: 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.

We've had the same experience with our VOLKSKAYAKs - the 4mm marine ply hull and deck aren't sheathed, just seam-taped and well encapsulated. My first, built in 2001, has needed only periodic cosmetic repair work on the hull and a few paint jobs. We did manage to split a bow panel on my wife's new VK last fall - to save paint scratches when launching the kayak after a lunch break,
I lifted the nose, pushed the boat as far out as I could and dropped it, duh - it came down hard on a real sharp rock hidden just beneath the surface. The resultant fracture in the ply (a 6 inch long split, no hole) was easily repaired with two FG/epoxy strips inside, and a thimbleful of fairing compound outside.

Apart from that, we've never had a hull leak in any of our VKs, nor has there been any damage or deterioration of the hulls and decks. The key seems to be to encapsulate the panels really well; besides making them almost impervious to water, multiple coats inside and out also stiffen the ply more than you might suspect.