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A sister tug IS DELIVERED After the very successful launching and delivery of the 15m tug PT May to Brisbane last year, the Whangarei shipyard of ShipCo, recently launched a new sister ship, destined for Pacific Tugs, Australia. T hese smaller tugs follow on the heels of two larger 32m sisters from the same yard, now working very successfully as ship assist tugs off the Western Australian iron ore mine Skipper Scott Logan at the helm conventional drives, the PT Mary, like her sister, stands out from any predecessors of similar size with a number of clever design features.This includes individual steerable quartz nozzles, making her perform more like a Z-drive ship-handling tractor tug than a traditional working towboat. "Independent steerable nozzles give her exceptional manoeuvrability, including the ability to move sideways, which is a step ahead from most standard twin-screw tugs." said her trial skipper, Scott Logan, a master for the Auckland company Thompson Towing who were contracted to trial and prepare the PT Mary for delivery. The nozzles are top-hung and have 35 degrees of steerage to port and starboard, taking a total of 12 seconds lock-to-lock. The amount of grunt this little workhorse delivers from 900kW is most impressive. During her trials she comfortably delivered her design bollard pull of 17 Bugger off. VIP.WB13 fields. Apart from three minor changes requested by the owners, PT Mary is a true sister to the first 15m tug PT May. These changes are a shift of the shower into the heads, turning the shower space on the portside of the lower flat into a small workshop. The second, was the reposition of the tow hook on the winch, and the third were some changes to the main switchboard. The first tug, the PT May, was the first small tug in her class to be built in New Zealand. That is, if you can call this tug design small. At nearly 16m overall, including the fenders, a 7m beam and drawing 2.7m aft, she takes up a fair hunk of water space while making sure she has a good grip on it as well. Her design incorporates a heap of new features not seen before in tugs of this size, with many of her innovations leading the way in new tug and towboat development in this part of the South Pacific. Her twin marine diesels, rated 447kW (600bhp) each at 1800rpm, are air-started and keel-cooled. They drive through detached 16:1 island-mounted gearboxes connected via a Centa CX-55-LFS2 input coupling. Another significant difference is that the propeller shafts are of mild steel running in oil-lubricated bronze bushes driving twin 1494mm-diameter four-bladed manganese bronze propellers. The propulsion train is remarkably free of vibration both ahead and astern and at all speed ranges, giving a no-load service speed of 10.5 knots. The main engines are mounted on LO-REZ BR4LS spring-type vibration isolators. They have a high load capacity, incorporating safety limit stops and neoprene dampers to prevent excessive vertical or rocking motion of isolated machinery. The exhaust pipes and mufflers are also resiliently mounted, so overall there is very good noise control. Electrical power is generated by two generator sets, both keel-cooled, rated at 80kW 380 volts 50Hz for general on-board power. The other, larger genset, rated at 136kW 380 volts 50Hz, supplies the power to drive the towing winch. Although her propulsion is twin screws through We clean your fuel, tanks, filters and lines. 0800 482 652 / dieselclean.co.nz NZ WORKBOAT REVIEW 2013 51