Karadeniz Holding, pp.54, İstanbul, 2021
With ship transportation picking up pace, the environmental effects of it is now surfacing. Among them, effects of noise pollution, especially on marine life, is highly prominent. Marine life is extremely sensitive to noise pollution. Due to their extreme reliance on underwater sounds for basic life functions like searching for food and mate and an absence of any mechanism to safeguard them against it, underwater noise pollution disrupts marine life in serious ways (Singla, 2020). In short, marine animals depend on sound to live, making and listening to it in various ways to perform various life functions (US Bureau of Ocean Energy Management, 2014).
Noise travels much more in water, covering greater distances than it would do on land while travelling through air. Underwater sound has both pressure and particle motion components and hearing can be defined as the relative contribution of each of these sound components to auditory detection (Popper AN, 2011). Sounds radiated from ships are among the underwater noise sources. Among shipborne Underwater Radiated Noise (URN) sources are the following:
● Propeller’s rotational turn and the blades hitting to water flow lines
● Propeller’s cavitation
● Ship hull structure’s interaction water (fluid-structure interaction)
● Mechanical noises from onboard machinery
All of these are important noise sources radiated to underwater from ships, especially when the ship speed is at higher rates, i.e. above 15 knots.
When a Powership, such as KarPowership, is considered, out of 4 aforementioned noises, only mechanical noises are of concern as there are no noises from the other three sources because the Powership is not underway. Mechanical onboard noises are still of concern and therefore need to be evaluated and tested for the assessment of their potential negative effects to marine life.