New Orleans-based Crescent Towing added the new 92'×38'×17', 5,500-hp, Z-drive ship escort/ship assist tug Mardi Gras to its New Orleans fleet back in March.

Two sisterships — Arkansas and South Carolina — are scheduled to be delivered by the end of 2016. The boats, designed by Jensen Maritime, Seattle, are being built at Steiner Shipyard, Bayou La Batre, Ala. The new Z-drives are the same size as the J.K. McLean, Lisa Cooper and David J. Cooper built in 2010-2011 at C&G Boat Works Inc. The difference between the tugs is the horsepower. The C&G-built Z-drives are 5,225 hp and the new tugs are 5,500 hp. After the South Carolina is delivered in December, Crescent will have nine Z-drives out of a fleet of 28 tugs, according to its website.

“Our customers drive this process. They are asking for more power, more maneuverability and for the tug to be in class (A-1 Towing),” said Crescent’s executive vice president, Keith Kettenring. “Two of these tugs (Mardi Gras and South Carolina) will operate in the northern harbor area of the Mississippi River between mile 106 (New Orleans) and mile 235 (Baton Rouge, La.) and the [Arkansas] will operate in Savannah, Georgia.”

Crescent Towing Z-drive tug spec boxWith a draft of 17', the Mardi Gras has been in operation for several months, and Kettenring said Crescent is very satisfied with the tug’s performance so far. “The first to be delivered has been operating in the (New Orleans) area since March with great reviews from the captains and river pilots,” he said.

The widening of the Panama Canal and an expected increase in grain exports played a part in the design of the Mardi Gras, Arkansas and South Carolina. Crescent Towing is betting that not only will grain exports stay strong, but that the expansion of the canal will mean more and larger containerships calling at East Coast ports. “Yes, the post-Panamax tonnage into Savannah helps with that decision” to build the new tugs, said Kettenring.

In addition to New Orleans, Crescent has operations in Savannah, Ga., and Mobile, Ala. “We have several new terminals under construction, the refiners continue to expand and the world is eating more proteins,” he said. “So in the long run — yes, we expect to see more ship calls,” he said.


Though Steiner Shipyard has built few tugs in its more than 50 years of operation, Russell Steiner, the yard’s owner said he didn’t hesitate to go after the job. “We had only done four or five tugs before this, but we really wanted to build these Z-drive tugs,” he said. “We knew what we were doing.”

“We embarked on our latest newbuilding program two years ago with a yard that was unknown to us,” said Kettenring. “This project was a first for Steiner Shipyard and a leap of faith into the unknown for Crescent. However, we were all placed at ease after our kick-off meeting when it became apparent that Steiner shared the same customer-centric philosophy which we hold dear.”

Steiner said he wanted to build the tugs because he knew Z-drives would give Crescent the flexibility it needed in the new tugs. “The maneuverability you get with Z-drives makes a huge difference,” Steiner said.

He speaks from experience, having built a series of 120'×34' Z-drive towboats for Southern Towing Co. over the past decade. At the time, no one else was putting Z-drives on towboats. Southern officials said the Z-drives provide a lot more thrust for the same horsepower as conventional power. “We had fewer problems building those boats than we did building shrimp boats,” said Steiner.

Bill Stegbauer, Southern Towing’s president told WorkBoat back in 2008 that with Z-drives, “there are no big rudders, no struts,” he said. “And the Z-drive is always going forward, even when the boat is going in reverse.”

That is the kind of maneuverability Crescent was looking for, said Steiner.

Rolls-Royce Z-drive units give the new tugs extra maneuverability. Steiner Shipyard/Crescent Towing photo.

Rolls-Royce Z-drive units give the new tugs extra maneuverability. Steiner Shipyard/Crescent Towing photo.

The new Crescent tugs are fitted with pairs of steerable Rolls-Royce US255FP Z-drive units connected to twin Tier 3 GE 8L250 diesel engines, producing 2,748 hp each. The engines turn P-30 2,800-mm fixed pitch propellers in nozzles. The units have hydraulic clutches and weld-in mountings, Vulkan carbon fiber straight shafting, Vulkan bulkhead mounted shaft bearings and Vulkan flywheel mounted flexible couplings. In the wheelhouse are mounted engine and thruster controls.

One of the challenges of working on the Mississippi River is operating during high-water events. The maneuverability of the new tugs makes fighting high water more manageable, said Kettenring. “In the spring the river swells with rain and snow melt and the increased velocity can cause ships to breakout, and they often require tugs to hold them in berth or anchorage.”


Another piece of equipment that is vital to the proper operation of these tugs are their winches. JonRie InterTech, Manahawkin, N.J., introduced its new Container Master winch series on the Mardi Gras.

The Container Master series was designed with increased braking capability and rope capacity to deal with larger containerships, such as the 8,000-TEU containerships that call at the Port of New Orleans. The new winch series is a heavy-duty design to deal with increased loading due to the increased sail area of today’s containerships, according to JonRie.

The tug’s winch holds 550' of 9" plasma line. Brandon Durar, JonRie’s president, told WorkBoat that this is a new line of heavy-duty winches so future winches “may hold more or less.”

The winch features JonRie’s new Gen-X controls with its hall effect foot pedal that has no moving parts that make contact with each other, thus reducing breakdowns. There is also a message screen showing the parameters of the winch and the cause of any malfunctions that occur.

If you need to quickly back off your tow, the proportional render block lets you do that with a controlled freewheeling of the drum that feathers line out at a rapid pace. The auto abort feature takes away any guesswork on the part of the operator. “You don’t have to think,” said Durar. “It starts the system, releases the brake, shuts down the motor, and if you lost power, a 24 VDC backup system comes into play.”

Some of JonRie’s standard features also come with the winch including a tension readout system with dimming controls for better night vision.

Steiner said the project has been a team effort. “Working for Crescent and its team was easy. They’re knowledgeable and were able to give us help if we needed it,” he said. Kettenring agreed. “When the rare problem did surface, it was always handled openly with honest communication and a willingness to work together in finding a solution,” he said.

Mardi Gras on the Mississippi River at New Orleans. Steiner Shipyard/Crescent Towing photo.

Mardi Gras on the Mississippi River at New Orleans. Steiner Shipyard/Crescent Towing photo.

Correspondent Michael Crowley contributed to this report.

Ken Hocke has been the senior editor of WorkBoat since 1999. He was the associate editor of WorkBoat from 1997 to 1999. Prior to that, he was the editor of the Daily Shipping Guide, a transportation daily in New Orleans. He has written for other publications including The Times-Picayune. He graduated from Louisiana State University with an arts and sciences degree, with a concentration in English, in 1978.