Allied Shipbuilders Deliver New Caterpillar-Powered Z-Drive Ship-Assist Tug
Allied Shipbuilders Ltd. of North Vancouver, Canada, recently delivered the 74-foot-long by 28-footbeam tug Charles H. Cates III (Cates 3) to C.H. Cates & Sons Ltd., also of North Vancouver. The vessel, constructed to the design of Robert Allan Ltd.. is the latest in C.H. Cates & Sons' fleet of Z-drive ship-assist tugs for service in the Port of Vancouver.
The Cates 3 is essentially identical to other Z-drive tugs in the Cates fleet, with twin Z-drives in a "reverse- tractor" configuration. The earlier vessels have proven to be almost ideal for service in the Port of Vancouver.
The tug is configured as a shift boat, with day room facilities only for the crew of two persons.
The wheelhouse is designed for one-man operation and has now been refined through three vessels to the point where every feature is situated optimally for safe and effective control of the tug. Visibility is virtually unimpeded through 360 degrees, with excellent downward and overhead vision all-round.
Main engines on the Cates 3 are a pair of CAT 3512 TA diesels, each rated 1,175 bhp at 1,600 rpm for the ship-berthing service. Each engine is connected to a Niigata Model ZP- 2A 360-degree azimuthing drive through a Niigata Model RGC- 130K clutch/reduction gear, and Geislinger torsionally resilient coupling. The electrical generating system on the Cates 3 comprises two main generator sets, each a 95-kw, 1,800- rpm CAT model 3304 B. The sets are connected for nonparallel operation, with automatic load transfer.
One of the many features of this tug is the use of electric power for the main steering motors and hawser winch. By use of a Mechtronics Series 59000 frequency controller, full variable speed control is obtained on these standard AC motors.
All crane and winch functions are controllable from within the wheelhouse, as well as from the foredeck of the tug.
The Cates 3 successfully completed all trials and is now actively in service. As well as demonstrating the exceptional maneuverability and control associated with the twin Z-drive configuration, the vessel recorded sustained bollard pulls of 34,015 kg ahead, and 30,720 kg astern, and a free running speed of 11 knots.
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