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Foss Maritime Proposes First Hybrid Tug Boat; SoCal Ports to Provide $1.35M to Support Development

A new hybrid tug boat proposed by Seattle-based Foss Maritime Company, and co-funded in part by the Port of Los Angeles, will be substantially less polluting, more fuel efficient and quieter than today’s modern tug boats.

The Port of Los Angeles, in association with the South Coast Air Quality Management District, has pledged $850,000 to the project, and the Long Beach Board of Harbor Commissioners preliminarily approved a $500,000 contribution to the vessel’s construction. In exchange for funding, Foss would agree to homeport the new hybrid tug in Southern California for five years.

The ports of Los Angeles and Long Beach, the nation’s no. 1 and no. 2 container ports, have expressed interest in funding Foss’ hybrid tug as part of their San Pedro Bay Ports Clean Air Action Plan. (Earlier post.)

With an anticipated delivery in 2008, the hybrid tug will reduce all emissions (NOx, PM, SO2 and CO2) and exceed the EPA’s Tier 2 emissions requirement for marine engines. Initial estimates are that particulate matter and nitrogen oxides are reduced by 44% for the same duty cycle as the current Dolphin tugs operating in San Pedro harbor.

The Foss hybrid tug is scheduled to go into production later this year. It is a new-build project, a continuation of the Dolphin-class tug boat series built at Foss’ Rainier, Oregon shipyard.

The hybrid tug’s drive units will be powered by batteries coupled with diesel generators and feature a modified engine room accommodating two 670 hp (500 kW) battery packs and two 335 hp (250 kW) generators. Although the main engines in the hybrid tug will have lower horsepower than the existing Dolphin engines, overall the tug will have the same total 5,000 hp (3,729 kW) as its sister tugs.

The hybrid tug design minimizes fuel consumption by using a power management system to match the required power to the most efficient combination of batteries, generators and main engines for that particular power level. For example, instead of idling the main engines while in standby mode when alongside a customer vessel awaiting orders from the pilot, the hybrid tug will run on battery power with the main engines shut down. The lower fuel consumption results in reductions of carbon emissions, a contributor to greenhouse gas, as well as sulfur emissions.

The hybrid tug will be introduced in the Los Angeles/Long Beach market, as hybrid tug technology is best suited for harbor tugs that need high amounts of power for short periods of time. While performing tug assist jobs in this Californian harbor, tug boats spend little time at peak RPM, rarely utilizing each tug’s full horsepower.

Tugs at the Los Angeles/Long Beach spend up to 50% of their time idling, with the main engines on and ready to respond, but with no power actually being used for propulsion. With Foss’ hybrid tug, energy is produced only on demand, so that idling of the main engines will no longer be necessary. The hybrid tug design will make it adaptable for retrofit of existing harbor tugs. The flexible design of the tug also has the ability to take advantage of emerging technologies such as improved battery and fuel advances. This tug could also take advantage of cleaner, less expensive shore power to charge the batteries.



Hate to be negative on hybrids, but this one is just brain-dead idiocy transparent to anyone even remotely familiar with the business.

hampden wireless

If the tug is idling half the time what makes it such a bad idea?


Hope the complex electronics will hold up against the heavy salt spray corrosions. For future increasing pure electric & hybrid cars on the roads, this tug will be like intense reliability & longevity tests. Andrey is sure the electronic hybrid will fail.


If the Navy's surface fleet's massive amount of electronics can survive in these conditions I think a hybrid tug will be able to cope with the coastal conditions of socal.

Rafael Seidl

It might be less sexy, but adding a small APU engine running on CNG that keeps the main engine warm and the electrical systems operational while the tug is in standby mode would probably achieve >80% of the emissions benefit at <20% of the cost.

In tug mode, the APU could power an auxiliary compressor to largely avoid the usual soot emissions in response to a load step change on the main engine until its turbocharger comes up to speed.

hampden wireless

A simple serial hybrid would work well as it does on many types of ships already. They have little battery capacity, but enough to do the job. The simpler all electric drive system can be more reliable then a non electric system due to the elimination of the transmission . Feedback from the propeller does less damage to an electric motor then it does to a geared transmission.

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