A tail propulsion system that apes dolphins
ROTTERDAM _ Dolphins move forward by flapping their tails up and down. So why do boats bother with propellers? A Dutch marine technology company thought about that and put a Dolphin tail propulsion system on the Triade, a 38.5m inland cargo vessel. Its O-foil (O for ‘oscillating’) system is primarily designed for shallow-draft, inland cargo ships. But since it promises big fuel savings and less engine noise, can ocean-going ships and yachts be far behind? Perhaps not.
“If there’s an interest from the yacht building sector, we’re open to explore anything,” says electro-technician Patrick Heuts. He and naval architect Bas Goris run O-foil BV which markets the eye-catching alternative to prop propulsion.
In the O-foil system, a horizontal wing oscillates up and down, much like a dolphin tail. Covering the stern’s width, it produces speed much more efficiently than a prop. That results in fuel savings of 50%. Dirty emissions and engine noise are reduced because hybrid _ diesel-electric or gas-electric _ engines are used. Scale model testing at the Dutch Maritime Research Institute gave Goris and Heuts enough confidence to rebuild the Triade. The vessel has recently returned to service. On the Triade, the stern foil beats 90 times a minute propelling the ship with a smaller engine.
“The O-foil system impacts the back end of a ship,” Heuts tells Yacht-and-Coast. “We have to discuss and think about possible solutions for yachts. In a yacht, the aft section is the cockpit area, often with a diving platform.”
Goris says the reaction from the Netherlands’ inland cargo shipping industry _ with 6,500 vessels, Europe’s largest _ was hesitant at first, but has since turned warmer. The dolphin-tail propulsion system is ideal for vessels that require shallow drafts and, therefore, tend to have relatively small, inefficient propellers.