15 November 2023 (Lloyd's List) - ENERGY efficiency products such as air lubrication systems, fixed-pitch propellers and speed cuts could significantly decrease ships’ underwater noise, helping the environment, according to a new paper by the University of Southampton.

Cutting speeds by 20% can reduce underwater radiated noise by up to six decibels and wind-assisted propulsion by up to 10 dB, according to the paper commissioned by the International Chamber of Shipping.

The findings suggested air lubrication systems can reduce underwater noise by more than 10 dB.

More shipowners are expected to use energy efficiency products in coming years on the back of more stringent environmental regulations including the

Carbon Intensity Indicator by the International Maritime Organization.

“The achievement of the 32% contribution from energy efficiency measures in GHG emission reduction by 2050 could effectively offset the effects of substantial seaborne trade growth and mitigate ambient noise levels, even in the most challenging scenarios,” the paper said.

Marine conservation NGO Okeanos supports a 3 dB per decade reduction target for underwater noise. The paper suggests achieving this target is feasible.

“The report shows that shipping has an opportunity to embrace energy efficiency technologies that will both help ensure it meets its essential greenhouse gas emission reduction targets, as well as reducing underwater radiated noise,” said Professor Stephen Turnock, of the University of Southampton’s Marine and Maritime Institute.

The IMO adopted revised non-mandatory guidelines on underwater noise in July this year and the UN body will finalise a list of suggested next steps to further prevent underwater noise in 2024.