Historic Liverpool maritime firm Bibby Marine is building a £50m zero-emission offshore wind farm support vessel and it transpires the ship will offer a particular unplanned benefit… and it’s good news for porpoises. Tony McDonough reports
It is tempting to think that life under the sea is quiet and peaceful but apparently in busy shipping lanes the noise can be disruptive to wildlife.
In the North Sea, for example, shipping noise now dominates the underwater soundscape and according to the Oslo and Paris Conventions, background noise in the busiest shipping lanes exceeds natural levels by more than 20 decibels for more than half the time.
For the harbour porpoise, the North Sea’s most common cetacean, that’s a near-constant disruption to the echolocation it relies on to feed and navigate.
Now Liverpool maritime firm Bibby Marine has discovered it has inadvertently created a remedy for the undersea racket. It is currently building a new zero-emission offshore wind farm support vessel to be ready for service in 2027.
Costing tens of millions of pounds, and backed by the UK Government, the electric commissioning service operation vessel (eCSOV) will feature a battery system complemented by dual-fuel methanol engines.
A division of Bibby Line Group, one of Liverpool’s oldest family firms, Bibby Marine has led a consortium developing its groundbreaking maintenance vessel for several years. In September 2023 it secured £20m from the Government to support the project.
Although it hasn’t revealed the cost of the eCSOV previous estimates have put the figure at between £40m and £50m. This new vessel is being built by Armon, which is located in Vigo in Spain.
While Bibby’s primary aim was to reduce emissions it has discovered a secondary benefit of a significant reduction in underwater noise, something its designers never had in mind.
In an interview with Maritime Reporter TV, Bibby Marine’s fleet director, Gavin Forward, said the eCSOV’s battery-first architecture means the battery pack, not the engines, is the vessel’s primary power source.
For extended periods, the engines can be shut down entirely, removing one of the two biggest sources of underwater noise before it’s generated rather than trying to insulate or dampen it afterwards.
The second source is propulsion. Kongsberg’s rim-drive thrusters integrate the electric motor directly into the propeller, eliminating the gearbox and the mechanical vibration and tonal noise that comes with it.
The design also smooths water flow through the propeller, reducing cavitation, which is one of the most common sources of underwater noise on a conventional vessel. Together, the two are expected to deliver a 40-60% reduction in underwater radiated noise.
“Rather than trying to reduce that noise, we just get rid of it altogether. We don’t have it in the first place,” said Gavin.
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Over a 10-year wind farm charter, Bibby estimates the eCSOV could deliver almost £5m in operating cost savings compared with a conventional vessel, through lower fuel consumption, fewer engine running hours and reduced maintenance.
Gavin added: “Design for where the industry’s going, rather than how it’s been done in the past. Look at electrification not simply as a decarbonisation requirement, but as an opportunity to build a better, more efficient and more resilient vessel.”