Water tank slosh

[Sailing Partner]

WE have a Ta Chiao 41. It has a large freash water SS tank under the mid bunk. The problem is at anchor it sloshes, bangs and flexes the metal sides. I was thinking of foaming the tank in to prevent flexing. Any ideas or proven solutions?

[onestepcsy37]

the proper solution, is, of course, baffles built into the tank. but since yours is welded stainless i see little chance of that happening....

[Dockhead]

It's not right without baffles. So you have a pretty big problem. Either live with a very annoying problem, or undertake a very serious reconstruction of that tank. Sorry.

[Lagoon4us]

Foaming will deaden the echo/hollow sound as would glueing on a sound attenuating rubber, if no baffles then you gonna always have a surfs up noise, if you don't do something you may get some cracking.....
Baffles are important.
Cheers

[Nemo55]

Isnt there some kind of injectable porous sterile foam you could put in the tank and then fill it??

[Lagoon4us]

Originally Posted by Nemo55

Isnt there some kind of injectable porous sterile foam you could put in the tank and then fill it??

Dont think there is anything potable like you mention, closest thing i can think of is a fuel cell on a race car.......lol

Damping the outside by foam or Barium style matting should reduce a lot of it,,,,,,,

Cheers Frank

[Tank Doctor]

Have you heard of baffle balls, they are plastic ball with cut outs, in the UK they are used in big transportable water tanks to reduce sloosh and surge, in a smaller tank, you'll have to check the size of the inspection hatch to make sure you can fit them in. You may have to cut a larger inspection hatch if that's an option for you. Off the shelf baffle balls take about 5% capacity from the tank. In the UK you can get them from Enduramaxx, not sure if they have an agent in the US but maybe worth a look.

Other that that, I would go with squarting PU foam round the outside of the tank as other have surgested.

Good Luck

[DeepFrz]

If you foam a stainless tank in place you are condemning it to an early death.

[Blue Stocking]

How big is the tank, and the access.
Maybe assemble an egg-crate type of baffle, similar to a 6-pack type of carton.

[Sailing Partner]

Originally Posted by DeepFrz

If you foam a stainless tank in place you are condemning it to an early death.

I don't understand how foaming would decrease the tank life?? I would think reducing the flexing would reduce metal fatique and increase tank life . . . please explain.

[foolishsailor]

Originally Posted by Sailing Partner

I don't understand how foaming would decrease the tank life?? I would think reducing the flexing would reduce metal fatique and increase tank life . . . please explain.

You cant reduce flexing by foaming. The tank will slowly compress the foam over time and it would be back to flexing again very shortly. Depriving stainless of oxygen in a wet environment creates opportunities for crevice corrosion, especially at welds. If you foam it you create that situation.

The baffle balls are your only solution besides cutting it open and placing baffles in it.

You can also either weld stainless bracing in the mid points on the long walls of the tank or similarly cut wood bracing to span the gap between the walls of the tank and it's compartment. This should stop a majority of the flexing and then you can take the option of possibly using soundproofing foam in the compartment the tank is in to alleviate noise...

...having a non baffled tank is an issue, is the boat a home built or custom boat? Or the tank an aftermarket install?

[Cheechako]

If it gets wet the foam is a bad idea. If not, I dont see any problem....?

[David M]

The only perfect solution is to replace it. Otherwise, the less than perfect solution is foam or noise insulation.

If the noise was making me crazy I would replace it with a polyethylene tank.

[roverhi]

Foaming in a metal tank is a bad idea because of corrosion. Water will, not might, get in between the metal and foam. Once there, it creates a corrosion pocket. The metal on the foamed in Aluminum tanks on a boat I just sold was almost totally gone where the foam was. The boat was 25 years old but the tanks had been leaking for way more than 10 years according to what the PO told me.

[Cheechako]

If it's like the tank under the pullman berth in my HC38. It's no where near water. In fact it was well above the cabin sole level. Also, if shaped longer in the fore and aft direction, a normal baffle athwartships may provide little relief! One solution: keep it full! I like the baffle balls idea....