Researchers and conservation groups are testing specialized ring-shaped marine propeller designs to reduce underwater noise pollution that disrupts whale communication, following data linking low-frequency vessel sounds to behavioral stress in marine life.
Commercial shipping, offshore drilling, and maritime traffic have dramatically altered the acoustic environment of the world’s oceans. While surface observers might notice little more than the low hum of passing vessels, scientists describe the shift in underwater soundscapes as a persistent roar that interferes with the ability of marine mammals to hunt, navigate, and communicate.
Low-Frequency Noise Disruption for Whales
Whales rely heavily on acoustic signals to maintain daily survival, social interaction, and mating habits. When ambient ocean noise drops, these massive mammals can hear each other’s calls across hundreds of miles.
Commercial vessel traffic generates persistent low-frequency noise ranging between 20 and 300 hertz, exactly the frequencies whales use to communicate. That man-made din effectively drowns out their social signals.
“Imagine if someone was hammering outside your window for months… that noise is painful and causes excruciating pain.”
Michelle Fournet, bioacoustics researcher at the University of New Hampshire
Researchers studying orca populations found that every single-decibel rise in surrounding noise reduces the whales’ ability to successfully capture fish by 12.5%. Fournet likens the constant acoustic assault to having a glaring light flashed directly into human eyes every single day.
Cavitation and Propeller Mechanics
The root cause of much ship-generated noise is a physical phenomenon known as cavitation. As traditional propeller blades spin to drive a vessel forward, they create millions of microscopic bubbles behind the craft every second.
These tiny bubbles hold immense stored energy. When they collapse and implode, they release sharp acoustic shockwaves that register as crackling or buzzing noises underwater.
Sharow Marine Propeller Redesign
To combat this chronic issue, Detroit-based engineering firm Sharow Marine has developed a specialized propeller configuration designed to minimize acoustic output. Instead of utilizing conventional blades with open tips, the company engineered ring-shaped blades that wrap around like ribbons during rotation.
This ringed geometry creates significantly fewer water vortices as the blades turn, cutting down on cavitation shocks. Independent testing on watercraft equipped with the new design showed a sound reduction of seven decibels within the specific frequency range utilized by whales for communication.
Conservation Leaders and Manufacturers Test New Engines Near Whale Habitats
The manufacturer has partnered with Ocean Alliance, a marine conservation organization, to test the new engines near active whale habitats. While Greg Sharow, the head and founder of the company, believes widespread adoption by shipping fleets could make oceans noticeably quieter, conservation leaders emphasize that evaluation remains in early stages.
“I think that any situation that is a win-win for the environment, for the marine life, for the consumer, or for the operator is a good situation… I see a great deal of logic” behind this new technology.
Ian Kerr, president of Ocean Alliance
Tourism operators utilizing the redesigned propellers on whale-watching vessels have reported larger numbers of whales lingering near the boats. The company attributed this to the significant drop in noise, making marine life feel curious about these sounds, or that they feel less threatened by the sounds that they emit.
While researchers agree that trimming vessel noise by seven decibels is an encouraging starting point, scientists note that further field testing is necessary before declaring the technology a complete fix, particularly as engineers work to scale the ringed design up for massive commercial cargo ships.
