OK, I'll help.
Go up the stairs onto the warehouse closest to the ship. you can either go there, or jump on the silo things, either way works. Take the Sniper rifle, and quickly shoot all of the gang members. Start with the several at the bottom of the ramp, and work your way across the boat. You will probably need to zoom in to get them, but you should be able to do it.
And ofcouse don't shoot the guy running with the package! (8 Ball you know...)