"Whale tails" could use waves to make ships more efficient
Ordinarily, when a ship is heading into waves, those waves cause it to work harder. An experimental new setup known as a "whale tail," however, utilizes wave action to actually help ships move forward, allowing them to use less fuel when tackling rough seas.
The whale tail is being developed by a team from the Norwegian University of Science and Technology (NTNU), working in partnership with Rolls-Royce and British companies Seaspeed and MOST. Led by NTNU postdoctoral fellow Eirik Bøckmann, the researchers have been testing a miniature version of the system on a model ship which is towed through a 200-m (656-ft) wave tank at the Norwegian Marine Technology Research Institute.
Although it's called a whale tail, the system actually looks more like a set of hydrofoil-like fins, and it's located at the front of the ship below the waterline.
As the main body of the ship is moved up and down by wave action, the two foils move with it. Due their unique shape, however, they generate lift that helps push the vessel through the water – just as a set of flukes do for a whale.
Scaling up from the model, it has been calculated the foils would reduce wave resistance by 9 to 17 percent if used on a full-sized vessel at wave heights of under three meters (9.8 ft). They should likewise help cut down on heaving and pitching by about the same amount – the figures would likely be higher if the hull shape were optimized for use with the whale tail.
While the technology is mainly intended to make ships more fuel-efficient (for now, at least), the Wave Glider aquatic robot already relies entirely on a wave-powered propulsion system.