Insulating the Engine Compartment

What is the problem? 
Motorruimte isolerenAn engine room that leaks sound is a complex problem. Sounds and vibration can be heard and felt in and around the ship in several ways. The issues can be dealt with well once you detect the place where sound and vibrations are leaking. Some places to investigate in order to discover sound leaks include:

Shutters, are these heavy enough and do they close well?
Floor and deck, are these properly decoupled and insulated?
Water and fuel tanks, have they bee anti-drummed?

What is the solution?
When the hatches and walls are well insulated in their entirety, it is generally only a matter of equipping the walls and ceiling of the engine room with an absorption material. The more times the engine can be 'wrapped', the better the result. A well-insulated engine room with a housing over the engine is the optimal solution. 

Which products to use where?

  • Low Temperature Machine Room
    Merfocell PU: up to +80 °C, with oil- and moisture-tight top layer.
    Acousticcell PU: up to +80 °C, equipped with an oil- and moisture-tight top layer.
  • High Temperature Machine Room
    Merfocell GW: up to 110°C.
    Merfocom: up to 100 °C, combined absorption and insulation board.
    Flamex GW: up to 150°C, can only be used on flat surfaces.

You will find all facets of yacht and ship insulation on the Boats and Yachts page and on the tipspage

All described products to insulate the engine compartment can be found below

  1. Flamex PU
    Flamex PU
    Dirt-resistant Absorption Panel
    • Melamine foam with PU top layer
    • Sound-absorbing panel with oil, moisture and dirt-resistant top layer
    • Equipped with adhesive

    Starting at £32.39

    (incl. tax)
  2. Acousticcell PU
    Acousticcell PU
    Dirt-resistant absorption foam
    • Moisture and dirt repellent
    • Application including engine compartment
    • Hygienic areas

    Starting at £28.01

    (incl. tax)
  3. Flamex FC
    Flamex FC
    Absorption plate
    • Fiberglass cloth (FC) top layer
    • Heat-resistant Max. 150 degrees
    • For boats and vehicles

    Starting at £52.97

    (incl. tax)
  4. Merfocom Combination
    Merfocom Combination
    Absorption and insulation board
    • Equipped with sound insulating barrier
    • Sound-absorbing and Sound-insulating
    • Equipped with an oil-resistant and fire-resistant top layer

    Starting at £106.36

    (incl. tax)
  5. Merfocell PU
    Merfocell PU
    Sound absorption with a top layer
    • Oil and moisture resistant top layer
    • Sound absorption
    • Self adhesive

    Starting at £32.40

    (incl. tax)
  6. Isomat TS
    Isomat TS
    Insulations for light materials/wood
    • Mass loaded vinyl
    • Sound insulating
    • For flat surfaces

    Starting at £26.15

    (incl. tax)
  7. Merfocell FC
    Merfocell FC
    Heat Resistant absorption
    • Glass fibre cloth (FC) top layer
    • Moisture and heat-resistant
    • Applicable in engine compartments

    Starting at £57.96

    (incl. tax)
  8. Acousticcell ALU
    Acousticcell ALU
    Absorption foam plate
    • PU foam with aluminium top layer
    • Oil, moisture and heat-resistant top layer, reinforced with fiberglass mesh.
    • Equipped with a sticker

    Starting at £33.70

    (incl. tax)

Place sound insulation and sound absorption in your boat's engine compartment

Sulating the engine room
The engine room is often adjacent to other rooms such as a sleeping area, wheelhouse or aft deck. The engine noise is best stopped by insulating walls and shutters by providing them with Isomat TS (or for larger projects with Isomat KE). These plates can be glued with Saba Select glue (use 0.5 liters/m²). For extra good fastening, we recommend using some flat-head screws on the corners of the plate.

Sound isolation, in the form of mass plates such as Isomat, works particularly against the low frequencies of engine noise. The best result is achieved when the mass of the walls and/or shutters can be doubled. Make sure that the insulation boards connect seamlessly so that there is no sound leak


After the application of sound-insulating products, a sound-absorbing material is applied to "extinguish" the sound from, for example, the engine, compressor or other sources. In an engine room there is generally enough space between the engine and the absorption material, heat is not a problem here. Acusticab, Merfocell PU or Flamex PU , the latter product can only be applied to flat parts! Here, too, the plates must connect well to each other to prevent sound leaks. Tape the seams between the plates with AcustiTape so that no moisture, dirt or dust can penetrate it.

Sulate the engine casing
In many pleasure craft, especially in sloops, the engine is shielded by a casing. This is often a "box" placed over the engine. The material of this box is often lightweight, for example thin plywood, and therefore does not block much noise. Also, the engine casing often does not connect to the bottom of the vessel which then forms a sound leak.

The easiest way of insulating is to provide the inside of the casing (box) with Merfocom. This combi plate consists of several layers and provides both insulation and absorption. You can also put together products yourself in order to achieve the optimal insulation for your situation. Provide the casing inside with Isomat TS (the heavier, the better) and finish this with an absorption material of your choice. If there is little space (-10 cm) between the motor and the absorption material, use Merfocell GW or Flamex GW. With a spacious (+12 cm) casing you can use Acusticab, Merfocell PU or Flamex PU. Instead of combining products, you can also only use absorption material, for example in a renovation job.

Attention points
Prevent sound leaks through cracks and seams, but make sure there is sufficient ventilation / cooling for the engine. Silent ventilation can be done by making a labyrinth through which the air is supplied or fed. You line this labyrinth from the inside with Acusticab 13mm thick. For example, air can go to the engine, but the sound can hardly go out.

Another way is to use the Aluphon damper. An aluminum tube with a 25 mm thick wall that is perforated inside and filled with an absorption material. If there are already ventilation facilities, you may be able to improve them acoustically by using Tecnocell or the round Inno dampers, depending on the shape of the ventilation duct.