Six month’s of service show savings from first retractable bow foils
In September 2019, the Faroese ferry Teistin owned by Strandfaraskip Landsins became the world's first ship with retractable bow foils from Norway-based Wavefoil and after half a year of operation, the company has now released official figures.
“We see that the fuel consumption has decreased by 9% after the installation. This is a dramatic
reduction in an industry where one has to fight for every percentage, said CEO Eirik Bøckmann of the ferry owners.
Nevertheless, it is the improvement in comfort the company highlights as the most positive. They state that Teistin has become calmer in the sea, which is much appreciated on the harsh route. “I notice that Teistin moves less in the sea than before, said the ship’s captain Jónleif Láberg.
Various bow foil concepts have been studied since the 19th century. CEO of Wavefoil, Eirik Bøckmann, has researched the effect of bow foils both as a PhD student, and postdoctoral researcher, at the Norwegian University of Science and Technology (NTNU). The foils dampen the pitch motion and give extra forward thrust in waves. A ship moving through waves will experience considerable additional resistance, and this will be reduced by dampening the pitch motion. In addition, the foils utilise wave energy to create forward thrust. To summarise, bow foils provide a financial, environmental and comfortable benefit in waves, but if the foils cannot be retracted in calm water, the disadvantages may be bigger than the benefits. A problem which Wavefoil now has solved with its retractable foil modules.
“If all suitable ships install our foil modules, 10-20 million tonnes of CO2 equivalents can be saved annually in greenhouse gas emissions,” said Bøckmann. With support from NTNU Discovery, the Norwegian Research Council, Innovation Norway and Climate-KIC, as well as private capital, Wavefoil has taken bow foils from an academic concept to a commercial product in record time.
“Our foils are delivered as a complete foil module. We have developed four foil modules with different sizes to meet the needs of all ships between 20 and 200m. The foil modules can be installed in both existing ships and new builds,” said Bøckmann.
The effect of bow foils is thoroughly documented through model experiments and simulations. Therefore, there should be no uncertainty regarding the benefits of bow foils, given that the vesselsare sailing in wave-rich waters. “We experience that shipowners believe in our value proposition. Many shipowners are sceptical of new technology, something we fully understand. It has therefore been of great importance for us to now have demonstrated operational reliability on Teistin. After all, we too need to be able to sleep at night, said CTO Audun Yrke
The use of the foils has become routine for the crew of Teistin. They choose themselves when to retract and deploy the foils. “It is gratifying to see that the foils are used almost all the time. This means that they experience the benefits, whilst relying on our system,” added Yrke.
The foils are retracted in extreme weather. In addition, the ferry visits a third port a couple of times a week, and some of the crew prefer to retract the foils then.
Wavefoil's smallest foil module is designed for high-speed catamarans, with a foil module in each hull. At the time of writing, foil modules are installed in Brim Explorer's hybrid sightseeing vessel, Bard. Wavefoil is also producing foil modules for Loppa Legeskyss' ambulance vessel that will be operating in very harsh conditions in northern Norway. Both vessels will be delivered from Maritime Partner in Ålesund.
Bard can initially operate for 10 hours on batteries in calm waters. As a result of increased resistance in waves, the battery capacity will get depleted quicker. The foils will help the battery so that Brim Explorer still will be able to offer silent zero emission trips even when there are waves. Regarding the ambulance vessel, the foils will help the vessel maintain higher speed in waves without compromising the necessary comfort for the patients. “For the ambulance vessel, the foils will be able to help save lives, which is not something a marine engineer experiences every day,” said Yrke. “We are very much looking forward to getting these vessels up and running. They show new aspects of using retractable bow foils that we are looking forward to demonstrating,” added Bøckmann.