This large canal-style tug was built in 1960 by Ingalls Shipbuilding as the Mobil 8 for Mobil Oil. In 1991 she was renamed Tatarrax. She was sold in 1993, and renamed Nan McKay. She was sold to Clearwater Marine of Philadelphia, PA in 1995, and renamed Tenacious. Ryba Marine Construction of Cheboygan, MI acquired the tug in 2005, and brought her into the Great Lakes. In 2016, she was sold to Marine Services Inc. of Oak Park, MI, where the tug retained its name.
Tenacious works in the marine contracting trades out of Detroit.
- Type: Single Screw Tugboat
- Year Built: 1960
- Builder: Ingalls Shipbuilding, Pascagoula, MS
- Hull No.: 135
- Engines: 1 EMD 16-567C
- Horsepower: 2,100 bhp
- Length: 79′ 01″
- Breadth: 25′ 06″
- Depth: 12′ 06″
- Port of Registry: Detroit, MI