Personally, I'd do a drive-by, communicating their needs while my motors kept running (though, I want a sailboat, which poses a whole different problem). Since I probably wouldn't be sailing alone, it would be prudent to have the firearm visible, but not being brandished.

Call the Coasties. Or the Navy. Or whoever you can get on the radio (assuming I'm not on a naval ship at the time).

Wait a safe distance, just like everyone says. And, I have to agree with the "bow on" approach. Damn the torpedos, full speed ahead. The ocean should do a good job of washing off the left overs.