TUGS & SALVAGE

RAL influence continues to spread

17 years ago

Barely a month goes by without news of more tugs being completed to designs from the Vancouver based design team of Robert Allan Ltd (RAL) naval architects. Among those designs are those that are now well established and others that are quickly gaining favour in various sectors of the towage market. The influence of this prolific design house has spread as widely as a virulent influenza, due largely to a design philosophy and support package that enables the vessels to be readily constructed by many competent shipyards worldwide.

The most popular design to date is undoubtedly the RAmparts 3200 class ASD shiphandling tug, now in service or under construction in very large numbers. Examples have been reported in the pages of Maritime Journal from as far apart as Brazil, Norway, the Netherlands, Australia and China, but strangely not yet in Britain. Several shipyards are doing good business, meeting the continuing demand for these powerful and agile vessels.

Among the latest deliveries of RAmparts 3200 tugs is the first of a pair to be ordered from Shipco Marine Constructors Ltd of Whangarei, New Zealand, for Rio Tinto in Australia. Named Pilbara Thor, the tug is now in service at the Pilbara ore terminal near Dampier.

RAL worked closely with the owner’s representatives to establish the final specification and vessel layout for the particularly demanding service expected of this tug. The hull reflects the very well proven double chine form that characterises all RAL designs, with a sweeping chine at the stern. A large escort skeg is fitted forward to enhance the indirect towing capability and to provide enhanced roll stability. The semi-raised forecastle runs nearly half the length of the tug to provide a high standard of accommodation and good seakeeping characteristic for operation in exposed conditions.

In keeping with others of the class, Pilbara Thor is 32.00m in length overall, with a moulded beam of 11.6m and maximum draft of 5.21m. On trials the vessel performed exceptionally well, achieving a sustained mean bollard pull of 70.5 tons ahead, and 67.5 tons astern at full power and a free running speed of 12.8 knots ahead and over 12 knots astern.

Pilbara Thor is powered by a pair of Niigata 6L 28HX diesel engines, each rated at 2,497 bhp (1,838 kW) at 750 rpm and driving a Niigata ZP 41 fixed pitch Z-drive unit through a Niigata HLP80Y type slipping clutch. Electrical power is supplied by two identical Volvo Penta diesel gensets, each with a power output of 120 kW at 415 volt/50 Hz.

Noise levels below 60dBA were achieved throughout the accommodation and control spaces of the tug by utilising advanced methods of isolating main propulsion machinery, as well as high grade insulation and floating floor techniques.

Two, separate, single drum towing winches on the foredeck were manufactured by Shipco Marine Constructors Ltd and each accommodates100m of 88mm polyester towline with 15m of 68mm sacrificial UHMPE pennant.