Built in 1964, by Main Iron Works Incorporated of Houma, Louisiana (hull #407) as the O.J. Cenac for the Cenac Towing Company Incorporated of Houma, Louisiana.
In 2002, the Cenac Towing Company renamed the tug as the Nan Cenac.
In 2008, the tug was acquired by Teppco Marine Services of Houma, Louisiana. Where she retained her name.
In 2009, she was acquired by Enterprise Marine Services of San Antonio, Texas. Where the tug was renamed as the Nan.
In 2015, the tug went out of documentation. Her current and, or final disposition is unknown.
Re powered in 1990, she was driven by two, Cummins KTA19-M2 diesel engines. With Twin Disc reduction gears, at a ratio of 5.92:1. Turning two, stainless steel, fixed pitch propellers. She was a twin screw tug, rated at 1,100 horsepower.