The U.S. Navy has renewed its charter (lease) for the high speed (60 kilometers an hour) catamaran, the Westpac Express. The Australian built ship has been in use by the navy since 2001, to move U.S. Marine Corps equipment around the Pacific. In this it has been very successful, and this has served to prove the ability of such a catamaran design to serve in a military role. The navy is developing warships based on the same catamaran design. The navy also calls this ship HSV (High Speed Vessel) 2. The HSV is actually a small ship, 320 feet long and displaces 2100 tons. It can carry up to 800 tons of cargo and has airline style seating for 300 troops, although up to 600 can be carried. The cargo can include vehicles of up to 70 tons each, including M-1 tanks. Vehicles are driven on and off. There is a trade off between tonnage carried, and speed and range. The twin hull design is also slowed down quite a bit in rough seas. This is not the kind of ship you can use much in the north Atlantic or Pacific.