High Tech Towboat: LNG-Powered Design Gets ABS Approval in Principle

Conrad Shipyard and The Shearer Group, Inc. (TSGI) said that its design of a 4,200 horsepower LNG-powered towboat received “Approval in Principle” (AIP) from the American Bureau of Shipping (ABS).

The boat is based on TSGI’s azimuth drive (Z-drive) towboat design that debuted in 2008 as the FRANK T. STEGBAUER. To date, eight of these towboats have been built for Southern Towing Company, which is a pioneer in the use of z-drives for brown water operations. The boats have shown significant fuel savings relative to conventional towboats.

The new LNG powered towboat design capitalizes on Wärtsilä’s dual fuel technology, but is not wedded to it. While Wärtsilä’s existing dual fuel engines are medium speed diesels, it is anticipated that future engine developments will result in lighter and smaller high speed units. The design is flexible enough to allow for the use of either engine option as determined by the operator.

“By combining two widely accepted technologies; Z-drives and Wärtsilä’s dual fuel engines and fuel system, we have mitigated most of the risks associated with being an early adopter of this novel technology” said Greg Beers, P.E., TSGI’s President. “By incorporating PROVEN technologies, we have minimized the risks that first movers will be taking with the switch to utilizing LNG as a fuel.” The Wärtsilä system specified is basically a smaller version of the system currently installed on the Harvey Gulf Multi Purpose Supply Vessels, and as noted above, the z-drive towboat designs have been operating successfully since 2008.
TSGI and sister company Bristol Harbor Group, Inc. have been involved in LNG projects since 2009, and are currently involved in five active LNG projects, including one for the United States Army Corps of Engineers.