The aim here is to keep the support chopper intact from the attack boats. You may not manage to keep it alive, but try regardless, as the longer it stays up the less chance they'll shoot you. The helicopter will make a few laps around the tanker; take out everybody you can see to prevent yourself from taking damage. After two runs it'll land on the bow.
You've reached a check point. There's a bomb and you've got a minute to defuse it. Take out the guy that is just in front of you, go down the right hand stairs, and shoot the guy going up the other side. Now shoot the guy coming along the side. Defuse the bomb now. After that, rush up to the bow of the ship and use the mounted gun to take out the two boats once they appear in range.
You now have three minutes to defuse the bomb in the cargo hold; things start to get difficult now. Make your way down to the cargo hold using the stairs, but don't hang around as you'll be shot at. Once you're down in the cargo hold, use your blind rage and duck in and out of the crates, there are a few health kits laying around so find them if you're running low. Once you've cleared the floor defuse the bomb.
You have three minutes to defuse the last bomb and it's right back at the stern. Head on up and don't worry about the boats that have appeared. Rush up, killing those that get in your way, and defuse the last bomb without worrying about wiping out all the gang members out, as they spawn infinitely. After you've defused the bomb, the captain will appear, so go up and take him out. Rage is good to use around this time, as you'll be surrounded. There are quite a few health kits lying around though.
You'll end up back in a dock in Miami. Once you reach the top of the ramp, you'll hit a checkpoint. Head towards the foreman and fill your rage meter. Once full, use it and you'll clear the dock in no time flat.