Making underwater radiated noise measurement practical for the world fleet

The problem

Dedicated sea trials cost an estimated USD 30,000–50,000 directly, and USD 40,000–250,000 per ship once diversion and lost revenue are included. Across a fleet of around 100,000 ships, one round of measurements could cost USD 4–25 billion, and repeat measurements may be needed.

Yet global capacity is only around 50 dedicated trials a year.

The proposed approach

• A network of autonomous measurement facilities at major pinch points (for example Suez, Panama, Gibraltar, Malacca, the Taiwan Strait and the English Channel) would measure ships during normal operation
• An illustrative network of five facilities would cost roughly USD 0.8–1.8 million in capital and USD 0.7–1.4 million a year to run: under USD 20 per ship in capital and under USD 15 per ship per year in operating costs. Ship-specific data checking and reporting would add around USD 4,424 per ship
• An ISO “Measurement of Opportunity” standard is needed for consistent results. It must be rigorous enough for quiet ship notations and repeatable enough to show trends. A network could be established in about four years
• Autonomous facilities will not cover everyone (short-sea ships, for example) and are one part of the solution. Onboard measurement, drone-deployed sensors and predictive modelling remain relevant.

Why it matters

Earlier case studies found that measurement costs below USD 15,500 could make environmental incentive schemes (such as ESI, Green Marine, Green Award, PIAQUO and ECHO) financially beneficial. Affordable baselines would also let shipowners show whether noise-reduction measures actually work.

Next steps

The co-sponsors are asking the IMO to recognise the importance of economically viable, accessible baseline measurements. They invite further proposals on feasible approaches, and ask that any URN Working Group’s terms of reference cover practical, affordable baselining options and timelines.