You might like a 'glued lapstrake' boat, where the planks are of plywood,
bevelled and glued together. There is minimal internal framing. Get a copy
of Tom Hill's book "Ultralight Boatbuilding". There's a video, too.
WoodenBoat Magazine sells 'em. Tom's Charlotte design might fit your needs.

For pix, google for "tom Hill" and Charlotte or canoe





Dick Robertson wrote:

Anyone have a suggestion for a plywood kayak able to carry about 250
lbs and around 12 ft long? I'd rather it not be 'stitch and glue' or
strip plank (I know, I'm old fashioned). Incidentally, I came across a
kayak plan in an old book called "The Boy Mechanic" published from
1920 thru 1950's; all you need to know to build this boat on 2 pages!
Has anybody ever seen or built one of these?

Thanks
Dick Robertson
Wilmington,NC