Thanks everyone for all the helpful responses so far!

The deck says "Hurka Pro-tech" on it. The thin spots are almost all around the edges [for lack of lingo, where the blue meets the white, in the photo], and I checked them out, none of them are soft at all. Their positioning suggest that they resulted from wear- is that correct? And in that case, even if they're not soft, it wouldn't hurt to beef up the thin spots from the inside with patches, would it?

I noticed that one of the patches was lifting up a bit at its edge, which is what I expected might happen in the long run with patches, which is why I thought putting a coating over the patches would be a good idea. Does that make any sense? Also, I noticed that whoever did these patches did not sand afterwards- aren't you supposed to?

Here is a picture of the edge of the kayak and the patches on it...