Rolls-Royce's new integrated prop and rudder retrofit package could cut the fuel bill for boats approaching factory-trawler size.

The first installation of Rolls-Royce’s Promas Lite on a commercial fishing vessel should be completed by the first of November at Vigor Shipyard in Seattle. The vessel is the 376-foot factory trawler Alaska Ocean owned by Seattle’s Glacier Fish.

There are three elements with a Promas Lite retrofit. A stainless steel hubcap goes over the propeller hub, while behind it is a prefabricated bulb that’s attached to the existing rudder. Then the propeller is either rebladed or replaced by one that allows maximum loading on the blade tips.

Put them all together and you have a streamlined waterflow across the rudder, as well as behind it. That results in increased propeller thrust, fuel reduction of 5 to 15 percent (It’s near the lower end of the scale when towing), and a reduction in emissions. It’s also possible that a reduced engine load will reduce the wear on the engine.

Promas Lite can go on single- and twin-screw vessels. While it has been installed on a number of cruise ships, this is the first commercial fishing vessel installation. The payback period should be two to three years.