In this paper, the noise predictions on board ro-ro passenger ship and self-propelled cutter suction dredger are performed, by means of the general noise assessment software Designer-NOISE which is based on the hybrid Statistical Energy Analysis. All typical noise sources in ships (main engine, auxiliary engines, propeller, HVAC, exhaust system, etc.) as well as the non-typical ones in the latter case (sand moving through the pipelines, winches, dredging pumps, etc.) are taken into account. The prediction is based on vessels drawings and noise source properties, both provided by the shipyard. The A-weighted noise levels are evaluated in the frequency range from 63 Hz to 4 kHz. From the regulation viewpoint, BV Guidance Note NI-174-DNC and IMO Resolution A.468 (12) were applied and conclusions on the ship noise performances are drawn.
In recent years noise problems on board ships attract much attention of both researchers and engineers. The reasons for that originate not only from the generally higher installed power in ships, but also from increased care for health of crew and passengers. Noise problems inherent to ships are research subject for long time, (Wilson, 1956), and different possibilities are investigated to reduce noise levels (Turner, 1969). Noise has negative effects not only on crew and passengers (reduced power of concentration, headache, stress, interference in sleeping pattern, reduced tolerance threshold, increased number of mistakes, reduced working capacity, etc.) (Tamura et al., 1997; Borelli et al., 2015; Kurt et al. 2016), but also on the sea life. Nowadays, there are many references to the influence of noise emitted by shipping on marine life, as for instance (Badino et al., 2012; Merchant et al., 2014) and actually underwater radiated noise is regularly treated as a kind of pollution.
General trend in marine sector (particularly for passenger ships) regarding vibration and noise is treating those phenomena not only within the Safety Class, but also within so called Comfort Class and Silent Class, which represent voluntary class notations and are introduced by DNV GL in 2011. Later Lloyd's Register and Bureau Veritas followed this initiative by introducing their definition of comfort level in 2016. All these steps lead to even more restrictive levels of noise and vibration treating them as a matter of not only safety, but improved habitability and ship quality. Regularly, noise levels on board are measured at ship delivery, and if problems are detected, they should be remedied in order to achieve vessel compliance with the prescribed values. In spite of variety of noise abatement methods, elimination of such problems the delivery stage becomes rather expensive, and therefore it is desirable to predict noise levels in the preliminary stage. For that purpose the hybrid Statistical Energy Analysis (SEA) seems to be reasonable choice, due to its simplicity and acceptable accuracy (particularly in high frequency domain).
