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Old 05-10-2016, 09:13 PM   #81
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Gonefarrel....I didn't use any of their products other than their excellent insight. As I recall, sourcing out the anodized perforated aluminum sheathig they use was the most challenging item.

Sound down is a good outfit

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Old 05-11-2016, 06:35 PM   #82
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15 knots in an American Tug 395...
The video makes it sound much noisier that it was in person but you get the idea!
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Old 05-11-2016, 06:54 PM   #83
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15 knots in an American Tug 395...
The video makes it sound much noisier that it was in person but you get the idea!
Wifey B: I'm not the only one who's made a catch fishing today. AT has you hook, line, and sinker. Nice boat. Good choice if you go that way.
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Old 05-11-2016, 07:19 PM   #84
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Wifey B: I'm not the only one who's made a catch fishing today. AT has you hook, line, and sinker. Nice boat. Good choice if you go that way.
I do believe you are correct! Too soon to say but "we" are beginning to like the idea... (I've been sold for some time now truth be told!)
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Old 05-11-2016, 07:29 PM   #85
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I do believe you are correct! Too soon to say but "we" are beginning to like the idea... (I've been sold for some time now truth be told!)
Bruce
Wifey B: But you still aren't completely sold till you can get out on one like you did today.
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Old 05-14-2016, 03:15 AM   #86
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Sound level readings from 20ft CC

Just returned from a pleasant 7:30am cruise in 100 degree heat to take average sound readings from the helm, at ear level, trying to block wind noise (2-5 db) as much as possible:
  • 780 rpm 80 db (idle)
  • 3000 rpm 89 db
  • 5500 rpm 94 db (normal cruise)
  • 6200 rpm 100 db (WOT) with peak readings at 115 db
No wonder I get headaches after an hour. Definitely have to fabricate a box to cover the outboard.
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Old 05-14-2016, 08:51 AM   #87
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Originally Posted by makobuilders View Post
Just returned from a pleasant 7:30am cruise in 100 degree heat to take average sound readings from the helm, at ear level, trying to block wind noise (2-5 db) as much as possible:
  • 780 rpm 80 db (idle)
  • 3000 rpm 89 db
  • 5500 rpm 94 db (normal cruise)
  • 6200 rpm 100 db (WOT) with peak readings at 115 db
No wonder I get headaches after an hour. Definitely have to fabricate a box to cover the outboard.
Level at which sustained exposure may result in hearing loss: 90-95 dB (and don't ignore the wind noise, it all adds up.

Maximum allowed per day at 95 dB by OSHA - 4 hours.
Maximum allowed per day at 94 dB by NIOSH - 1 hour.
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Old 05-14-2016, 11:15 AM   #88
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There are a few things you can do with an outboard powered boat to reduce noise.

You can replace whatever insulation is inside the cowl with an insulation that incorporates a mass loaded vinyl noise barrier. These are available in 1/2" thick.

You can have a canvas cover made for the outside of the cowl and sew in or make pockets to hold insulation with a mass loaded vinyl noise barrier. Particular care needs to be taken to leave the air intake open at the top back of the engine cowl.

Something that's common in the Keys and especially Key West on light tackle boats is a cover/cowl/cutting board/bait station over the outboards from gunnel to gunnel covering the entire outboard well a little higher than the O/B's and leaving room for full turns and tilt.

All 3 will significantly reduce noise on an outboard powered boat.
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Old 05-14-2016, 11:43 AM   #89
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Originally Posted by makobuilders View Post
Just returned from a pleasant 7:30am cruise in 100 degree heat to take average sound readings from the helm, at ear level, trying to block wind noise (2-5 db) as much as possible:
  • 780 rpm 80 db (idle)
  • 3000 rpm 89 db
  • 5500 rpm 94 db (normal cruise)
  • 6200 rpm 100 db (WOT) with peak readings at 115 db
No wonder I get headaches after an hour. Definitely have to fabricate a box to cover the outboard.
I just find those numbers staggering and would quieten with sound insulation. What kind of engine is that? I know you said 60 hp 4 stroke. I don't know if you noticed the numbers I posted from a 60 hp Yamaha equipped similar CC.

http://www.boattest.com/review/edgewater/192_155-cc

At 780 RPM, you're at 80 dB. At 1000 RPM, that boat is at 67 dBA.
At 3000 RPM, you're at 89 and they're at 74
At 5500 RPM, you're at 94 and they're at 86
At WOT you're at 100 dB and they're at 90.

I think I just realized part of the difference. They're measuring dBA and I'm assuming you're measuring dB?
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Old 05-14-2016, 11:54 AM   #90
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BandB-

I didn't have a chance to log sound levels versus frequency, which would be more useful information. Perhaps I could calculate dbA with that info?

In any case, I like all three of Keysdisease's suggestions. The engine is a new Mercury Bigfoot 60hp and there is no sound insulation in the cowl cover. I'll search to see if I can find some mass loaded insulation in Qatar. If not then I can bring some back from vacation this summer in America.

I like the idea of installing it both inside the cover and also on a canvas engine cover, so in effect there would be two layers. A lot simpler to build those than to create the hard fiberglass box.
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Old 05-14-2016, 12:51 PM   #91
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BandB-

I didn't have a chance to log sound levels versus frequency, which would be more useful information. Perhaps I could calculate dbA with that info?

In any case, I like all three of Keysdisease's suggestions. The engine is a new Mercury Bigfoot 60hp and there is no sound insulation in the cowl cover. I'll search to see if I can find some mass loaded insulation in Qatar. If not then I can bring some back from vacation this summer in America.

I like the idea of installing it both inside the cover and also on a canvas engine cover, so in effect there would be two layers. A lot simpler to build those than to create the hard fiberglass box.
This page discusses converting, although I've never done it, just used a dBA test unit. There is one chart in the middle of the page that shows some frequency conversions.

Decibel A, B and C
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Old 05-14-2016, 04:26 PM   #92
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What you want is a "an insulation that incorporates a mass loaded vinyl noise barrier" as in a vinyl/foam composite insulation, see picture.

In many insulation installations on boats you see a silver or white mylar face with foam behind it. Foam is a noise absorber, but does little to stop the transmission of noise. Real noise insulation incorporates a mass layer between an absorption layer and a decoupler layer. 20 years ago the mass layer was lead, today it's mass loaded vinyl which works just as well.

Technically mass loaded vinyl alone would be effective incorporated into a cover on the outside because it was not directly exposed to the noise. On the inside a 1/2" overall thick vinyl / foam composite would be best.



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I'll search to see if I can find some mass loaded insulation in Qatar. If not then I can bring some back from vacation this summer in America.
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Old 05-14-2016, 07:25 PM   #93
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FWIW, today running at 1500 rpm we recorded about 70db in the Pilothouse, 75db in the saloon, and about 80db down in the companionway between the cabins and head.
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Old 05-15-2016, 06:18 PM   #94
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That's a very comfortable level, Dave! I'm not as lucky but I'm planning to improve the situation soon with Soundown carpet underlayment. My wallet just needs to recover after back-to-back battery and refrigerator replacements.

I downloaded the Sound Meter android app and measure the sound levels in the salon and at the lower helm today. They measured a consistent 78-79 dB at my cruise 1800 RPM. I didn't measure the FB or forward cabins.
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Old 07-18-2016, 12:03 AM   #95
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Level at which sustained exposure may result in hearing loss: 90-95 dB (and don't ignore the wind noise, it all adds up.

Maximum allowed per day at 95 dB by OSHA - 4 hours.
Maximum allowed per day at 94 dB by NIOSH - 1 hour.
I just finished a 15 hour transatlantic flight on a new Boeing 777 and was wondering why it was so noisy. Then I remembered the handy little app on my phone so I took sound readings, which were very surprising:

* Noise level at front of plane (economy seating) 90 dbA
* Noise level towards rear of plane 95 dbA
* Peak levels about 100 dbA

The foam ear plugs quickly went back into my ears! I wonder how many pilots and cabin crew suffer from permanent hearing loss?
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Old 07-18-2016, 12:26 AM   #96
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Quote:
Originally Posted by makobuilders View Post
I just finished a 15 hour transatlantic flight on a new Boeing 777 and was wondering why it was so noisy. Then I remembered the handy little app on my phone so I took sound readings, which were very surprising:

* Noise level at front of plane (economy seating) 90 dbA
* Noise level towards rear of plane 95 dbA
* Peak levels about 100 dbA

The foam ear plugs quickly went back into my ears! I wonder how many pilots and cabin crew suffer from permanent hearing loss?
Wow, I would not have thought it was that loud in a 777. I've been to the UK and back, (20 hours each way accumulatively), and I thought they were quite quiet. I have the same app, and in my car at 100kph, (your 60mph approx), it is 55dB in the driver's seat. I have yet to test the boat. Haven't been out in it since I dowloaded the app.
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Old 07-18-2016, 12:47 AM   #97
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20 hours Peter, that is just insane! Was that nonstop to Heathrow?

Beats my 9 hour flight to London all to HECK, I can barely get off the 777, go through Passport control, screening and walk to the other end of the terminal for my connecting flight to Madrid. They must take you off on a gurney.

Thank God for Bose Noise Canceling headphones. A must have for long flights and screaming babies.
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Old 07-18-2016, 02:05 AM   #98
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Another vote for noise cancelling earphones on our recent long haul 777 and 787 flights. They work, but so do earplugs.
There are no nonstop commercial Sydney-UK(or Europe) flights. Qantas once flew London to Sydney with a lightly loaded specially fueled 747-400 as a stunt, but commercially it`s not on.
Aussies are used to long flights, with stopover, to Europe. West coast Canada and USA at 13-15 hours are easy.
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Old 07-18-2016, 02:45 AM   #99
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20 hours Peter, that is just insane! Was that nonstop to Heathrow?

Beats my 9 hour flight to London all to HECK, I can barely get off the 777, go through Passport control, screening and walk to the other end of the terminal for my connecting flight to Madrid. They must take you off on a gurney.

Thank God for Bose Noise Canceling headphones. A must have for long flights and screaming babies.
That was 14 hrs Brisbane to Dubai, then 6 hours Dubai to Heathrow. 2 day stopover in Dubai on the way, to visit Ferrari world, and sus out the Yas Marina F1 circuit. Only a short 3 hr stopover on way back in reverse direction. I won't do it again unless I go at least premium economy.
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Old 07-18-2016, 10:30 AM   #100
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Many years ago there was a 20+ hour non stop flight from Chicago, Ill to Perth, Aus. At the time, it was billed as the longest regularly scheduled non stop passenger flight in the world. Don't remember the airline, might have been Qantas, but had two flight crews on a long haul 747.
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Even with the layover that would still be a killer for me Peter. My regular trip is 9 hours to Heathrow, 2 or 3 hr layover, 2 hours to Madrid. Overnight there, then next morning 2 hr high speed train to Valencia and I'm dead for the next 2 days.

I usually fly British Airways.
Yes premium economy gives you a better seat, fewer passengers and if available a bulk head facing seat gives you much more leg room. Down side they won't let you use the head on the other side of the bulkhead which is Business Class. Have to walk through Premium and Economy to the tail of the plane and compete for the two heads there.
Ooops!!
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