Feature 7 | PROPULSION
Unique waterjets for unique fast landing craft
MJP Waterjets in Sweden recently combined the steering and reversing functions of two waterjets on a central column, with both jets operating in parallel by means of a single hydraulic control system, and has successfully applied the concept to a new type of landing craſt.
A prototype of the EDA-R under way during trials.
T
he new steering and reversing unit, the CSUI, was recently tested for the first time on a new type of
fast landing craſt, the EDA-R, developed by CNIM in France. Te first production version of the EDA-R started trials towards the end of 2011. Four examples of the EDA-R have been ordered by the Marine Nationale under a contract signed in 2010. Te first EDA-R was due to be delivered
to the French Navy in mid-October 2011; the second was due to be delivered by the end of 2011, with the remaining units to be delivered in 2012. Te vessel is designed to operate in two different modes: catamaran mode and barge mode. Te vessel is equipped with four engines
and four waterjets driven by a MJP 650 mixed-flow pump. Te intakes have been
Warship Technology January 2012
adapted and designed according to the constraints of the hull using computational fluid dynamics (CFD). Te EDA-R has a small waterplane area twin hull (SWATH) hullform with a pronounced ‘hour glass’ shape which results in a narrow waist at the waterline. The section beneath the waterline has been reduced to the absolute minimum. During the design phase MJP made use
of CFD also to optimize the flow in the bucket in order to enhance the reversing performance of the propulsors. Tis is particularly important on a landing craſt in order to ensure safe disembarkation from a beach. Sea trials demonstrated that the vessel is able to operate at a speed of 10knots in reverse, at full load, in open sea conditions.
In catamaran mode, the centre platform
is high above the waterline and the waterjets deeply immersed. When the centre platform is lowered and the vessel is in barge mode, the jets are in a conventional position, so the jets need to fulfill the requirements for both operating conditions. Because the jets are placed very deep
in the water in catamaran mode, inboard hydraulics area used to avoid the use of external hydraulics several metres below the water. Tis also means that the increased wetted are and increased drag that would otherwise result from the use of external hydraulics is eliminated. Due to the limited space inside the hull,
the traditional MJP double reverse bucket (DRB) design could not be used so MJP had to come up with a completely new design,
31
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36