An exceptional comfort standard has been achieved onboard the four RCCL sister vessels Radiance, Brilliance, Serenade and Jewel of the Seas. Based on extensive noise and vibration measurements, DNV concludes that all four ships meet the strictest Comfort Class requirements with exceptional margins. The vessels are also assigned DNV's highest environmental class notation, Clean Design.
When the four sister vessels are sailing at 23 knots, only a slight whisper of pleasant vibration is felt onboard. The vibration levels are below 0.3 mm/s in all accommodation spaces. The most stringent DNV Comfort Class requirement is 1.5 mm/s, which is regarded as strict in the market.
The noise and vibration control of a cruise vessel starts early in the design phase. Comprehensive studies are performed, particularly relating to the propellers, which are an extremely important source of noise and vibration. Large finite element models of the structure were developed for the purpose of calculating the vibration levels onboard the ship.
DNV introduced the voluntary Comfort Class notation in 1995 as the first classification society. Comfort is divided into three ratings, from 1 to 3, which reflect “high” to “acceptable” comfort. Comfort rating 1, requiring vibration levels not to exceed 1.5 mm/s for passenger cabins and public spaces, was regarded as unachievable by many industry experts. To demonstrate the nature of this vibration, it corresponds to a displacement of about only +/- 0.02 mm (two hundredths of a millimetre).
This is the first series of cruise vessels in DNV’s long experience of measuring vibrations where a level of 1 mm/s is not exceeded in one single position onboard and where vibration levels inside all the passenger accommodation are below 0.3 mm/s.
This record-breaking result has been achieved by the yard in close co-operation with DNV and the owner by means of proactive sound and vibration control throughout the entire process.
Clean Design as well
In 2000, DNV introduced class notations covering additional requirements to limit operational discharges and emissions from ships. All four sister vessels have been assigned DNV's highest environmental class notation, Clean Design.
In practical terms, this means that both sewage (black water) and other waste water (grey water) are taken care of onboard. Black water is treated in a sewage-treatment plant designed to produce effluent that more than complies with the limits set by the US Coast Guard. The treated effluent is either discharged more than 12 nautical miles off the coast or delivered to shore-based facilities. Grey water from sinks and showers is kept onboard and either discharged more than 12 nautical miles off the coast or delivered to shore.
The ships have special garbage-treatment equipment to sort and treat garbage in a controlled manner.
Typical ship discharges, such as bilge water from machinery spaces, are not prohibited but are strictly regulated. The equipment onboard the four sister vessels will control the oil content in any discharged water to ensure it is at a level far below the maximum limit permitted by international legislation.
The owner has implemented stricter operational limitations than those set by international regulations. Through the Clean Design notation, DNV requires annual surveys to be carried out by a qualified DNV surveyor. During these surveys, DNV will check and verify logbooks to ensure that the operational procedures have been followed.