Built in 1957, by the Pacific Tow Boat Company of Anacortes, Washington as the Sea Mule for the Pacific Tow Boat Company of Everett, Washington.
In 1969, Pacific Tow Boat and the Foss Launch and Tug Company of Tacoma, Washington were acquired as subsidiaries of the Dillingham Corporation of Honolulu, Hawaii. Operations of the two companies were united under the Foss name, where the tug retained her name.
In 1997, the tug was acquired by the Sea and Shore Construction Company of Seattle, Washington. Where she was renamed as Kristina H.
In 2013, she was acquired by the Fremont Tugboat Company of Seattle, Washington. Where she was renamed as Yankee.
Powered by a single, Detroit Diesel 8V-92 diesel engine. Turning a single, 49(in) by 46(in), RH, 3 bladed, fixed pitch propeller. She is a single screw tug, rated at 312 horsepower.
The tug's capacities are 1,600 gallons of fuel oil, 18 gallons of lube oil, and 60 gallons of potable water.