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08/05/2013
GE introduces thriftier thruster
New design could see 10% fuel savings over standard pods.

TAGS
fuel economy  |  offshore  |  propulsion  |  
May 8, 2013: General Electric's Power Conversion arm has launched a new podded thruster aimed at the platform support vessel market that it claims could cut fuel use by up to 10 percent over conventional azimuth propulsion. The company's Inovelis design is based on pump jet principles, and features fixed stator vanes and a nozzle that act together to guide the water flow across the electrically-powered impeller blades, "substantially enhancing" propulsion efficiency, according to the company.

GE claims that the design has higher thrust capability than a more conventional propulsion system, as well as improved hydrodynamics, providing higher efficiency over a wider range of operations, in dynamic positioning and in transit. "A traditional propulsion setup for a PSV has a large propeller with a nozzle, which has reduced performance when the speed of the ship increases," GE said in a statement. "Whereas a vessel with a traditional propulsion system has a propeller pushing on the water, a pump jet draws in water and then forcibly ejects it out through a nozzle. It is the marine equivalent of a jet engine, except that while jet engines are fixed, Inovelis can be pointed in any direction on a horizontal plane."

GE Power Conversion's marine leader Paul English said: "There is a clear trend towards larger, more capable offshore support vessels and a second trend towards the search for oil and gas taking these vessels ever further from home ports,” says English. “Ship operators are looking for systems that support cost-effective, fuel-efficient, rapid transit without sacrificing the capability to operate effectively and efficiently once on site in DP mode. This raises a dilemma as many current designs are a compromise between these two differing requirements."

Citing an example PSV driven by two 2.5MW pods, 30 percent of the time at full speed in transit, that could see annual fuel savings of up to US$250,000, English said that the "no man access" design's advantage was so significant that it had the potential to permit ship designers to incorporate reduced capacity power plant—fewer cylinders or smaller engines—when designing offshore vessels.

"“When the combination of engines, electrical power plant, Inovelis thruster and control systems such as DP are correctly designed and optimized as a system, there can be massive advantages in terms of initial cost and lifetime cost," he said.

GE already has a number of orders for the system for installation on large PSVs, including 8 being built for Swire Pacific in Japan and Brazil.