Built in 1970, the Marinette Marine Corporation of Marinette, Wisconsin (hull #YTB 786) as YTB-786 (Tonkawa) for the United States Navy.
Her keel was laid down on December 22nd, 1965. The tug was launched on March 3rd, 1966, and was delivered to the United Stated Navy on May 19th, 1966. The tug was placed in service in June of 1966. Where she was assigned to duty at Advanced Bases, Atlantic Area, Naval Station in Rota, Spain.
The date she was placed out of service is unknown. However, she was transferred to the General Services Administration (GSA) for reuse
In 2000, the tug was acquired by McAllister Towing and Transportation of New York, New York. Where she was renamed as the Margaret McAllister.
In 2006, the tug was repowered/reconfigured. Originally powered by a single, ten cylinder, Fairbanks Morse diesel engine. Turning and single propeller, for a rated 2,000 horsepower. She was repowered with two, Caterpillar 3516B diesel engines. Driving a pair Schottel SRP 1012 "z drives." For a rated 4,000 horsepower.
The Margaret McAllister was the ninth conversion of a United States Naval tug by McAllister Towing. From a single screw configuration, to a "z drive" configuration. And, the seventh conversion to feature twin "z drives."
The Margaret McAllister was the seventeenth tractor tug to enter service for the McAllister Towing and Transportation Company.
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 Goulds fire pump, driven by a 6-71 diesel engine. Rated at 2,000 Gallons Per Minute. Feeding two fire monitors rated at 1,500 Gallons Per Minute foam capacity.
Her towing gear consists of a JonRie InterTech 200 series bow winch. Equipped 450(ft) of 7(in) of Neutron Rope. Her original underwater submarine fendering was kept, and refurbished.