Drives and Controls Magazine

Hybrid tug boat will be clean and quiet

10 April, 2007

A US boat-builder is designing what it claims will be the "world’s first true hybrid tug boat". Seattle-based Foss Maritime says that the vessel will emit significantly less nitrogen oxide, sulphur dioxide, carbon and particles than conventional tugs, as well as consuming less fuel and being much quieter.

The 5,000hp (3,73MW) vessel, which has received $850,000 of funding from the Port of Los Angeles, will combine electric drives powered by two 500kW battery packs and two 250kW diesel generators.

Conventional tug boats spend up to half of their time idling with their main engines running and ready to respond, but not using much of the power they are producing. The hybrid tug’s engines and generators will only run when full power is needed. At other times, the batteries alone will power the vessel.

Dolphin class tug boats

Foss estimates that the hybrid tug will produce 40% less particles and nitrogen oxide than a standard Dolphin-class tug (shown above) on which it is based. The company hopes to put the first hybrid tug into service next year. It is designing the hybrid technology so that it can be retrofitted to existing tugs.