A quest for quiet

Chris Mardon replaces the engine mounts on his Dufour 40

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Manufacturers all too often install engines on mounts that do not isolate noise as well as they could. My mounts were 13 years old and I wanted to make my engine quieter so I took the opportunity to replace them.

The rubber bonded within engine mounts comes in varying degrees of hardness. Softer rubber gives better isolation but it has less load support and may allow more engine movement, so you need to check the mount supplier's maximum load.

Anti-vibration (AV) rubber hardness is expressed in 'shore' units from 30 at the soft end to 75 shore at the hard end.

Engine weight is usually specified as 'dry weight' so I added the weight of engine oil, gearbox oil and coolant (another 12kg to the dry weight of my 40hp engine).