ABS AiP for LNG Towboat

By MarEx 2014-12-02 15:58:00

Conrad Shipyard, L.L.C. and The Shearer Group, Inc. (TSGI) 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 that debuted in 2008 with the “FRANK T. STEGBAUER”. To date, eight of these 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, as illustrated in a paper recently published on TSGI’s website: http://shearer-group.com/docs/z-drive-technology.pdf.

Further, this new LNG powered towboat design capitalizes on Wärtsilä’s proven dual fuel technology, but is not wedded to it. This technology is 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. “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.

The economic and environmental benefits of using LNG as a fuel source for high horsepower applications like towboats are widely understood. The beauty of the TSGI design is that it marries these benefits with the proven benefits of utilizing z-drives on a towboat. These efficiencies compound, providing an owner with operational cost savings that can exceed 35% of the cost of operating a conventional towboat. TSGI and Conrad Shipyard, L.L.C. believe that these savings will prove to be very attractive to towing companies, and look forward to working with operators that share our vision.

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. The Shearer Group, Inc., provides naval architecture, marine engineering, marine surveying and professional engineering services to the inland service marine industry. Their designs have been used to produce over 3000 dry and liquid cargo barges, towboats,dry docks, crane barges and floating facilities. As noted above, Ed Shearer, P.E. and TSGI lead the way for the inland marine industry’s adoption of azimuth drives for brown water applications with the design of Southern Towing Company’s 3,200 bhp and 2,400 bhp z-drive towboats.Further, TSGI provided engineering support for Deloach Marine Services’ conversion of a conventional 90’ towboat to a 2,400 bhp z-drive vessel.


The products and services herein described in this press release are not endorsed by The Maritime Executive.