I've never seen more than one guy on a ship before actually hitting the "board" button.

Oh.. they take a bit of time in between ... but they do keep coming up over and over. I usually kill about 4 or 5 before I board. It is a big help when boarding alone.

That's interesting. I'll keep an eye open next time.

Grapple it as fast as you can. Kill the captain and wait. I've never shot down the masts while waiting, so I doubt it's a factor. After a bit they come out one at a time. Just watch the clock so you don't miss your chance to board.

Last night I got 80 rep killing the captain with cannon balls... so I knew the crew was going to wipe me out, but I went over anyway.