CLEVELAND, Ohio – Rolls-Royce Commercial Marine announced this week it has been contracted to upgrade Interlake Steamship Company’s tug Dorothy Ann. The 124′, 7,200-horsepower Z-drive tug is the largest Z-drive ATB tug built to date in North America, according to Rolls Royce, and is mated to the barge Pathfinder. The duo is engaged in hauling bulk commodities on the Great Lakes.
The upgrade will convert the Dorothy Ann’s Rolls-Royce/Ulstien azimuth thrusters from fixed-pitch to controllable-pitch propellers. The project will include replacement of the lower drive units as well as all thruster control systems on the vessel. Great Lakes Shipyard will perform this conversion under its new affiliation as the Rolls-Royce Regional Service Center on the Great Lakes with an eye toward improving the reliability of the vessel’s propulsion system equipment and reduce overall maintenance costs. This contract is the first to take place since Great Lakes Shipyard and Rolls-Royce Commercial Marine Inc. teamed up to create the Marine Service Center, according to a press release.