Brawny Crescent z-drive takes on all comers in Big Easy

On an overcast day last November, the bright yellow Crescent Towing tugs Mardi Gras and South Carolina, bows bibbed for Navy work, lent color to the metal gray day. They were escorting USS Arlington, a San Antonio-class amphibious transport dock, up the Mississippi River to the Governor Nicholls Street Wharf in New Orleans.

A few years ago, Crescent Towing, a Cooper/T. Smith company, made the decision to build a series of high-horsepower, high-bollard-pull tugs in anticipation of the massive new ships expected at the company’s ports in New Orleans, Mobile, Ala., and Savannah, Ga. The first of the series, the 5,496-hp Mardi Gras, was delivered to the New Orleans fleet in March 2016. The second, Arkansas, joined the Savannah fleet in November 2016, and South Carolina arrived in New Orleans in June 2017.

Jensen Maritime Consultants of Seattle, Wash., designed the tugs, and Steiner Shipyard of Bayou La Batre, Ala., built them. Crescent increased the bollard pull by choosing eight-cylinder GE engines instead of the six-cylinder GE units that the company had mounted in three earlier tugs of the same design and dimensions. Lisa Cooper, J.K. McLean and David J. Cooper were built from 2010 to 2012.

“We wanted to increase the horsepower and accommodate a 2,800-millimeter (110-inch) propeller on the outdrives to increase our overall bollard pull,” said Keith Kettenring, Crescent Towing’s executive vice president. The increased horsepower and larger wheels in type 19A nozzles produced an increase in bollard pull from 65 tons to 75 tons.

Personnel on the deck of USS Arlington watch as South Carolina assists the Navy ship to the dock at the Governor Nicholls Street Wharf in New Orleans.

Kettenring explained that the high horsepower and deep-draft design of the tugs is important for their long-term serviceability and safety, given the ever-increasing size, tonnage and draft of the ships calling at U.S. ports.

The JonRie InterTech 230 Super Series hawser winch, wound with 550 feet of Plasma line, has more drum capacity than the earlier tugs, another safety component added to help when assisting larger ships.

Crescent Towing used recommendations from its port engineers and senior captains to improve tug operations and increase crew comfort. For example, positioning the staple 6.5 feet back from its position on the previous tugs changed the center of gravity. The modification improved the steering by 30 percent and increased the vessel’s stability during operations.

Isolation mounts on the engines and a generous amount of insulation throughout the vessel contribute to a quiet ride. “It’s a very comfortable boat,” said senior Capt. Terry Murley.

The engineer, Jamie Ortiz, concurred. “The generators and compressor are way back in the z-drive room, so it’s very quiet,” he said. “It’s a sweet boat.”

The delivery of South Carolina brings the number of azimuthing stern drive (ASD) tugs in the Crescent fleet to nine, five of which are operating in New Orleans.

Senior Capt. Terry Murley multitasks on the radio and z-drive controls as South Carolina gets into assist mode on the Mississippi.		South Carolina’s crew is comprised of Murley, engineer Jamie Ortiz, deck hand Greg Gerrets and deck hand Chase McClean.
The JonRie escort winch mounted on the bow is wound with 550 feet of 9-inch Plasma synthetic line from Puget Sound Rope.		Rolls-Royce z-drives and a pair of GE main engines give the tugboat 75 tons of bollard pull.