Silence Water Tanks?

[johngsandusky]

Under certain conditions my monel water tanks act as a drum set. The volume and variety of sound is amazing. They are cylinders, under the v-berth. Probably not baffled, but retrofitting would not be easy. My wife was not pleased to hear this "music" until 0130. My only idea is to wrap them in foam or replace them. I also think I remember something about putting a weight in the middle of a panel to reduce vibration. Most of the sound must come from the ends. Has anyone solved this problem?

[Ron Williamson]

You might try a bit of "ice and water shield" from a roofer.
We were discussing sound deadening for metal sinks on a motorwell thread.
R

[Capt Zatarra]

Perhaps you could cut a slice across the top, from side to side. With a round tank you will need to cut half way around the tank to fit a full size baffle. Slide a sheet of monel with holes drilled in it, into the cut. The sheet should be slightly higher then the cut. Then weld the cut and the sheet closed. Grind the weld smooth. You now have a baffled tank. You should be able to do this with out taking the tank out. If you leave the tank 1/4 full of water it will work as a heat sink to protect the surrounding boat. You will need to use heat and spark blankets to lay around the weld. A professional will have them. even if you put in partial baffles the water will swirl enough to reduce the pressure striking the ends of the tank, reducing the noise. I personally would put a baffle with 1/2 inch holes, one inch on center, about eight to ten inches from each end of your tank. After that I doubt you will ever hear it again. Capt. Z.

[Chip Chester]

Are the ends 'oil-canning' as the water sloshes? You might check to see if a well-padded block of wood pushing in on the center of the tank end would calm the noise. (Won't help with the water noise, though.) If it does help, look to make that pressure permanent without damaging the tank or surrounding framing. At speed, that water's going to be sloshing quite a bit. I don't know if there's a food-safe, taste-free foam you could insert so it acts like a fuel cell in a race car... Chip

[Lew Barrett]

My monel tanks would oil can when filling (or as they were drawn down). I think the vents may have been clogged or crimped, but I was never able to clear them. However, they only did it once while filling, and then once when emptying. At 135 gallons each, I'm sure they were baffled as I never heard water sloshing around.

If you have clear access all the way around, you can swathe them in sound deadening material. The challenge there will be covering all of the surface, as any un-damped and open metal will probably transmit sounds and the rest of the exercise will be mostly waste. Alternately, you can try deadening them by putting material on just the areas you can reach, and hope that will be enough to do the trick, but usually partial solutions with noise control don't work.

Here's the sort of product that could help: Dynamat Otherwise, isolating the area that the tanks are in is the next option if you want to contain the noise rather than do something about it at the source, and I understand completely why removing monel water tanks for modification is not first on your list.

[Tonyr]

If the existing tank has an access panel in the top (or if you could make one) then inserting a complete flexible tank would pretty well guarantee silence. Mine is not audible.

Regards, Tony.

[Garret]

If it is the ends, I'm with Chip above. You could also put a block on each end & hold 'em on with a ratchet strap or 2 - at least for testing. Make the block substantially smaller than the diameter - is it's the center you want to stop from moving.

If that works, pull the tanks & weld a brace across each end & then foam them - whether wrapped or sprayed on.

[Lew Barrett]

If its anything like mine were, pulling the tanks is not a practical option. A lot depends on circumstances I'd suppose. I'm guessing the tanks are not easily removed but if they are and they are not too big then the world of options opens of course.

[johngsandusky]

Thanks. It's not too hard to remove the tanks, they are braced in top and bottom. I'd like to avoid cutting and welding. I don't think that the ends are oilcanning, but strapping something to the ends might help anyway. If I decide to baffle it, I would cut off the end, and fiberglass it back.

[Garret]

Getting food grade epoxy in small quantities is not easy. Non-food grade can cause taste & health issues.

You probably already know this....

[Figment]

I'll be the third one to say it: Dynamat.
It doesn't take much, and it's a very easy non-destructive install, certainly worth a try.

[Lew Barrett]

Thanks. It's not too hard to remove the tanks, they are braced in top and bottom. I'd like to avoid cutting and welding. I don't think that the ends are oilcanning, but strapping something to the ends might help anyway. If I decide to baffle it, I would cut off the end, and fiberglass it back.

Wrap them. Figment, I think it's just you and me on the Dynamet band wagon, but it is good stuff. I used it in mu house's ducts and venting to help minimize transmission between floors. Works.

[Garret]

Wrap them. Figment, I think it's just you and me on the Dynamet band wagon, but it is good stuff. I used it in mu house's ducts and venting to help minimize transmission between floors. Works.

Sound insulation certainly is a good option - in fact I use it on mine (though I used leftover Soundown from the engine area). However, if the tanks are oilcanning it will only muffle the sound & - even worse - hide the metal fatigue that the oilcanning is causing.

My 2 cents.

[Lew Barrett]

John said he didn't think they were oilcanning, although mine did and it always bothered me. Monel is pretty tough stuff though; about as good as it gets. I suppose there is always a question about the seams.

[Garret]

Monel is tough & you are correct about the seams.

I hope John posts back about what he does & discovers!

[johngsandusky]

I will, but not too soon. I am advised to wear a sling on my arm for three more weeks. Certainly won't be moving any water tanks. And it is probably a winter job, when the tanks will be empty.
I'm not worried about metal fatigue, the tanks are 44 years old and tight.
Thank you all for your advice.

[Figment]

Wrap them. Figment, I think it's just you and me on the Dynamet band wagon

I was counting the ice&water shield suggestion from post#2, same general idea.

You don't really NEED to totally wrap the tanks in the stuff. Just a few patches wherever you can easily reach will be helpful.

I dynamatted every carpet-hidden inch of the cab of my jeep. Yes it makes a remarkable difference, I was quite pleased and I thought it well worth the effort.
Then I rode in one that had been done in conveniently located and much more easily applied 1" strips which really only covered about 25% of the area I covered, and it really wasn't much different. He spent about a third as much money and about a quarter as much time as I did. Bastard.

[wingnut247]

Cut out a hole in the top of the tank for access and use a rubber bladder.

[Lew Barrett]

I was counting the ice&water shield suggestion from post#2, same general idea.

You don't really NEED to totally wrap the tanks in the stuff. Just a few patches wherever you can easily reach will be helpful.

I dynamatted every carpet-hidden inch of the cab of my jeep. Yes it makes a remarkable difference, I was quite pleased and I thought it well worth the effort.
Then I rode in one that had been done in conveniently located and much more easily applied 1" strips which really only covered about 25% of the area I covered, and it really wasn't much different. He spent about a third as much money and about a quarter as much time as I did. Bastard.

Yours is quieter, guaranteed. Maybe not enough to pay you for the difference, but everything else equal, this is one place where more is usually better. Take comfort in that.

But John could start by judiciously placing material and looking for the undeniable damping effects that this stuff brings to bear.

A lot of design, certainly not excluding industrial noise control, shoots for a median or acceptable level of difference that is cost justifiable. Wife grousing justifies a bit of extra cost, using the "two bag/belt and suspendors" philosophy!

[meuritt]

I plan to install this into my fiberglass built into the hull water tank. I have very large access hatch so no issue for me

http://www.agrimaxx.com/products/baffle-ball-75.cfm