Busy times for Robert Allan Ltd

Peter Barker
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Canadian naval architect Robert Allan Ltd (RAL) is once again demonstrating a global presence with news taking us from the USA to Chile, Australia, Singapore, Indonesia, Dubai and Mauritius.

Globally, hundreds of shipyards are in the market for building tugs. There are however just a handful of what can be described as large-scale design houses providing series built solutions for individual tug owners and operators who may for example be looking for a vessel or vessels to suit the individual requirements of a specific contract.

RAL fits the description above providing design packages, in some cases specific classes of tugs exclusive to individual shipyards, Turkey’s Sanmar Shipyard and Hong Kong-based Cheoy Lee Shipyards are two such examples and it is with the latter that we start this round-up of RAL news.

The RAmparts 3200-CL was developed exclusively for Cheoy Lee Shipyards with over 20 examples delivered since 2011 and recent months have seen delivery of Hawksbill, Flatback and Loggerhead to Loreto Maritime Pte of Singapore and Limin ASD 55 for Limin Marine & Offshore Pte Indonesia.

Published technical details are the same for all four, the Lloyd’s Register classed tugs measuring 32m LOA with a beam of 12.4m and maximum draught 5m. Machinery comprises two Caterpillar 3516C diesels developing 5,364bhp in total, driving Schottel SPR 1515 fixed-pitch Z-drive units in ASD configuration. Performance figures include bollard pull ahead 71t and speed 13.4kn. Deck machinery includes a ship-assist winch forward and towing winch aft along with a knuckle-boom crane. Fifi1 provision is included together with accommodation for up to 10 persons.

A delivery of note from the RAL catalogue is the RAmpage 5500-ZH diesel-hybrid Infield Support Vessel Seaways 24 built by Keppel Singmarine for Seaways International. An indication of the multifunctional capabilities of this impressive vessel are in the extensive ABS class notation: +A1, Offshore Support Vessel (AH, TWO, SUPPLY-HNLS, FFV1+FFV2, OSR-S1), +DP-2, +AMS, +ACCU, UWILD, Green Passport, ENVIRO+, SSR-GR B (300), BP125, BWT+, NBLES, CRC.

Duties include: tanker handling and berthing; SBM holdback duties; ocean towing: anchor handling; deck and liquid cargo transfer; fifi and ROV ops; oil recovery and finally stand-by and rescue operations. Seaways 24 is a substantial vessel of 55m LOA and 15m beam with fuel capacity of 590m3.

Two MAK 9M25, 3,000kW main engines connect to CAT MTA8 Z-drives each with two PTI shaft connections turning CPP propellers in nozzles. Propulsion is supplemented by two 560kW PTI propulsion booster/economical speed/DP operation electric motors and two PTO gearboxes driving fifi pumps and 1,200ekW constant speed shaft alternators. Caterpillar also provide three gensets and performance figures include 125tbp ahead and free-running speed 15kn. Several diesel-electric, diesel-mechanical and hybrid modes are available depending on requirements and the towing provision includes a double-drum towing winch forward and double-drum waterfall type anchor-handling/towing winch aft. An extra tugger winch is included for connection of floating pipes to the FPSO pipe-flushing connection.

Delivery of a series of RAstar 3200 ASD tugs for SAAM S.A. is the first of two reports concerning vessels of this class bound for Chile and Mauritius. Four of these popular ASD tugs have now been delivered to SAAM S.A. Chile: Maneador, Arrie, Yunco and Huairavo. The last two were christened recently in Valparaiso following a 60-day trans-Pacific delivery voyage from builders Bonny Fair Development Limited in China. This pair will provide ship-handling and escort towage services at the Bay of Quintero LNG terminal.

The series are built to ABS class including offshore/escort tug designation reserved for tugs with sponsonsed hull forms offering reduced motions and accelerations compared to more standard hulls. GE provide the main machinery with two 8L250 diesels, each rated 2,440kW at 1,050rpm driving Rolls-Royce US 255 azimuth thrusters and delivering a bollard pull ahead of 85t and speed 13.8kn.

A further RAstar 3200 to mention from Cheoy Lee Shipyards is Sir Edouard for Mauritius Ports Authority, to be operated at Port Louis. Caterpillar provide main machinery for this example with two 3516C HD diesels developing 4,480kW and driving Schottel SRP 4000 fixed-pitch Z-drives. Performance figures include bollard pull ahead 79.6t and speed 13.8kn. Towing arrangements comprise a split-drum hawser winch forward and tow hook aft with accommodation for a normal operating crew of six.

Finally, RAL has provided interesting background to what is involved when shipyards turn to naval architects with vessel specification requirements to be translated into practical design solutions facilitating actual construction.

Two 24.9m twin Z-drive ATB pusher tugs for service on the US West Coast are currently in build at ITB Marine Group’s Annacis Island Shipyard near Vancouver. ITB had a relatively clear vision of the vessels’ desired layout and along with RAL developed GA plans followed by detailed and comprehensive design, engineering and support packages including: hull form optimisation study using CFD; design drawings; detailed resistance, propeller design and (articulated) pin loading studies; production design package including jigs for ITB’s yard; CFD manoeuvring studies to develop training simulator models and finally in-construction support.

The selected hull form has a relatively low depth to beam ratio with resultant efficiencies in a relatively easy to construct form. Drawings included standard structural, machinery and piping layout but also finer detail such as ladders and railings, window and door schedules and tank and anode arrangements.

The tugs will connect to existing oil barges via articulated pin systems, the barges receiving retrofitted pin ladders and stern extensions for connecting to the tugs. CFD was used for this element involving: tug/barge notch optimisation; resistance and propulsion; propeller pitch verification and verification of ATB connection pin loads. Edge preparation allowed components to be delivered ‘ready to weld’ and RAL is providing engineering assistance as and when needed by ITB. The first of the two is due for delivery in Q2 2017.

'Seaways 24' is a significant hybrid delivery from Keppel Simgmarine (RAL)