Built in in 1957, by Ira S. Bushey and Sons of Brooklyn, New York (hull #612) as the tug Port Jefferson for the Red Star Towing Company Incorporated of Brooklyn, New York.
In 1977, the Red Star Towing Company was acquired by the Hess Oil Corporation of New York, New York. To form the Spentonbush-Red Star Companies of Brooklyn, New York. Where the tug retained her name.
In 1989, the Spentonbush-Red Star Companies were acquired the Hess Oil Corporation of New York, New York. Establishing the Hess Oil Corporation's marine division.
In 2001, the Hess Oil Corporation's fleet was acquired by Leevac Marine Incorporated of Jennings, Louisiana. Where the tug was renamed as the Port Service.
In 2001, she was acquired by Constellation Towing Company of Manchester, Massachusetts. Where the tug was renamed as the Ursa.
In 2006, the Constellation Towing Company was acquired by the Foss Maritime Company of Seattle, Washington. Where the tug retained her name, but was "laid up" at Boston, Massachusetts.
In 2008, the tug was acquired by the Krause Marine Towing Company of Perry Hall, Maryland. Where she was renamed as the Austin Krause.
In 2019, she was acquired by an undisclosed interest located Port Orange, Florida. where she was renamed as the Single D. And the tug was "laid up" at Salisbury, Maryland.
Powered by a single, EMD diesel engine. She was a single screw tug, rated at 2,400 horsepower.
Her electrical service was provided by two, 75kW general sets. Driven by two, Detroit Diesel 4-71 Diesel engines.
(Captain Christopher Roehrig, Robert Silva)