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INLAND PROPULSION “Z-Drive towboats have now operated long enough to gather comparative data for trip times and fuel used on the same trips with the same tows as conventional towboats … It appears the Z-Drive towboats do make quicker trip times by one to two days per trip and the fuel consumed per trip is typically reduced in excess of twenty percent. In fact, the average fuel savings for a Z-Drive towboat versus a conventional towboat is 28 percent for the data in question.” – The Shearer Group’s white paper on the next generation of inland vessels

Drive towboats have now operated long enough to gather aguay-Paraná River System, which extends over 2,500 km comparative data for trip times and fuel used on the same and is characterized by a winding river, creating alterations trips with the same tows as conventional towboats … It of the rivers’ ? ow, dams, silting and pollution which have appears the Z-Drive towboats do make quicker trip times great impact on a vessel’s propulsion system. The push by one to two days per trip and the fuel consumed per trip boats of Hidrovias do Brasil, a South American logistics is typically reduced in excess of twenty percent. In fact, the specialist; operate in this demanding environment with average fuel savings for a Z-Drive towboat versus a con- heavily laden barges over long distances at a high average ventional towboat is 28 percent for the data in question.” speed. Eight new push boats in total will reinforce the ? eet by pushing a 16 barge train of 285 meters length each. A powerful propulsion system is their constant companion:

Early Adopters and Visionaries

In every industry, there are early adopters, leaders and They have been equipped with 3 SCHOTTEL SRP 1215 quite simply, companies and managers who embrace (1,600 kW each) Rudderpropellers, driven by electric mo- new technology in a quicker fashion. If you are talking tors and designed to resist large and heavy ? oating debris.

about LNG propulsion in U.S. waters, then that discus- sion would have to include Harvey Gulf’s CEO, Shane Eastern Thunderbolt

Towboat Proposal Pro? le

Guidry. When it comes to Z-Drives, the inland industry has its own list of owners, operators and designers who ? nd themselves out in front of the pack. We picked out just a few for the purposes of this article.

For example, and seeking a complete power and pro- pulsion system designed speci? cally for tug operations,

Seattle-based Harley Marine Services recently turned to

Caterpillar – ordering four Cat 3516 marine propulsion engines and four Cat Propulsion Marine Thruster Azi- muth-Tug (MTA-T) rated drives. These units will power two new Harley Marine harbor tug vessels currently under construction at Diversi? ed Marine Incorporated, a ship- yard in Portland, Ore. Each Harley Marine harbor tug will feature a pair of 3516 engines, each delivering 2,575 hp (1,920 kW) at 1,600 rpm and two MTA 524-T thrusters with a 95.5 inch (2,400mm) propeller diameter. The MTA 524-T is a new version of a proven design, speci? cally op- timized for the operation pro? le of a tug. Cat Propulsion’s complete package for tugs includes engines, high-speed shafting, clutches, and controls.

In South America, SCHOTTEL has taken on the Par-

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