News: 8,000-hp Offshore Tug First With QSK60s

Cenac Towing of Houma, La., has long had a reputation for quality boats. Both their inland waterway push boats and their off-shore tugs are meticulous in their design, construction and maintenance. In the spring of 2000, the company commissioned a Cummins-powered 2,550 hp, 100 x 34-ft. triple screw off-shore tug, the Andrea Cenac. This May, Cenac is putting their newest and largest tug into service. As with their other new boats, the O.J. Cenac will be Cummins powered. At 130 x 38 ft. with a 15-ft. molded depth, this is a big boat. The new boat marks a milestone for both Cenac and Cummins as it is the first tug into service with Cummins' recently introduced QSK60 engines. With three of these new engines, each turning its own propeller, the O.J. Cenac, will work as an 8,000-hp classed vessel. The engines turn into Twin Disc MG DR5600 marine gears with 7:1 ratios. The 90-in. props are enclosed in kort nozzles that have been faired into the hull to maintain the boat's 12-ft. working draft. The massive props are mounted on nine-in. shafts equipped with Kobelt 527A shaft brakes. Steering to the boat's three rudders was supplied by St. Rose, Louisiana-based EMI. The electronic clutch and throttle controls were supplied by Twin Disc. Tankage on the O.J. Cenac includes 100,000 gallons of fuel in multiple tanks with a common day tank. There is an Alpha Laval SB104 centrifuge through which fuel is pumped. The centrifuge is also employed to circulate fuel in the tank. Accommodation for a crew of up to 12 people is provided in a traditionally styled three level deck house.

Auxiliary power employs two Cummins 6CT-powered 130 kW generator sets in addition to a Cummins QSM11 for the boat's Intercon winch.

The waterfall-type winch has a capacity of 3,000 ft. of 2.5-in. wire per drum and 315,000 pounds of line pull. The boat has a fixed onboard CO2 fire suppression system for unmanned machinery and cargo spaces and is built to an ABS load line but is not classed.

The boat will tow a 425 by 70-ft. 50,000-barrel barge in deep water Gulf of Mexico service. "The Andrea Cenac has been a very successful strong pulling boat and that success has led to this larger boat," Cenac said, "The design is a collaboration between Maine Iron Works and Cenac Towing, We like a boat with classic lines but the latest equipment."

Leroy Molaison, of Main Iron Works in Houma, explains that this boat is one of 20 or 25 vessels the two companies have collaborated on, "I've been here since 1961 and I know they did boats before that," he explains.

"Depending on the work schedule at Cenac we do more or less of the finish. On this boat, we did the steel work, installed the props, shaft and some of the piping before delivering it to the Cenac yard."

The vessel has a hard chine design with the relatively shallow 12-ft. working draft determined by the maximum 13.5-ft. availability at the Cenac facility in Houma. "This boat is a totally new design," says Molaison, "That grows out of the combined experience of years and years of working together by our two companies."