Built in 1970, Marinette Marine Corporation, Marinette, Wisconsin (hull #YTB 786) as YTB 786 (Tonkawa) for the United States Navy.
Her Keel was laid down, on the 22nd of December 1965, she was launched on the 3rd of March 1966 and delivered to the Navy on May 19, 1966. She was placed in service in June of 1966 and assigned to duty at Advanced Bases, Atlantic Area, Naval Station in Rota, Spain.
The date she was placed out of service is unknown, she was sold through the General Services Administration (GSA) for reuse, on the 6th of October 2000 to McAllister Towing and Transportation of New York, New York. Where she was renamed as the Margaret McAllister.
She worked for McAllister under her original configuration for a time before being reconfigured and repowered.
In 2006, her original 10-cylinder Fairbanks-Morse diesel engine, and single propeller where removed. Two Caterpillar 3516B diesel engines where installed driving a pair Schottel SRP 1012 "z-dives" for a rated 4,000 horsepower.
She is also fitted with underwater submarine fendering. The tug's capacities are 20,000 gallons of fuel oil, 710 gallons of lube oil and 1,290 gallons of potable water.
She was outfitted with a 6-71 engine driving a Goulds fire pump rated at 2,000 Gallons Per Minute tied in with two fire monitors rated for 1,500 gallons foam capacity.
Her towing gear consists of a Jon Rie InterTech Series 200 bow winch equipped 450(ft) of 7(in) of Neutron Rope.