The science of silencing

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According to UK-based marine noise and vibration specialist, Halyard, commercial boats of all sizes can produce overbearing noise from their engines, generators and exhaust systems. This, Halyard says, can make for an extremely unpleasant and unproductive environment to work in, with prolonged exposure to high levels of engine and mechanical noise proven to result in crew fatigue and seasickness.

Halyard fitted exhaust systems to each of Alicat’s four Wind Farm Support Vessels built for energy supplier E.ON

Halyard fitted exhaust systems to each of Alicat’s four wind farm support vessels built for energy supplier E.ON

Limiting noise and vibration at the build stage is far more effective and efficient, and there are plenty of modern solutions available on the market. Consulting a professional at the design stage will enable the boat builder to optimise the noise and vibration reduction for the most effective solution within budget.

Andrew Davies, Sales & Marketing Director at Halyard (M&I), told Maritime Journal, “Whether wet or dry, an exhaust system should be emitting minimum noise while still working at optimum performance. The type of silencer needed depends on the type of exhaust system, how large it is and if it’s above or below the waterline. Most commercial vessels have previously opted for dry exhaust systems, but these have a tendency to be heavier and hotter than a wet system. This is where a water injected systems with a wet silencer can be hugely beneficial, and more cost-effective than a dry system.”

Other options include silencer/separators and dual chamber silencers, which can offer over 70% noise reduction. Andrew added: “On the vibration reduction side, systems are available now which aid the installation of the engine in a horizontal position, resulting in permanent, guaranteed alignment. Using a system that comprises softer engine mounts, a CV shaft and thrust bearings, can immediately reduce vibration levels. As the permanent alignment improves the driveline and reduces the vibration caused by stiff mounts, vibration can be reduced by up to 90%. Although the engine mounts are soft, there is still enough freedom of movement so as to not hamper the boat’s performance. These systems work by transmitting the thrust to the hull instead of the engine, reducing wear and tear significantly.”

As the welfare of crews and passengers on board vessels becomes an increasingly high profile issue, boat builders need to do all they can to reduce noise and vibration levels at build stage, to provide a safe and healthy working environment for crews.

Halyard has been supplying equipment for commercial craft for over thirty years and today is a key supplier for yards across the globe. Be it a wind farm support vessel, a lifeboat, a passenger ferry, a pilot boat or a landing craft or patrol vessel for the military.

By Jake Frith