In reply to Oceanrower:
> These suggest 4mm Okoume ply with a clear fibreglass/resin lay up for the hull and cedar strip for the decking.
> A 17' sea kayak should come in at about 20kg though I suspect I'll be using too much resin to start with!
> Never heard of polypipe canoes before. Off to YouTube I go....
Sea kayaks are usually lighter for length as they are narrower and have a deck to stiffen them, a 16ft Canadian is for mayge 400kg payload or more and nearly flat bottomed.
The usual poly-pipe canoes on the internet are rubbish, I do 5 chine ones identical to a ply Canadian. The trick is to heat form the tube (I work with electrical conduit) with hot water to make all the frames and the keel form then bend tubes to make the chines. From the outside they look identical to any hard-chine canoe. Cheap as hell depending on the skin cost, maybe £200 or less. Skin on frame is good if you make the whole thing flexible, they just slide over rocks and stuff, I've a roll of Kevlar truck tarp somewhere!
Done week long camping trips no problem with all the junk.
Might have to look into an Eskimo kayak, see what's possible!