I used to suggest sanding away bad glass. Now I'm leaning toward heating an area to about 300 degrees F or hot enough to soften the epoxy but not hot enough to char it, or the wood. That would be somewhere around 150 degrees C. Then grip the glass cloth with a pliers and peel it back. Heat the adjacent area and continue peeling until the glass comes.

Once you get it started you can cut it into a strip 6 to 12 inches wide and work along that if you find it easier.

You can remove the glass quickly with far less mess this way. and, you save on the cost of a lot of sandpaper.

Another plus is that you don't have a lot of finely ground glass particles floating in the air for you or family members to inhale. Sure, you'll be wearing a respirator while you are sanding, but any dust you don't pick up is going to stay around the shop.

For small areas and patching, sanding is the way to go. And wet sanding if possible is even better. But for removing large areas of glass cloth from kayaks, I'd try applying gentle heat first.

You will need to give a gentle sanding to the boat after you peel off the glass. If you keep it gentle (use fine grit paper and little pressure) you will not go through the seal coat, saving you time and resin when you put on the next glass.

Just my thoughts on this.

PGJ