November 2008 - Chapelle 35' Utility Launch

After comparing marine plywood prices, I decided I'd rather have a paper cut on my eye than spend that much money on a prototype. So here's a warning: the prototype is not for sale. My choice: Sureply Plus.

Decision point: laminate 2 layers into one large sheet, lay it on the boat and cut it? Or lay on a piece at a time? I voted for the latter. Since I would be handling most of the ply myself, I didn't want to have to lug huge, heavy bottom and sidepanels around while marking and cutting. So I started slapping on one piece at a time, lined them up, and marked them out.

Once all of the station marks are transferred (you have to get the correct side of the frame when you do this (I usually mess up at least twice)), you can lay out a batten to ensure there's a somewhat decent curve in the plank edge. This isn't critical with this type of arrangement. I actually cut the plywood a little shy of the mark in the end. Why? -Since the plywood will sit on enough frames to keep the designer's shape, the only thing critical in the end is to get stiff enough planking to spring a fair curve (same as you'd get w/ a chine log or sheer clamp). If you use the edge of the ply as a guide, it probably won't match the lay of the ply once you spring it into place.

Here's another way to look at it: If you use the stitch n' glue method, the plywood edges define the shape. They have to be close to the end result or you'll have a different boat than you started out building. But if you're using the plank on frame method, the shape comes from the frames and the curves between them based on the lay of the planking and longitudinals. It seems to me you have to do one or the other. My cuts are pretty good (sometimes), but the two methods don't jive unless you get everything perfect. I'm not close to perfect (just ask my wife).

So, since I chose the plank on frame method (this way I get the exact shape I'm looking for), I don't want the edges to get in the way of letting the planks sit where they want to. (Later, we'll see that the problem I encountered immediately was that twenty loose sheets, -not scarfed, nor even butt joined, just tacked in place, are REALLY not stiff).

One last comment on that Sureply Plus: I threw a sheet on the ground in the yard last fall. It's still in good shape. That's after sun, rain, a foot of snow at times, and everything else nature had to throw at it. Maybe I'll keep the prototype...

























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