2 Tugs from Robert Allan for Tauranga Port
The Tai Pari and Tai Timu, two RAmparts 2400W Class tugs designed by Robert Allan Ltd of Vancouver, Canada, have been delivered by Cheoy Lee Shipyards to the Port of Tauranga Limited. The Tai Pari arrived in New Zealand on June 5 after a 30 day voyage on her own bottom. The Tai Timu departed Hong Kong on May 30 and is expected to arrive at the end of June. These two vessels represent a significant upgrade to the Port of Tauranga's fleet.
These RAmparts 2400W hulls feature standard RAmparts class characteristics including good dead-rise for improved thruster performance, modest side flare, a half-raised forecastle deck for good sea keeping, and the characteristic conically shaped double chine stern developed by Robert Allan Ltd., and now being oft emulated, ensuring that the tug can run astern at high speed and maintain good control and directional stability. The hull is under the 24 metre rule length for load line and tonnage conventions.
The Port of Tauranga provided significant input into customizing the design for their operations. One of the Port's requirements was a high side stepping speed but still capable of some modest indirect towing capability. Robert Allan Ltd. thus conducted a detailed CFD study to determine optimal skeg geometry to achieve these requirements. The tests were done self-propelled with the Z-drive thrusters completely modeled including rotating propellers. The images below show the underwater view of shear stress contours with first the thrusters oriented for side stepping and second an overhead view of water velocity with the tug slipping sideways through the water.
Particulars of the Tai Pari and Tai Timu are as follows:
Hull
Length overall: 24.40 metres
Beam: 11.25 metres
Depth (least moulded): 4.22 metres
Extreme draft full load: - 5.30 metres
Capacities
Fuel oil capacity: 76.80 m³
Fresh water capacity: - 10.10 m³
-
Machinery
Main Engines: - two CAT 3516C HD, each rated 2,350 kW at 1,800 rpm ("C" rated, IMO Tier II Compliant)
Z-Drives: 2 x Rolls Royce US 255 FP with 2.6 metre fixed-pitch propellers
Gen-Sets: 2 x CAT C6.6 rated 125 ekW at 1,500 rpm
Winch: MacGregor MG-HAT/SGD-22 hawser winch with split drum, 175 tonne brake holding load, and haul-in rating of 10 tonnes at 20 metres/minute
The Tai Pari is fitted with Fi-Fi ½ equipment including a single centrifugal pump driven off the port main engine and one 1,200 m³/hour monitor mounted port forward
Mampaey aft tow hook (100 T SWL)
5 T aft capstan
Ship-handling fenders at the bow comprise an upper row of 800 mm diameter cylindrical fender and a lower course of W-fender. Sheer fendering consists of 300 mm D-rubber. "W" block type fendering is fitted at the stern.
Typical of Robert Allan Ltd. tug designs, significant noise and vibration reduction measures have been implemented throughout, including resiliently mounted main engines, resiliently mounted gensets and auxiliary engine, high attenuation engine exhaust silencer systems, ventilation intake air silencers, sound dampening deck treatments, and insulation measures.
The tug was constructed to Lloyd's Register Class requirements with the following notation:
LR 100A1 TUG, LMC, UMS, IWS
The vessels have been outfitted to high standards for a crew of six. The main deckhouse contains the entrance lobby, galley, mess, two officer cabins, and a common WC. The lower deck contains two double berth cabins, a common WC with laundry, and a store room. The wheelhouse offers excellent unobstructed views of the entire forward and aft working decks and to the contact zones port and starboard.
On trials, both tugs achieved ahead speeds of over 13 knots and side-stepped at over 5.5 knots. Both easily achieved over 70 tonnes bollard pull. With an exceptional power to size ratio, modern high performance hull form, and excellent wheelhouse views, the Tai Pari and Tai Timu represent a valuable addition to the Port of Tauranga's fleet.
