By David Tinsley, technical editor
Confounding the skeptics who said the 70,300-gt Queen Elizabeth 2 would be the last transatlantic liner ever built, the 150,000-gt Queen Mary 2 is set to make her service debut in January 2004, signifying a $780-million investment in a luxury passenger ship structurally engineered for the North Atlantic.
Destined to uphold and revitalize the Cunard liner tradition, the 30-knot QM2 will break new ground in passenger ship technology, while incorporating lessons learned with the 1969-commissioned QE2. The challenge of fulfilling an extremely tough schedule in a notoriously harsh environment, and of meeting rising customer expectations as to service quality, comfort and reliability in all conditions, permeates every aspect of the technical design. Carnival Corporation's decision to build on the Cunard legacy, taken forward so successfully over the past three decades and more by the QE2, denotes the U.S. group's perception of the long-term potential in a specialized or niche market for point-to-point voyages, a field entirely distinct from the general cruise holiday business.
The newbuilding's design is based on an operating requirement for a minimum eight or nine months' deployment each year on the North Atlantic. Longer cruises to destinations worldwide will complement her regular operating schedule on the transatlantic run between Southampton and New York. Since the vessel has been conceived to maintain the link between the UK and USA in accordance with a six-day rotation, she embodies the margin of power and speed to skirt especially rough weather, or to recover time lost in slowing for navigation through such adverse conditions, obviating scheduling delays. QM2 offers a capacity for 2,620 passengers, on the basis of lower berth occupancy alone, rising to a maximum of 3,090 passengers if upper berths are taken into account. The intention with the prestigious new vessel has been to achieve the requisite, exacting operational performance criteria, using innovative maritime and engineering technologies, and to evoke a feeling of grandeur, elegance and comfort, without sacrificing contemporary style and amenities, to meet the target market's expectations of the Cunard brand.
Stylish restaurants, expansive promenades, sweeping staircases, and public rooms on an imposing scale are among the Cunard hallmarks manifested in the QM2, while a space ratio of 57.25-sq ft per passenger, and the sheer size of the vessel at 150,000-gt, rate her among the roomiest of the world's largest passenger ships.
The original ship design concept was formulated between Carnival Corp Technical Services of London, now Carnival Corporate Shipbuilding, and Cunard Line over a period of two years. The basic parameters were verified prior to contract, such that the design was largely established by the time the order was awarded to Chantiers de l'Atlantique.
Structural analysis was undertaken in conjunction with Lloyd's Register, with which the ship is classed. It is understood that, as a result of the society's research, the QM2's design sagging wave-bending moment will be some 22-percent greater than the current IACS requirement in consideration of the operational profile, 40-year design life and low block coefficient. So as to confirm that the design was in compliance with LR's ShipRight structural design assessment procedure for the primary structure, the builder undertook a full-scale, global finite element model(FEM) analysis. Parts of the Cunarder's shell plating are as thick as 28-mm, to manage the demands of the vessel's primary operational route. The ship's spine is formed of four longitudinal bulkheads running the length of the vessel.
So as to provide the raw power to cover the requisite propulsive power and meet the anticipated 16-MW hotel load, with the flexibility to efficiently cater to different service modes, QM2 has been specified with a combined diesel-electric and gas turbine (CODAG) plant, arranged in a classical power station configuration. The two GE Marine LM2500+ gas turbines of 25-MW unit power and four Wärtsilä 16V46 diesels of 16.8-MW apiece, each drive generators for a total plant output of 117,200-kW. The electrical alternators have been supplied by ABB Finland, and Valmarine has provided the integrated automation control system.
Besides covering the hotel load, the three main service conditions for which the CODAG plant has been sized and configured are an economical, diesel-only cruising mode, a service speed condition, and a maximum speed condition, with all machinery in operation. The service speed mode, allowing an adequate sea margin for adverse weather, assumes that all prime movers bar one diesel engine are in operation.
The 46C-series diesels, designated as EnviroEngines, utilize the Finnish designer's common rail fuel injection and water injection technology, curbing noxious exhaust emissions and ensuring that no visible smoke will be produced at any load. The application of EnviroEngine methodologies to the diesel prime movers in conjunction with the adoption of aeroderivative gas turbines promises favorable environmental properties along with the requisite operating flexibility. In fact, the EnviroEngine concept bears the Carnival imprint, having arisen from a joint project initiated between the US group and Wärtsilä to develop a new 'earth-friendly' power system.
The clean combustion properties of the EnviroEngines will provide particular benefits in port, promising no discernible smoke even when run under light load for producing energy for lighting, air conditioning and other hotel systems.
The diesel-based gensets are housed in two separate engine rooms, while the two gas turbines are mounted below the funnel casing, a position which favors the air intake requirements of the machinery. The use of gas turbines for location high up in the ship has enabled the designers to dispense with a second engine room casing, freeing up additional volume within the ship's given dimensional envelope. The design of the funnel was influenced by the air draft limitation set by the Verazzano Narrows Bridge, and it embodies an exaggerated wind scoop so as to give added upward thrust to the exhaust from the ship's machinery.
Wind tunnel testing for the design had been carried out at the Danish Maritime Institute(DMI) and comprised wind force coefficient measurements, funnel opimization, and wind comfort tests for the open decks.
The LM2500+ class of gas turbine specified in the prestigious Cunarder project had its first marine applications during the year 2000 in Celebrity's gas turbo-electric cruiseship Millennium and in the French high-speed ferry NGV Liamone. A whole new generation of Celebrity and Royal Caribbean cruiseships encapsulating combined gas turbine and steam turbine, integrated electric drive systems(COGES) has now been fitted with the LM2500+. Delivering up to 25-percent more power than the standard LM2500, the LM2500+ has demonstrated consistent in-service reliability and availability.
Propulsion is provided through four variable-speed, reversible pods. The selection of four 21.5-MW Mermaid pods, comprising two fixed units and two azimuthing, steerable units, is one of the most compelling aspects of the technical project. QM2 will be the world's first vessel propelled by four pods, translating a maximum 86-MW into propulsive effect. Each unit has a four-bladed, 5.9-metre diameter propeller running at a maximum 150 rpm. Specified maximum speed is 29.35-knots.
Furthermore, the vital need for enhanced maneuverability to ensure efficient and safe turnrounds, without the need for tugs, led to the nomination of a potent array of bow thrusters. Three transverse thrusters of 3,200-kW apiece, each incorporating a fixed-pitch, stainless-steel propeller, are fitted in tunnels of 3-m diameter with chamfered ends. For noise and vibration attenuation, the type selected is of reinforced tunnel design.
Dutch research institute MARIN was entrusted with model tests relating to hull optimization and the disposition of the four pods, and the layout and equipment adopted is expected to confer maximum maneuverability and the means to sustain speeds up to 30-knots, with pressure pulses kept below specified limits.
Propulsion tests carried out at MARIN's Wageningen tank laboratories also indicated that the large openings to the thruster tunnels in the bow created the potential for hydrodynamic inefficiency and speed loss. This led the shipowner to specify thruster doors to obviate such losses, and various arrangements were considered. Drawing on experience with the QE2, butterfly valve-type doors were selected. However, the thruster doors in the QM2 are substantially more complex, being much larger and shaped to a tunnel chamfer, than those in the QE2 installation.
Passenger comfort in the often rigorous conditions of the North Atlantic should
be better assured through the adoption of a Brown Brothers stabilizer system designed and produced in the UK by Rolls-Royce. Four VM Series-type folding fin units promise a roll reduction of as much as 90-percent when deployed in combination. Each stabilizer is 2.5m-wide and extends beyond the ship's side by 6.25-m, affording 1,070-kN of lift.
The deck machinery is of Scandinavian origin, comprising equipment from the Rauma Brattvaag range of Rolls-Royce. The outfit comprises two anchor windlasses with individual frequency converter drive, and eight frequency converter-driven AC electric mooring winches. The self-tensioning facility will be independently applied to each drum of the twin-drum winches, making for a total of 16 split type mooring drums. Stepless speed control is one of the main assets of the drive arrangements adopted for both windlasses and winches, while the system also has merits in terms of reduced noise level, a distinct asset for a luxury passenger vessel.
Extending some 45-m from wing to wing, the Cunarder's bridge is a showcase for technological innovation and radical new thinking in terms of equipment layout, housing an integrated system distinguished by multifunction workstations using flat screen displays.
One of the step changes in layout denoted by the QM2 installation is the separation of the center console from the displays. This has enabled more equipment to be incorporated on the main console, while allowing bridge personnel free access to all displays. The arrangements draw on the revolutionary Manta design concept unveiled four years ago by turnkey supplier Kelvin Hughes, whereby individual, flat panel screens could be used to view and control any of a range of functions associated with the navigation and operation of the ship.
The separate Center Console Concept applied to the QM2 has achieved the twin goals of integrating as many systems as possible for centralized control at sea, while allowing unrestricted access around the bridge for a larger number of people while entering harbor and during mooring or anchoring operations. The center suite comprises five main consoles, each having a dedicated function as follows:
• Maneuvering console, containing pod and thruster controls and autopilots;
• Center console, mounting five Manta displays;
• Communications console, for all external communications;
• Safety console, for all alarm and internal communications;
• Navigation console, including a chart table.
In addition, wing consoles, incorporating parts of all the above systems, permit full control and monitoring from the bridge wings.
The heart of the integrated navigation system is the new Kelvin Hughes Multi-Function Screen Technology (MFST) system, employing eight 23.1-in. TFT(thin film transistor) workstations, comprising four at the center console and two in each bridge wing. MFST enables any of the eight connected screens to display and control any of the seven connected processors, two governing the ECDIS (electronic chart display and information system) function, four covering radar, and one for dynamic positioning. In addition, all the center displays can be remotely controlled from either bridge chair by way of the proprietary Ergopod device.
As opposed to the network solution employed by other companies, the Manta/MFST technology allows integration of third-party systems, without modifications. This capability is expressed on the QM2 in the supply of a dedicated, ninth Manta 2300 display for the Valmarine safety system in the center console and full integration of the APC dynamic positioning system into MFST.
The Kelvin Hughes Manta 2300A ARPA(automatic radar positioning aid) systems are connected to a six-way radar interswitch unit with three 25-kW downmast X-band, one 10-kW upmast X-band, and two 30-kW downmast S-band transmitters. The arrangements permit any of the eight displays to fully control any of the five transmitters. The Manta 2300 dual ECDIS system lends itself to operation in two modes, namely ECDIS and harbour approach and pilotage (HAP), and the whole includes a route planning terminal in the chart room. Carrying two type-approved ECDIS has allowed the vessel to greatly reduce its portfolio of paper charts.
Kelvin Hughes' scope of supply to the Cunarder included C Plath fiber-optic gyrocompasses, magnetic compass and fully adaptive, Navipilot autopilot. The latter lends itself to control from the ECDIS, and accordingly comprises an automatic navigation and track-keeping system(ANTS) used on one man-operated vessels.
The QM2 outfit also features the compact NDR2002 voyage data recorder, designed by the UK marine electronics specialist. The VDR logs salient data from shipboard systems and stores the information in a crash-survivable module, which can be retrieved for investigation in the event of an accident. It can record any pictures from the primary navigation