Scale Up Stealth Trimaran for New US Destroyer

In "Clad in controversy" (IEEE Spectrum, August 2013), Drvis Schneider discusses the  new technology in the US Navy's first Zumwalt Class Destroyer, currently under construction. At 14,798 t, this is considerably larger than the Arleigh Burke-class destroyers (9,800 t) it was intended to replace. Controversial features of the Zumwalt-class include a  tumblehome hull for stealth, two long range Advanced Gun Systems, an 80 cell Peripheral Vertical Launch System and a deck-house made of a carbon fiber/balsa-wood sandwich. Perhaps most controversial is the purpose of the ship, which is for bombardment of the shore, in effect being a replacement for battleships.

The tumblehome hull slopes inwards to reflect radar signals up and away, making the ship more stealthy. But this may also makes it more unstable. The two advanced gun systems are designed for shore bombardment over 100 km, but this required design and development of a new gun and ammunition, unique to the Zumwalt Class. Such gun systems have in the past taken decades to work reliably (if ever). The launch cells for missiles will be placed around the periphery of the ship rather than as a cluster in the center as is usual. This is to ensure than a hit on one missile will not destroy the ship, but such a design is harder to engineer and maintain. The carbon fiber and balsa-wood sandwich deck-house is expensive to make and maintain may be a problem (later ships may revet to steel).

A better alternative might be a vessel about the same size, or smaller than current destroyers, with just one main gun and about 48 launch cells. An example of this is the Hobart class destroyer for the Royal Australian Navy. At 6,250 t this is half the size of the Zumwalt-class, but with With guided munitions the smaller ship's gun would have the same range as the Zumwalt. The Hobart class has a conventional hull and a radar reduction deck-house of conventional welded metal. About three Hobart class destroyers could be built and operated for the cost of one
Zumwalt-class ship.

For a more stealthy vessel the Australian designed Independence-class littoral combat ship could be scaled up from 2,307 t, to destroyer size. These ships have a partly tumble-home hull-form, but gain stability by being a trimaran. The hull and deck-house is made of conventionally welded metal, with no carbon fiber or other exotic material, so is cheaper and easier to build. The trimaran design results in a very large flight deck, with a reconfigurable area underneath. The interchangeable mission modules (fitted in standard shipping containers), already developed for the LCS, could be reused in a larger destroyer version.

Offshore Combatant Vessel

Australian Defence project SEA 1180, proposes to replace patrol, mine and survey ships with one design of "Offshore Combatant Vessel" (OCV). Containerized equipment would be placed on the ships temporarily to suit the mission. The obvious design for this would be the Austal Multi Role Vessel (MRV 80). This is a trimaran, which looks like a patrol boat at the front and a car ferry at the back. The proposed MRV 80 is about 50% longer and heavier than the current Armidale class patrol boa,. Due to the trimaran design the MRV 80 is twice as wide as the patrol boats, providing room for a helicopter flight deck and hangar, as well as 500m2 of covered space to accommodate cargo, vehicles, or containerized equipment.

The MRV 80 resembles the US  Independence class littoral combat vessel from the same designers. But the MRV 80 is smaller and leaves out the high tech weaponry and complex systems of the LCS.  The LCS has a stern door for launching boats and sensors at sea, with a side ramp for loading equipment in port. In contrast the MRV 80 has boats stored in open areas on each side and a stern ramp for loading equipment. The stern ramp is based on a proven design used on car ferries and might be used to launch sensors at sea and transfer cargo while underway, as well as in port.

Littoral Combat Ship Mission Modules

The USA's two designs of Littoral Combat Ship (LCS) look very different. The Freedom class is a monohull ship, whereas the Independence class. is a trimaran (designed by Australian shipbuilder Austral). The ships were in a competition from which one was to be selected, but the US Government decided to acquire both types. The Freedom is smaller and more suited to short missions, whereas the Independence is larger with longer range. The cost and complexity of acquiring two different ship types is lessened by using a common set of interchangeable Mission Modules. The modules are shipping container sized units, with standard electrical, cooling and data interfaces, holding anti-submarine, mine warfare or other equipment. Also accommodation modules can be used for extra personnel. There is an "Interface Control Document" (ICD) defining the hardware interface between the ship and module (such as how much 440VAC 60Hz 3 phase electrical power is available) and a "Interface Design Specification" (IDS) defining the data communications interface (including use of CORBA). In theory, much of the cost and complexity of the ships is thus in the modules. Also it would be possible to change the ships for different missions, but this is proving problematic in practice. One interesting aspect of the mission modules is their use of Linux software. This opens the possibility of creating new modules with commercial off the shelf equipment. The modules could also be used in other ships, including civilian vessels pressed into service for military use. Rather than use the exact specification of the USA's LCS mission modules, a more flexible approach could be used with a blend of commercial and military interfaces. As an example, the same interfaces used for networking separate military platforms, such as ships, aircraft and vehicles, could be used to interface the mission modules. The fact that the modules where physically next to each other within a ship would not stop the use of the same networked interfaces as would be used if the modules where on independent ships, aircraft or vehicles. The ship would simply act as a way to house and transport the modules. Australia has acquired and on order several amphibious transport ships with generous space for ISO sized modules. In his 2006 thesis for the US Naval Postgraduate School, Aykut Kertmen carried out an "EVALUATION OF THE LITTORAL COMBAT SHIP (LCS) POTENTIAL FOR THE TURKISH NAVY", including likening the mission modules to Lego. The company Sea Bos, offer a "Mission Module Container", which is essentially a standard ISO shipping container modified for military use. In place of the usual double doors on the end of the container, it has two bi fold doors, making access easier on board ship. There is also a side door for personnel and an additional door opposite the cargo doors. The container has raceways in each top corner for cabling. The container is also fitted with insulated walls and air-conditioning. The walls, ceiling and floor are fitted with a rail system for installing equipment racks. Lastly teh container is painted standard military grey. Integral refrigerated ("reefer") ISO containers have a standard power connection defined by ISO 1496-2 and can have a microprocessor for controlling temperature and communicate with the ship via a data sent over the power line using the ISO 10368 Standard. As these standards are in widespread civillain use, they may be of value for adoption for military modules.

Stern Landing Vessels for Australian Military

Sea Transport Corporation has proposed a militarized version of their Stern Landing Vessel (SLV) for use as a heavy landing craft for the Royal Australian Navy (RAN). The SLV design has been used for civilian passenger ferries. The vessel has a conventional "V" shaped bow at one end and a ramp at the other. This way the ship can travel efficiently in heavy seas and need only back into the beach to unload.

The 65m vessel depicted would have a payload of 400 tons for the ADF Landing Craft Heavy Replacement (Phase 5 t JP 2048 Phase 3 of Amphibious Watercraft Replacement). The 2000Kw propulsion would give a speed of 15 knots and range of 2600 n miles with 83T fuel. This is about twice the capacity and speed of the current Balikpapan class LCH (Landing Craft, Heavy), over a similar range.

The SLV design has an open vehicle deck, typical of military landing craft. However, landing craft of the RAN tend to be used for general duties and rarely for beach landings. It might therefore make sense to build them with a covered vehicle deck. There would be space for a passenger deck behind the bridge (as with the JHSV) and a medium sized helipad above the rear vehicle deck. This would restrict the view from the bridge when beach landing, but video cameras could be used, along with large format high resolution flat screen displays to provide virtual windows on the bridge (also providing some protection for the crew).

The covered vehicle deck would be able to hold ISO shipping container sized equipment modules, as used on littoral combat ships. This would make for a versatile general purpose ship.

Common electronic system for multi-hull Australian warships

In Naval Systems (Proceedings of the US Naval Institute, June 2009) Edward J. Walsh describes the electronic core mission system to be used on the Australian designed USN Navy littoral combat ship Coronado (LCS-4). The Coronado will be the second trimaran LCS for the UN Navy, following the USS Independence (LCS-2), which began sea trials recently. He reports at a simplified version of the same electronic system will be used for the Joint High Speed Vessels (JHSV). The JHSVs are designed by the same Australian company, Austral, as the LCS-2 and LCS-4.

Austal are using a similar trimaran hull for the lower cost Multi-Role Vessel and so the same core mission system would be an option for these vessels. If the MRV was purchased by Australia, that would provide some commonality with UNS systems, as well as between different classes of Australian ships.

The Austral design for the LCS is competing with the Freedom class mono hull design by Lockheed Martin. The Israel Navy has abandoned plans to acquire Freedom class ships and is now reported to be looking at the more conventional German Kedah class ships, as used by Malaysia.

Australian Offshore Combatant Vessels

According to "Navy the Big Winner - but but when" (Kym Bergmann, Asia-Pacific Defence Reporter, May 2009), the Australian Government has decided to rationalise the Navy's patrol boats, mine counter measures, hydrographic and oceanographic vessels into one class of twenty "Offshore Combatant Vessels". These will be larger than the current patrol boats, at up to 2,000 tonnes. This would appear to be the role the Austal Multi-Role Vessel was designed for. The MRV can be thought of as an Armidale patrol boat welded onto the front of a Joint High Speed Vessel (JHSV), making a lightly armed trimaran which can also carry containerised loads and operate a helicopter, or even a F-35B.

Austal Multi-Role Vessel

Austal have proposed a long range, high speed, patrol ship called the Multi-Role Vessel (MRV). This is essentially the Independence-class littoral combat ship (LCS), which was designed for the US Navy, but with the expensive weapons and electronics removed to make a lower cost, long range multi-purpose ship for military and policing purposes.

The MRV is a trimaran with one large hull in the middle and two outriggers. This gives a wide area accross the three hulls at the rear for cargo and a large helicopter flight deck on top. The wider hull projecting at the front provides good sea keeping and space for weapons and sensors. The slim outer hulls allow for high speed.

The Austal Multi-Role Vessel can provide offshore and littoral war fighting roles, border protection tasks, long range counter-terrorism and counter piracy operations, support to special forces and missions in support of security and stability in the immediate neighbourhood surroundings.

The Austal Multi-Role Vessel (MRV) utilises the unique and proven Austal Trimaran platform coupling high speed and superior seakeeping performance with unparalleled deck space.

From border patrol to ASW to humanitarian relief missions the Austal Multi-Role Vessel (MRV) is the truly reconfigurable seaframe.

See Also:

• Austal Trimaran Technology Brochure
• View the Multi Role Vessel Image Gallery
• Austal Defence News - July 2008
• Austal Defence News - March 2008
• Austal Defence News - May 2007

Features

Multi-mission helicopter capability
Large flexible mission / logistics deck
Open architecture systems network
Systems packaged mission modules

• EEZ border patrol
• Command & control
• Surveillance
• Humanitarian support
• Theatre hospital
• At sea replenishment
• Force transportation
• Special forces support
• Amphibious operations
• SAR
• ASW

From: Multi-Role Vessel, Austral, 2009

Australian design selected for US Military Transport Ships

The design from West Australian based Austal has been selected by the US Department of Defence for the Joint High Speed Vessel (JHSV), worth around US$1.6 billion, if all ten ships are built. The aluminium 103-metre ship design is derived from that of Austal's car ferries, one of which, the “WestPac Express” was leased to the US Marines. Austral's main rival is also Australian: Incat of Hobart, who have also leased ships to the US military. One reason for Australia's success in building such ships is expertise in welding aluminium.

The JHSV ships will be built in Mobile, Alabama, USA, not in Australia. These vessels are likely to be less controversial than the Littoral Combat Ship, USS Independence (LCS 2), being completed by Austal. The Independence was due for sea trials in early 2009. But both it and the competing design from Lockeed Martin (USS Freedom LCS1) have had problems with delays and cost overruns. See: "Checkered Past, Uncertain Future" By Commander Otto Kreisher, U.S. Navy Reserve (Retired) in Proceedings U.S. NAVAL INSTITUTE, January 2009.

Unlike the complex weapons and sensors used in the LCS ships, the JHSVs are more basic conversions of civilian transport ship design. Also the role of the transport ships is less controversial. This raises the interesting possibility of using the JHSVs for some of the roles envisaged for the LCSs.

The LCS are designed to use removable "mission modules". These are typically housed in ISO shipping container sized units loaded onto the ship as required. Some of these modules contain off board sensors and weapons, such as UAV helicopters and some the control consoles. Such containers could easily be accommodated in the JHSV's large interior . Modern computer technology may make much of the mission modules unnecessary.

Modern sensors and weapons can be controlled from ordinary laptop and desktop computers, with no need for specially designed operator consoles. Therefore the ships could be equipped with general purpose computer consoles which could be used for whatever sensors or weapons were placed on board. In other cases the operators of the modules could arrive carrying the laptops needed to operate the equipment.

The JHSV's are designed for roll-on/roll-off operation with a rear ramp allowing large articulated trucks with shipping container sized units to drive on board.

Equipment designed for field use by the military could therefore be driven onto the ship and operated on-board, without the need to develop special modules or interfaces. Equipment from the Army, Navy or Marines could be used on the ship. The generous space available would remove the need for expensive compact packaging of equipment and the design lead time which goes with it.

Clearly the JHSV's could not do every role the LCSs are intended for, but could many of them and at a lower cost.