Filling Hull Voids with Expanding Foam: Good Idea/Bad Idea

[d_coyne1984]

I figured out that most of the noise from my boat is coming from the swim platform area. As has been proven time and time again, mass loading does very little to eliminate that noise so I went the other way and used open cell foam in a very unprofessional looking install throughout the swim platform area. The rear of the boat is acting like a drum and the noise resonates back there like crazy. What do drummers do to tame the resonance in a kick drum? They stuff a soft fluffy pillow in there to dampen the heads and slow the sound waves. It made a fairly big difference. I am now under the belief that if I fill up the open voids in the boat as much as possible, that there will be little airspace left for which the sound can resonate through.

So here is my new thought: Before I put my seadek down, I am thinking I can drill a couple small holes, and pump it full of expanding foam. My main area of focus is the area in front of the floor locker where there is a fair amount of dead space on the 192. I would leave the rear of the boat alone so as not to gum up the cables and path to the bilge. The only issue I can potentially see is drainage, but unless I go crazy with the foam, it should not block every path and if it is full of non absorbent foam, it can't get full of water anyway. Is my logic flawed anywhere here???????

 

[SamCF]

I figured out that most of the noise from my boat is coming from the swim platform area. As has been proven time and time again, mass loading does very little to eliminate that noise so I went the other way and used open cell foam in a very unprofessional looking install throughout the swim platform area. The rear of the boat is acting like a drum and the noise resonates back there like crazy. What do drummers do to tame the resonance in a kick drum? They stuff a soft fluffy pillow in there to dampen the heads and slow the sound waves. It made a fairly big difference. I am now under the belief that if I fill up the open voids in the boat as much as possible, that there will be little airspace left for which the sound can resonate through.

So here is my new thought: Before I put my seadek down, I am thinking I can drill a couple small holes, and pump it full of expanding foam. My main area of focus is the area in front of the floor locker where there is a fair amount of dead space on the 192. I would leave the rear of the boat alone so as not to gum up the cables and path to the bilge. The only issue I can potentially see is drainage, but unless I go crazy with the foam, it should not block every path and if it is full of non absorbent foam, it can't get full of water anyway. Is my logic flawed anywhere here???????

We had an old Stingray years ago. It was a fast boat at one time, but in its last years was a dog. It was so weighted down with waterlogged foam it struggled to get on plane. Just be careful not to block drainage as you said. Open cell foam has no place on a boat.

 

[Bruce]

I worry about overfilling then finding a cracked hull!

 

[d_coyne1984]

We had an old Stingray years ago. It was a fast boat at one time, but in its last years was a dog. It was so weighted down with waterlogged foam it struggled to get on plane. Just be carful not to block drainage as you said. Open cell foam has no place on a boat.[/QUOTE

I thought for sure the foam would be moldy within a year, but then I thought what the hell because I had a bunch laying around. It was just going to be temporary as an experiment, but so far it's just fine. I obviously kept it away from the bottom of the boat.

 

[d_coyne1984]

I worry about overfilling then finding a cracked hull!

I wish I could separate the hull and the deck and just spray a nice even coat on the underside of the deck.I might try to rig up something to see if I can try to keep most of it on the deck and off the bottom. I am definitely not going to go crazy with the stuff.

 

[Bruce]

How are the upper and lower hulls attached? Is it just screws and bolts or are they glued together?

 

[Seadeals]

Not sure about this thought; but one concern might be turning your boat into a mold factory with possible pockets between the hull/foam that trap water but offer little room for air circulation/evaporation.

 

[swatski]

I figured out that most of the noise from my boat is coming from the swim platform area. As has been proven time and time again, mass loading does very little to eliminate that noise so I went the other way and used open cell foam in a very unprofessional looking install throughout the swim platform area. The rear of the boat is acting like a drum and the noise resonates back there like crazy. What do drummers do to tame the resonance in a kick drum? They stuff a soft fluffy pillow in there to dampen the heads and slow the sound waves. It made a fairly big difference. I am now under the belief that if I fill up the open voids in the boat as much as possible, that there will be little airspace left for which the sound can resonate through.

So here is my new thought: Before I put my seadek down, I am thinking I can drill a couple small holes, and pump it full of expanding foam. My main area of focus is the area in front of the floor locker where there is a fair amount of dead space on the 192. I would leave the rear of the boat alone so as not to gum up the cables and path to the bilge. The only issue I can potentially see is drainage, but unless I go crazy with the foam, it should not block every path and if it is full of non absorbent foam, it can't get full of water anyway. Is my logic flawed anywhere here???????

Funny you posted that. Yes, I wouldn't hesitate to do it at all. This is one of the main things what separates Yamaha jet boats from more expensive brands - those are all loaded with foam and every internal surface is covered and spaces are filled - for excellent sound deadening.
I didn't have time to post on mine as I've been traveling too much, but I'm in the middle of doing mine - same project, basically.
I believe that filling the voids is absolutely THE WAY to soundproof with these boats.
As far as sound deadening, the only other thing that is similar in terms of cost/effort effectiveness is the engine hatch seal and foam, everything else is less effective in my experience.
I did not drill any holes, yet, but filled up the bow compartments (all around the anchor locker) - which are wide open. I squeezed some 20 containers of those (closed cell expanding polyurethane foam):

and I'm not even half done it seems! I just keep buying those and packing it in.
The effects so far are quite substantial - in terms of stopping the sound from carrying up around the hull - which is like a guitar box otherwise - and generally taming it.
I have also been filling in the dead spaces under the stern and under the hull cap with a combination of foam, poly foam and carpet stain-free padding material (it is very hydrophobic) - as I can not spray up into those spaces




These are huge voids

^^^^those are all filled and it makes a big difference.

I'll post more pics when I get back. But this is definitely the way to go, IMO.

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[Bearsar240]

I would recommend this over great stuff. I've had more problems with Great Stuff not mixing and expanding correctly. When this happens there are voids of air in the middle of what looks like a good foam job when cut in half. Also the 2 part expands 10times what great stuff does. Just my opinion.

 

[spatty99]

How are the upper and lower hulls attached? Is it just screws and bolts or are they glued together?

I think most boat hulls these days are mechanically (screwed) and chemically (glued) together. Mates for life.

 

[ripler]

Or you can use this. I did the electrical engineering and automation on this machine, it poured foam at 1000 lbs/min at 2500 PSI. It did 1 continuous pour in 1 hole, if for any reason the machine stopped pouring the hull was ruined.
The foaming process starts at 53 sec.

 

[the MfM]

Lots of whalers in the bone yards with water logged foam. Not worth fixing/restoring.

 

[Captain Obvious]

What about that dynamat stuff they put in cars with annoying stereo systems?

 

[d_coyne1984]

Funny you posted that. Yes, I wouldn't hesitate to do it at all. This is one of the main things what separates Yamaha jet boats from more expensive brands - those are all loaded with foam and every internal surface is covered and spaces are filled - for excellent sound deadening.
I didn't have time to post on mine as I've been traveling too much, but I'm in the middle of doing mine - same project, basically.
I believe that filling the voids is absolutely THE WAY to soundproof with these boats.
As far as sound deadening, the only other thing that is similar in terms of cost/effort effectiveness is the engine hatch seal and foam, everything else is less effective in my experience.
I did not drill any holes, yet, but filled up the bow compartments (all around the anchor locker) - which are wide open. I squeezed some 20 containers of those (closed cell expanding polyurethane foam):
View attachment 75634
and I'm not even half done it seems! I just keep buying those and packing it in.
The effects so far are quite substantial - in terms of stopping the sound from carrying up around the hull - which is like a guitar box otherwise - and generally taming it.
I have also been filling in the dead spaces under the stern and under the hull cap with a combination of foam, poly foam and carpet stain-free padding material (it is very hydrophobic) - as I can not spray up into those spaces
View attachment 75636

View attachment 75637

These are huge voids
View attachment 75638
^^^^those are all filled and it makes a big difference.

I'll post more pics when I get back. But this is definitely the way to go, IMO.

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Have you had a chance to test your results with the expanding foam. I am definitely going to look into getting some of that carpet padding.

 

[justason]

What about that dynamat stuff they put in cars with annoying stereo systems?

i installed dynamat and a rubber counterpart to my fuel tank hatch, made little difference. theres a post on here someplace for it that gave me the lead. its expensive stuff too.

 

[d_coyne1984]

i installed dynamat and a rubber counterpart to my fuel tank hatch, made little difference. theres a post on here someplace for it that gave me the lead. its expensive stuff too.

I am trying a different method of attack. Myself and @swatski (correct me if I am wrong) are under the impression that filling the large open air spaces on our boats with soft material has the greatest effect on noise reduction. The soft material acts to slow the speed of the sound waves and by filling the voids we are eliminating the amount of space that the sound can freely resonate in, the transom area behind the engine being the worst.

 

[Captain Obvious]

I definitely like the idea of sound deadening and am interested to see what comes of this thread.

 

[swatski]

I have done a lot of various things, some work better than other. MLV/Dynamat are very expensive and really work well on sheath metal, but not so much on fiberglass panels, probably just because of the thickness difference if it is all about mass ratios.

Filling int he space works better, especially for the money.
I have been slowly filling the voids I can access in my 240, and I see very nice improvements. All of it is above the water line, so far, and I do think that the Big Gap generic polyurethane foam is plenty good enough.

Like all boats these days, our boats have flotation foam built in to the hulls, if you are concerned about it becoming waterlogged. Nothing new there, if a boat is not moored in a wet slip it rarely is an issue.

Here is a pic of my 2012 190 with Dynamat extreme and polyurethane - under the swim deck


Dynamat everywhere, some 100lbs of it



The engine hatch had 5-6 layers of dynamat/aluminum backed insulation and acoustic foam - that made a big difference, along with a seal




In the new boat, 2016 240
filling the spaces in the bow made a big difference, here are the sides/bulkheads being filled through the cup holder holes


Some of the large vertical spaces I started filling with foam/pillows - here is the space under the hull cap where I can not inject polyurethane, those foam pillows work great - I stuffed dozens of those in there; getting those from Sam's at $20 a pair - cheaper than dynmat by a long shot, and if they ever get wet, easy to replace.


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[Jgorm]

I bought a 1/2"thick closed cell foam yoga mat for 17 bucks. I'm going to install it on my yamaha Viking to quiet it down. It's cheap foam that won't hold water . i might add a few to the boat.