Upcoming underwater noise restrictions: what can cruisers and yacht industry learn from FRV’s design?
Publio Beltrán Palomo, Alfonso Moreno, TSI-Técnicas y Servicios de Ingeniería, Madrid/Spanien
After more than five decades of research, in 1985 it was published by the International Council for the Exploration of the Sea (ICES) its Report Nº 209. This publication addressed together the two essential targets of any ship dedicated to perform both, fishery and geological research: avoiding the disturbance of the marine species and improving the performance of the sophisticated electronic equipment fitted onboard these ships. It has been a milestone of the Civilian Shipbuilding.
ICES Report Nº 209 focused on establishing a limit to the Underwater Radiated Noise (URN) of this type of ships (nothing more and nothing less and for the first time in the civilian shipbuilding sector) to guarantee compliance with the aforementioned objectives. To fulfil the ICES requirements, the URN values of the Fishery and Research Vessels (FRV) must be controlled since their “earliest design stages” in order to be below the URN pre-established limits.
Nowadays, it is feasible to find some “small segment" modern FRVs fulfilling ICES regulations with maximum structural vibration levels of 0,6-0,7 mm/s (rms), noise levels in the machinery room of 89 dB(A) and 39 dB(A) in some accommodation spaces. These experimental data, in some cases certified by BUREAU VERITAS, are the consequence of the technological developments applied to the design and construction of ICES 209 certified vessels to comply its strict URN requirements and converting them in one of the most brilliant “technological references” of the maritime sector, as it has been recognised during the specific investigations carried out in the framework of the European Research Projects "BESST”, "SILENTV" and "AQUO", dedicated to the characterisation and reduction of the “underwater signature” of cruisers and all type of commercial ships. These research projects have used some of these vessels as a reference to develop its “Guidelines to Reduce the Underwater Signature of the Commercial Ships”.
As a direct consequence of the strict URN requirement imposed to these “few but sophisticated” vessels, one “stealthy technological revolution” has been generated around their designs, construction and sea trials. This revolution has affected not only the traditional Noise & Vibrations Control Techniques, including the Factory Acceptance Tests (FAT) of critical equipment, but also the sector of the most recent and modern software for simulation and the URN measurement procedures, which experimental data are essential to validate the different design and software tools.
As a consequence of the justified demand coming from the Society and the Scientific Community to reduce drastically the URN generated by all type of commercial ships, the new Regulations and Directives coming into force in 2020 will definitely drive the Maritime Sector to one of the most outstanding and difficult challenge ever faced. But we must not be worry because authors’ opinion is that the “Noise & Vibration black box” is already open and the technical solutions are available out there. It is time for decision making.
The Authors has over 40 years of experience as noise and vibration Consultant and has been involved in the acoustical and dynamic design of seven FRV’s. Very recently, this practical knowledge has been applied to reduce the acoustic signature of submarines. They will present how "lessons learnt" in this process could be used to reduce the URN of Cruise ships and Yachts for this qualified segment of maritime industry.