High water brings out the beast in Crescent Towing z-drive


On a sun-splashed February morning, the Crescent Towing tugboat Mardi Gras met the 751-foot tanker Flagship Sage south of New Orleans on the Mississippi River. As was the case a year earlier, high water was coming early in the season and the river had swollen to 15 feet on the levee at the Carrollton Gauge. With flood stage at 17 feet, the current was showing its muscle.

The 92-by-38-foot Mardi Gras is an azimuthing stern drive tug designed by Jensen Maritime of Seattle, one of three sister vessels built at Steiner Shipyard in Bayou La Batre, Ala., in 2016 and 2017. Two General Electric Tier 3 main engines, shafted to Rolls-Royce z-drives, produce 5,496 horsepower, impressive for eight-cylinder power plants.

The sister tugs, Arkansas and South Carolina, are part of Crescent Towing’s fleets in Savannah, Ga., and New Orleans, respectively. The high-horsepower, deep-draft escort tugs answer the call to handle the ever-increasing size, tonnage and draft of ships calling at the company’s ports in New Orleans, Savannah and Mobile, Ala.

“Horsepower is needed to better control these ships in order to avoid accidents and environmental casualties,” said Keith Kettenring, Crescent Towing’s executive vice president.

Three other Jensen-designed tugs with similar dimensions to Mardi Gras but powered by six-cylinder GE engines were built by C&G Boat Works for Crescent in 2010 and 2011. Lisa Cooper and J.K. McLean are in the Mobile fleet, and David J. Cooper is in New Orleans.

The bow staple on Mardi Gras is set closer to the escort winch than usual, improving the tug’s maneuverability and stability while towing.

“We wanted to increase the horsepower and accommodate a 2,800-millimeter (110-inch) propeller on the outdrives to increase our overall bollard pull,” Kettenring said. The changes increased it from 65 to 75 metric tons.

Another change was fitting the bow staple 6.5 feet back, closer to the JonRie escort winch, from its location on the earlier tugs. This changed the center of gravity when towing, improved maneuverability and increased the vessels’ stability.

Capt. Roy Helmstetter, at the helm of Mardi Gras, maneuvered the tug to the bow of Flagship Sage and watched deck hand Christian Breithaupt put a line up to the ship. Helmstetter ran with the tanker, slack line, upriver against the robust current to the Valero Meraux refinery. A second tug, the twin-screw Miriam Walmsley Cooper, was tethered to the stern of the ship. 

Helmstetter said adapting to the complexity of operating z-drives was a hard transition at first.

“After learning what not to do over all those years on conventional tugs, on this one you can do them,” he said. “The possibilities are only confined to the imagination.”

It took an hour and half to dock Flagship Sage because of the high water and the need for extra lines. Then began a two-day hold in assignment, but not for Mardi Gras. Crescent Towing’s twin-screw Angus R. Cooper was called in to relieve the ASD tug, much too valuable of an asset to be out of pocket for that long with the current up.


The tug displays its power as it assists the tanker into the refinery dock at mile marker 87.


Two GE L250 eight-cylinder main engines deliver nearly 5,500 horsepower.


The tug’s crew: chief engineer A.J. Campbell, left, Capt. Roy Helmstetter, center, and deck hand Christian Breithaupt.


“After learning what not to do all those years on conventional tugs, on this one you can do them,” says Helmstetter, relaxing in the wheelhouse between jobs.


Mardi Gras specifications

Owner/operator: Crescent Towing, New Orleans, La.
Designer/builder: Jensen Maritime, Seattle, Wash./Steiner Shipyard, Bayou La Batre, Ala.
Dimensions: L: 92’ B: 38’ D: 19.5’
Mission: Harbor tug
Crew size: Four

• (2) General Electric eight-cylinder L250 Tier 3 main engines, 2,748 hp each
• (2) Rolls-Royce US 255 FP z-drives 
• (2) John Deere 4045AFM85 99-kW auxiliary generators
• Bollard pull: 75 metric tons • Speed: 13 knots

• JonRie InterTech Series 230 escort winch with 550 feet of 9-inch Samson AmSteel-Blue line
• JonRie 424 hydraulic capstan • Schuyler Cos. fendering

• Furuno FR-8125 radar system
• Furuno NavNet TZTL12F chartplotter
• Furuno FA150 AIS
• Furuno GP1850W chartplotter with WAAS/GPS
• Cassens & Plath IOTA 2 compass
• (2) Standard Horizon GX550 VHF radios


By Professional Mariner Staff