Professional Engineering

The waterjet-powered navy vessel has us outmanoeuvred as we cruise on the sailing ship on Lake Vänern, the largest lake in Sweden, on a fine summer’s evening. 

As our ship leisurely makes its way towards land with a contingent of Rolls-Royce customers and crew on board, we are treated to a demonstration by the navy craft of the power of waterjet technology: rapid acceleration and deceleration, the ability to turn on a sixpence, attributes that make it a choice for high-speed operation among ferry operators as well as the military. 

We are in the Swedish town of Kristinehamn to celebrate 40 years of research at Rolls-Royce’s Hydrodynamic Research Centre and to observe production of propellers and waterjets at the nearby Gustavsvik site. Both are key elements of Rolls’ marine division, which employs 9,000 people globally. 

The origins of the research centre and factory lie in the Swedish company Kamewa, which became part of the Vickers Ulstein Marine Group in 1999, and was subsequently acquired by Rolls-Royce. Kamewa was producing propellers as early as 1937 and had inaugurated a test laboratory in the early 1940s. The lab now known as the Rolls-Royce Hydrodynamic Research Centre was created in 1970. 

The lab is moving with the times. The key trend affecting operations is the desire for improved environmental performance among Rolls-Royce’s customers. Göran Grunditz, its manager, says: “Since I started 11 years ago, we have seen an increased requirement for fuel efficiency and the request for more environmentally-friendly designs. 

“And that comes back to us in hydrodynamics, because it’s us that can deliver better propulsive efficiency.”

Testing of propeller designs at Kristinehamn involves physical testing and computer modelling. The key phenomenon that engineers observe is the process of cavitation, or the formation of empty cavities in a liquid by high forces and the immediate implosion of them – a liquid is a continuum and repairs itself if it is torn apart. Cavitation occurs when a liquid is subjected to rapid changes of pressure, causing the formation of cavities in the lower-pressure regions of the liquid.