Deck gun time!
I've been in those conditions. I got within 500 yards and fired a few shells blindly down the bearing. After a few shots I set his deck cargo on fire, that made it easier to aim. With the bad conditions, they never shot back and I was able to pound him.
Of course, the whole time I was thinking, "This is how Rockin Robbins ended up in the brig..."
TMO+RSRD
