Sheer Clamps – Second Layer

Double Sheer Clamp Lamination

 

(to start of project)

An odd and disconcerting thing about this sort of project is it takes just as long to make a little piece of wood fit as it does a big one. This means when you make a lot of little pieces it doesn’t look like you’ve accomplished much for the time spent. It makes it hard to gauge how long it will take you to finish, since you tend to overlook the little things when thinking of what’s left, and the little things add up.

Friday’s good day was spent making all the little filler pieces for the second lamination of the sheer clamps – all 52 of them. It was a very good day, and all of them got done, each one carefully cut and shaped to fit, so snug they stay in place with friction alone. Still, doesn’t look like I did much.

 

 

The scantlings call for a 1” thick by 1.5” wide sheer clamp, but that much wood is quite difficult to bend in place. It was easier to use 3/4” dimensional lumber. You probably could get away just one layer of 3/4”, but better safe than sorry. The sheer clamps will be shot through with screws from every angle for their full length by the time the boats are complete, significantly weakening them – 36 to 48 screws in each piece, minimum. They’re an important structural element like the keel, one of the bones that defines the shape of the boat and makes it rigid. Seems worth the extra effort to insure they don’t break later.

 

 

I tried just cutting flat filler pieces to go between the beams, then clamping them to the existing curve, but this pulled the first curved piece flat, making a kind of faceted shape down the hull. Mmmm, no good. So, to keep the sheer fair, each piece was shaped individually to nest in place. Not as hard as it sounds, as epoxy will fill any small gaps, so close enough is good enough.

 

 

This double lamination is extra work, though it’s in small, manageable bites. But the trade off is doing it this way has a couple of bonus advantages, beside the easier initial bend. The filler pieces bring the thickness of the sheer clamps to 1.5” square, making a kind of small deck knee that runs the full length of the hull on each side. It’s a small thing, but may help limit the twist of the boat under strain. It also locks the beam ends solidly in place, again acting like little knees or braces. If you didn’t do this, you’d need to at least notch the sheer clamps to seat the beam ends, or something comparable – just driving screws through the hull sides into the end grain alone would not be nearly strong enough. Twisting of the hull would eventually loosen them, wracking more and more over time, and slowly pull the boat apart. Notching seats for the beams is the standard method, but that, too, is time consuming, so the method you use may come down to what you’re most comfortable with. At least this way, you also have a nice big target to hit with screws when mounting hardware, trim, and toe rails.

 

melonseed skiff, mellonseed skiff, melon seed, mellon seed   

 

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