Adding 'whale tails' could improve maritime transport fuel efficiency
18 June 2015
Researchers from the Norwegian University of Science and Technology (NTNU) are testing a model 'whale's tail' that can be attached to ships to improve fuel efficiency.
NTNU is conducting these tests on a 1:16.57 scale model ship at the Marintek Towing Tank in Tyholt, Trondheim, in cooperation with Rolls-Royce and British companies, Seaspeed and MOST. The main goal of the whale's tail is to help reduce fuel use by using wave energy to help the ship move forward.
Two of these whale tails, looking like wings or fins, are attached to the front of the ship. The waves that hit the ship model cause it to move, which in turn causes the fins to move up and down just like a natural whale's tail does. The shape of these fins allows energy from the waves to help the ship move forward.
“The foils reduced resistance on the ship by between 9 and 17 percent at wave heights of under three metres, under the conditions that we’ve tested,” says Eirik Bøckmann, a postdoctoral fellow at the Department of Marine Technology at NTNU who has been working on this idea for several years.
“The resistance can probably be further reduced by optimising the ship’s hull for the wave foils. The foils also reduced the ship’s heaving and pitching by about the same amount as for resistance.” The results are promising, but they are still in the early stages of testing.
“We need to see how things work, and then choose the best way forward based on that,” says Alastair Sim, a technologist at the Rolls-Royce Strategic Research Centre. Sim, who is responsible for evaluating new marine technologies and deciding what Rolls-Royce should fund, sees a lot of potential for this invention if it works the way it is intended.
It isn’t enough for the wings to just work. Other factors also play a role. For example, the wings also need to be able to take a beating and not destabilise the ship.
“Experience from similar ideas shows that collisions where the wings are damaged doesn’t affect the actual stability of the ship,” Sim adds.
“British authorities wanted to include us in this project,” says managing director of Seaspeed, Stephen Phillips. Phillips started Seaspeed in 1990, and has a few decades of experience working with, and improving, high speed ships. Seaspeed has experimented with fins, or what are also called 'wave foils' for several years.
“There has already been small scale development of boats that use only wave power, and have no motors,” says Ie-Bum Shin, who is a naval architect at Seaspeed.
However, it will be some time before this technology can be used at full scale. For the moment, the current goal is just to cut fuel costs.