Engine compartment soundproofing

[ACroteau]

I would like to know if anyone has had success with soundproofing an engine compartment. Did it make an appreciable difference and if yes, what is the best material to use, how was it installed, how extensive was the coverage (sides, underside of cockpit floor etc)?? Our A4 is currently out of the compartment because this spring, I need to work on the engine mounts, renew the cutlass bearing and rewire using the Moyer DC kit including new guages etc so this is an opportune time to tackle soundproofing if at all. Our boat is a Canadian made 1973 Douglas 32 (Ted Brewer design) and has a good amount of space in the engine compartment so not too concerned about clearances. Any advice would be appreciated.

[marthur]

Sound proofing

We have experimented with sound reduction on our catalina 27.

The biggest gain has been adding a waterlift muffler.

We also added foam sound proofing insulation (from McMaster Carr) to the engine room door, fiberglass enclosure and several places sound would tend to leak through. It was helpful and made a noticeable difference, but was no magic bullet.

What would make a big difference in our boat would be to isolate the engine vibrations from the hull. In other words, spend the money on the best engine mounts you can find. This would prevent the sound from conducting through the fiberglass, which is a very significant source of sound in the cabin.

Good Luck!

Mike