Built in 1977, by Main Iron Works Incorporated of Houma, Louisiana (hull #323) as the Peter Foss for the Foss Maritime Company of Seattle, Washington.
In 2004, the tug was transferred to AmNAV Maritime Services of Oakland, California. A subsidiary of the Foss Maritime Company of Seattle, Washington. Where she was renamed as the Liberty.
In 2012, AmNAV Maritime Services was reabsorbed back into Foss Marine Holdings Company of Seattle, Washington. Where the tug retained her name.
Powered by two, Caterpillar 3512 diesel engines. With Ulstein 900 H z drives, outfitted with Nautican, fixed pitch propellers. For a rated 3,300 horsepower.
Her electrical service is provided by two, 75kW generator sets. Driven by two, GM Detroit Diesel 6-71 diesel engines. The tug's capacities are 37,500 gallons of fuel, 300 gallons of hydraulic oil, 1,050 gallons of lube oil, and 2,100 gallons of water.
The towing equipment consists of a Markey DYSW 32-18, hawser winch. Outfitted with 425(ft) of 6(in) plasma line. A Markey DD4-71, TDSD-28, double drum, towing winch. Outfitted with 2,000(ft) of 1.75(in) towing wire on the primary drum. And, 600(ft) of 10(in) TQ-12 P.E. towing wire on the secondary drum. Driven by a dedicated GM Detroit Diesel 4-71 diesel engine.