You rang???? I can't imagine trying to cover a canoe with regular Dacron sailcloth. It has totally different properties from the ceconite-style Dacron used for heat-shrunk aircraft applications or the old Featherweight canoes. To start with, it's already been heat-shrunk about as far as it's going to go. Then it's been fixed with resin (melamine or epoxy). Nearly everything that's done to process raw Dacron into sailcloth is done to keep it from stretching and/or changing shape. It's made flat to stay flat and will likely self-destruct long before you ever get it even close to being canoe-shaped.
Especially in light weights like 4-6 oz. or less it's also important to understand Dacron's tear strength. The Dacron fibers (or any polyester fiber for that matter - Dacron is simply Dupont's trade name for their polyester) are quite strong and resist stretch better than most other synthetics. They're also decently abrasion and U.V. resistant, but they tend to take tearing or ripping force one yarn at a time in woven applications. Where the woven yarns in a hunk of nylon will tend to stretch as a localized group when tearing force is applied, spreading the strain over a lot of yarns, Dacron yarns tend to try to take that force one yarn at a time. This is because they don't stretch enough to help each other out. The first yarn stresses until it breaks, then the second, the third and so on. It happens so fast that it's called "explosive tearing". You can take a piece of very heavy Dacron sailcloth (10-12 oz.) cut a small slit in one edge, grab either side, pull hard and it will split wide open. The same is not usually true of nylon, acrylic, cotton canvas, and most other synthetics, which will at least put up a fight as stressed yarns are helped by their neighbors. If you can pull hard enough to pop the first yarn on Dacron, you can easily tear the piece in half, so a fairly minor tear could end up 15' long if the force isn't removed. Sailcloth is also frequently treated with stuff like silicone, so finding filler materials which will stick well to it may be a problem.
The heat shrink-types of Dacron have these same tearing properties and should be used with care if the canoe is going to come in contact with rocks. The fact that the fabric is shrunken into canoe shape as part of the covering process may build in a little more stretchability than sailcloth has, but it's still very light and they're still Dacron fibers and limited in durability and elasticity.
I believe that the sailcloth which was tried out for canoe covering was North's "Oceanus", which is a heavy canvas-like fabric developed for square-rigger sails. It might work and at least can be stretched (or at least distorted from a flat state) to some extent, mostly because it has far less stabilizing stuff on it. The lightest weight is 7 oz. (measured in sailmaker's yards which are 36"x30" and once processed sail fabric is often as much as 25% or so heavier than the quoted weight). A very similar fabric is Richard Hayward "Clipper Light" canvas, made in England. I haven't used much of it because these fabrics are too heavy for the small sails that I build (makes a hell of a dog bed though) and could possibly be a good non-rotting substitute for cotton canvas on canoes, saving a certain amount of weight. I would imagine that durability-wise the Oceanus and Clipper 7-8 oz. fabrics would be similar to the light-to-medium weights of cotton canvas. They're fairly smooth though and absorb less liquid, so you might save more weight by needing less filler. Cost-wise, expect to pay $20-$25 per yard, 54" wide, so they aren't going to be cheap.
