Built in 1949 by MARCO Shipbuilding of Seattle, Washington as the Sea Horse 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 she retained her name.
She was later acquired by Cook Inlet Tug & Barge, a division of Anderson Tug & Barge of Anchorage, Alaska, where she was renamed to Junior.
However, in 2013 Cook Inlet Tug and Barge was acquired by Saltchuk Resources of Seattle, Washington, and established as an independent subsidiary of Foss Marine Holdings.
Powered by two Caterpillar 34-12 diesels turning two propellers rated at 1,300 horsepower.