Ship and boat propellers
Ship and boat propellers work by creating a pressure difference between the front and the back of the propeller blades. This generates the thrust which drives the vessel. At high revolutions, cavitation occurs which is the formation and explosive collapse of air bubbles on the blade surfaces creating heat and pressure. This causes substantial noise and significant damage to propeller blades. Large cargo ships routinely have Underwater Radiated Noise (URN) signatures from their propellers of 150dB+, louder than jet engine take-off noise.
These noise levels are damaging to marine fauna including cetaceans, affecting their ability to communicate, find food and reproduce. Marine noise is now at critical levels and a major cause for concern.
The strategic application of Oscar PressurePoresTM on propeller blades reduces URN by between 17dB and 21dB (85.4% to 90.6% noise reduction) in the frequency range most damaging to marine fauna.
Image source: https://propdoctorsllc.com/propeller-disorders
Environmental impact of Propeller noise
The number and size of commercial ships using the oceans is estimated to double, if not triple, by 2025 due to the rise in population and global trade.
Many studies have been carried out which point to a global growing awareness of marine noise pollution. The International Maritime Organisation has submitted that technology and ship design can have a big effect in reducing URN. It also recognises that propeller cavitation is one of the primary noise contributors; reducing this would go a long way to reducing URN in the marine environment.