tURN it down!

tURN it down!

Underwater radiated noise (URN) is a major issue for the environment, and a growing concern for shipowners and operators worldwide. With existing IMO guidelines under review, new regulations could be set to make their own ‘noise’ in the near future. What can the industry do to minimize the impact of underwater noise in a commercial climate of ever-growing activity?

If you look around, almost every product on your desk, every article of clothing you have on, and the majority of things you put into your mouth – even down to the coffee in your cup – has a marine noise footprint.

With approximately 90 percent of global goods transported by sea, the chances are those items you’re quietly considering have beaten a rather noisy path to your door – sitting on ships that, through engine noise and the cavitation bubbles produced by propellers, send sound off to propagate endlessly through the oceans.

Whereas to us, the rumble of a ship may be a distraction, even a relatively pleasant one, to aquatic lifeforms it’s something else. Noise dissipates rapidly in ‘thin air’, but travels far through denser H2O molecules, racing right down to the depths at speeds four times faster than above the surface, and transmitting for many miles through both the water and the life that inhabits it. It ‘fogs’ the environment, impacting upon how ocean life finds prey - through, for example, echolocating as whales do - how creatures navigate, communicate, interact and survive, often in complete darkness.

With the growing importance and size of the global merchant fleet, according to Clarkson’s Research now around 100,000 vessels, it’s an issue leaping up the green, media and regulatory agendas.

Tomi Veikonheimo, R&D Senior Principal Engineer, Hydrodynamics, ABB Marine and Ports, says the industry, and particularly those considering newbuild projects, need to prepare for a future where everyone listens to the noise debate.

From left: Tomi Veikonheimo, Tuomo Salmi
From left: Tomi Veikonheimo, Tuomo Salmi

The need for clarity

“There are no mandatory regulations on URN at present, but there are guidelines,” Veikonheimo explains, referring to the IMO Marine Environment Protection Committee (MEPC), ‘Guidelines for the reduction of underwater noise from commercial shipping to address adverse impacts on marine life’, 2014. “We see the demand for quiet, or silent, notations growing, with an increasing number of passenger ships, led by expedition cruise ships, joining the research and naval vessels that have pioneered operations with reduced noise signatures."

“And really, this is just the start of something much, much bigger.”

Veikonheimo says that the 2014 guidelines are currently being updated for submission to MEPC in 2023 , a process that he and his team at ABB Marine & Ports are involved in. These will build on the start made in 2014, which, he notes, was well intentioned but ‘lacking in clear advice on how to solve the noise emission dilemma’.

According to Veikonheimo, the new guidelines will deliver a better tool for owners and shipyards to build vessels which reduce URN emissions while minimizing efficiency loss, and, most probably, signal a step further down the path to eventual mandatory measures.

We see the demand for quiet, or silent, notations growing.

Collaboration is key

“Anyone looking at investing in an asset with an operational lifespan of 20-30 years needs to consider its ability to adapt to changing regulatory requirements and, as such, ways to future-proof today’s newbuilds,” Veikonheimo stresses. “In terms of URN mitigation the way to do that is to start at the very outset of vessel design, as that way you can look to fulfil individual project requirements with the minimum penalties in terms of efficiency and fuel economy. That demands early collaboration between all project partners, as this is a ‘joined up’ process.”

The actual paths to reduced URN are limited, and come at a cost. Propeller design and installation are arguably the main tools, but as designs are tailored to reduce noise rather than maximize efficiency there’s an energy consumption price to pay. However, less speed generally equates to less noise, so energy can be saved there, as it will be with the complementary actions of regular hull and propeller cleaning.

“You can see why it’s better to raise the issue sooner rather than later in the project phase,” Veikonheimo says. “By working with expert partners from day one you can refine designs to minimize any efficiency loss and get a vessel that offers optimized operations without the URN usually associated with that kind of performance.”

The path to progress

The team at ABB has been focused on researching and developing underwater noise technologies for more than a decade – collaborating with industry partners, classification societies and regulators, culminating in the current review of 2023 guidelines.

“We have a long track record in an area that is moving from niche segments to the wider industry radar,” opines Tuomo Salmi, Sales Manager at ABB Marine & Ports, and a specialist in fulfilling the strictest URN notations. “We work with customers to simulate and analyze noise signatures, delivering the expertise and solutions to understand the challenges and optimize operations. The closer the collaboration we can initiate with the yards and owners, the better the results we can achieve.”

Like his colleague, Salmi sees future regulations as “an inevitability” and believes 2023 developments will help steer the industry down the right path.

“At present there’s not much clarity,” he surmises. “There are local and regional URN initiatives, such as in Canada and the EU, but nothing that reaches further, while class societies have their own notations, but they lack harmonization. This creates confusion, but shows how developments are gathering pace and evolving internationally. We are slowly moving towards a consensus on what is a very important issue, for everyone.”

For forward-thinking shipowners this really is ‘low hanging fruit’ in the effort to transition to a more sustainable industry.

A measure of success

One thing the 2023 IMO revision should shed some light on is measurement. One of the key issues dogging progress at present is how URN should be measured, when and for how long. At the moment “far field” testing is often the preferred methodology when awarding notations, involving measuring noise from a support vessel at a distance between 50 meters and 200 meters away utilizing a hydrophone lowered over the side. This is an effective way to assess the ‘complete’ vessel noise signature, but can’t be done at all times in all conditions.

A possible future solution, that could be mentioned in the 2023 guidelines, is provided by “near field” continuous measurement whereby sensors are installed close to vessel propellers to capture pressure pulses emanating onto the hull.

“This is an interesting solution,” Salmi says, “as data can be captured and sent onshore to be analyzed, performance monitored and then decisions made to help vessels reduce URN and meet whatever requirements are necessary. In terms of reporting for future regulatory compliance, this would also be greatly simplified. We see this as a strong potential development and something stakeholders should be aware of going forward.”

The power to change

Although marine noise impact and the prospect of increasing regulations (in an already complex operational picture) is growing, there is a silver lining to this particular emissions cloud.

Veikonheimo is keen to point this out, concluding proceedings on an optimistic note: “This is not chemical pollution in the water, plastics, or GHG gases escaping into the atmosphere – this is noise. It doesn’t take years to disperse, or billions of dollars for society to clean up. It is, pure and simple, mechanical sound that can be switched off or, at the very least, turned down.

“Do that and we can change the situation straight away – like that,” he says, with a swipe of his hand. “As such this is one environmental issue where we can make a real impact, very quickly, with a collective, informed approach. For forward-thinking shipowners this really is ‘low hanging fruit’ in the effort to transition to a more sustainable industry.

“I hope that’s an argument that makes a ‘noise’ of its own in the coming years.”

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