The engine causes nuisance noise: by means of air noise and by means of contact noise. In order to stop the contact noise you must anti-drum the hull. You stop the air noise by insulation and absorption of the noise. This explanation is a combination of the explanation about the stopping of engine noise and the anti-druming of the hull.

With Vibradamp A90-P anti-drumming paste you glue zincor plates on the under surface to be anti-drummed. The minimum thickness which you keep here is 4 : 1 : 1. if the under surface is 4 mm thick, then the layer thickness of the two component paste (Vibradamp A90-P) is 1 mm and the thickness of the zincor plate is also 1 mm. You need per square meter (with a layer thickness of 1 mm) around 1,5 kg of paste.

There are two ways to place the plates: you can smear the surface and then press the steel plates into the paste, or you can smear the plates themselves and then press these firmly onto the surface. We advise to smear the surface itself; in this way you use more material but this is much less labour intensive.

The zincor plates are delivered in a length of 20 cm (10 cm width). So, possible curves on the surface can be easily covered without having to bend the plates. In any case, for optimal anti-drumming these places where the vibrations are introduced must be treated. This is around the engine foundation and the surface above the propeller. The bigger the surface anti-drummed, the better the result. In the case of strict noise requirements, e.g. all engine room partitions, the tanks and the area of the engine room bulkhead to the afterpeak are anti-drummed.

Insulation is working against the engine’s low frequencies. In order to combat this as much as possible the wood/multiplex on the inner or outer side of the engine space must be covered with an Isomat TS14 insulation plate. Glue these plates with Saba Select AAC (0.5litre/m2). For extra good fitting we advise the use of a few screws. Pay attention that the insulation plates are seamlessly connected so that no noise-crack exists.

You must absorb the noise from the inside of the engine space. Here you can use Merfocell GW. This is a CE-tested foam with a strong oil resistance, inflammable coating which is specially developed for the building yachts/boats. You can chose from two variants (25 of 40 mm thick). We advise you to use the thickest variant (the thicker, the better the absorption) when the space allows.

Merfocell GW is self-adhesive and can be stuck directly over the Isomat TS. Depending on the under surface (rough or lacquered) the under surface can be treated with Saba Select contact glue.

Specially for engine noise in yacht building Merford has developed Merfocom. This material is insulation and absorption in one. The noise insulation plate is glued between the two sides of foam so that the mass layer can move freely in relation to the under surface. Here a so called "double partition" exists, which insulates certain noises better than a single partition. The plate is built up as follows: 25 mm Merfocell GW grey + 4 mm Isomat TS 8 + 5 mm Merfocell + self-adhesive layer. The total thickness is 35 mm.