Sound deading material.

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Bill McNamara
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Joined: Wed Mar 11, 2015 8:52 am
Location: Ontario Canada

Sound deading material.

Postby Bill McNamara » Mon Sep 10, 2018 10:54 pm

I love the sound of these older engines but some passengers have mentioned that conversation is a bit difficult, especially in the aft seat at WOT. Different strokes I guess?

Two possible solutions:
1) Stop talking while underway.
2) Apply some sort of sound deadening material inside the aluminum cowls. Have any of you guys tried this sort of "modification"?

Bill.

Bill McNamara
Posts: 217
Joined: Wed Mar 11, 2015 8:52 am
Location: Ontario Canada

Re: Sound deading material.

Postby Bill McNamara » Mon Sep 10, 2018 10:56 pm

Ophs, sorry about the typo in the title. Lets edit with "deadening".

outbdnut2
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Re: Sound deading material.

Postby outbdnut2 » Mon Sep 10, 2018 11:14 pm

There are rolls of thin (approx 1/4 inch) foam insulation with foil on one side and stickyback adhesive on the other available at a lot of hardware stores. Old car restorers put it under carpeting and behind the rear seat back to reduce road noise - this stuff may stick inside outboard cowls, but I've never tried that. The stuff is a lot cheaper than what looks like the same stuff marketed for the car hobby. Old car resto TV show "Garage Squad" often uses this, and tells you to get it at a hardware store.
Dave

bobw
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Re: Sound deading material.

Postby bobw » Mon Sep 10, 2018 11:35 pm

I looked at either Soundown Insulation or Dynamat when I was restoring my '72 Evinrude. It pays to shop around as prices on both seem to vary quite a bit. Boaters Plus store had a large inventory of Soundown they were selling at a decent price a few months ago.
Bob
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1954 Johnson CD-11
1958 Johnson QD-19
1972 Evinrude 25202

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Garry in Tampa
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Location: Florida

Re: Sound deading material.

Postby Garry in Tampa » Tue Sep 11, 2018 4:49 am

I cut up an old wet suit for the inside of the '58 StarFlite cover I put on my V4 hot rod. You could not hear the motor run, It was like being on a sail boat. Many times I hit the starter forgetting I had not shut it off. Easy on the ears, hard on the starter pinion. . . :lol:
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crosbyman
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Location: Montreal Canada

Re: Sound deading material.

Postby crosbyman » Tue Sep 11, 2018 7:40 am

I used cheap rubber floor mats from the Dollar store for the cowls ofa couple of 9.5 turtles

I used the old oily dirty foam liners as a pattern to cut up the floor mats which fitted nicely, then glued them up with contact glue.

I did buy a can of spray glue but never got around to using it I plan to use spray glue next time

Bill McNamara
Posts: 217
Joined: Wed Mar 11, 2015 8:52 am
Location: Ontario Canada

Re: Sound deading material.

Postby Bill McNamara » Tue Sep 11, 2018 8:27 am

Thanks guys, great ideas and info.
Also just realized that the foam interlocking tiles that are sold for kids play areas, or garage floors might do the trick also. I've got some of those on hand.

NJ-boatbuilder57
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Location: New Jersey

Re: Sound deading material.

Postby NJ-boatbuilder57 » Tue Sep 11, 2018 9:12 am

I was thinking about trying something under the cowling of my Javelin. I looked at Dynamat, but their published data shows a 3db reduction which doesn't seem worth it to me.

Foam interlocking tiles might be with a try...and cheaper!

david bartlett
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Location: Western Maine

Re: Sound deading material.

Postby david bartlett » Tue Sep 11, 2018 9:30 am

Bill,

I have used Dynamat on my Johnson RD16 with some success. It cuts down on the metallic vibration but trust me you can tell it is a big Twin under the cover.
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crosbyman
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Location: Montreal Canada

Re: Sound deading material.

Postby crosbyman » Tue Sep 11, 2018 10:52 am

it is hard to conceive but…. 3db loss equates to a 50% drop in noise level.


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