Built in 1965, by the Wiley Manufacturing Company of Port Deposit, Maryland (hull #657) as the Big Bill for the Steuart Transportation Company of Piney Point, Maryland.
In 1990, the tug was acquired by Express Marine Incorporated of Camden, New Jersey. Where she was renamed as the Guardian.
In 2009, she was acquired the Puerto Rico Maritime Company of Ponce, Puerto Rico. Where the tug retained her name.
Rebuilt in 1983, she was powered by two eight cylinder, Crepelle diesel engines. With a Lufkin reverse/reduction gear, at a ratio of 5.559:1. Turning a single, 135(in) by 120(in), four bladed, stainless steel, propeller, mounted in a kort nozzle for a rated 3,200 horsepower.
Her towing gear consisted of a Clyde, single drum, towing winch. Outfitted with 2,500(ft) 2.25(in) towing wire.