: Just for a starting point for figuring how many plys of Kevlar would be
: needed, does anybody know the layup schedule for Kevlar kayaks or canoe
: hulls?

Only one ply needed. By definition a skin on frame kayak has a frame which supports the loads. The skin just keeps the water out.

With a canoe or kayak that is constructed without a frame, as is typical of rotomolded, molded and laid-up boats, the shape and stiffness of the hull is significantly determined by the layup of the hull components. However,in addition, the shape of the hull and deck, as well as the size and spacing of gunwales and thwarts on a canoe add to the structural strength.

To confuse things more, consider the use of bulkheads, ribs, and keels. All these elements affect structural strength. A look at the interior of an aluminum canoe will give you an appreciation for these items -- particularly the keel. Not only does it serve as a seam for joining the two sides, it significantly stiffens the bottom of the boat.

PGJ