A propeller blade replacement claimed to fit “any hub” has reduced fuel consumption and vibration for a long-serving Baltic ferry.
Berg Propulsion developed new blades for the 15,900-gt Stena Danica (built 1983 and renewed in 2005) which sails between Sweden and Denmark, connecting Gothenburg and Frederikshavn.
Stena Line asked the Swedish engineering firm to revise the ship’s twin-propeller blades, with the aim of eliminating a persistent cavitation issue and enhancing fuel efficiency.
Berg’s solution, which also met requirements to cut machinery vibrations, needed to be reverse-engineered to fit the existing propeller hub as it was originally manufactured by another company.
Senior naval architect at Stena Teknik, Per Wimby said it is the third blade replacement for the Stena Danica over the years.
“But this one is especially timely, given that it anticipates new regulatory requirements for all ships to demonstrate their energy efficiency,” he said.
After several months of commercial operations in multiple sea states, Wimby said the new blades have reduced average fuel consumption while neutralising a longstanding issue with vibrations.
Stena Danica’s twin control pitch propellers are served by two Sulzer 12ZV40 medium-speed engines per shaft and the new blade design was optimised to reflect a planned reduction in operating speeds.
Blade geometry has improved in recent years, and enhanced efficiencies can be achieved using slimmer profiles and blades which cover less area, Berg Propulsion said.
Energy & efficiency account manager for Berg Propulsion, Magnus Thoren said the project
demonstrates what is possible using an existing propeller hub. “Our designers and shipyard project teams could do this for any hub,” he said.
