Yah, I bet this is quite a quagmire. Certainly I'd be interesting in hearing more about this.

Obviously the big issue is piracy. Considering they are going to be armed, and probably likely to kill you anyway, I'd want a semi automatic rifle. Considering the other boat may be metal, I'd be inclined to go with a larger caliber like the AR10. Oh, and you probably want a good light on it with a turbohead. I'd want some sort of built in locker to protect it. I'd probably also want a handgun as backup.

The problem of course, that both those types of weapons are probably going to be a major problem when going to port in most places.

A good pump shotgun might be acceptable in more places, but a lot less effective.

Oh, and whatever you get, you'd better be proficient with it.

-john