Leaking Water Tank

[alanperry]

I just filled my water tanks about a week ago and came back to the boat yeaterday to find about 2 1/2 gallons in my "forward bilge" near the water tank. On the Cheoy Lee the water tanks are under the dinette seats molded into the boat with access only through the top (under the settee cushions)

Note: this was an unusually long period for me to be away I am usually there everyday. It had not rained and I can see no other explanation for the water.

It appears that I will have to open up some areas so I can access the tank better.

So what kind of remedies are there for sealing this tank that are compatible with drinking water? (That is short of installing those bladders which I really do not want to do.) Is there a spray product on the market? Or a roll on sealer?

Alan Perry
S/V Oceanus
Seattle WA

[CSY Man]

Is yer water tank fiberglass or metal...?

I had a thread going on my water tank last year. (Fiberglass)
I coated the inside of my tank with West System epoxy.

Not because it was leaking, but rather because the gel-coat was breaking down giving the water a foul taste and odor.

Epoxy is not officially a "food grade" material, but I talked to the chief chemist at a water lab here in town and he said it is perfectly safe to use as it is inert and the US Navy coats their water tanks with the stuff.

So far , so good for my tank.

[alanperry]

It is fiberglass as best I can tell. How did you apply the epoxy? How thick did you make it? There are so many inaccesable ares in this tank I will have to do it with a very small roller I think.

Thanks for the tip.

Alan

[CSY Man]

I have 3 access holes on the top of my tank.
They are big enough to get my arm in there with a foam brush.

First I let the tank dry for several weeks with a fan running just over the access holes. Then I cleaned with rags and acetone or denatured alcohol, whatever.

Tried to sand some of the surfaces, then clean again, but gave up on sanding all the surfaces.

Had to tape the foam brushes to sticks so as to reach all around in the tank.
Also used mirrors and lights and stuff to see if I got all the surfaces as I was coating in the blind...Could not stick my head in there..(Big head )

If ya don't have the inspection ports or holes, ya can always cut some, then make a plate and secure with a rubber gasket and sheet metal screws.

To find the actual leak, put a strong light in the tank and look on the bottom or side outside of the tank (at night) to see if any light is seeping out.....

[CSY Man]

Link to my water tank problem thread...

http://www.cruisersforum.com/forums/...ead.php?t=2215

[Alan Wheeler]

OK, so just before we dive into a tank, lets eliminate one possible. Had you filled the tank before you left the boat?? If yes, is it possible the water has come from a filler or breater hose joint or hose itself and NOT the tank???
If you can somehow inspect the water level of the tank, it will be obviouse that the possible leak is now sitting at or close to the water level. Identify the cause of the leak and then we could perhaps advise on a more accurate cure.

[Sunspot Baby]

Before seeking solutions, find the problem.

Find the leak.
Then worry about fixing it.

George

[alanperry]

Thanks for the replies and help.

Alan; Good points. The water fill hoses are all tight and not leaking. I had just re tightened them and ispected them (they are new). the vent hoses empty into sealed containers in a locker, no water there. No leaks at any of the pipes exiting the tank. Besides these pipes are no where near where the water is collecting and with not a very good way to get there.

The problem in finding the leak point is that the tank is molded into the boat and under the settee seats of the dinette. However the tank does not comprise the "outer vertical wall" that makes the kickboard of the settee seat. But it is quite close behind it. So finding the leak will entail either some telltale sign from inside the tank (very difficult) or cutting access holes in the settee seat vertical wall at likely places.

So while it may seem that finding the leak would be the logical first step. It actually might be easier and more effective to just effect a repair to the whole tank. The tank is also partitioned and while there are two access holes, quite large ones, still the far end of the tank is barely reachable with an extended arm much less being able to see in there. (these are big tanks they are essentially 7' 5'' long and about 32" wide and varying in depth from about 2.5 feet to approx 18") the 18" dimension is of course the hardest to reach...and they are curved!)

So I can spend hours cutting up the settee in a very likely futile attempt to find a crack that is leaking 2.5 gals/week. or I can spend hours fixing the inside of the tank... I think I need suggestions on fixes that are compatible with drinking water.

The epoxy seems a very good candidate...any naysayers out there?

[Richhh]

Alan -
The following recommendation will solve two problems at the same time for your leaking fiberglass tank.
I would recommend an epoxy product called NSP-120. http://www.epoxyproducts.com/nsp120.html.

This is a roll-on or spray-on epoxy coating system that will 1. seal pin hole leaks, 2. put a food grade (NSF* / FDA* approved for contact with potable water - most polyesters and epoxies are NOT suitable for potable water).

Ive used this material several times for internal coating of large aluminum and fiberglass tanks with success. Obviously if there are structural anomalies in the tank that need attention (loose or absent baffles) do these first, then overcoat with the above *low leachable* epoxy. I use WEST short knap foam rollers .... the stuff 'flows' so you have to apply it on a horizontal surface; very careful mixing ratios are needed of the components. You will need large access holes ... when needed I simply cut them in on the top of the tank into each baffle compartment, make a new plate/cover for the 'hole' with mounting studs and close up with silicone caulk.
* NSF National Sanitation Foundation
* FDA US Food and Drug Administration

hope this helps.