Page 32: of Marine News Magazine (February 2015)

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INLAND TOWBOAT DESIGN

Powering Ahead with a Clean Design

The Shearer Group and Conrad Shipyard collaborate on an ABS approved LNG

Towboat Design. What happens next could change inland shipping forever.

By Joseph Keefe he December announcement that Conrad Ship- gines are medium speed diesels, it is anticipated that future yard, L.L.C. and The Shearer Group, Inc. (TSGI) engine developments will result in lighter and smaller high

Thad worked together to develop the design of a speed units. The design is ? exible enough to allow for the

Lique? ed Natural Gas (LNG) powered 4,200 horsepower use of either engine option as determined by the operator.

towboat utilizing a proven TSGI design was, perhaps, ex- The Wärtsilä system speci? ed is a smaller version of the citing enough on its own merits. That the team had also system currently installed on the Harvey Gulf Multi Pur- been awarded an “Approval in Principle” (AIP) by the pose Supply Vessels. According to Bristol Harbor Group

American Bureau of Shipping (ABS) for the design was President Greg Beers, it is important to note that a con- especially signi? cant for the nation’s inland waterfront. ventional towboat is not diesel electric like an OSV. Diesel

Packing clean LNG power into an inland towboat was no electric applications are perfect for LNG adoption because easy task. And yet, the potential for the concept to blossom they allow the prime movers to run at constant speed. He in this largely ? xed, point-to-point market is very real. adds, “We have mitigated this with our towboat design by using dual fuel engines which reduce the throttle lag, and

Proven Technology Removes Risk z-dives which allow for more control at a given throttle

The towboat is based on TSGI’s proven azimuth drive setting. In fact to go from full forward to full reverse with (z-drive) towboat design that debuted in 2008. Eight of a z-drive, you do not adjust the throttle setting at all, you these towboats, which also pioneered the use of z-drives simple rotate the thruster 140 to 150 degrees.” for brown water operations, have been built for Southern Perhaps the biggest selling point for the new concept,

Towing Company, where signi? cant fuel savings relative at least from Beers’ point of view, is that the new design to conventional towboats have been well documented. Be- removes the risk from ‘early adopters.’ Asked to further yond this, the LNG powered towboat design capitalizes elaborate on that point, Beers replied, “In two words: on Wärtsilä’s proven dual fuel technology, but is not nec- proven technologies. Moving to a z-drive design would be essarily wedded to it. This technology is the most widely a risk for many operators on its own. By using our proven accepted dual fuel technology currently in use in the do- z-drive design as the basis for our LNG towboat design, we mestic U.S. market. While Wärtsilä’s existing dual fuel en- have mitigated that risk. Further, Wärtsilä’s dual fuel en-

February 2015

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