Repairing Hole in a Vinyl Raft

Try this website. You type in what you want to glue together and it lists several possibilities usually. It is: www.thistothat.com

I think a repair kit for a vinyl swimming pool liner would work well, it's waterproof.

I used to have a rubber raft and found repair kits at fishing bait and tackle stores or large sporting goods stores.

Try a bicycle tire patch kit.