Horizon Shipbuilding of Bayou La Batre, Ala., delivered a Cummins-powered Z-drive tug to Dixie Towing of Jacksonville Florida on January 12, 2001. The 70 x 26-ft. boat is powered by a pair of Cummins KTA19 M3 engines rated for 500 hp each at 1,800 rpm. The engines turn Ustein-Aquamaster 370H Z-drives with 52-in.(1321 m/m) propeller diameters.
Dixie Towing owner Robert Gibbs explains
that the new boat, named M/V Belle Watling, was nearly two years in planning. "I wanted a boat that would do all of the things expected of a vessel of her size and horsepower, only better."
Working with Jacksonville based naval architect Ed Glowacki, Gibbs settled on an azimuthing stern Z-drive design for its versatility. The original plans for a 24-ft. beam on the hard chine hull was broadened to 26 ft. in order to achieve the nine-foot draft limit of much of the Intercoastal Waterway. Gibbs points out additional advantages of the Z-drives including that he has done away with stuffing boxes and the costs of disposing of most bilge water. At the same time he has separated hull maintenance from the power train maintenance in that he can pull the stern mounted Z-drives without drydocking the boat. It was also practical considerations that brought him to the well proven Cummins KTA 19 M3 engine, "We like the separate cylinder heads on the in-line six-cylinder engine as well as the funding package available."
The new boat is equipped with a pair of Cummins Onan 35 Kw gensets and an electric over hydraulic Pullmaster winch generating 50,000 pounds of line pull and loaded with 1500 feet of 1.25-in. wire. "We will be experimenting with the winch both with conventional line towing and made up to barges bridals for pushing," explains Gibbs.
Gibbs spoke with a number of other operators using Z-drives for conventional towing work and says, "Whereas the Z-drives cost more up front, in the long run the efficiencies, flexibility and industry demand should more than offset those costs."