Grand Theft Auto IV Walkthrough

Begin following the ship, using this opportunity to get as close to it as humanly possible. That's because before long, the ship you're tailing will be assailed by numerous ships. Don't fall into the trap of trying to shoot and drive your boat at the same time, because not only is it next-to-impossible, but it's not necessary. Instead, concentrate on driving the boat, keeping close to your Korean friends, and Derrick will do all of the necessary shooting. You can help him out if you're a good gunner, but, well... good luck steering the ship and keeping up with the melee if you decide to do so.

After Derrick has managed to nullify a number of boats, a helicopter will appear overhead. He'll tell you to get up from your seat manning the ship (follow the on-screen prompt). Then, equip the RPG he gives you, aim it at the helicopter above, and quickly eliminate it. Then, put away your RPG and equip an automatic weapon to kill the drivers and any remaining gunners on the boats swarming your location. Resist the urge to use RPGs here since the explosion can very well take out you or your friends. When everyone's dead, all you have to do is follow the ship you're accompanying to a nearby dock, where the money will arrive to the hands of those who needed it safely.