Built in 1976, by Quality Equipment Incorporated of Houma, Louisiana (hull #132) as the Sea Vixen for Crowley Marine Services Incorporated of San Francisco, California.
In 1988, the tug was sold. Where she was renamed as the Margaret George.
In 1990, she was sold. And, renamed as the Chinook.
In 1995, the tug was acquired by the Foss Maritime Company of Seattle, Washington. Where she was renamed as the Ellen Foss.
In 1999, she suffered an electrical fire. Which started in the galley, and damaged the tug while she was underway off of the Alaskan coast. After the fire was extinguished, the tug was towed to Seattle, Washington. Where she was "laid up," and declared as a constructive total loss.
In 2001, the tug was acquired "as is" by the Smith Maritime Company Honolulu, Hawaii. Which was part of the Hawaiian InterIsland Towing Company Incorporated of Honolulu, Hawaii. Where she was completely refurbished, and renamed as the Nakoa.
In 2002, she was chartered to the Sirius Maritime Company of Seattle, Washington. Which was also a part of the Hawaiian InterIsland Towing Company Incorporated of Honolulu, Hawaii. Where the tug retained her name.
In 2004, the tug was chartered to Chevron Incorporated of Washington, D.C. Where the she renamed as the Ellen Ross.
In 2004, she was returned to the Smith Maritime Company of Honolulu, Hawaii. Where the tug was renamed as the Nakoa.
In 2006, the Smith Maritime Company was acquired by the K-Sea Transportation Partnership Incorporated of East Brunswick, New Jersey. Where the tug retained her name.
In 2011, the K-Sea Transportation Partnership Incorporated was acquired by the Kirby Corporation of Channelview, Texas. Where the tug retained her name.
In 2017, the tug was phased out of active service. And, was "laid up" at Lake Union in Seattle, Washington.
Powered by two, sixteen cylinder, EMD 16-645-E2 diesel engines. Turning two, cast steel, fixed pitch propellers. She was a twin screw tug, rated at 5,750 horsepower.
Her electrical service was provided by two, 99kW, Stamford generator sets. The tug's capacities were 160,000 gallons of fuel.
Her towing gear consisted of an INTERcon, double drum, SLP anchor handling, towing winch. Outfitted with 4,000(ft) 1.25(in) wire.