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More towing operators are choosing z-drives for inland river work

Jul 31, 2014 02:28 PM
The new American Commercial Lines pushboat American Way is the company’s first vessel with azimuthing stern drives.

(Photo courtesy Steiner Construction)

The new American Commercial Lines pushboat American Way is the company’s first vessel with azimuthing stern drives.

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Although it’s one of the nation’s largest inland operators, American Commercial Lines (ACL) hadn’t ordered any new vessels since 1982. When the Jeffersonville, Ind.-based company finally acquired two new pushboats this year, those vessels were equipped with z-drive propulsion systems.

The azimuthing-stern-drive design debuted on the inland rivers only about six years ago. Suppliers said the recent deliveries to ACL, Southern Towing and a few other operators in 2014 are an indication that the towing industry is finally embracing the new technology.

The birthplace of many of these new towboats is the Bayou La Batre, Ala., area, where three shipbuilding businesses are producing the high concentration of z-drive inland vessels.

(Photo courtesy Steiner Construction)

The z-drive systems before the boat was launched at Steiner Construction Inc.

In the spring of 2014, Steiner Construction Inc. delivered a pair of 2,000-hp boats to ACL, which plans to exercise options for more. The 70-foot American Way went to work for ACL in the Baton Rouge, La., barge fleet, while the 75-foot American Spirit is headed for the Gulf Intracoastal Waterway between New Orleans and Houston.

Z-drives, which provide a 360° directional option, are more efficient than a traditional rudder configuration because they focus all of the engine’s force toward pushing the boat in the direction the pilot wants. With a traditional rudder, much of the thrust gets deflected — and wasted — as the water is directed away at an angle to create resistance and drag.

Compared to the rest of the ACL fleet, the two new boats operate more efficiently, respond to commands quickly and are easier to navigate, said David Abney, marine superintendent for ACL’s southern division.

“It’s everything we expected and more,” Abney said. “You can get the work done faster and safer at the same time, because of the maneuverability. It’s a lot easier to handle the barges too. You’re not losing any thrust. You always get what we call ‘clean water.’”

The designer of the two new ACL vessels was Gulf Breeze, Fla.-based Sterling Marine LLC. As part of the project, Steiner Construction acquired the rights to and modified an original z-drive design from Rodriguez Shipbuilding Inc. in Coden, Ala. ZF Marine supplied the z-drives.

In addition to the greater maneuverability and the safety benefits, the z-drives improve fuel efficiency by allowing the operator to keep the boat moving in exactly the intended direction.

“That’s where the value of the z-drives will really show up, we believe,” said Bill Foster, ACL’s vice president of boat maintenance. “We looked at the whole life-cycle cost and see potential value — a half-million dollars a year over a conventional boat. Sixty to 70 percent of that is fuel, and the rest of it is maintenance that I’m comparing with our 30- to 40-year-old tugboat fleet.”

The pioneer of using z-drives for inland river work was Southern Towing Co. In 2008-09, the Memphis, Tenn.-based operator debuted the 3,800-hp Frank T. Stegbauer, David Stegbauer and Scott Stegbauer. Convinced that the z-drive configuration was the way to go, Southern has added more of the vessels over the years. Its three newest z-drives are the 2,300-hp Paula Fortier, Theresa Echols and, most recently in 2014, Capt. Tommy Parrish.

Another large operator, Marquette Transportation, said it will take delivery of three z-drive towing vessels for its Gulf-Inland division this year. The builder is Bayou La Batre-based Master Marine.

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