Taking more than three-years research and development, the new A5 Series improves upon the popular FF range of Rolls-Royce Kamewa waterjets by providing greater thrust from a waterjet with a more compact inboard footprint.
Geared towards smaller boats and craft up to 25m in length, the A5 series is manufactured from high-grade marine aluminium and available in seven sizes with power outputs between 100kW and 1230kW. The A5 will eventually replace the FF range and size 29 will be first to hit the market.
Speaking at the A5’s official unveiling, Fredrik Appel, Rolls-Royce General Manager Product – Waterjets, said: “The A5 is a completely new product, which is developed on the same design principles as our renowned steel series. All aspects of the product are improved compared to our existing FF series. Overall pump efficiency is improved by 3%. Steering and reversing efficiency is improved by 8% and bollard pull is improved by 13%”.
“Besides the propulsion improvements, we have reworked the mechanical design to gain the benefits of a harmonized series, and by this gaining more accurate performance predictions. We have listened to our customers asking for a smaller inboard footprint and adapted the design to meet this by reducing the space by 20%. However, we have also maintained an inlet waterway to accommodate the propulsion improvements.”
Extensive Computational Fluid Dynamics (CFD) analysis and model scale testing at the company’s hydrodynamic research facility in Kristinehamn, Sweden, was involved in the A5’s development. Additionally, by incorporating elements from the proven S4 and S3/CA steel series of waterjets, Rolls-Royce has improved the axial-flow type waterjet to produce a smaller waterjet without the need for a comparative reduction in the power requirement.
“Working with our colleagues in Finland and Sweden, we have produced an axial flow waterjet that has a smaller footprint yet delivers improved steering and reversing efficiency, higher thrust at low to medium speeds and increased bollard pull performance.”
Shival Sapre, Rolls-Royce General Manager Sales, Americas, added: “The Rolls-Royce Kamewa A5 Series offers the best price per performance for vessels operating at speeds between 25 and 40 knots. The Kamewa A5 is a cost-effective waterjet solution for workboats, motor yachts, smaller passenger vessels, patrol boats and other high-speed, shallow draught vessels.
Rolls-Royce has successfully carried out in-service trials of the new waterjet onboard its own demonstration vessel – a crew transfer/harbour patrol vessel operating in Kokola, Finland.
An A29-5 unit, the first product in the series to be released, is exhibited at the International Work Boat Show on the Rolls-Royce booth 2501.