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Triton Trimaran

The Triton trimaran research ship was a technology demonstrator ship for the Royal Navy's future surface combatant (FSC)

Vosper Thornycroft

Gardline Marine Sciences

44 (14 civilian crew + 30 officers)

Gross Tonnage

Diesel electric propulsion

2 × Paxman 12VP185 2MW diesel engines

1 × five-bladed composite propeller

2 × 350kW electric side thrusters

The Triton trimaran research ship was a technology demonstrator ship for the Royal Navy’s future surface combatant (FSC) frigate requirement, due to enter service from 2013 and replace the Type 23 frigates. Triton is the world’s largest motor powered trimaran (triple-hulled) vessel, with a length of 90m and beam of 22m. QinetiQ (formerly DERA, the Defence Evaluation and Research Agency) funded the design and manufacture of the vessel, to be used to quantify the structural and seakeeping performance of the trimaran.

In August 1998, the UK Ministry of Defence (MoD) awarded a contract to Vosper Thornycroft to construct the Trimaran, called RV (research vessel) Triton. The vessel was launched in May 2000 and delivered in August 2000. Triton then began a two-year risk reduction trials programme for the UK MoD and the US Department of Defense.

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Following completion of the trials programme, Triton has been used as a trials platform for other QinetiQ technologies including the composite propeller.

In January 2005, Triton was sold to Gardline Marine Sciences, a UK company based in Great Yarmouth, Norfolk. Triton was used for hydrographic survey work for the civil hydrography programme (CHP) on behalf of the Maritime and Coastguard Agency (MCA). The vessel was fitted with a sensor suite which includes the Kongsberg Simrad EM1002 multibeam echo-sounder, a GPS attitude / heading system, surface navigation and ultra-short baseline sub-surface acoustic tracking system, Gardline Voyager5 integrated survey system and Caris post-processing system.

Triton was the launch vessel for the QinetiQ 1 programme to break the world altitude record for a manned balloon. The target altitude of 25 miles (132,000ft) would take the two pilots into the stratosphere.

The giant helium-filled balloon had a nine-acre area and was as high as the Empire State Building. An attempt on the record, in September 2003, was aborted after an 8m tear appeared in the helium balloon envelope during launch.

Triton has become a patrol vessel since it was chartered to the Australian Customs Service in December 2006. It has been deployed in northern waters of Australia to work along with other customs and Royal Australian Navy patrol boats.

The vessel has been modified to provide additional accommodation and also fitted with two 0.50-calibre machine guns to perform patrol operations. The vessel is also equipped with two 7.3m high-speed rigid hull inflatable boats (RHIBs). The boats are powered by Evinrude outboard motors and have the range of 200nm at 30kt speed. Following the modifications in the UK and Singapore shipyards, it was delivered to the customs in January 2007.

Trimaran hullform trials programme

The trials programme to determine the suitability of the trimaran hullform began in October 2000 and included operations in a variety of sea states and at differing speeds. Triton successfully completed replenishment at sea (RAS), structural loading and seakeeping trials, landing and take-off trials by a Royal Navy Lynx mk8 helicopter, towing operations and small boat launch and recovery. It also took part in trials with the US Coastguard. The trials were concluded in September 2002, successfully proving that the design could operate in exactly the same way as an equivalent mono-hull vessel.

Advantages of trimaran design

The advantages of a trimaran hullform over conventional mono-hulls are thought to be: reduced costs, reduced signature, significantly less drag increased speed, increased length, giving greater stability, and more room for the upper deck, which could be used for the flight deck as well as hangars for helicopters and extra armaments.

Applications

The Trimaran development has been driven by frigate type applications. Concept studies have been carried out for other roles including offshore patrol, concept studies for future vessel development – for example, the mini landing platform helicopter ship (mini LPH), fast roll-on / roll-off rapid deployment support ships, and air-capable stealth vessels.

Demonstrator vessel contruction

The demonstrator is built at two thirds the size of a full-scale warship and although not armed it is capable of carrying containerised Naval military systems at sea. The 90m length of the Trimaran demonstrator meets the structural constraints of the ship’s plating and longitudinal stiffening. The main hulls and bridge deck are of steel construction.

A comprehensive ballast system accommodates trials in various operating conditions. The structure will accept containerised trials equipment. The flight deck strength is to be rated to accommodate a Lynx helicopter and be capable of operating unmanned aerial vehicles.

Provision is made for future electric propulsion trials involving the installation of exchange permanent magnetic main motors, a battery/fuel cell compartment, and flight deck and engine room sites for at-sea tests of future gas turbine alternators. The demonstrator will accommodate integrated technology masts.

The engines exhaust between the hulls as a method of reducing the thermal signature of the ship. Low noise and radar signatures are achieved using commercially available materials and services.

Navigation and communications

The Triton navigation suite included Northrop Grumman Sperry Marine Bridgemaster E S-band and X-band flat screen radars with ARPA (Automatic Radar Plotting Aids), two Northrop Grumman (Litton) LMX400 GPS receivers, Furuno Loran-C receiver, Northrop Grumman electronic chart system and Skipper GDS 101 echo sounder.

Satellite communications systems include Northrop Grumman (Litton) INMARSAT SAT-C and INMARSAT SAT-M and Nera INMARSAT SAT-B.

Trials instrumentation system

The demonstrator had two laboratories. One laboratory housed the Trials Instrumentation System (TIS) which collected data including wind speed and direction, temperature, wave height and ship’s motion, with the other for general trials purposes. The TIS system can record over 400 channels of data at sampling rates of either 20Hz, 200Hz or 2,000Hz. All the data is time-stamped from a GPS sourced time synchronisation signal. TIS sensors include: Miros WAVEX wave height radar, TSK wave height radar, Trimble AGPS system, AGI windspeed and environmental monitoring system.

The propulsion system consists of two Paxman 12VP185 2MW diesel generators and two 350kW electric side thrusters with a single central screw. QinetiQ has replaced the fixed pitch propeller with a new composite propeller. The five-bladed composite propeller has a diameter of 2.9m. The use of the lighter composite allows for thicker blades which reduces vibration and consequently acoustic signature. Dowty Propellers manufactured the blades and Wärtsilä Propulsion the nickel aluminium bronze hub.

Accommodation

Accommodation for 14 civilian crew and up to 30 customs boarding party officers is provided in 48 berths. The other onboard features include a first aid centre, health screening and quarantine isolation area and secure holding areas.

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Iran Unveils Blueprint for its Planned Trimaran Destroyer

The Iranian navy plans to manufacture a home-made trimaran (with three hulls in parallel) destroyer named Safineh to be used in asymmetric coastal warfare and rapid reaction operations.

The blueprint of the heavy vessel (photo) which is 100 meters long and enjoys the trimaran technology was unveiled on Saturday, Fars News Agency (FNA) reported.

In addition, low hydrodynamic resistance in high speed and a floating propulsion system appropriate to the needed corresponding dimensions and speed are among other features of Safineh.

The warship also has a large deck, twice as big as a single-hull vessel of the same tonnage, and it can carry all types of helicopters operating in the Iranian Navy, including RH.

The trimaran vessel is still in the research phase in the Iranian Navy.

Last Saturday, Iran delivered its most advanced home-made destroyer, Sahand, to the naval forces in the Persian Gulf.

Sahand destroyer was launched in Bandar Abbas port city in a ceremony participated by Iran’s Army Commander, Navy Commander and Deputy Defense Minister.

The Iranian Navy announced late 2013 that it planned to equip its (then) under-construction Sahand destroyer with more advanced weapons and electronic war systems than its first generation destroyer, Jamaran.

“The first feature of Sahand is that its radar-evading capability has increased up to 30% and the form of its hull makes its detection by radars more difficult,” Head of the Self-Sufficiency Jihad of the Iranian Navy Rear Admiral Ali Qolamzadeh told FNA at the time.

He said that the volume of Sahand’s store, deposit and stock rooms had increased in a way that it could continue sailing distances twice farther than what Jamaran could traverse.

“Also the number of its radar and weapons system has at least been doubled and new electronic war systems have been mounted on it,” Qolamzadeh said.

He said that the Navy would also mount its new long-range phased-array radar system, named ‘Asr’, on Sahand if no newer radar system is made in the country until the destroyer is prepared for mission.

The destroyer is also able to journey across the faraway oceans for 150 days along with a logistic vessel. 

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Meet China’s triple-hulled warship of the future

A trimaran vessel with all-electric propulsion, multiple helicopters, and anti-ship missiles.

By Jeffrey Lin and P.W. Singer | Published Feb 23, 2017 9:44 PM EST

At the Dubai IDEX defense exposition, arms makers from around the world show off their latest wares. A notable debut at the recent 2017 show: a new, triple hulled Chinese warship design.

While showing off a model of the planned ship, China Shipbuilding Trading Company announced that it is aiming to start construction on a “trimaran” warship in 2018 for the People’s Liberation Army Navy (PLAN).

The Chinese navy already uses smaller trimaran ships for noncombat missions—think training torpedo recovery, search and rescue, and oceanographic research.

So what exactly are trimaran ships? The major distinction is they three hulls: one large, central one and two rearward smaller hulls connected by decks or girders. The design is used in the U.S. Navy’s new USS Independence subclass of the Littorial Combat Ship, and in fact the new Chinese ship looks very similar to that class.

The design means the ships have the advantage of a wider deck to operate more aircraft; this frigate design has a two-door hangar for helicopters and vertical take-off landing (VTOL) unmanned aircraft systems (UAS). Trimarans can also reach higher speeds, due to the reduced drag of having three hulls instead of a single wider one.

Heavy Firepower

The Chinese trimaran frigate will be about 465 feet long, and has a beam of 105 feet and a weight of 2,450 tons. Interestingly, it may be the first Chinese warship to use an integrated electrical propulsion system (IEPS) to provide the power for driving its three pumpjets. It is unclear if the announced 2,450-ton displacement is full or light.

USS Independence

If we’re comparing the vessel to the USS Independence subclass of the Littorial Combat Ship, the latter is designed as a high-speed platform, with a top speed estimated at 50 knots, which is faster than the Chinese trimaran frigate’s announced 30-35-knot top speed. The Chinese trimaran frigate is far more heavily armed for conventional warfare; the American ship mounts only a 57mm cannon plus provisions for anti-ship missiles while the Chinese ship boasts the capacity for a 76mm cannon, anti-ship missiles, and vertical-launching system cells for carrying anti-ship, land attack cruise and anti-air missiles.

That being said, the USS Independence offers the flexibility of changing out mission modules (such as between anti-submarine and mine countermeasure missions). This flexibility may be overstated, however, as both trimaran designs have wide decks for intensive helicopter operations, and the Chinese version also appears to have ample cargo spaces to embark maritime special forces and unmanned surface and underwater systems.

If built, the trimaran frigate would provide the PLAN with a high-speed, heavily armed warship for littoral operations in the East and South China Seas. It would likely serve as a complement to smaller Type 022 stealth missile boats and Type 056 corvettes; fast enough to keep up with them, and provide them with area air defense and helicopter coverage. Its space for special operations and aviation units also makes it a candidate for Chinese special operations in the littoral environment, and its speed makes it a good rapid-response unit to regional emergencies. Finally, its large carrying capacity could come into play as a heavily armed mothership and command center for Chinese drones, unmanned boats, and submarine robots. If the PLAN does buy this trimaran frigate, it’ll have a warship that will open up new places in high paced 21st-century naval combat.

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The Navy Test-Fired a Powerful Supersonic Missile From One of Its Tiniest Ships

Maybe Littoral Combat Ships are more impressive than we thought.

The radar was, curiously, an AN/TPQ-53 “Firefinder” counter-battery radar, used by the U.S. Army (and in combat by Ukraine’s ground forces ) to calculate the position of hostile ground artillery so as to launch retaliatory fire. Meanwhile, the non-descript grey container had the snooze-worthy designation Mark 70 Mod 1 Payload Delivery System.

But as it turns out, the boring grey box could enable the slight corvette to hold its head a little higher in the company of U.S. destroyers and cruisers bristling with powerful missiles.

The U.S. Pacific fleet announced last week that it had successfully test-launched its SM-6 supersonic missiles in the eastern Pacific to strike a “designated target” (seemingly, a surface target.) The container, therefore, may have carried up to four of the 6.6-meter-long missiles.

You can see the launch of one the missiles —which accelerates up to 3.5 times the speed of sound—in the video below.

Also known as the RIM-174 Standard Extend Range Active Missile (ERAM), the SM-6 is a highly versatile, long-range, radar-guided air defense missile (max 150 miles) equally capable of destroying sea-skimming cruise missiles, high-flying aircraft, and medium-range ballistic missiles.

But it also proved suitable as quick-reaction weapon against maritime or ground targets—so much so that the Army is actually putting SM-6s in modified Mark 70s to serve as ‘mid-range capable’ surface-attack weapons .

The SM-6’s Mach 3.5 speed makes it a challenging target for air defenses, and its active radar seeker should allow for the tracking of moving targets like ships or ground vehicles. Admittedly, its 140-pound warhead may be insufficient to ensure the destruction or crippling of larger warships , but a strike-optimized enlarged SM-6 Block 1B version is in development with longer range and hypersonic speeds (Mach 5+).

The SM-6’s speed and versatility is valuable, given the challenge of figuring out the right mix of air defense and surface-attack missiles to load onto a warship. That doesn’t come cheap—each missile costs nearly $5 million. But it’s much more powerful than any of the weapons a Littoral Combat Ship is designed to carry.

Ordinarily, integrating a new class of weapon unsupported by a ship’s existing launchers requires an expensive and time-consuming R&D program and installation, with costs easily running into the hundreds of millions of dollars.

Containerized missile launchers have recently grown in popularity as a way to rapidly deploy powerful weapons onto trucks, trains , or ships (military and civilian alike) without years of R&D and installation.

In a naval context, containerized missiles condense the engineering problem to making sure that the missiles works with the container launcher, the container is seaworthy and can be bolted onto a ship, and any wired and wireless connections can both link the container to the ship’s power supply and fire control and sensor systems.

Of course, containerization is not without complications and costs. For instance, it’s not as space efficient as missile cells penetrating into the decks of larger surface warships—an LCS with containers on its flight deck is one that can’t put valuable aircraft there instead. Containers may also impose performance deficits due to their electrical demands (competing with radars and perhaps future close defense lasers) and added weight. And while LCSs are designed for stealth, deck containers likely increase radar cross-section unless carefully situated and/or fitted with conformal paneling.

Still, there’s no denying that the Mark 70 enables a little LCS to (briefly) punch as hard as a much more powerful destroyer. Each of its four full-length missile cells can swing up from their horizontal position for vertical launch, and they are all compatible with any weapons used in the Mark 41 vertical launch systems of powerful U.S. destroyers and cruisers.

That encompasses a staggering range of weapons—long-distance Tomahawk cruise missiles , quad-packed RIM-162 Extended Sea Sparrow air defense missiles, SM-3 ballistic missile interceptors , and more.

It’s worth noting that the SM-6’s range likely exceeds that of the Savannah ’s SPS-77(V)2 Sea Giraffe radar, which is instrumented out to 110 miles and up to 66,000 ft. To fully leverage the SM-6’s capabilities, an LCS would likely receive target cueing or sensor data from another ship or aircraft with more powerful sensors (or one that has crept closer to the target).

The desire to simulate handing-off targeting data may explain the AN/TPQ-53 radar. Perhaps the test mission concept revolved around using the radar to detect an attack and pass on coordinates for a rapid counterstrike to be executed by the containerized SM-6s. Admittedly, the AN/TPQ-53’s instrumented range of 38 miles seems too short to be practical in a naval role other than coastal fire support. Perhaps it is seen as a good testing stand-in for more powerful alternatives used in an operational context.

Indeed, the combo of a TPQ-53 radar and Mark 70 container were previously spotted on the LCS Tulsa during the 2022 RIMPAC exercise—though further details about how they were used aren’t public.

Turning a new page for the Navy’s troubled Littoral Combat Ships?

The LCS program—intended to generate a fleet of two different types of small, cheap, fast, and stealthy multi-role corvettes—has long been beset by troubles with their hybrid-electric propulsion systems, modular mission payloads and crewing concepts. These have been issues to such an extent that the Navy has controversially decommissioned several rently-built LCSs because it didn’t want to pay the costs of sustaining them .

The problem is that the LCS program failed on two fronts—at achieving the cost-efficiency and versatility it was sold on, and by being comically ill-suited to the Navy’s strategic priority of preparing for a possible knockdown-drag-out fight with China’s powerful People’s Liberation Army Navy (PLAN).

Intended to skirmish with Iranian motorboats, LCSs were badly outgunned by China’s smaller Type 056 corvettes. Kyle Mizokame once simulated an engagement involving LCSs (armed with just 57-millimeter guns and Hellfire anti-tank missiles with a range of 7 miles) and Chinese corvettes (lobbing YJ-83 anti-ship missiles from up to 75 miles away). It went about as well as one would expect.

The trimaran Independence -class has had fewer problems, boasts a large flight deck supporting up to two helicopters, and will begin integrating specialized counter-mine warfare mission packages starting in 2025. Meanwhile, the Navy’s primary intended fix for the firepower deficit in LCSs is to install Naval Strike Missiles with an engagement range of 110 miles.

In any case, the LCS is far from the only platform on which the Navy is considering employing the SM-6. The first launch of an SM-6 from an Mark 70 involved the Ranger , an unmanned drone combat ship (USV) intended to help pioneer a potential future “ghost fleet.”

The Navy has also test-fired SM-6s from Mark 70s on trucks in Europe as an example of a rapid-deployable coastal defense capability.

Container madness and the hypothetical war over Taiwan

Why is the Navy tinkering with containerized missiles? Most likely, it’s thinking about ways to quickly and cheaply generate more long-distance missile shots in the event of the nightmare scenario: a full-on naval war defending Taiwan from a Chinese invasion.

A series of wargames simulating such a conflict by the CSIS think tank found that the results of such a conflict ground down to inventories of long-range missiles. The U.S. won, at great cost, when it had enough missiles that it could launch from relatively safer distances (300+ miles) to sink China’s amphibious landing ships. Closing to use shorter-range weapons proved suicidal due to China’s large missile arsenal—unless those weapons were delivered by stealth platforms like submarines or stealth jets.

While an LCS is stealthy for a warship, it would remain at extreme risk if it tried to close within range to employ even Naval Strike Missiles. But, under certain circumstances, slapping down container launchers on their flight decks could allow these craft to contribute useful ship-sinking shots from hundreds of miles away in a fight dominated by much bigger destroyers carrying around 100 missiles each.

The Navy is keen on ‘distributed firepower’ as of late, so it can avoid losing too many eggs per basket (ie. destroyer) hit with a hostile missile. In a wartime emergency, slapping containerized missiles on anything that floats could represent a quick and dirty way to achieve distributed mass without the years needed to build lots of costly, dedicated warships.

Indeed, the possibilities for containerized missiles go far beyond LCSs—think amphibious carriers, drone ships, or even militarized civilian container ships.

An operational concept could see destroyers, with their powerful radars, anti-air defenses, and anti-submarine defenses, screening an otherwise vulnerable squadron of arsenal ships loaded with missile containers. The destroyers, along with the air- and sea-based surveillance assets, could relay firing data to the ‘blind’ arsenals ships to launch missiles en masse at enemy targets.

Slower (but very stealthy) LRASM anti-ship stealth missiles and cheaper, very-long-range Maritime Strike Tomahawks—both with big, ship-sinking warheads—may better fit the job than pricy SM-6s. However, the forthcoming strike-optimized SM-6 Block 1B could represent an attractive alternative.

Despite the possibilities opened up by missile containers, there are many technical and operational issues to resolve. For example, the questions of how and where the containers could be repaired and replenished remains. Furthermore their reliability, their durability at sea, and the integration of their connecting power and control system cabling into ships must all still be stress-tested.

This likely explains Savannah ’s test of this powerful capability. If the Navy is enticed, more such containerized test shots are likely follow—potentially involving additional types of ships and munitions.

Sébastien Roblin has written on the technical, historical, and political aspects of international security and conflict for publications including 19FortyFive, The National Interest, MSNBC, Forbes.com, Inside Unmanned Systems and War is Boring. He holds a Master’s degree from Georgetown University and served with the Peace Corps in China. You can follow his articles on Twitter . 

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• Environment

The Chinese navy, currently the biggest in the world by count of warships , just keeps growing. Meanwhile the US Navy – the world’s second most numerous fleet – is struggling to grow at all, to say nothing of getting bigger fast enough to keep pace with the Chinese fleet.

And there’s one major reason why. The USN spent 15 years pouring billions of dollars into buying, though seldom deploying, a numerous class of fast, shallow-water warships that it has now decided are too fragile, too unreliable and too lightly armed for a major war.

Today the US Navy is decommissioning barely-used Littoral Combat Ships as fast as the newest vessels in the class, having been paid for years ago, belatedly come into service. It’s the military-industrial equivalent of treading water. 

But American fleet leaders know they have a problem. They know they must find some way to make the majority of the $500-million-apiece LCSs useful in a major war. If the ships are actually useful, the fleet might be able to justify keeping them for their full 25-year planned service lives instead of prematurely sending them to the breakers. 

Retaining a couple of dozen LCSs through the 2030s and 2040s should help the fleet jumpstart its long-stalled plan to grow from today’s 290 front-line warships to 350 ships in two decades or so. The Chinese navy would still have more ships, overall, but the American navy might take comfort in the likelihood that its own ships would be bigger and more heavily-armed, on average.

The LCS program originated in the 1990s and began spending real money, and building ships, in the early 2000s – an era where land warfare dominated Pentagon planning. The idea was to equip the US fleet with 50 or more vessels that could move fast in shallow, near-shore littorals. Their weaponry would be light; in the place of heavy missile batteries, they’d have drones.

American naval leaders bizarrely chose to pay two different companies – Lockheed Martin and Austal USA – to each build their totally different LCS designs, both around 400 feet long. The Lockheed design, based on a huge luxury yacht, had a single hull. The Austal design was a three-hull trimaran.

Both LCS types turned out to be more expensive and more complex than the US Navy anticipated. And the Lockheed version also suffered serious problems with its complex engines. Perhaps more seriously, fleet leaders soon regretted their decision to omit heavy weaponry from the lightweight vessels. 

Unlike a destroyer or cruiser, an LCS cannot fire long-range missiles at enemy ships or ground forces; it can’t shoot down incoming enemy missiles from a hundred miles away. An LCS depends on other, better-equipped ships for protection from a high-tech foe.

In a major war with China, the LCSs would be a costly liability. So it came as no surprise when, starting around a decade ago, the US Navy first cut back on the number of LCSs it planned to buy, and also began decommissioning the oldest ships in the class – even though none were more than 15 years old. That’s young by naval standards.

Today the LCS class numbers 35 ships either in commission or under construction. Nine have already decommissioned , or should do so next year. While the class shrinks, some admirals and captains are doing their best to make the remaining ships work.

They’re adding containerized anti-ship missiles and air-defense missiles, organizing better maintenance and support practices and developing new tactics that could see some LCSs sail independently at the forward edge of larger fleet formations, sticking close to shore in order to hide from enemy forces.

The Austal-built trimarans, which have proved more reliable than the Lockheed-built monohull LCSs, benefit the most from these developments. And it’s these ships the US Navy is pushing forward into the western Pacific, where a naval war with China is a real possibility.

Admiral Sam Paparo, commander of the US Pacific Fleet, set a goal of deploying at least six LCSs into the western Pacific at the same time by 2025. His sailors achieved the goal two years early. “That’s a Herculean effort,” Paparo told reporters in early November.

Around the same time, the US Navy was wrapping up a major test that added the fleet’s best multi-role missile – the Standard Missile 6 – to a trimaran LCS by packing the missile into a metal box and bolting it to the ship’s large helicopter deck. Cued by radar, an SM-6 can hit ships, aircraft, missiles and even targets on land from a distance of at least 130 miles.

The improvised SM-6 armament is inefficient. US Navy destroyers fire SM-6s from vertical cells that take up minimal deck space; that’s why a destroyer might carry nearly 100 missiles like the SM-6. An LCS might be able to carry just a few SM-6s before the missiles, which are stored horizontally before they’re fired, make it impossible for the ship to launch and land its helicopter.

Which might be why American fleet leaders aren’t committing to a sweeping rearmament of the trimarans. Instead, the SM-6 test “will inform continued testing, evaluation and integration of containerized weapons systems on afloat platforms,” the US Navy stated. 

The test is at least evidence that the US Navy is serious about doing something to make its dozens of LCSs useful in a major war. If the effort fails, the American fleet might decide to cut its losses, decommission the under-armed ships despite many of them being practically brand new – and accept that the cuts prevent the fleet from growing for several years.

Meanwhile the Chinese navy is growing by a dozen or so ships a year.

The post The US Navy’s hi-tech war trimarans are finally going up against China appeared first on The Telegraph .

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Research into trimaran hullforms exploited in novel ship designs by commercial and naval shipping

Submitting institution, unit of assessment, summary impact type, research subject area(s).

Engineering:  Maritime Engineering

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Summary of the impact.

A number of trimaran ocean-going ships, based on original designs conceived by UCL researchers, are currently in use. RV Triton , the demonstrator trimaran, is presently employed as a patrol vessel to provide Australian Customs and Border Protection with increased capability and lower fuel consumption compared to a monohull. The Independence Class of littoral combat ships currently entering service in the US Navy offers improved military capability and one-third lower fuel consumption, with the ensuing benefit of creating almost 2,000 jobs at the shipbuilder, Austal. Similarly, trimaran ferries with their inherent stability have improved passenger comfort and their reduced fuel consumption has lowered operating costs.

Underpinning research

Research at UCL into trimaran hullforms for ocean-going ships was initially stimulated through examining trimaran performance in smaller vessels, notably yachts e.g. America's Cup and powerboats e.g. Ilan Voyager , which won the coveted `Round Britain Speed Boat' record in 1990. UCL developed the ocean-going trimaran ship concept and led research activities in this field from initial concept through design, computational and experimental research and analysis of ship trials, along with contributions to a Classification Societies Ship Design Rules.

The university received its first funding for this work in 1993 and the first study of trimaran ship design demonstrated real advantages over monohull ships in the areas of layout, survivability and powering. The trimaran consists of three parallel slim hullforms joined using a cross-deck structure rather than a single wider monohull. Research at UCL demonstrated, through a series of computational and experimental research studies, that the trimaran hullform offers lower resistance at high speeds and a wide deck area. Further ship research had a specific focus on exploring naval architectural characteristics of the configuration, such as stability and roll characteristics [1]. The concept was then taken up in the UK Ministry of Defence (MoD) with a major design study that involved an extensive programme of experimental and design research centring on a scaled 6-metre trimaran model of a 3,000-tonne destroyer, designed at UCL and tested at the Haslar Towing Tank (see references included in [2]). The results of this experimental research work were considered sufficiently promising for the Defence Evaluation and Research Agency (DERA) to build an ocean-going two-thirds-scale Trimaran Technology Demonstrator. The demonstrator, named Research Vessel Triton , was principally built to de-risk the structural design. However, it was heavily instrumented to provide data on motions and sea-keeping performance too. Ultimately it was critical to the procurement process considering whether the new trimaran configuration could provide better value for money than the conventional monohull for the Royal Navy's Future Surface Combatant.

RV Triton was built by Vosper Thornycroft, Southampton, UK in 1998 and accepted in 2000 when it commenced an extensive series of trials for design and operational performance, e.g. sea-keeping and helicopter operations. The project included UCL evaluation to compare actual and predicted performance and substantial US Navy involvement such as to monitor structural bending [3]. Also around this period research was undertaken at UCL to explore the challenges of marine engineering the trimaran hullform. High-power propulsion plants are needed for trimarans and whilst these are straightforward to fit into wider-bodied monohulls, the trimaran's narrower centrehull makes installing these a far more challenging issue, if the advantage of increased efficiency offered by the slimmer hullforms is not to be compromised [4].

To initially size a trimaran vessel at the start of preliminary design, it is necessary to determine practically all the principal form parameters. Once the form parameters have been obtained the designer can be reasonably confident that the initial default hull parameter values will only need refining beyond the initial sizing. The degree of that commitment differs substantially from monohull vessels, where it is possible to delay full parametric selection because there is a large historical database upon which to draw information. UCL has published a comprehensive description of the preliminary design of a trimaran vessel i.e. the 5000-tonne Trimaran Destroyer, for which the DERA Haslar 6m model tests were conducted [2].

Further work in trimaran research was funded through an Office of Naval Research (ONR) initiative. The Atlantic Center for the Innovative Design and Control of Ships (ACCeSS) was founded in 2002 to establish an academic environment where engineering disciplines associated with novel hull design and ship automation could be brought together within the context of the total ship system architecture. The academic partners in ACCeSS ( http://www.stevens.edu/access ) are many USA universities, UCL (the only UK partner) and industry. Importantly, the partners include the Davidson (High Speed Tow Tank) Laboratory and US Naval Academy (Large Tow Tank), Annapolis. The consortium worked with NSWC Carderock on the design, testing and technology development for trimaran hullforms. As part of ACCeSS research activities further research was undertaken on two trimaran models — one large and one small. Specific areas of research addressed were parametric resonance (the interaction of waves with hullform) and side-hull positioning i.e. the relative location of the smaller sidehulls to the centre hullform. The findings were passed into ONR to support US naval interest in trimarans, which was gathering pace with the building of the littoral combat ship. Collaborative research was carried out in several areas, with UCL primarily involved with trimaran resistance characterisation obtained through experimentation in tow tanks, stability analysis including parametric roll and the development of design tools for comparative analysis [5] and [6].

To assist with the work undertaken in the USA, ONR supported sabbaticals (Drs Greig and Bucknall) at the Davidson Laboratory and through an EPSRC award `Trimaran Resistance Studies' for Visiting Researcher at UCL (Prof R. Royce, Webb Institute) and later a Royal Academy of Engineering (RAE) Global Research Award to Dr T.P. McDonald.

Key researchers

Professor David Andrews — Professor of Naval Architecture 1993-98 (subsequently Professor of Engineering Design 2000 to date) Professor Richard Bucknall — Professor of Marine Systems 1995-present Professor Douglas Pattison — Professor of Naval Architecture 1989-93 Dr Alistair Greig — Senior Lecturer 1987 — present Dr J W Zhang — Lecturer (deceased), 1996-2004 Dr T.P. McDonald — Post-doctoral Researcher 2010-12 Dr T Grafton — Research Assistant 2003-2007

References to the research

References [1], [2] and [5] best indicate research quality.

[1] Pattison, D.R. and Zhang, J.W.; `Trimaran Ships' Transactions RINA, Vol 137. (1995). Available on request.

[2] Andrews D.J.; Chapter 46 `Multihulls', Ship Design and Construction (Ed. T. Lamb) SNAME, New Jersey. (2004). Available on request. Volume II: ISBN-13: 9780939773411

[3] Greig, A.R. and Bucknall, RWG; `Marine engineering the Trimaran hull form — Opportunities and constraints'. Proceedings of the IMarEST vol 110 (3), p. 181 — 193. (1998). Available on request.

[4] Royce, R; Jianjun, Q; Waters, J; Bucknall, RWG; Greig, A; Smith, T.; `Facility Comparison on Model Calm Water Resistance Characteristics of the Trimaran'. American Tow Tank Conference, Washington, (2010). Available on request.

[5] McDonald, T.P.; Rusling, S; Greig, A.R.; Bucknall, R; `A Comparative Study of the US Navy Littoral Combat Ship', Proceedings RINA Intl. Conf. Design and Operation of Trimaran Ships, London (2004). Available on request.

[6] McDonald T.P; Bucknall R.W.G and Greig A.R. `Comparing Trimaran Small Waterplane Area Center Hull (TriSWACH), Monohull and Trimaran Hullforms: Some Initial Results', Journal of Ship Production and Design, Vol 29 No 4 (2013). http://doi.org/p3b

The ongoing design challenges and applications for trimaran research have been met with continuous support from industry (MOD (FBG) 2002, US Office of Naval Research 2003 ($58k), TMC LNK SSA 2003 £110k, MOD (NDP) 2009 £7k, MOD DESH/EPSRC CASE 2010 (£89k), ACCeSS 1 Funding from ONR ($390k), ACCeSS 2 Funding from ONR (£200k), together with EPSRC (EP/G033846/1) and RAE travel grants.

Details of the impact

The global impact of research undertaken in trimaran ships by the Marine Research Group at UCL over the past 20 years, which influenced Classification Design Rules for Trimaran Ships, can be identified in the period 2008-13 by considering how RV Triton has been adopted as a tropical patrol vessel and the building of new trimaran ships, notably the Independence Class of littoral combat ships for the US Navy [f] and the introduction of a new trimaran-variant car ferry.

As described in Section 2, initial research into ocean-going trimaran vessels was undertaken at UCL with a focus on structure, form, seakeeping, resistance, and propulsion arrangements. This led to the building of a research vessel RV Triton, which was sold in 2002 after having completed extensive trials. Over the past 5+ years it has been used by the Australian Customs and Border Protection Service (ACBP) as a coastal patrol and fisheries protection vessel on the northern tropical coast of Australia. ACV Triton was refitted with additional accommodation, a more powerful propulsion plant, and a command and control centre which was easily facilitated within its trimaran hullform, which itself remained unchanged. Triton was selected over alternative equivalent monohull vessels for the patrol role because the trimaran hullform that UCL designed offers lower resistance, improved sea-keeping and improved larger upper deck area, which enhances operational capability. These advantages manifest themselves in achieving a superior range and improved fuel economy resulting from its inherently lower resistance; higher operating speeds which is important to the ACBP since the ships are used to catch smugglers; and its large working deck area which allows for multiple operations of helicopters and boats. Overall, the impact of using a trimaran in this role has provided enhanced capability at lower fuel consumption and reduced emissions over similar sized monohull or catamaran vessels [a].

At the end of the Cold War the US Navy determined a need for new ship types to combat asymmetrical littoral (close to shore) threats and the littoral combat ship (LCS) concept was born. In 2010, Austal's USS Independence was the first modular high-speed trimaran LCS to be commissioned into the US Navy; this was followed in 2012 by USS Coronado, a second trimaran vessel of similar design that completed trials in August 2013. Four more trimaran Independence Class vessels have been ordered since 2008, including USS Jackson , construction of which began in 2012 [d], and eventually a fleet of 20+ LCS trimaran vessels are expected [b]. An important economic benefit of the trimaran LCS programme has been to support jobs at Austal in Alabama, USA, which has been able to double its workforce to 3,800 [e]. In 2010, the Navy awarded Austal a $432-million contract to build a trimaran LCS, with a further $681-million contract for two more ships awarded in March 2013 [b, c].

The trimaran Independence Class LCS design has been tested thoroughly by the US Navy and shown to provide significant benefits to naval operations, including the largest usable payload volume per tonne of ship displacement of all US Navy surface combatants, a large flight deck that has facilitated near simultaneous operation of two helicopters and proven capability of operating the large H-53 helicopter, and operations of multiple unmanned vehicles for reconnaissance and warfare operations. The increased stability of the trimaran hullform has improved flight operations by allowing them to be achieved in higher sea-states than equivalent-sized monohulls and catamarans. Other operational benefits result from the ability of the trimaran configuration to effectively decouple the resistance/powering from the stability relative to an equivalent monohull which can yield a reduction in resistance at higher speeds. The subsequent reduction in the vessel's full-speed power requirements allows a corresponding reduction of around one-third in both fuel consumption and associated emissions [c]. Chief of Naval Operations Adm. Gary Roughead praised the Navy's plan to add both ship designs to the fleet [2010]: "The LCS is uniquely designed to win against 21st century threats in coastal waters posed by increasingly capable submarines, mines and swarming small craft. Both designs provide the capabilities our Navy needs, and each offers unique features that will provide fleet commanders with a high level of flexibility in employing these ships." [c]

The trimaran concept is also useful for commercial vessels: the trimaran ferry Benchijigua Express entered service in 2005 and has been successfully used to carry cars and passengers between the Canary Islands throughout the REF impact period. The design of the ferry, also built by Austal, draws on the experimental results UCL obtained from its role in the development of RV Triton [h]. In common with other trimaran designs, the reduced resistance resulting from its three slender hullforms means the ferry uses much less fuel at its high speed (40+ knot operation) when compared to an equivalent-sized catarmaran or monohull, which confers an important advantage in the competitive ferry market [i]. Benchijigua Express ferry's improved stability also ensures a softer roll, enhancing passenger comfort. Auto-Express , the second generation of trimaran passenger ferries launched in 2012, offers further benefits still. The improved design has resulted in an increased waterline length providing improved internal volume and a speed of 39 knots [g]. According to the Head of Research and Development at Austal: " The trimaran offers greater speed for the same cargo weight and the same power compared to a monohull and a catamaran. It's got better passenger comfort, by which I mean less sea-sickness. It's got a better sea-keeping ability — able to operate in higher sea states ... The power consumption is reduced about 20% when operating in a seaway compared to a catamaran...and reduced by as much as 50% when compared with a monohull operating in waves..." [g].

The rules governing the design of ships (naval and commercial) are predominantly the responsibility of national Classification Societies such as Lloyds Register (LR) for UK. New Classification Society Rules for Trimaran Ships were developed in 2004, with UCL involvement and drawing on expertise developed during the research described in Section 2. Since 2008, the Marine Research Group at UCL has been assisting LR with the approval of new rules governing naval vessel designs including structure and propulsion, thereby providing the foundations that enable ship builders to offer trimaran ships to their customers. Transfer of specialist advice based on our research has been effected via Professor Bucknall's provision of expertise into the LR Naval Rules Technical Committee, of which he is a member [i].

Sources to corroborate the impact

[a] Benefits of RV Triton to Australian Customs and Border Protection Service: www.customs.gov.au/webdata/resources/files/NorthernPatrolVessel-ACVTriton.pdf

[b] Award of $681-million contract to Austal http://gcaptain.com/us-navy-awards-four-new-lcs-contracts/

[c] Quote from Chief of Naval Operations on how the LCS meets the Navy's needs, and $432-million contract award: http://gcaptain.com/littoral-combat-ship-contract/

[d] Corroborates orders of Independence Class LCS: www.naval-technology.com/projects/littoral/

[e] Doubling of Austal's US workforce: http://gcaptain.com/navy-places-order-austal/

[f] Senior Project Manager, Office of Naval Research, USA, can corroborate that UCL's research contribution and specifically the work of the ACCeSS group has contributed to the wider knowledge base that has enabled the development of the trimaran LCS warships. Contact details provided separately.

[g] Quote from Austal about benefits of trimaran ferry: http://bit.ly/GCOYvA [h] Confirmation that Austal's ferry development drew on UCL's results from RV Triton in "Coming soon to a port near you: the 126m Trimaran", The Naval Architect p78, September 2004. Available on request.

[i] Technical Director of Austal, Australia can confirm UCL's trimaran's research has contributed to the development of the commercial ferries and the benefits thereof. Contact details provided separately.

[j] Head of Strategic Research and Technology Policy, Lloyds Register, UK, can corroborate UCL's ongoing involvement with developing design rules. Contact details provided separately.