Stretching canvas on a frame in preparation to sew up the seams.

(I've never seen this trick in the voluminous literature on kayak building but it's probably somewhere!)

I suspect that there are a lot of craftspeople out there who, like me, have no trouble cutting and bending and lashing wood but have little experience with cloth and have found their canvas skins weren't as tight as the rest of their construction

The easiest, best known and traditional way to get a canvas skin tight while sewing up the seams is to pre-tension it by zig-zagging a length of line between loops of string sewn temporarily into opposite sides of the canvas skin just above the gunwales.

Instead of just sewing loops into the skin If the loops in the skin are threaded through little plates (sort of like buttons) you can really pull the skin tight without serious puckering of the cloth.

I used some poleythelene about 1/16 inch thick left from an industrial job but anything more rigid than cardboard, even aluminum sheet would work. I make the plates about 1 by 1/2 inch with 1/8" holes punched right near the end. The plates are sewn to the top (outside) of the skin with 2” loops of nylon line. It’s the inside of the loops that the zig zag tension lines go throough

The skin should be stretched lengthwise, I use porch posts and vise grips and Spanish windlass things tight.

Nylon cord works well for the same reason that it doesn't hold knots well - low coefficient of friction - the long zig-zag tightener slides through the loops quit easily. I tie (bowline!) it onto the stem- and stern-most loop and work back to the cockpit, not by pulling on the line to tighten, but rather by grabbing the two edges of the skin above the center deck beam and squeezing and twisting a bit with one hand while taking up a little tension on the long running string. Do this in several passes

and you’ll find that the cloth will get quite taut.

I sew the seams from the cockpit to the ends, figuring that the ends can absorb any longitudinal slack that may be developed in the skin, whereas sewing from ends to cockpit I've had to put in a gusset occasionally

LOL

BV