Feature 2 | ADVANCED HULLFORMS
Air-supported landing craft under development
Effect Ships International in Norway and Damen Schelde Naval Shipbuilding in Te Netherlands are exploring the development of a new series of high- speed medium-sized landing craſt that make use of air support.
advantages compared with conventional landing craft. It has its origins in a design study ESI and Damen conducted to
W complement Damen’s smallest
‘Enforcer’ Landing Platform Dock (LPD) vessels (which have a displacement of 7000-10,000tonnes) with an enhanced amphibious craſt. Te air-supported landing craſt is ESI
and Damen’s response to the growing need for amphibious operations to be launched from vessels far offshore or ‘over the horizon.’ Tere is also a growing requirement for missions carried out to using a forward operating base (FOB) at a considerable distance from a mother ship. Tis in turn had led to requirements for high-speed landing craſt with speeds of in excess of 30knots.
Hull resistance Studies carried out by ESI and Damen quickly demonstrated that in order to achieve a speed of 30-40knots, fully loaded, with acceptable levels of installed power and using conventional diesel engines, hull resistance would have to be significantly reduced, so Damen began to investigate several high-speed, low-resistance technologies. ESI’s patented ASV monohull
technology supports up to 80% of the displacement of a vessel on a cushion of pressurised air in a fixed bottom cavity. In planing mode, the resistance of such a craft is significantly reduced due to the reduction of wetted surface-induced frictional resistance. Te air-supported vessel (ASV) concept
does not use rubber skirts – as on surface effect ships (SES), hovercraſt or partially air-supported designs – and the average power required to compensate for air
20 ith a payload of around
35tonnes, the new design could have a number of
The ASV LC concept would be significantly faster than conventional designs.
leakage amounts to only a few per cent of the total propulsion power. In the design study conducted by
ESI and Damen, the ASV landing craſt (ASV LC) was benchmarked against conventional planing landing craſt hulls scaled to the same dimensions, available power, propulsion, arrangement and loading. Te comparisons revealed several interesting facts. Ulf Tudem, General Manager at ESI
says: “Hull resistance for the ASV LC is significantly reduced in the relevant speed ranges, and for all load cases from light weight to full load. “At light loads, in calm water and at
30knots the ASV has approximately 45% less resistance; at 40knots it has more than 50% less. At full load and 30knots the ASV has 35% less resistance.” Tudem says that, in terms of
speed-performance, an ASV LC can complete a round trip to and from a landing area at an average speed of 31knots, whereas a conventional
landing craft Warship Technology October 2011
cruises at an average of 23knots. “A light load/sprint speed of in excess of 40knots is achievable for the ASV-LC,” he explains. “In terms of range, with same amount
of fuel the conventional landing craft will have a range of around 200nm (at
TECHNICAL PARTICULARS ASV LC
Length.....................................................25m Beam.........................................................6m Draught (full load) ...................................1m Installed power propulsion ....... 2 x 1200kW Installed power lift fan system..........300kW Lift fans.......2 x centrifugal fans – hydraulic Payload
...............circa 35tonnes (CV9035, Boxer, 4 x BV206 or 3 x BVS10)
Speed, fully loaded..................27knots plus Speed, lightweight .......................... 42knots Construction................................ aluminium Propulsion .......................................waterjets Bow ramp width ...................................3.5m Aft ramp width......................................3.0m
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