The boatyard is located in Viceport, on the far southern tip of the west island. It's the same location as "The Fastest Boat" mission for Ricardo Diaz earlier in the game.
Another boat checkpoint mission, as with the Cubans' "Stuntboat Challenge" mission. Pick your boat wisely before you start - you can either choose the Squalo II on the left or the Cuban Jetmax on the right. The Squalo II has more speed, the Jetmax handles better - but in the water that's very comparative.
The mission is simple - collect all of the packages before the timer runs out. Each package is attached to a blue checkpoint, so it's simply a matter of passing through all the checkpoints. You're given 2'30 to manage all 26 checkpoints.
The practice of the mission is a little trickier than that. Unlike other checkpoint missions, the next-but-one checkpoint is not indicated on your map, so it's a case of memorising the route. After the first three checkpoints turn hard right, then take the next two and turn hard left, watching out for a little islet. Then it's simply a case of driving up the passage through Washington Beach, left at the junction, right at the next junction (between Leaf Links and it's tiny one-hole south island), around the west side of Leaf Links, into the inlet on your right and ending up in the same place as you did for Diaz's "The Fastest Boat" mission.
Mission Reward: $5000; Boatyard Asset Completed.