Abstract: Noise propagation inside a relatively small vessels such as AHTS, PSV is a growing issue. On one hand there is a growth in power demand on vessel (towing and DP purposes) and on the other hand maintaining crew comfort according to more restrict Classification Societies rules and recommendations. Usually in contract one puts strict conditions for accepting noise levels onboard (mostly according to IMO or Classification Society rules). In this paper one can see that statistical approach could be adopted in contract in order to benefit both sides, shipyard and ship-owner.