Conrad Shipyard, L.L.C. of Louisiana and The Shearer Group, Inc. (TSGI) based in Texas have worked together to develop the design of a Liquefied Natural Gas (LNG) powered towboat utilizing a proven design from TSGI. The team has been awarded an “Approval in Principle” (AIP) by the American Bureau of Shipping (ABS) for the design of the 4,200 horsepower LNG towboat.
The towboat is based on TSGI’s proven azimuth drive (z-drive) towboat design, from which eight towboats have been built for Southern Towing Company. The original Southern Towing boats helped pioneer the use of z-drives for brown water operations and have shown significant fuel savings relative to conventional towboats.
The LNG powered towboat design capitalizes on Wärtsilä’s proven dual-fuel technology, the most widely accepted dual-fuel technology currently in use in the domestic U.S. market. 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” says Greg Beers, P.E., TSGI’s President. 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.
The economic and environmental benefits of using LNG as a fuel source for high horsepower applications like towboats, when combined with the proven benefits of utilizing z-drives on a towboat, provide an owner with operational cost savings that can exceed 35% of the cost of operating a conventional towboat.
TSGI and its 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.
(Source: The Shearer Group)