UK: Rolls-Royce Introduces New Series of Waterjets

A new series of waterjets, the A3, was introduced in 2008 by Rolls-Royce. This range has proved attractive in the market and is now being extended with a larger unit, the 63A3. In addition to the largest unit the A3 series waterjet family has been strengthened by two smaller sizes, the 25A3 and the 28A3.

These sizes incorporate experience from the A3-range waterjets already in service including a fully stainless steel pump unit and aluminium inlet duct with inboard hydraulics and thrust bearing. This new size in the 2,500+kW power bracket enables larger vessels to incorporate the modular arrangement and reap the benefits of easy installation, guaranteed performance and durability in all applications.

Less fuel

New Rolls-Royce A3 sizes offer significant increase in efficiency, which translates into reduced fuel consumption for a given workload and, consequently, reduced CO2 emissions. At the same time there is a reduction in size, weight and life-cycle costs compared to other waterjets available on the market in the same size range.

Compact design

Proven design with guaranteed performance and durability take this product range to a completely new level. Compact and proven design combined with the recently launched Rolls-Royce Compact Control System makes the waterjet system very easy to design into any modern fast craft with a safe and proven technology. A factory calibrated control system and scalable CAN-BUS principle with numerous safety interlocks make this new package desirable to designers, yards and end users. All main components are ready built on each waterjet unit, further reducing installation time by the yard. All sizes are approved by the main classification societies.

Tested developments

These advantages are achieved through a variety of developments. At the heart of the waterjet is the mixed flow stainless steel pump. The impeller of the new sizes offers superior cavitation margin and efficiency, designed using the latest computational fluid dynamics (CFD) techniques combined with extensive testing in the cavitation tunnels at the Rolls-Royce Hydrodynamics Research Centre. In addition to the comprehensive testing made earlier, there are already several hundred similar Rolls-Royce A3/S3 pump types in service in different types of fast craft around the world.

Agile manoeuvring

A compact and highly efficient reversing bucket provides the high figure of 65% reversing thrust compared to maximum ahead thrust. This makes the jet very efficient, and also improves safety and agility in manoeuvring situations, saving time and energy with reduced emissions. In addition to savings in time and fuel this design also provides superior position keeping and manoeuvrability at zero speed, making the units suitable for Dynamic Positioning operations.

The steering nozzle, manufactured in stainless steel, provides 2-3 knots higher speed in sharp turns. In addition, the full scale tests have proven the new nozzle to be much more silent compared to earlier designs.

Interceptors for trim control

All the largest Rolls-Royce A3- series waterjets can be delivered with the new modular interceptor trim tabs bolted directly on the waterjet, including hydraulics and control panels for electronics. Modular bolt installation enables easy retrofitting. The interceptor trim system improves acceleration and low speed characteristics, in addition to providing trim angle adjustment.

A3- series waterjets can be supplied as a steering and reversing units, or as simpler boosters giving ahead thrust only, enabling the ideal system to be configured for multi-jet installations. As in earlier sizes introduced, the inlet duct of 63A3 is fabricated by Rolls-Royce as an integral part of waterjet unit from aluminium plate.

The complete range of Rolls-Royce A3 waterjets are available in sizes 25-63 for delivery from the second quarter in 2013.

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Rolls-Royce, December 6, 2012