A brief review on mechanical noise of vessels

Noise is unwanted sound in the ocean, since it generally, interferes with the operation of sonar or other underwater sound registration equipment. The principal sources of radiated sound from ships are (1) the propulsion system; (2) the propeller; (3) the auxiliary machinery; (4) the hydrodynamic effects and (5) the hull movements. One of the sources of artificial noise in the sea environment is the noise from the machines inside the vessels. This noise is caused by the inherent vibration of mechanical systems. The presence of small instabilities along with the forces and torques that produce the work creates vibrations that are eventually transmitted to the radiation surfaces and are therefore a source of noise. This type of noise is caused by the following 5 factors: mechanical unbalances, electromagnetic force fluctuations, impact sounds, piston sound in reciprocating machines and bearing noise. In this article, we only examine the noise generated by a floating machine and describe the frequency range as well as the noise level produced.