Tug Repower Overcomes Logistical Challenges

Repowering a tug is a big deal for small towing companies, and Interport Towing & Transportation, Southport, Maine, U.S.A., is a good example. The company has three tugs and a crewboat that are constantly in use. The vessel to be repowered, the tug Lucinda Smith was built in 1975 and has had three names before its current one. It is 24.8 m by 8.5 m with a 3.6 m molded depth. “While it was difficult to rework our schedule so the Lucinda Smith could be made available for repowering, we all pulled together to make it happen,” reported Jon Smith, who along with his wife Cindy owns Interport.

“There are a lot of criteria that go into choosing just the right engine for our repower,” Smith said.“First, will they fit in the space occupied by the old engines and also, will they work with existing gears, shafts and propellers. Also, we were looking for power in the range of 969 to 1044 kW for each engine. After a lot of searching we decided to go with one of the new low emissions engines. The Cummins QSK 38 seemed to fit the bill perfectly.”

The repowering took place at a wharf in Boothbay Harbor, Maine. “We chose the one wharf that could support the engines, gears and crane,” Smith said. He did the engine change out along with his crew from Interport and Boothbay Harbor Shipyard. “From there the boat went to the Boothbay Harbor Shipyard, so we had welders, and other shipyard services available.” Smith added. “At the same time we were repowering the boat, we added an upper wheelhouse that now gives us 14 meters of height, a feature that both our captains and the customers like. They also like the hydraulic crane on the boat. It makes a lot of things easier — both on the job and for the crew loading job materials,” Smith stated.

“We supplied the QSK 38 engines that have low emission Tier 2 technology,” said Cheryl Lavalley, P.E., application engineer with Cummins Northeast Inc. “The engines were supplied with our new electronic control system — the C-Commander — to protect and enhance engine operation with a variety of monitoring and display options for marine operations.” Also installed were ZF gears with a 5.61:1 ratio. The shafts, propellers and Kort nozzles were retained. “We are still fine tuning the 190.5 cm propellers. The diameter will stay the same so we can reuse the Kort nozzles. But the pitch may change from 190.5 cm to 185.4 cm,” said Smith.

The Lucinda Smith on sea trials after installation of the new Tier 2, Cummins QSK 38’s diesel engines. The vessel belongs to Interport Towing & Transportation, Southport, Maine, U.S.A.

“Low-emission engines have become important to the customers as well,” said Smith. “In New York City, dredging jobs may involve three dredges, six tugs and other support vessels. In some harbors, the EPA adds up all the emissions from a job site and that site will have a certain allotment of emissions per year. Once that allotment is met, the job site can be closed down. So our new low-emission power can help the customer meet his restrictions, and that is another reason why we went with Tier 2 power.” Smith said.

For the past 23 years Interport has used its vessels to assist dredging companies clear inlets and harbors, but this work alone does not define the company. Lucinda, or Cindy, (namesake of the vessel) is one of a growing number of tugboat captains. She has a 200 ton master’s license with towing endorsement. At present, both Jon and Cindy are administrators or port captains/ engineers for Interport Towing. “Our vessels have recently helped lay fiber optic cable in the Bahamas and assist in the old Jamestown bridge demolition in Narragansett Bay,” Cindy Smith said. “When all of our boats are in service we have 26 employees.”