Conventional propulsion systems for yachts typically consist of an engine, gear, shaft line and propeller in a straight line. The energy efficiency of these systems is far from optimal, and they are a source of noise and vibration.
Lightweight, energy-efficient propulsion system
The Rolls-Royce research and technology team set out to remedy these problems by exploring the use of a single, efficient and steerable thruster unit, as well as the use of new materials to develop a more energy efficient and silent solution.
The Azipull Carbon uses carbon fibre material in load carrying parts, substantially reducing the weight of the propulsion system. The new thrusters also facilitate better vessel layout, while providing high propulsion efficiency, excellent manoeuvring capabilities and easy maintenance.
The first thruster in the series, AZP C65, is designed for a power rating of 2 MW and fitted with a fixed pitch, pulling type propeller – meaning the propeller faces forward. The driveline has two spiral bevel gear sets, installed in a supporting structure that ensures optimum load carrying capacity in all operating conditions. The thruster can be steered using a hydraulic system. An automation and control system has also been developed for the new thrusters.
By reducing weight and developing a compact, steerable thruster, Rolls-Royce Commercial Marine has achieved an increase in efficiency of 10–15 per cent, with a corresponding reduction of emissions. The unit weighs only 2.7 metric tons and can provide an output of up to 2 MW.
Using composites also offers other benefits, such as greater freedom in designing the unit and adapting its shape to the hull to substantially decrease noise and vibration.
The Azipull Carbon is a gamechanger in the yacht market. So far, the Italian yacht builder Benetti has delivered six luxury superyachts featuring the lightweight, reliable and highly efficient propulsion system. There is further potential in the passenger vessel and workboat markets as well.