailer, but only the back 2 will be under the keel).

I am hoping to at least be able to launch directly from the trailer, and in my optimistic dreams, retrieve with the trailer too. In that case it would be nice to have some padded guides to force the keel into the channel so that it could not end up in the wrong place.

Unfortunately where I live in Puget Sound (Bainbridge Island, to be precise) we have a lot of sailboats and zero convenient travel lift facilities. There used to be nice little boat yard on the island, but the state ferry system took over the propert by imminent domain in order to enlarge the parking lot for the ferry maintenance yard. A waterfront parking lot. Unbelievable. After sept. 11 they added a chain link fence around the whole thing right to the edge of the bulkhead. So much for habitat.

Also, I am a notorious cheapskate, so avoiding travel lift time is a goal. I am calling this whole project "recessioneering". I want to do first quality work on the boat itself, but I am trying to be as cheap as possible on everything else, without ending up with a piece of junk, of course.

I got the trailer almost free in exchange for having to cut up and dispose of the power boat hulk that was sitting on it. Nice double axle galvanized trailer with surge brakes. No rust on it.

Rico, I have been making extensive use of your dimensions and the ariel line drawing in laying out the supports. The boat is still in the water, so I have to estimate the contact points by plotting on the lines drawing. The jack stand tops I am going to use should leave me enough adjustment for errors. I will post pictures when I get to welding.

Ebb, if you get a chance with that cardboard, or whatever it takes to get that dimension, I would be thrilled to have it.

[ebb]

3/10
Plan to get down to the boat today.

google> Five O'Clock Somewhere: How to Launch and Retrieve a Sailboat with...
itsfiveoclocksomewhere.blogspot.com.../how-to-launch-and-retrieve-sailboat.html

Launching a 2 1/2 ton keelboat from a trailer is a BIG DEAL. At least for someone like myself who hasn't done it, probably never, knock on wood!

This blog describes (without pics) how it's done. Back the trailer down the ramp, block the wheels, lower the tongue wheel, disengage the hitch, attach the winch cable, remove the chocks, chock the pickup truck which should have a 4-wheel drive option. Then winch the trailer into the water. Hopefully the ramp is in good shape. Hopefully you got depth.
The blog has a couple good tips (like having pvc pipe stanchions to locate the boat back onto the trailer) from readers who also have done it.

[Frenna]

Thanks for the line, Ebb.

I was not really considering the option seriously until I saw a couple retrieving a 3500 lb wooden sailboat with a Triad sailboat trailer and a little dinky pickup on one of the steepest ramps around.

I watched very carefully the entire process, which they say they do every year to get the boat out of the water for the rainy season and to do annual maintenance in the backyard.

The only hard part seemed to be getting it into position properly since the trailer is non-visible underwater, buth they had enough references and a strap made up which they hooked onto the rudder shoe while the boat was in the water. It was the exact length to hook onto the winch post, which fixes the boat over the trailer in the right spot. Then they dragged it up the ramp just enough to get some weigth on the trailer so they could adjust the jacks. Then they pulled it all the way out.

The trailer had a wheel wich supported the tongue end.

The only part I though was to flakey was the folding tongue extension they used to connect the trailer to their truck. It was made of a pair of 2x6's, but with just a half inch bolt connecting the tow lenghts. Wood can split suddenly under that kind of load, it should have been metal.

But it worked.

I am thinking of using the falling tide to retrieve, which moves nice and slow.

But maybe I will chicken out.

The city of Edmonds on the other side of the sound has a sling launcher which they offer to keep trailers out of the salt water. Only $26.00 round trip, good for 28 feet or 7000 lbs, but to get there I have to take the trailer on the ferry, which is about $68.00 each way due to the lenght. FOILED AGAIN.

I am hoping to make the tide a powerful ally in my cheapness campaign.

Oh, and the ramp I have in mind is a double with a floating finger pier in between, so I will not be hogging the ramp for hours. Gets little use anwyay.

Looking forward to the keel data.

-Frank

[carl291]

Frenna,
Please go to : gallery and search " Ariel 259 " scroll down on the first page and look at that trailer. If you need dimensions let me know I'm home today and get pull quick measurements. It is a float on trailer. Cheers Carl

[Frenna]

Ah, that looks a lot like what I am putting together. Can you tell me the width of the plank the keel sits on, and at the wides part of the keel, how much narrower is the keel than the plank.

The picture is great, it gives me a good feel for the shape of the keel bottom.

As you can now seen in the C231 thread, I did careen my boat, but the part I am interested was burried in gravel/sand when the water went away. At least I got the growth off most of the hull.

-Frank

[carl291]

The plank is 7 inches wide, the very bottom of the keel is very rounded and maybe a 2-3 inch wide strip sits on the board.
You can see the keel guide in the photo sets up about 15 inches, the angle iron upright is spaced 16 inches wide with a 2x4 on each side to inside of the upright. This gives you about 1.5 inch clearance on each side. I don't think you would want this any narrower.
Hope this helped, Carl

[ebb]

But I promise on a stack of Ariel/Commander Manuals that I will tomorrow!

I've been interested for awhile just where the fore and aft tipping point for these hulls is?
Using expanded to scale Alberg lines drawing on page 144 in the Manual, if I lay a straight edge along the bottom of the keel and measure up from that line to the LWL at the transom, I get 46".
Measuring up from the same keel line extension to the LWL at the bow, I get 40".
That means our 25'7" hull when sitting on its keel tips forward 6" OA. Therefor the LWL of furniture, like settees, cabin sole, cockpit seats also will be tilted forward when resting on the keel. By the way, Alberg notations on this 1961 drawing says the lead in the keel is 2300#. And it shows that about 1/2 the weight of the ballast is right where the hull starts going up to the stem. There is only about 5 1/2 feet of well rounded keel mostly in the back half of the boat to balance on.


Do you think it a good idea to have a jack on the stem when on the road?
It could also help keep the boat on its spot if you suddenly have to brake hard - with the boat still going forward!
Do think that the boat could pivot forward on its forefoot - altho I've never seen anything on this possibility.

By measure off my "scale" copy. Alberg shows the keel right where it radiuses under to dead bottom is 9" side to side. The siding gets wider going up - there are NO right angles anywhere on the A/C hull. From the drawing one cannot make the assumption that there is any flat to the bottom, the bottom is imco a compass round section. Except of course where it starts to narrow at the forefoot and rises to become the stem. Alberg has a second notation at the forefoot, where the keel turns up, it's 3' 6 1/2" below the LWL. His first notation is that the draft of the keel at the rudder is 3' 8".
Don't know about the Commander - assume it sails lighter than the Ariel. Many boats have raised their LWL over the years, sitting lower in the water.

Seems to me to be safe you need 4' of water over the main trailer beam - with the trailer at X height added to the water depth needed. That's a lot of water imco!:eek:

There is also a definite hollow to the stem, with the fullest indent of the curve
at 18" below the LWL. Isn't it possible that this hollow (for lack of the correct word) creates lift and could be partly responsible for the hull's reputation for pointing well and exceeding hull speed?
__________________________________________________ __________________________________
By contrast the accommodation drawings in the Manual of the Ariel by one J.L.Lee show the bottom of the keel to be parallel with the LWL.
There are a raft of other inaccuracies in J.L.Lee's rendering of the Ariel.

To say that if you are taking measurements from drawings in the Manual make sure they are signed by Alberg.

[Frenna]

Thanks,

I have been working from a printout of lines drawings with dimension notes, I think from Rico from his trailer ordering process. It has Carl Alberg in the title block, and No. 33 in the lower right corner of the title block. It only shows the hull, and seems accurate, but how would I know?

It does indicate a rise to the keel bottom, which is a typical detail for many full keel boats. I believe the rational is that if you drive it up onto a rock ledge or shoal it should be easier to pull back off than if it were simply horizontal.

There is a slope to the support on the trailer too, as the laterals rise moving forward, so it should work out to be about level when sitting on it.

This is a drop frame trailer, so keel should only end up being about 16 or 17" above the road, maybe less.

I am designing the vertical support posts with lots of lateral bracing fore and aft to deal with the shifting thing, in either direction. But to answer your question, yes a support post under the bow would be good too, but the trailer lacks much structure there. I will likely add SOMETHING to the winch post to address that, as well as serve as a locating point for the hull, but I am expecting the braces on the side posts to handle most of it. Besides it is hard to imagine the brakes on my Miata are going to slow it down TOO quickly anyway. Just kidding about that :D.

It seems like the overall keel width is about 9", but if the radius gives me a couple inches of cheat, all the better. I may even end up using a half section of half in thick steel boiler tube, which I saw cut open at the scrap yard to get the copper tubes out from inside. It was about 24" across, but a third of it would have nice gentle radius, and I suspect adequate strength. It may have already been cut up for scrap by now, though.

[ebb]

Can't say this is actual measure - or virtual. But it does confirm Alberg and Rico.
The keel IS rounded and curved everywhere.
I had two strate L's of cardboard. Held the long side against the keel vertically and opposite each other with the bottom of the L's crossing each other.
What came out was that strate across the bottom it is indeed 9" wide.
16" up the keel from the strate across and measuring across it is 10" wide.
The bottom is also radius round, with no flat to the very bottom.
So laying this out on paper, there would be two lines on either side of a 90 degree center line off a base line.
There'd be 4 1/2" on either side of the base. 16" up, 5" on either side of the center line.
Put the compass on the centerline and scribe the curve that is the bottom of the keel. Most likely.

Did this best I could to the widest part of the keel which happens to be right at the forefoot. And right under the forefoot there is a block with a pad and shims that wouldn't allow me to get what A338 might actually have as its widest - but maybe what we have is pretty accurate.

That's basically it. Should be able to reproduce a section from the info here.

I can see getting a 10" wide metal channel and welding in plates at at angle to make a cradle. Or fabricate a scoop-like stopping point, a housing that you'd float the forefoot into. Or further back you could use narrower open channel with some angled strip to help center the boat on the trailer. Replaceable wood wedges would be more forgiving to the plastic.

One skipper in the above blog uses stand-up pvc pipes on his trailer to clue the boat into position with the trailer sunk out of sight.

Where the forefoot just rises to become the stem that is also where the keel is its widest. The keel starts getting narrower pretty quick as it glides toward the rudder. Studying the plans (haven't for a long time)...not only is the keel widest at its forefoot, it is also the center of the casting of the 2300 # hunk of lead ballast.

There is a mighty concentration of half of the total weight of the boat at the forefoot.

[Frenna]

Thanks for all that detailed information. I will see if I can track down a good cheap piece of 10" channel. I was thinking I might be able to get away with something narrower, but it seems like a bad idea. It would also give me some extra room for padding on the sides and attachment of some float-on guides.

I will keep the group posted with the progress of the trailer project, and then the boat itself, if all goes well.

[Rico]

Here is what those 9" look like... Looking from the bow.

Great sailing grounds around Bainbridge and the whole sound! I was fortunate to live in Seattle for a couple of years - did not get nearly enough sailing done up there!


PS. If you turn the channel upside-down and notch the flanges, you will not weaken the section as long as you fully attach (weld-up) the missing perimeter to the interfering metal (as long as it is similar thickness metal).

[Frenna]

Thanks, what a great picture. I am scheduled to weld the supports this weekend. I am afraid almost all of the weight is going to end up on the center lateral anyway, but I like the idea of some transfer to the other 2 laterals that run across the trailer.

Even so, I might cheap out for now and go with a lumber solution for the kell to sit on. Then I can through bolt some adjustable rails on either side of the keel as a back up.

I do like the those side supports, though. Might have to think about that when I see what my steel scrap pile looks like when I get done.

I will post pics when I have some progress to show.