PressurePores propeller tech cuts underwater noise pollution

Now a new technology capable of reducing the underwater radiated noise generated by ships’ propeller cavitation has been developed by researchers at Strathclyde University and West Sussex-based Oscar Propulsion.

Cavitation occurs when tiny bubbles form in the water as a result of the propeller moving through it. When these bubbles collapse, they create an audible shock wave.

Propeller cavitation can generate as much as 180 decibels of underwater radiated noise, and can be heard by marine life 100 miles away. It can also damage the propellers themselves.

The new system, known as PressurePores, reduces propeller tip vortex cavitation by applying a small number of strategically bored holes in the propeller blades. This reduces the sound produced by the propellers, without significantly reducing their efficiency, according to David Taylor, CEO of Oscar Propulsion.

The team first tested the idea in a cavitation tunnel at Newcastle University, said Taylor. “We made some relatively randomly-placed holes in different propeller models, and compared these with propellers without holes, and with that relatively crude test we managed to get about a 14dB reduction in noise,” he said.