Page 29: of Marine News Magazine (February 2011)

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www.marinelink.com MN 29 some design work off the cuff that might be interesting in the future,”

Comer said. So they put together an

LNG towboat concept and submitted it to the Coast Guard and classifica- tion societies last December. “Some of the issues are that there are no applicable [LNG] regulations for the rivers.” But at this stage, he said, Ship Architects isn’t seeking clas- sification approval, but rather collect- ing input and comments from experts. “All we have in their hands at this point is a general arrangement.”

The concept design features a 150 ft long, 4,000 horsepower vessel. “There had been a lot of discussion on how, and even if, you could carry the fuel,” Comer said. Because the fuel tank would need to be larger for the same range, Comer said, there was talk of putting it on a barge pushed by the vessel. But Ship

Architects’ concept design includes the fuel tank onboard the vessel. “The mid-body of the boat is dedicated to fuel storage to get the capacity that we need,” Comer said. “The fuel storage area is isolated from the engine room and berthing areas.”

While the LNG towboat concept design is the same length as a tradi- tional river vessel, its 50-ft beam is a little wider than average. The 14-ft hull is also deeper than traditional towboat hulls (usually at 12.5 ft).

These dimensions accommodate the larger fuel tank which allows the ves- sel to maintain the traditional 1,200 mile range, or a trip from New

Orleans to St. Louis.

As far as LNG power, Hatley said “Wärtsilä can provide a wide range of engine sizes and power that are par- ticularly well suited to the require- ments of [inland towboat] vessels.

With the new Wärtsilä 20DF engine complimenting the larger power of the 34DF duel fuel engines we can encompass virtually all the power needs of the vessels that would ply the inland rivers and our coasts.” These dual fuel engines burn natural gas and control the combustion process with a less than one percent mixture of diesel as a pilot fuel.

Norway & DNV: The First LNG-

Fueled Vessels “This propulsion system has been in existence for about 10 years now in

Norway,” said Teo. “Our rules were written in parallel with the prototype vessel, called the Glutra (a ro/ro pas- senger ferry). Today there are about 21 [LNG-fueled] vessels in Norway,

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