The best advice so far is going to NRS. Another option is Cascade river outfitters. As a former commercial
raft guide I've repaired lots of rafts, both hypalon and Pvc. Good repairs
on either all begin with the prep. Taking your time and properly cleaning
the surface will make a huge difference in the longevity of the repair. PVC boats can come from the factory welded or glued. Most of the PVC boats in the early 90's were glued and many of them didn't hold up nearly as well as the hypalon boats. Advance's in manufacturing and the material has made PVC boats much better across the board. I have several PVC boats that I really like primarily because of the performance advantage of the stiffer material. I also have a set of WWII Hypalon bridge pontoons that are still in remarkable shape.
So back to your question. "sorry for rambling"
1. Determine your material
2. Get the proper glue for you material, and possible watch a couple of how to videos.
3. Prep the material well and take your time and execute a great fix.
4. Enjoy the fruits of your labor.