8-Ball, knowing about the meeting after a phone call from Salvatore Leone, tells Claude that he needs $100,000 for the explosives and tells Claude to return when he has the money. After obtaining the necessary money, Claude returns to 8-Ball's and the two head to Portland Harbor, with 8-Ball giving Claude a Remington 700, since his hands are still in a condition bad enough to handle a weapon. After arriving at Portland Harbor, Claude gets a good vantage point (likely the staircase on the warehouse) and begins to kill the Colombian Cartel gang members guarding the Les Cargo container ship, with 8-Ball planting the explosives. He detonates the explosives, getting off the ship's bridge just before it sinks.
Take the adrenaline pill just around the corner of the warehouse complex. That will make aiming a lot smoother. Also, its effect won't go until you exit the scoped zoom.
A good vantage point would be the roof just up the staircase. Don't waste time, run to it as soon as you pick the adrenaline pill, before its effect wears off.
You have to pinpoint the priority enemies so as to quickly clear the way for 8-Ball, because he will run towards the ship as soon as you fire the first shot. First kill the 2 guarding the entrance of the ship, then the 2 up the plank. Then, kill those that are individually in the corridor. Then, shoot at the explosive barrels, and finish killing the single enemy on top of the boxes.
The reward for completing this mission is $150,000 and the mission Last Requests is unlocked.