: Why do you want to do this? Do these pieces of wood offend you or take up to
: much interior space? Is this an engineering problem you wish to solve?

: You'll need to fabricate
: something to serve the purpose of the deck beams, too.

Maybe not. After making my earlier post, I remembered that Betsie Bay Kayaks have no shear clamps and no deck beams. The only thing on the inside is taped joints and a generous, thickened fillet at the shear. So it can be done. However, BBK supposedly has a reverse-vacuum-forming operation to accomplish that. The draw a vacuum under the inverted deck, which draws the 'bulge' over your legs into place, and then they attach the hull. I think. Rumor has it they do a pretty good job of keeping their shop from prying eyes.

The result is that they make 17'x20.5" kayaks that are 36# -- fully rigged. (they are supposedly durable kayaks, but I don't like the fact that the insides are only taped, not fully glassed) Their cockpit coamings are pretty robust, so they may be playing a part in keeping the bulge in the deck 'bulged', in lieu of deckbeams.

Maybe a compromise is in order. Make the deck flat everywhere except for the bulge over your legs, and put short shear clamps in the area over your legs where you need something to nail/glue to. Since this tortures the plywood, you'd best go with a 3mm deck.

Another idea would be to use a shear clamp that's more like a corner molding than a square cross-section. Maybe a wainscoating would look nice on the inside of a kayak...

Dean