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Feature 2 | PASSENGER AND FREIGHT FERRIES


propulsion arrangements has been conceived to ensure that the vessel will be capable of sustained economic service, at a speed below the resistance ‘hump’, with maximum load and 1700dwt at 90% maximum continuous rating(MCR) of the main engines. Te crucial speed is around 29knots. Lower loads at substantially less power, for example 200tonnes at 50% MCR, will correspondingly be attainable. At 29knots, the vessel will be operating


in displacement mode. As a consequence, the hull form has been optimised for displacement speeds by shifting the longitudinal centre of buoyancy further forward, and by taking measures to reduce transom immersion. Low profile or retractable appendages are necessary to minimise appendage drag. Te influence of size or capacity on transport efficiency, using the calculation ‘deadweight multiplied by speed and divided by power’, the 130m catamaran’s efficiency is 1.42, relative to 0.97 for the 112m series of wavepiercers, and 0.86 for the 85m design. Engine power will be converted to


propulsive thrust by way of LJX-series waterjets from Wartsila, which made their debut in the 112m class of wave piercers built by Incat. In comparison with other designs, the LJX confers a 25% reduction in mounting flange diameter, a 10% overall weight reduction and a 35% increase in cavitation margin, all contributing to the lighter seaframe, more efficient ship. The Wartsila propulsor has a


1500mm-diameter, high flow impeller and employs an inboard layout for steering and reversing hydraulic cylinders, resulting in lower vibration levels and less noise as well as enhanced vessel manoeuvrability. Not only will the ship have bow thrusters, but these will be integrated with the Wartsila waterjet control system, contributing to slow-speed manoeuvring and berthing precision. Furthermore, it is claimed that the combination of thrusters and high mass flow jets will reduce power requirements in such circumstances, with the added advantage of reducing the impact on the seabed and marine life within the port. Another strand of environmental


engineering which is likely to assume increasing importance in the coming years,


100


that of noise attenuation, has also been carefully addressed. “The world’s most stringent ‘low noise emission’ standard will be met by the ecoship 130 through a series of engine room innovations, reducing machinery noise while the ship is alongside, and ensuring interior noise levels are well below recommendations,” stated Incat. The ‘green’ credentials attributed to


the latest design of large catamaran passenger/vehicle ferry also spring from a specification which includes solar panels and wind turbines on the superstructure roof, as sources of energy for the shipboard electrical power network, and the adoption of a waste heat recovery system, based on the main engine exhaust lines, and providing heat for cabins and the domestic water system. Other aspects of the outfit that offer


environmental benefits include thermal reductive glass in the passenger spaces, the use of emerging LED (light emitting diode) lighting technology, and the adoption of toxin-free hull antifoulings. Furthermore, a minimum of 20 sockets will be provided for refigerated containers or trailers, to allow connection with the ship’s electrical network, so that the units’ integral reefer power packs can be turned off while onboard, reducing harmful exhaust emissions. The Tasmanian yard’s past three


deliveries have all been examples of the Evolution 112 class, its largest ships to date. The most recent completion, the 112m wave piercer Norman Arrow, was initially assigned by charterer LD Lines to Dover/Boulogne service in June 2009. At the time, she was the largest high-speed ferry to have been introduced to the cross-Channel traffic between England and France. Norman Arrow has this year been


allocated to a longer Channel run, the Portsmouth/Le Havre route, for the period between Easter and September. The vessel has enabled crossings to be made in three hours 15 minutes compared to conventional ferry transit times of five hours 30 minutes on day sailings. Norman Arrow can accommodate 1200


passengers and crew, and has capacity for 567 lane-metres of goods vehicles plus 195 cars on a separate car deck, with a


service speed of some 39knots attainable on a draught of 3.93m. Te ro-ro freight intake corresponds to 28 truck-trailer combinations. Her four-engine, MAN 20V28/33D installation and associated drive arrangements confer a dual-speed operating capability, at 23knots or 39knots-plus, allowing power to be closely matched to actual scheduling requirements, and benefiting efficiency. Relat ive to earlier-generat ion


high-speed ferries used on the Channel, the Evolution 112-class cat is also claimed to offer improved seakeeping qualities and passenger comfort, vital operational and commercial attributes for year-round duties. Incat has recently also augmented its


range with a new wave piercing design of approximately 85m length, offering a number of options as to vehicle deck and cargo access arrangements, main machinery and hull appendages. While the ability to make at least 36knots on a deadweight of 500tonnes, and 40knots-plus with 200tonnes, is core to the performance attributes, Incat says that improved efficiency and overall economy have been key considerations. Vehicles load from shore-based ramps


over the stern or by way of an optional stern quarter ramp from alongside. Furthermore, customers may specify a bow ramp. An optional mezzanine deck can be fitted to increase car capacity if required, while the design also lends itself to the installation of the proprietary, rectractable T-foil system to reduce motions. By these and other means, an operator can customise the design to the specific needs of a service route and customer base. Te 85m cat provides for about 600


passengers, with facilities concentrated on Tier 2 deck and including three lounges. The vehicle deck below offers 545 lane metres for passengers’ cars, corresponding to 121 units, and alternatively provides 330 lane metres for trucks at 4.6m clear height, plus 300m2


at


a minimum 4.0m headroom. Te choice of main machinery is four


12-cylinder models of MAN’s 28/33D engine, giving total propulsion power of 21,600kW, or four 16-cylinder versions of Caterpillar’s C280 diesel. NA


The Naval Architect September 2010


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