'She sounded like a Lancaster bomber circling behind us and we soon realised why ear defender notices were posted on the aft deck.'

The 65ft Category One workboat had been used for 17 years by the Scottish Fisheries Protection Agency and the permanent crew of five living onboard must have spent all their time on board wearing earplugs.

Readings taken on board showed a noise level of 106dbA on the stern, making it impossible to sleep in the aft cabins whilst underway.

Realising something had to be done urgently in order to make Morven suitable for charter, Marico contacted marine exhaust and engine noise reduction specialists Halyard and outlined the problem.

'We have twin Detroit V8 two stroke engines, limited space, and the need to reduce noise levels drastically', said Bob Fitch.

Halyard Sales Director Bob Doyle visited the vessel himself and realised that there was no room for a traditional wet silencer as the wet pipes ran from the engine room to the transom through the accommodation area.

He recommended the use of a new type of dry silencer which could be hung above the engines.

The specially designed stainless steel injection heads were linked back into the existing exhaust system. The injection heads were manufactured by Sabre Fabrications, which has recently been acquired by the Halyard Group. The dry silencers were installed by Bob Fitch and colleagues, who had to remove the wheelhouse top and floor to gain access. Once inside the engine room there was just 10cm clearance between the engines and the deckhead to slide the silencers into position, but the fit was perfect."The results have been amazing, says Bob Fitch.

"Now we can even hold a mobile phone conversation while standing on the aft deck at full speed."

MJ Information No: 17128