Didn't the currents from the island in Papyon come in toward the island making it nearly impossible to escape? I haven't seen the movie in a while and wasn't entirely paying attention when I did (it was on tv).

As far melee weapons wouldn't something like a shovel be more useful? You don't really have to worry about technique, it can be easily replaced, and you can use it to dig as well as smack zombie is the head with. Granted, it might not be the fastest weapon in CQC but I think in most of our cases it would probably end up being the most effective.