Europe’s four leading passenger-ship builders – Fincantieri, Kvaerner-Masa, Chantiers de l’Atlantique and Meyer Werft – last year delivered a massive 92 per cent of the world’s new cruise-ship tonnage. Most current orders at Germany’s Mayer Werft yard are to DNV class.
One of the most significant cruise ships completed in recent months though far from the largest is the first of four DNV-classed newbuildings from Meyer Verft, Papenburg, for Royal Caribbean. At 90,000grt, Radiance of the Seas is markedly smaller than the same operators recent giant cruise ships from Kvaerner-Masa Yard the 137,000grt Voyager of the Seas and her Eagle class sisters. For this latest addition to the RCCL fleet, a 32m beam permits passage through the Panama Canal. Powered by twin gas turbines and azipod propellers, Radiance has proved on sea trials to be remarkably silent and vibration-free. At all speeds up to 23 knots, most vibration levels were measured at less than 0.3mm/s, and throughout the ship none were greater than 1mm/s. The vessel thus exceeds the highest rating standard of DNVs Comfort Class rating 1 calls for vibration levels of no more than 1.5mm/s for passenger cabins and public spaces. DNVs noise and vibration calculations are carried out in three stages: noise and vibration review; excitation force and structural-dynamics calculations, including propeller dynamics; and noise and vibration response analysis. Following the classification societys report and recommendations, a variety of measures can be incorporated during construction to ensure passenger comfort. Use of resilient mounts for engines, thrusters and other machinery, plus optimised propeller design, should control excitation from these sources. Then floors, cabin walls and ceilings can be similarly isolated from the steel structure by elastic mountings. A particular challenge on luxury cruise vessels is that the low cabin noise level can make other sounds more intrusive; hence special attention must be given to partition walls, deck coverings and acoustic insulation. In that recent cruise-ship design places cabins and open spaces directly above the propellers, the very satisfactory results on board Radiance of the Seas are evidence of the value of gas-turbine propulsion and podded propeller units, as well as in-built acoustic measures. The vessel will begin U.S. West Coast/ Alaskan cruises this summer. Sister ship Brilliance of the Seas will follow next year, with two further deliveries due in 2003 and 04.
New demands on fire safety Another passenger ship currently in the news is the unique (until launch of her sister ship) cruising hotel World of ResidenSea. This40,000grt vessel, designed as a permanent home to the leisured owners of its residential apartments, is under construction at the Fosen Mek. Verks. Yard in Rissa, west Norway. For this ship, too, DNV has carried out comprehensive noise and vibration studies to ensure that the highest Comfort Class standards are met, a scope of work which again will culminate in sea-trials measurements. ResidenSeas 110 residential apartments range in size from 100 to 300 square metres, and are each equipped with a private kitchen, dining room and two or three bedrooms. There are also some 80 guest suites for visitors and short-haul cruise passengers. The ships design concept, with its novel approach to domestic life at sea not the least of which is the 110 private galleys, each posing a fire risk is a challenge to the SOLAS regime in several respects. In cooperation with DNV, the owner and yard have adopted the solution of each kitchen being surrounded by class A fire boundaries, and fitted with a dedicated exhaust and fire-extinguishing system.
Survival capability
DNV is presently developing new Rules to enhance the survival capability of passenger vessels in the event of collision or grounding. The basic philosophy is to reduce the need for evacuation a serious matter in ships of many decks and with perhaps 5,000 persons aboard and in the worst case to prevent a large heeling angle occurring before evacuation is completed. Using formal safety assessment (FSA) methodology, rule development includes damage calculations from various scenarios, and simulations of operational measures. A proposal for the new ESC class notation (Enhanced Survival Capability) is scheduled for later this year.
R. Keith Evans
Date: 2001-03-15