: Hi, I'm looking for various suggestions on building light/superlight s&g
: kayaks. If we leave the design aside- the use will be jetty stair launched
: and paddled in an estuary and an open harbour/coast with sea swell but no
: breaking waves.

: what would you usually build and what would be your lightest version?

: I also read of a thin frame with open bulkheads that thin ply was then added
: to is this light?

Multi chine hulls require lots of taping and are easier to just sheath. If you are building a single chine design then you can just fillet and tape the joins inside and just tape them outside. The deck, if it is ply, really needs no cloth, even if you think the hull does. The hull chines, keel and gunwhale corners stiffen the boat along its length more than enough. If you want to stiffen the hull a bit below your seat then then a couple of short perpendicular stiffeners in the bottom is an option,but probably not really required. The bulkheads serve this purpose further out. You could also just sheath the outside and not the inside.

This all works much better if you use top quality marine ply. You will be saving on glass and epoxy so quality wood is justified.

I am guessing that epoxy saturation on the raw ply and then varnish works out a tiny fraction heavier than just varnish, but it is not worth the maintenance that will be required later. Sun will heat the wood through the varnish and it will inevitably blister. This does not occur with epoxy saturation as it properly bonds to the wood and also bonds very well if keyed properly with most varnishes.

Before the advent of epoxy people did not as a rule sheath S&G. There is a much abused Kayak I built 30 years ago that is still in use locally. This boat was not sheathed. Just taped with old fashioned GRP and varnished, and later painted.

Et