Published on December 29th, 2016 | by Steve Hanley
Dolphin Tail More Efficient Than Propeller For Ships
Scientists and engineers in Norway have developed a new way of moving ships through the water that resembles how a dolphin tail or whale tail propels those animals forward. They say the new design is up to 90% efficient whereas a traditional propeller is only about 50% efficient. Once perfected, the so-called “Flapping Foil” could reduce fuel costs for ships dramatically.
Shipping is vitally important to Norway’s economy. The nation is nearly surrounded by the sea. It also has hundreds of fjords and lakes that must be crossed regularly by people and cargo. Increasing the fuel economy of its many ferries and freighters would pay big dividends for the local economy, benefits that could apply to all ships eventually.
Working at the Norwegian University of Science and Technology (NTNU), doctoral candidate John Martin Kleven Godo has been studying how dolphins and whales use their powerful tails to move through the water. “The concept is the result of conversations and discussions Sverre Steen and I’ve had around earlier work done here at NTNU.” says Godo. “We have [concentrated] on high speed catamarans because the environmental benefits are largest in that segment. But the technology can also be used in other hull types and speed segments.”
In a conventional ship, the up and down movement of a piston is changed to rotational motion to turn a propeller shaft. In the Flapping Foil system, the idea is to use an electric motor to move the flaps/foils. Using an electric motor opens the door to zero emissions ships as battery technology improves and becomes more affordable.
Professor Steen says getting the correct mechanical solution is quite a challenge. “Several people have tried to combine the the vertical and horizontal motion of a dolphin or whale tail, but so far no one has succeeding. I have faith that we will achieve it. The big question is how effective it is and at what cost.”
Godo and NTNU are collaborating with a design and engineering company to create a concept vessel. It will have a speed of 30 to 40 knots, and, at 120 feet long, will accommodate up to 300 passengers. “For credibility’s sake, it is best if we can demonstrate it with potential partners and customers on board,” says Godo. Professor Steen hopes to have a demonstration model completed within the next two years. After that, a new corporation may be formed to attract investors and work with established shipyards to perfect the “swimming boat” concept.
Looking to nature to solve transportation issues is as old as the legend of Icarus. Airplane wings don’t flap up and down like a bird’s wing, but the shape that creates lift that allows them to fly was first suggested by studying birds. Coatings that mimic the properties of shark skin reduce drag on ships and airplanes. Will commercial vessels one day cross the oceans using electric power and Flapping Foil technology? If so, it may be thanks to the pioneering work Steen and Godo.
Source: TU Norway Hat tip: Leif Hansen