Trimaran ships are those that have three hulls: one main one, and two outriggers. The British and American navies are both involved in a joint experiment to develop this technology for use in future warships as part of the "Navy After Next" Program. Ships ranging from full-scale battleships to patrol boats are being designed and tested in computer wargames at the Naval Sea Systems Command.
Trimaran ships are able to operate in much stormier waters than conventional monohulls, and are also more stable, allowing more accurate targeting. The triple-hull layout offers better manueverability, increased speed and fuel efficiency (about 20%), as well as a decreased radar cross section. The outriggers on either side also help to absorb damage from torpedoes and shells, adding to ship survivability.
Live tests are being conducted by the RV Triton. Built by Britain's Defense Evaluation and Research Agency for $20 million, the electronics and sensors were donated by the United States Navy. The Triton set sail about two years ago, and has a crew of twelve, plus twelve scientists, and is also used for testing electronic propulsion. It is the world's largest powered trimaran, and has a top speed of 20 knots, a range of 3,000 nautical miles, and displaces 1,100 tons. One of the key purposes of the ship is to test the stress produced on the outriggers, so that the ship can be braced against damage.
One of the main ships considered by the US Navy, is known as the Leviathan. The ship would have electric motors that could propel all of its 25,745 tons to 32 knots. The ship is armed with twin rail guns, that can accelerate a shell (1 out of a magazine of 12,240) up to mach 10. Despite their smaller calibre size, each shell has the impact velocity of a 16-inch gun from an Iowa Class battleship. The energy necessary to fire only requires a decrease of speed to 30 knots. The Leviathan is also armed with missile systems, as well as unmanned aerial reconaissance/attack underwater vessels and aircraft for self-defense. All this manned by only 88 sailors and officers, with room for up to 142 special operations soldiers. The ship is powered by six gas turbines, each distributed throughout the vessel with flexible power routing, allowing the ship to remain powered after sustaining combat damage. The ship has a satellite linked network, allowing it to direct and control the operations of its entire battle group. It's hull also has an inner liner, providing underwater explosion protection against torpedoes and mines. Another innovative concept introduced in the Leviathan is side thrusters, known as azipods, on the outriggers. With the outboard thrusted pods aimed in opposite directions, the ship could rotate in place. Such manueverability is unavailable in current ships, and is especially useful in anti-submarine warfare. It would also allow the ship to dock in less developed ports, and without the aid of local tugs.
Another one of the ships that the Navy is putting a lot of time and thought into is called the Blue Knight. This is a considerably smaller ship that comes in both manned and unmanned variants. Blue Knights can be deployed by a Leviathan to act as both intelligence gatherers, and (when used en masse) as a fighting force. To save time and money, the Blue Knight uses the combat control and weapons systems of the RAH-66 Commanche. The computer, as well as the Stinger anti-aircraft missiles, and the Hellfire anti-ship missiles (anti-armor on land) are all staight from the Commanche. The Knight is also armed with Penguin anti-surface warship missiles, and a 30-mm cannon.
Also among consideration for the Coast Guard, as well as export to various US allies, are a trimaran frigate, and a trimaran corvette among others. Trimaran warships are still at least a decade down the road, and the first examples of trimaran hulls will probably be on troop transports and landing craft to gain the increased speed and survivability. The new DD-21 destroyer will come before the Leviathan to test some of the new concepts like distributed electric drive technologies. The trimaran design is not without drawbacks though. Among them are greater cost and weight, as well as decreased interior volume, and reduced fuel capacity. Below are some of the ships being designed and considered as part of the program.
Power: Diesel waterjet
Max Speed: 47.7 knots
Length: 132.6 feet
Beam: 56.0 feet
Weight: 129 tons
Weapons: 30-mm cannon and pop-up missile system.
Operating Sea State: 3(This refers to the sea roughness the ship can handle. The scale is from 1-5 with 5 being the greatest.)
Purpose: Manned and unmanned reconaissance and combat.
Max Speed: 30 plus knots
Length: 489.8 feet
Beam: 71.5 feet
Weight: 2,828 tons
Weapons: Multiple missile launchers
Operating Sea State: 5
Purpose: Advanced electronics warfare, drug interdiction, and law enforcement.
Max Speed: 30 plus knots.
Power: Generators and fuel cells
Length: 528.2 feet
Weight: 5,620 tons
Weapons: Missiles, medium calibre gun, torpedoes
Operating Sea State: 5
Purpose: Search and rescue, surveillance, and intelligence gathering.
Max Speed: 32 knots
Power: Electric and diesel
Length: 750.0 feet
Beam: 121.4 feet
Weight: 25,745 tons
Weapons: Two rail guns, missiles, up to 80 unmanned aerial and underwater vehicles.
Operating Sea State: 5
Purpose: Fleet combat ship
* This information was obtained from Popular Science's September 2001 issue.