engine noise solution

[George]

We have an 1977 Islander 32, which has been repowered with a Westerbeke 20B2, from the original Atomic 4. Great engine, but very noisy. Problem is the complete lack of any sound insulation. Most of the space to starboard surrounding the engine will be easy to cover, just tack insulating material up on existing surfaces, but on the port side and aft the engine, is just open space, accessable through the port cockpit locker. Does anyone have any suggestions or experience installing sound deadening material in this situation? I have in mind that I've have to build some sort of a light framework to support sound deadening panels. Does anyone have a less expensive alternative to the sound deadening material sold by places like West Marine? Pretty expensive stuff. Any suggestions would be appreciated

 

[Bill]

Me too

The sound insulation in the engine box of the Yanmar 3GMF on my Hunter 34 is falling apart from age, so the following passage from Dave Gerr's book The Nature of Boats caught my eye on the topic of soundproofing the engine room."To accomplish this you have to do two things. First, you should seal the engine compartment as well as possible from the rest of the boat-make sure you don't interfere with ventilation. Gaskets and spring-type lock-down latches or clamps should be fitted on all engine hatches and engine box covers. Then you should apply proper soundproofing sheets to the inside faces of the engine compartment bulkheads, overhead, hatches, and so on.One of the best soundproofing materials is 1 inch of open-cell foam (or fiberglass) with 1-pound-per-square-foot lead sheet embedded in it. The foam absorbs much noise energy and the weight or inertia of the lead dampens vibration very effectively. A really first-class job will use 3 inches of foam with lead. A nice feature offered by commercial suppliers of marine soundproofing is a surface coating of aluminized mylar or a similar substance. These tough, smooth surfaces protect the foam and make it far easier to clean.Sound insulation need not be costly. One- to -3inch insulation of this type runs about four to six dollars per square foot."Perhaps he won't mind me quoting him verbatim. His book is one I'd highly recommend, packed with useful information of all kinds.West Marine's catalog has one-inch foam at what works out to $7.50 / sq ft. I'm also checking the web, haven't found anything yet.

 

[Jack Tyler]

Soundown, Pegboard and Cleats...

I truly admire Dave Gerr and think The Nature of Boats is excellent. But you'll find the folks who make some of the best engine sound insulating material - Soundown - don't find his argument for lead-lined foam to be valid. Their studies show a heavy vinyl mid-layer with 1" sound-deadening foam on each side performs about the same as their same product with a lead mid-layer. Plus it costs less to buy and ship, and is easier (lighter) to handle.Our Pearson came with pegboard used as the engine compartment bulkheads. These are attached with screws to cleats glassed lightly into the hull. I used Soundown 2" foam where it was feasible and where the engine shared space with the aft cabin (not the entire area behind the engine) and the difference was remarkable. This replaced 1" foam more often found and, when comparing the two, the density and weight of the Soundown material is striking.I would think this basic approach would work on any boat provided you find it worth the effort and expense. Recommend you start with areas that need it the most - e.g. at the forward end of the engine compartment, where it is adjacent to the main cabin. You'll find heat insulation benefits, as well.Jack

 

[Bill]

Thanks Jack

Good info. That's a keeper.