>>2949816
if you're still here then yeah, you definitely shouldn't use chopped strand mat for structural applications because the actual strength of it is not as good as something like a woven plain weave (checkerboard style) fiberglass
the type of damage you have makes all the difference in terms of how you should go about repairing it - is it a small hairline crack or is it a gaping shred like a dinosaur's claw went through it? is it on the side or on the very front? is the canoe entirely fiberglass or are there aramid sections?
the reason there are different weights to fiberglass cloth is so that you can just lay up one heavy layer instead of having to build up multiple lighter layers to reach that same weight, that's the general principle behind the different weights

i'm not a boat builder but i work with fiberglass and composites relatively often and if i were to do it, i'd start by using 180 grit to scuff up the surface around the crack to smooth it out and provide a mechanical key. clean it and then tape one side using teflon tape or flash release tape and start applying 4oz fiberglass to the side where the fiberglass is visible (i'm assuming it is) while matching the orientation of the weave and 2 layers should do the trick. if that doesn't feel right, put on another 4oz layer. for the outside, i'm guessing the other side that touches the water is gelcoated? that just means you'll have to apply probably a few layers of fiberglass on that side as well and i'd finish it with a tissue cloth, then an application of gelcoat with a brush and make sure you mix wax additive into that gelcoat otherwise it won't cure as it'll be exposed to air

remember - you'll need about 2.2x the cloth's weight in polyester resin to cover 1 square metre, so 1 square metre of 8oz will require about 495 grams of polyester resin
take that into account. i hope that answers everything, have fun!