For sailing in silence

Replacing the foam in the motor compartment is not a pleasant task. The old kind was difficult to remove (often soaked in oil,) necessitating the dismantling of certain equipment (electrical wire, filter, pump…) attached to the wall in order to prepare the surface. Not technically difficult this task is within the reach of any boater who has free time and is not afraid to slip into the engine compartment. If your boat is older than 15years, there is a strong chance that it is equipped with convoluted foam which lacks efficiency concerning low frequencies, such as diesel engines; this only worsens as it gets older. You may also have flat, lightweight foam, a little more efficient on low frequencies, but whose main plus is to be easier to clean. On more modern boats, it really depends on where they were made, or the range of boat, wheteher they have the worst (convoluted lightweight foam,) or the best (PVC with prtotective film.)

The choice of foam determines the result obtained. Whether you take an entry range foam with an average efficiency or a high range efficient type, the work is the same. If you are looking for comfort, without doubt, take a PVC foam with a mass of 5 kg / m² and PU film with a thickness of 30 mm or 54 mm. If you want to minimize noise without adding weight (boat racing or cruising race), the minimum is to take a flat foam with a PU film. Melamine foam accompanied by an aluminum film is classified M1 (not flammable). It is recommended if there is risk of fire (gasoline engine, diving compressor...) Agglomerated polyurethane foam has a large mass (100 kg/m3), it is very effective against noise but less so against vibration.

The foam must absorb sound to reduce reverberation (echo) on the walls of the compartment, providing insulation to prevent noise transmission and cushioned to stop resonance. Research in acoustics has enabled the development of materials that meet all three criteria. It is a conglomerate of a number of different materials: a polyurethane foam for absorption and insulation, as well as a heavy PVC mass to prevent resonance. Often it is covered with a polyurethane film for easy maintenance.