4 Definitions
Clasification Society 2024 - Version 9.40
Statutory Documents - IMO Publications and Documents - Circulars - Marine Environment Protection Committee - MEPC.1/Circular.833 – Guidelines for the Reduction Of Underwater Noise From Commercial Shipping to Address Adverse Impacts on Marine Life – (07 April 2014) - Annex – Guidelines for the Reduction Of Underwater Noise From Commercial Shipping to Address Adverse Impacts on Marine Life - 4 Definitions

4 Definitions

  4.1 Cavitation inception speed is the lowest ship speed at which cavitation occurs.

  4.2 Propeller cavitation is the formation and implosion of water vapour cavities caused by the decrease and increase in pressure as water moves across a propeller blade. Cavitation causes broadband noise and discrete peaks at harmonics of the blade passage frequency in the underwater noise spectrum. The broadband noise is caused by growth and collapse of a vast amount of individual cavitation bubbles in water. The discrete noise peaks are caused by the volume fluctuations of the sheet and tip vortex cavities.

  4.3 Underwater noise, or the underwater-radiated noise level, for the purposes of these Guidelines refers to noise from commercial shipsfootnote.

Parent topic: Annex – Guidelines for the Reduction Of Underwater Noise From Commercial Shipping to Address Adverse Impacts on Marine Life
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