water tank leak

[QP Chuck]

I have the 1982 model H37C. The water tank under the starboard settee has sprung a leak, bad enough that I lose at least 10 gallons overnight. If I were in the States in a marina and just day sailing I wouldn't mind so much, but I am in Mexico, about 300 miles southeast of Acapulco and ready to head back north.

The leak appears to be in a welded seam on the bottom of the tank, the side nearest the hull. The tank is aluminum, by the way.

If any of you great folks have encountered this problem and know of a solution that involves very limited local expertise and equipment, please let me know. In fact, I welcome any suggestions!

 

[Ed Schenck]

Leaking H37C water tank.

That is really bad luck, especially when you are where you need the water. My own H37C has a slow leak that I have not isolated yet. I have known of many boats having this problem, aluminum tanks do not last.

I have known three owners that have tackled this problem and all three fixes are major. Hardest of course is cutting out the old tank and fitting in a new poly tank. This requires cutting out the entire top of the settee. That project was documented here on HOW a few years ago. I may have kept those pictures somewhere.

Next would be cutting out the top of the tank and patching from the inside. This also requires cutting out at least part of the settee for room to cut a hole in the tank . I think you will find the insides so corroded that it would be better to just take it out.

Then there was the bladder fix. Cut a hole in the tank closest to the corner where the hose connects(aft and inboard). This will require cutting out some settee top I think. Put a large bladder tank in there and connect the starboard tank hose to the bladder. You will have to open up that corner of the old tank to gain access.

Bladders make pretty good water tanks. If you put in one of say 50 gallon capacity it will expand to fit the old tank and you will have all the original capacity.

I look forward to other ideas. I need to do something but will probably entirely replace with a Ronco poly tank. Right now I am coastal cruising so having just one tank is just a minor annoyance.
An update, I found the old post:
http://hunter.sailboatowners.com/index.php?option=com_mtree&task=viewlink&link_id=6545&Itemid=247

 

[Peggie Hall HeadMistress]

Quick fix if you have access to the leak

Slap some JB Weld or MarineTex on it, on the outside of the tank...following directions for use, of course. JB Weld is the first choice...it'll hold for a long time. MarineTex will hold at least long enough to get you back to the US where you can get a replacement tank.

 

[Manny]

I've had pretty good luck "painting" thickened West System epoxy in my aluminum water tank. I had to apply it from the inside of the tank since I don't have access to most of the exterior. I have a 4" access plate on mine which let me get to most of the tank. Just to be on the safe side I don't use the water in the tank for drinking, only for clean up.

Manny

 

[Ed Schenck]

Peggy would be right. . .

if you could get to those seams. Of course you cannot because the tanks were tabbed in and the inner-liner installed over them. I still think you will fiind the tank so corroded that any patch is strictly temporary. Marine-Tex will even work from the inside if you want to try that. But you have to cut an opening both through the settee and the tank if the seam is where I think it is.

As for a bladder you might be able to cut a hole in the end of the tank working through that locker, the one in front of the galley sink. That would save any fiberglass work until you were ready for the "big fix".

 

[QP Chuck]

Thanks to all of you! I think I'll try Peggie's suggestion first since I do have fairly good access to that seam. A previous owner cut holes in the cabin sole and made storage compartments. I can reach most of the seam (including the area where the leak seems to be) from underneath. I've used JB Weld for other stuff before and found it to be amazing stuff. I'll let you all know how it turns out in a few days.

Re the bladder suggestion: I gather there are no baffles inside the tank. -Chuck-

 

[Ed Schenck]

More on H37C water tanks.

Sorry Chuck, the way I read your original post I thought the seam was on the back. And I wondered how you knew that. The inside seam will be much easier to work on.

Here are a couple of links that you might find useful:
http://forums.hunter.sailboatowners.com/showthread.php?t=66606&#post299286
http://forums.hunter.sailboatowners.com/showthread.php?p=294003
http://www.geocities.com/rainbow_chaser.geo/upgrades.html

You are correct, I had forgotten about the baffles. I do know about the one in the fuel tank. For these kinds of problems I always go to Rainbow Chaser first because Gene tackled so many of the H37C issues. By using Search here on HOW you will also find tons of info. I am going to ask Phil how to find the photos that were originally part of the first two links above.

Good luck and keep us posted.

 

[Jim Legere]

Aluminum Tank repair

I like the idea of epoxy coating the inside of the tanks. Mine aren't leaking yet, but I plan to epoxy the inside as a proactive response. The only challenge is access. From what I can see of other owner's work, there are 2 baffles in each water tank, so I think 3 x 6" access hatches (the good ones that screw down with o-ring seals) will need to be fitted to each tank. This will involve cutting an access hole in the settee between the existing two sqare access holes. Then the challenge is to get all the crud out and get the tanks really dry. I think 3 or 4 coats of West epoxy or similar should do it. At this point there is essentially an epoxy "bladder" in the tank. Almost all epoxy resin is considered "food grade" once cured, so using the water as potable should be no problem. I'll probably do the holding tank the same way, with access through the forward side of the tank.

 

[Ed Schenck]

H37C tank epoxy.

Coating the inside of the tank is an appealing fix. But I think it would be really difficult through three six inch openings. I did two eight inch cleanouts on my fuel tank(only one baffle) and it was hard working through such a small hole. I bought a sheet of heavy aluminum and made my own covers. I would do the same thing for the water tanks and make them at least ten inches.

How do you mix the epoxy so that it is thick enough and adheres to the sides? Does everyone agree that this is a permanent fix and not just a band-aid?

 

[Richard Shelby]

I can report that my epoxy fix for one tank lasted about 2 years before the leak came back. The bladder fix on the port side is still just fine. I have the new Plastimo for the stbd tank ready to install. The problem is getting a thick enough uniform layer of epoxy to coat the inside.

 

[Manny]

Ed, I would say it's really only temporary fix to coat the inside of the tank with epoxy - unless the tank is still in decent shape. If that is the case it could probably extend the life of the tank considerably. I painted mine last season and had to do it again this season. I used west system mixed with 406 Colloidal Silica to thicken it up. Disposable brushes were used to apply the epoxy. Took less than an hour in both cases to clean and prep the tank and apply the epoxy.
Replacing my water tank is a project that I am trying to postpone. The amount of work involved would make it the largest repair project on the boat to date.

Manny

 

[Ed Schenck]

H37C water tank replacement.

Besides the expense and work involved there is the loss of capacity issue. Ronco, for example, makes many sizes and shapes. But there is nothing like our H37C tanks which are fit to the hull. So any poly tank is going to cost you several gallons. That is one point in favor of a bladder.

And yes, you can have a custom poly tank welded up. A very expensive proposition. If I could afford that I would just trade for a Swan. Just kidding, why would I want less boat.

I have yet to locate my leak, not even sure which tank. The boat sits with empty tanks right now. Next trip down I will dry the bilge and fill one tank and see what happens.

 

[Johnb]

A friend of mine put red food color in one tank and green in the other. You could be a real rebel and put the red in the starboard tank.

John Brecher

 

[Ed Schenck]

Won't work John.

I actually am color blind. The Navy almost mustered me out because of it. Now that I think of it why did I fight to stay in? Well I really do enjoy Veterans Day.

 

[QP Chuck]

Thanks again, everyone. A few days ago I said I would try Peggie's suggestion of applying JB Weld from the outside but it turns out I don;t have as good access as I thought. So I cut a 6" diameter hole in the top of the tank above where the leak appeared to be. At night I shined a light on the bottom of the tank while my co-captain looked into the hole. She saw about a half-dozen pinholes and that there is a baffle in the tank. So I cut another hole in the aft half. Of course I had to cut a hole in the settee base in order to reach the tank top.

We repeated the light from the bottom experiment last night and saw a couple more pinholes. Incidentally, almost all these holes are in the bottom along the weld seam nearest the hull, but a couple are 5 or 6 inches up on the side near centerline.

There is relatively little mineral deposit inside, perhaps because we have put almost nothing but watermaker water into that tank for the last nine years that the boat has been in Mexico.

Since a bladder is out of the question because of the baffle (even if I could get one here) I have decided to go with coating the inside with epoxy. The only stuff available locally is two-part epoxy primer, but I will try to find a source for actual epoxy resin.

I'll keep you all informed as things proceed. -Chuck-

 

[Ed Schenck]

Cutting inspection holes.

Chuck, what are you using to cut the inspection holes in the aluminum tank?

I have been using a RotoZip drill for fiberglass with good results. But when I cut the cleanout ports in my fuel tank I guess I did not have the right tool. I ended up drilling a circle of holes and then cutting and filing.

Sounds like you have a handle on things. I look forward to the next report. I do NOT look forward to tackling the same project on Ladylove.

 

[Manny]

If I may make a suggestion, if you can get a small cordless drill in the access holes you created, chuck a wire wheel or similar attachment on the drill and use that to prep the surface of the water tank. It will help knock down any deposits or corrosion plus "clean" the tank. Use a wet vac to get any of the dust or deposits. Then carefully wipe down the surface with acetone. After that apply the epoxy.

Manny

 

[Jim Legere]

A very relevant thread

I think this thread will be very relevant to all of us with older Hunters fitted with aluminum (or aluminium, if you're British!) tanks. Some thoughts:

Aluminum doesn't 'rust' like steel because it continuously forms an oxide layer that actually protects the pure metal underneath. Anodizing makes the oxide layer more durable. However, this same oxide layer can compromise the bond with paint, epoxy, etc. so wire brushing followed by immediate coating is your best bet. There are effective primers (i.e. zinc chromate) but most are VERY TOXIC - not something you want in a water tank!

Aluminum is one of the least noble in the galvanic scale, meaning it sacriifices its self to 'plate' other more noble metals, such as steel and brass - which is why it is used in sacrificial anodes for your prop shaft. Make sure that any screws, rivets etc used for access covers and other fittings attached to the tanks are high quality stainless steel (e.g. 316) and coat them with Teflon paste or at least grease. Also avoid any electrical connection - ground wires, level transmitter wiring, etc. - that would provide an electrical path between the tank and the rest of the boat.

I think if you get a reasonable primary bond between the aluminum & the epoxy and are able to build up several coats (layers), the repair should last some years. I hope so, 'cause thats what I'm planning to do! Good luck with the repairs and please keep us informed (pictures if possible?) of how it all goes.

Jim Legere
SV CALYPSO
Halifax, Nova Scotia

 

[QP Chuck]

To cut the holes I drew a circle by the simple expedient of tracing the outline of an inverted bowl! Then I drilled a hole large enough that the metal-cutting blade of my jigsaw could be inserted. For the first hole I drilled smaller holes about half way around the perimeter and cut with the jigsaw between them. I soon found that I didn't really need to drill the smaller holes, so I finished the first cut without further drilling. For the second hole I drilled only the one large hole (3/8") and cut around the circumference with the jigsaw without much difficulty. I did break a couple of saw blades when I hurried too much.

The resulting holes are far from things of beauty, but I am having a local machine shop fabricate a cover plate system of stainless steel that will be 1/4" smaller in diameter than the holes. That way the ugly edges won't show! Incidentally, I filed the cut edges to reduce the probability of cutting my arm when I reach inside. After I install the cover system this won't be a problem.

For the covers I will have a "sandwich". The bottom of the sandwich will be two semicircular pieces of ss drilled to accept three 1/4"X3/4" ss hex screws in each piece. The hex screws will be tack welded to the plate. Between these plates and the tank I will put a donut shaped piece of rubber sheet. Holes will be drilled in the tank top for the hex screws to fit through, then another rubber donut and finally a solid ss circular cover plate with, of course, holes for the hex screws. Flat washers, lock washers and nuts will complete the installation. Since there will be no direct contact between the tank and the stainless there should be no galvanic problem.

I have been in touch with the Gougeon Brothers company. They are the folks that developed and manufacture the West System epoxy products. They recommend the 105 resin with either 205 or 206 hardener with a low proportion of hardener. They also recommend wire brushing or using coarse (60 grit) sandpaper to get to bare metal. They advise NOT to use solvents of any kind, even alcohol or vinegar, just plain tap water for rinsing.

I will try to get good photos of this process and post them. Maybe I can get my wife to nag me!

Chuck

 

[Ed Schenck]

Why the complicated cleanout covers?

Why so much work in covering the cleanouts Chuck? If you use aluminum for covers there is no corrosion issue. On my fuel tank covers(I cannot find those pictures) I drilled and tapped a 1/4" hole every one or two inches. Then screwed in the bolts from underneath. I make gaskets and added Permatex. Put the top plate on and put on washers and nuts to bolt it down, nothing to it. If you are real paranoid then use lock nuts.