Waterjets tested for slower steaming

The S4 series was developed specifically to meet the reduced speed requirements of high-speed ferry operators. Previously, most high-speed ferries were designed for service speeds of 45 knots or more, but due to increasing fuel costs operators are looking for waterjets optimised for lower speed and fuel consumption whilst improving ship efficiency.

The trials aboard the recently upgraded Tangalooma Jet, a 350 passenger-carrying high-speed catamaran operating off the Australian coast near Brisbane, indicated a 3% increase in thrust when compared to the previously installed waterjets.

Daniel Wikström, product sales manager for Kamewa Waterjets, said: “Two 63S4 units were installed on a ferry in service previously equipped with our Kamewa 63SII waterjets. The ferry upgrade involved a complete repowering of the drive train, including engines, and the waterjets performed exactly as we predicted.

“Efficiency is improved over the whole speed range, matching the increased demand requirement for vessels operating around 30 knots, were waterjet propulsion has traditionally been less efficient. This translates into reduced fuel consumption for a given workload and, consequently, reduced CO2 emissions, as well as increased range for the ferry. Environmental benefits are achieved not only by increasing efficiency, but the inboard hydraulics also reduces the risk of oil spill.”

Rolls-Royce hydrodynamic research centre manager, Reima Aartojärvi, who took part in the sea trials, said: “With a 3% increase in thrust and improved manoeuvring capabilities, the 63S4 waterjets are a significant improvement on the propulsive performance of the previous installation. We also found that noise and vibration levels were lower, significantly improving passenger comfort. The owner is very happy with the improved performance, which is easily understandable since the new arrangement can save the operator about AUS$80,000 per annum in fuel costs.”