Measured noise levels in cabin

[baz]

Subject: Measured noise levels in cabin

Back in March 2013 I used an application on my mobile phone to measure noise levels in the cabin of an R-25 (Classic). Below was my recorded dB measurements. I will be doing the same measuring for my new R-21EC and wonder if any owners of R-25SC, R-27, R-29, R-29s, R-31, etc care to post back their noise level measurements.

My mobile phone was placed on the dinette table in the cabin when taking dB measurements. I also did the same measurements while holding the mobile phone in my left hand while at the helm. The dB numbers below were an average of the dinette table and hand held measurements.

 

[JamesTXSD]

5 years ago, during a Coast Guard inspection on boats I was driving, the inspector put a deciblemeter in various places... we had to put in more engine room insulation when he got a reading of 90db in one place. He said 89db was acceptable, 90 was not. By that measure, your readings at 3,500 to 4,000 RPMs would be considered "potentially damaging."

For what it's worth, I have been through many of those inspections, and much depends on the individual doing the inspection.

 

[baz]

Back in 2013 when I took dB measurements I was concerned about noise and wanted to figure out ways to lessen the noise in the cabin of the R-25 (Classic). There was not much I came up with. My wife is hard of hearing so the noise made it difficult holding a conversation with her when underway. Keeping the RPM low was the only recourse I had.

Our new R-21EC with the engine completely outside the cabin makes for a much quieter ride and I will take dB measurements as I did for our R-25 to have a comparison. Overall, the R-21EC is very much quieter for us even though I personally love the 3-cylinder diesel engine noise. At 3000 RPM my 1st mate and I can have a conversation without shouting. 😀 Even with both of us sitting on the transom seat bench with the engine running at 3000 RPM we can converse without too much effort.

I agree, 90 dB is bordering on being harmful, especially over a long period of time.

 

[K7MXE]

I made the R21EC quiet with addition of sheets of foam stuffed in where ever I could. It would be interesting to see exactly how quiet it is. I even have it in the engine box. Yes, you loose some room in the cabinets, but its also more pleasing on the ears.
Bob H