2015 June 22 13:32

Two Robert Allan designed RAmparts 2400W tugs delivered to the Port of Tauranga

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, the Company said in a press release.

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.

Key specifications: LOA - 24.40 metres; Beam - 11.25m; Depth (least moulded) - 4.22 m; Extreme draft full load - 5.30m.    
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.

Robert Allan Ltd. is an independent, privately owned firm of Consulting Naval Architects, established in Vancouver. The business was founded in 1930 when Robert Allan commenced private practice as a Consulting Naval Architect after managing a local shipyard. He was responsible for numerous enduring designs produced for the growing British Columbia fishing fleet and for coastal ferry services, among others. The firm's reputation was also enhanced by the design of the notable and enduring ocean-going motor yachts Meander and Fifer.