Coamings Question

[CupOTea]

Somehow in the pandemonium of total disassembly I neither saved nor documented the means of fastening the cockpit part of the coamings assembly to the cabin parts. I have a vague recollection of 6 (3 each)
long (3"? 4"?) wood screws. After a forest worth of sandpaper and 10 coats of Epiphanes I am ready to remount them - bedded in Dolphinite - but need the hardware spec for fastening them to each other. Have all the other screws (2.5" #14 oval heads - for anyone who's interested) for fastening them to the cockpit and cabin.

Can anyone refresh the old memory?

Also great fastener resource: www.boltdepot.com

Thanks

Scott

[mbd]

Scott, not sure if this is what you're asking, but there are 4 smaller-than-the-cockpit wood screws for each side on mine that fasten from the interior and through the cabin into the coamings.

You can see them to the right of the electrical box in this picture...

PS. I'll bet your coamings are beautiful! In 2007, I put three coats of Epiphanes on, which didn't quite last for the season. Last year, I did and additional six coats and they held up great. 10 should hold up very well and look fantastic! Got any pics?

[CupOTea]

Wow - that's some spanking clean cabin you have there, Mike. Something to aspire to!

I have the screws that attach those pieces to the cabin (my Commander actually attaches them with 3 instead of 4 like yours) - I'm after the screws that attach them on the other side to the long cockpit coaming planks.

I've tried to use the screw size that attaches the coaming planks to the cockpit (#14 2.5") but the don't fit in there and don't seem long enough.

I'm wondering if they are like #12 3" or something. Can't find them anywhere.

Scott

[ebb]

Bolt Depot has silicon bronze FHWS per each. Including #12.
Jamestown has them also but you have to buy a box of 100. There used to be a way of ordering smaller quantities from Jamestown, you might call them and ask. Ask if they have cut or rolled threads. Cut threads are usually US - rolled threads are probably asian.

Traditional depth of wood screw is twice the thickness of the piece you are fastening. If the coamings are in tension, then you use oversize screws (for wider thread) and add length. 3/4" coaming with 2" screws.
A338's corner posts were each held on from the inside the cabin with 4 #12s, each 3" long. The cabin side is 1/2". I doubt anything was gained by using those long screws, 2" would have been plenty.

Traditional wood screws require tapered drill bits so that the screw thread holds to the work with its whole length. You can use two or three regular drill bits to produce a similar tapered hole. Larger size and longer length Fuller taper bits are expensive.

A338's old coamings were screwed to the corner post rabbet with three #10 screws and plugged. I think 2" is long enough. All the other screws (coaming to the cockpit side and stacked mahogany winch island) were #14 (1/4") wood screw.
Heads exposed, no plugs.

Most bronze screws have slotted heads. You need screw blades that fit the slots tight. Full length of the slot and no slop. And being soft bronze the hole you ar putting the screw into has to be nearly perfect - because you can't force a bronze screw into too small a hole.

You may be using a variable speed drill to drive the screws. I don't think I've ever seen a driver bit large enough for #12 and #14. I've used an old brace that held larger square shank bits and produced slow powerful turns. With a brace and bit you can FEEL if the screw is being held up by too small a hole. And do something like drill the hole a skoch deeper before you screw up a two dollar screw.:D

I would experiment with some screws to see if the old hole will thread a new screw into it. The woods are teak and Honduras mahogany. Good wood that may still have perfect original threaded holes ready to go. They'll hold for another 40 years. (add a little epoxy in the hole.) imco

[Rico]

CupOtea,
I took a look this morning at C-155 and it seems that I have 4 screws per side instead of your 3...

The screws are not arranged in a square as MBD's Ariel shows above, but they are in an equally-spaced straight line from top to bottom ( a line slanted forward) following the attaching block on the Commander's coambings on the cabin end.

I remember that there are 3 screws of the same size on each side, followed by a larger one at the top (where the coambing block is thickest) In my case, all these screws were smaller diameter than the ones that attach the coambing to the sides of the cockpit. As I recall, the 3 smaller ones are about 2.5 - 3 inches, and the longer one is 3 - 3.5 inches.

I hope this helps...

[CupOTea]

Thanks Rico and Ebb.

Nothing like a little terminology to clear up the picture, Ebb. Blocks and rabbets.

I will do the toothpick forensics because it looks to me like there is room in the rabbet joint of the block for a deeper penetration from the fastening screw - even though the angle they have it going in at looks like it could end up in a crack if it goes too far. I think BoltDepot maxes out on slotted oval
#12s at 3" so that may be the best I can do.

The hole tapers are what's keeping the #14s I have from going in there, so I think the idea of going to #12s is a good one. As far as I can tell the screw holes) have never been messed with so hopefully (not a good word to use in boat building) they will be nice and tight and will take the original screw size.

I always assemble for disassembly but it's tempting to put some adhesive in that rabbet joint - although Pearson just had silicone in there, which I removed when I reconditioned them.

[ebb]

Cuppa,
sorry I erased some verbiage and it included the toothpick forensics. If the wood is rotless, the holes will be just as good as the day the screw was put in. And taken out.

I really think that length does not necessarily equate to strength.
You know like the wood is punky or something, then maybe. But bad wood must be replaced. So extra long fastenings are redundant.
If you are really paranoid you can drill straight thru and make bolts with allthread, washers and nuts (they'd be clamps) - and plug the holes on each side.


Screw sizes: #10 = 1/8"
#12 = 3/16"
#14 = 1/4"
You can measure the old holes to find out what screws were in there.
The screws unthreaded shoulder determines its size. Except for the 1/4" the other inch sizes are approximate.

[CupOTea]

Got it, Ebb - thanks.

The wood is rock hard. No rot. Never been disassembled. So we're good there, I think.

I am really parranoid, but I don't think I'll through-bolt it. I'll just go with those big nasty 3" #12s (after measuring).

While we're on the subject. On the wooden hand rails. The bolts on the two ends (the middle two screw in from the cabin out) they really didn't counter sink enough to allow for a bung. And 10 coats of Epiphanes later, I'm loathe to start modifying the holes (just want to get in the water at this point) I'm planning to fill the bolt hole with polysulfide. Any thoughts?

[ebb]

H m m m m m..
Hand rail is pretty skinny - like 3/4". If old stock it could be a little fatter.
If it's not screws securing the ends of the rails, it has to be a bolt/machine screw of some sort.
A 1/4" carriage bolt would make a nice exposed nip of bronze that wouldn't offend the eye. But it has at least a 9/16"D head. And if the fastening is in the end curve of the rail, you'd have to forgive a little funkiness because the head wouldn't lay flat on the wood. But you can chisel in a bit of flat for the head to rest on, it will look just fine. Could grind the carriage bolt head a little smaller on a stand-alone disk sander.
BUT the carriage bolts should be dead center of the rail (unlikely) to look pro.

Another way but not as secure is to find a flat head machine screw of the same size the interior screws are and use a nut and washer on the cabin liner.
you'd bury the head a little deeper in the rail and then glue in a wood plug - carve and sand it to the curved rounded shape.
Instead of a FHMS you could use a round or panhead machine screw - maybe even adding a small washer. Would make a better 'clamp'. No bronze for this esoterica. Maybe 316.


If I understand correctly, you have polysulfide where a plug ought to be on all four ends of the rails. If you only had a little extra depth to work with (a shorter fastening for instance), you might pare the rubber area flat with a chisel.and make a 90degree cut on the high side....making a little ledge. Then glue in a little chunk of the same wood and sand to shape. Rail dentistry.


[This is a 'cosmetic'repair:
I'm thinking you could just flatten (plane) the polysulfide filler down to the buried fastening, maybe a little more by Dremel grinding the fastening down A LITTLE. Leave whatever goop is left in the hole there if it is holding good. Make sure the old fastenings are holding the rail-ends tight.

Use your block plane at any appropriate angle that ends up with good fresh wood on BOTH sides of the rubber filled cavity. Hope you have a very sharp low-angle hand plane. Old polysulfide gets hard and may plane just like wood.
Epoxy glue a strip of mahogany directly onto this very flat flatness - covering up the hole, fastening and rubber-plugger.
Shape and sand that down to the continuity of the rail.
Less noticable than the notch idea. Might be a classic invisible repair.
90 coats of best UVEpifanes.

If the end fastenings are too close to the surface then you might have to remove the bolt/machine screw and put it in a little lower down in the rail (have to take the rubber out) to do the glue-on strip thing. Hopefully there is enough meat there in the rail ends,] It's hard not knowing exactly what they have there!

Next time the rail has to come off you'll probably just replace it....anyway.
Couple ales and we could keep this up all night....especially with feedback.. Have fun!

[CupOTea]

Maybe ale is the answer.

These are the original 45 year old rails. Adequate but not as hefty as today's versions. I've decided to go with them for the aesthetics for now but I can forsee replacing them down the road.

The way Pearson set them up on my Commander is with carraige bolts down through the end legs and bolted in the cabin (with a finishing washer) and then wood screws screwing up from and through the cabin liner into the middle two support legs.

As you describe - I've put flat head bolts in the two ends now and they don't really sit in the existing counter sunk holes very well. I thought of going to an oval head (that's what was on there orinigally) instead of the flat-heads I went with for convenience (local shop has them) - but the oval heads have their own issues since they raise up out of the wood. I was concerned with messing with the holes but it didn't occur to me to grind the bolt head instead. :o

On the other hand - instead of making the hole bigger (in an already skimpy rail) why not - as you suggest - look for a bolt with a smaller head that will fit down in the hole and then wood plug it. That would keep the water out which is what the polysulfide question regarding filling the bolt hole was all about. Nicer look too...

On it this weekend...thanks again.

[ebb]

Cuppa,
The large head of a bronze carriage bolt wouldn't look too bad on the ends of those old rails. The head would nearly take up the width of the rail and provide another roundness that imco wouldn't look too bad.

If you took the present fastenings out (I'm still not sure what type head they have) and repaired the hole with new bungs glued in with epoxy.... then drill up thru the existing holes, from the inside, thru the repair.... and then put the carriage bolt thru with a smidgeon of flatness under its head....
I think the 'boss' effect of the 1/4" carriage bolt's dome would look pretty :cool: imco.

BUT
Like I say you can make the whole end fastening bruhaha disappear by installing a smaller head machine screw (probably a #12 FHMS or even a RHMS with a small diameter washer under the head*). If it is lowered in the hole you can dispense with bunging the hole (which is probably miss-shapened) and just flatten the area around the hole and glue a piece of mahogany on top
that will virtually disappear once you sand it to the shape of the rail.
UV varnish should protect the epoxy glue holding this unconventional 'feather' strip repair.
Bolted, the nuts and washers are accessible inside. That means when you take the rail off you just remove the nuts (and unscrew the intermediate fastenings) and lift the rail with the bolt off the cabin. You don't need access thru the top.
Epoxy on the fastening head will help set the screw and insure watertightness there. No problema, senor.:D

Repeating myself because I mumble a lot.
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*a #10 washer will just slip onto a #12 screw shank and is 7/16" in diameter.. It will therefor easily fit a common 1/2" countersink. A #12 washer is 1/2" and could be a problem getting in a 1/2" hole, especially a tapered bung hole.

[CupOTea]

Install a smaller head machine screw (probably a #12 FHMS or even a RHMS with a small diameter washer under the head*). flatten the area around the hole and glue a piece of mahogany on top UV varnish should protect the epoxy glue holding this unconventional 'feather' strip repair.

Bolted, the nuts and washers are inside. just remove the nuts and lift the rail with the bolt off the cabin. don't need access thru the top.
Epoxy on the fastening head will help set the screw and insure watertightness there.

That's the ticket! Brewer's nearby has plenty 'o mahogany scraps.

This process belongs on the "classics" list.

Nice one, Ebb.;)

[Commander 274]

I am looking to construct some new coamings for C274, as the old ones are rotting away. I am aware that the Commander has a 9 foot cockpit. With the overlap on the cabin and the trailing edge to the stern, am I good just ordering 10 feet in length? I guess I could always just be on the safe side and go longer.

My search came back with some results, but the words: coamings, dimensions, measurements, etc... are all used far too much on this board! Has anybody documented the new construction process?

Thanks,
Michael

[kendall]

Most bronze screws have slotted heads. You need screw blades that fit the slots tight. Full length of the slot and no slop. And being soft bronze the hole you ar putting the screw into has to be nearly perfect - because you can't force a bronze screw into too small a hole.

You may be using a variable speed drill to drive the screws. I don't think I've ever seen a driver bit large enough for #12 and #14. I've used an old brace that held larger square shank bits and produced slow powerful turns. Would just like to add to that, You can buy the 1/4 or 3/8 drive socket adapters for cordless drills, -most- braces will also accept them, if you buy a set of those, then pick up some drag link sockets, you will have screw drivers that will fit most screws. Also, if you file the edges of the screwdriver part at an angle so they have the same taper as the screw head, you can completely fill the top of the slot, and won't mar the wood under the screw. Another trick is to use a short length of tubing (metal or vinyl/rubber) slipped over the screw head and screwdriver tip to keep it aligned, that way you can run them home quickly, I normally keep two or three different lengths in my pocket when I get into 'production' mode. sockets: http://www.sears.com/shc/s/p_10153_12605_00934299000P Ken.

[ebb]

Great tip! Gonna get me a set of those.

GETTING A SCREW OUT:
I imagine, now that you mention it, that it would very efficient to get close to the screw with a well fit bit in a quality socket wrench.
Can see covering the tool head with the other hand to keep it in place, level, and steady.
It's much better than a vertical screw driver. And better even than the battery impact driver (Hitatchi) whose torque hammer action can do miracles at times getting a screw out. But you're 10" away from the work - drill head, chock, loose fitting adapter, shank, bit.....

Thing about an antique brace is that it can often break a screw (origin of the expression 'screwed') because it is SO powerful.

However, This breaking the head off one or more coaming screws IS a way of getting the coaming off if the screws are frozen.
Because the coaming will slip off the headless screw, and the remains of the screw can then be turned with a Visegrip. This may be the RIGHT way!

cool tip on
angle grinding screw blade ends back so as not to scour the chamfer.
Large screws may have wide slots. Make sure the driver bit is totally snug in the slot - so it doesn't slip or slide or crawl out!
__________________________________________________ ________________________
McmasterCarr has individual socket driver blades beginning with the smallest at 11/16" across the blade. 3/8" socket. Of course the Sears $30 set is guaranteed for life - but the other socket blades are HUGE.
Happened across a HarborFreight set $4.77 - (1/2" socket) whose smallest blade is 9/16" across and looks easy to grind corners and otherwise alter the blade. May have to buy a 1/2" wrench to go with 'em...but there you are at Harbor Freight!
The drag link will have to be worked on as the 1/4" flat head screw is less than 1/2"D across its top. The #16 head diameter is just a little bit larger than 1/2". Size 18 screws are in the 9/16"D range.
__________________________________________________ __________________________
SCREWS
CCFasteners of Tonawanda NY has a full range of bronze screws available, unlike Jamestown, or Bolt Depot. You may be able to size up using the old holes - if you have to. Online store.
Haven't dealt with them, or compared prices.
Their site has phone numbers and is easy to navigate. Looks like you can get single screws in some styles and sizes. ( Sorry, only in 16s and 18s. "Coaming sizes.")
They have a few non-slotted screws that might work for our coamings:
SQUARE DRIVE bronze screws: #16 - 2 1/2" - $0.86. #18 - 2" - $1.69 and #18 - 4 1/2" - $3.38. Those 2 1/2" look VERY interesting!
You gotta admit that a square drive bronze head would look very cool in the varnished mahogany.
__________________________________________________ ___________________________
Did you know a DRAG LINK is "A link for transmitting rotary motion between cranks on two parallel but slightly offset shafts, such as the rod connecting the lever of the steering gear to the steering arm in an automobile." Now you know. I still don't know.:confused:

[commanderpete]

Michael, for the board part of my Commander coamings I got somewhere around 10 feet 2 inches at the longest part and 13 1/8" max height

[Commander 274]

Thanks commanderpete! You saved me a very long drive.

I aspire to make my Old Glory as beautiful as your Grace.

[ebb]

www.wlfuller.com (type in search window: wood screw chart)
Three perfect charts on drilling for screws from #2 thru #18
using their taper point drill bits and countersink OR straight bits.
Have to get the chamfer/countersink just so if you want the screw head to be flush with the mahogany. Or just below the surface so you don't sand the patina off when prepping for a fresh coat of varnish.
With an expensive probably one time use taper bit you would be buying the matching countersink so that you'd have the option to drill for plugs or just deep enough for the head. The countersink bit is oversized for plugs - so you have to eyeball the chamfer for exposed heads - difficult with a machine.

With a set of regular drill bits you can get the holes correct (with the coaming braced in place).
Jamestown 2009 holiday catalog (#54) on page 124 has an Austrian HAND COUNTERSINK -RLC-5706100- for $20.61. With this you could finesse the countersinking of the #14 or #16 screw head to perfection. And you'd have this tool for any size flat head screw you need to get flush with out a special countersink.

Somebody above here mentioned having problems getting the screws in. Could be that unforgiving fiberglass is right under the coaming. Might relieve the hole in the glass with a slightly larger bit than the shoulder of the screw. But continue into the wood backing with smaller strate bits or the appropriate taper.
Appropriate taper means you have matched the screw length to the taper bit, which come in short, regular and long, see chart.

Like the idea of the larger deeper threads of #16. More holding power.

No doubt you have varnished ALL sides of the coamings before putting them on. Imco dipping the screws in varnish when driving them home is tradition.
Recommend butyl for the bedding, because you will be taking the coamings off again...... sometime!
__________________________________________________ __________________________________________________ _________
Traditional tapered screws are becoming a thing of the past. This goes for slotted heads too. McMasterCarr, who carry a range of every imaginable type of fastening, have 304 and 316 wood screws.
I use non-tapered, sometimes sold as 'sheetmetal' screws (which also come flathead.) They are usually skinny with prominent threads, so that in the small sizes (#6, 8, 9, & 10) I feel they do a better job grabbing than tapered. And you predrill with strate bits.
Tapered screws have to be driven all the way home to work. Straight shank hold throughout their length.