Built in 2008, by the Foss Maritime Shipyard of Rainier, Oregon (hull #11) as the Carolyn Dorothy for the Foss Maritime Company of Seattle, Washington.
She was the ninth Dolphin class tractor tug designed by Robert Allan Limited of Vancouver, British Columbia. For the Foss Maritime Company of Seattle, Washington. And, first tug to feature a hybrid propulsion system.
The hybrid system in the Carolyn Dorothy. Was conceived by Jason Aspin of Aspin Kemp and Associates (AKA) of Montague, Prince Edward Island. And, John Eldridge of XeroPoint Energy (XPE) also of Montague, Prince Edward Island.
Powered by two, Tier II compliant, Cummins QSK50 diesel engines. With Rolls Royce US205 z drives. For a rated 5,080 horsepower.
Her electrical service is provided by two, Siemens Motor generators. Driven by two, Cummins QSM11 diesel generators. With one hundred and twenty-six, gel cell, lead acid batteries.
The tug is fitted with a computerized energy management system, or EMS. The EMS is designed to reduce all possible combinations of power into four power bands. And, automatically configure power sources to the propulsion, and hotel loads required according to demand. These power bands are given user-friendly labels such as "Minimal Emissions," "Eco-Cruise," "Mid Range," and "Full Power."
The operator may choose whatever level is appropriate: "stop," "idle," "transit," or "assist." All are arranged on a small panel in front of the operator. Then as the operator makes demands on the z drives, via the joystick, and winch controls. The system engages the required power plant combinations. The bands are designed to automatically conserve the most fuel, and emit the least emissions for each mode of power required.
Stop mode is when the vessel is idling between assignments. And, or is using less than five percent of her propulsion power, and the power configuration is typically for one, or two auxiliary generators running. And, stored energy available for use.
Transit mode is for continuous, and slow transits. As well as, low power work using less than twenty two percent loads for extended periods. A typical plant configuration is one main engine, and two auxiliary generators running. One main engine on one driveline, and a powered MG on the opposite side to provide propulsion. The system permits both ASD's to be operated by one main engine. Battery power can be used as a temporary ride through of transient demands.
Assist mode is during continuous, fast transit, and a large percentage of ship assist work. Where maximum power requirements do not exceed forty six percent for extended periods. The typical configuration is two main engines. If the batteries need recharging in this mode, one or both auxiliary generators will engage.
Full Power is for continuous fast transit, and full power ship assist work. A typical configuration is two main engines, plus two auxiliary generators, with battery stored energy available to reach full power, and most transient demands. The plant is also capable of providing full shaft horsepower for propulsion.
Her towing gear consists of a Markey DEPGF 42 winch on her bow. Outfitted with 500(ft) of 8.5(in), plasma line. And another Markey DEPGF 42 winch on her stern. Outfitted with 300(ft) of 6.2(in) plasma line. The tug's power system can accept regenerated power from the winch. The DEPGF 42 hybrid winch, is configured to generate power back into the batteries when the winch is rendering, the motor acts as a generator.