Water tank leak fix 2004 35 CB

[Deedee]

When we purchased our 2004 35 CB earlier this year we knew she had a forward water tank leak. Upon inspection we discovered that the 35 CB has two water tanks which are connected with a short hose. The leak was at the aft end of the forward tank where there is a soft “V” at a weld point. When you fill your water tanks it fills the aft tank which then flows (via the hose) into the forward tank. So my husband removed the hose and plugged it up so we could use the aft tank and let the forward tank dry up for the fix.

I took on the job and figured I could use the Water JB Weld outside the tank but that didn’t work. I think I learned too late the importance of prepping the area. I Googled how to fix water tank leaks and was directed to a product called Microseal. Google it and you’ll see why I decided to use it. However I had to get into the tank and there’s no inspection plate. So we cut into the top of the tank and installed a plate which would give me great access to the leak.

I found where the leak was and also lots of muddy stuff but was pleased I didn’t have a serious science project going on in the tank. There were also numerous areas I referred to as barnacles where a deposit had started to eat into the metal tank. I cleaned up and let the tank dry out for a few days. After a few days of drying I started getting chunks of stuff where I guess the muddy areas (that I couldn’t reach) started drying out. Also the barnacles started drying up too and they turned into chunky pieces that chipped off when I brushed the tank. This concerned me as it was leaving a pitted area.

Microseal is mainly for pinhole leaks and the product is brushed (or sprayed) on, seeks its lowest point, fills in and dries quickly fixing the leak. My leak area was bigger than a pinhole as the deposits had eaten away some of the metal where it was welded. But the Microseal guy said just apply the product several times making sure it’s dried between applications and it should work. So that’s what I did drying it out with a drop light and fan after each application. I also sprayed as much area as I could where the barnacles were so as to make sure I filled in the pitted areas. I’m happy to report my leak is fixed!

Microseal has some strong stuff in it so I took caution and used a fan and mask for fumes. I also found it easier to paint on the Microseal where my leak was but I did spray the rest of the tank. Feel free to contact me if you have any questions.

[RobS]

Way to go right at it. Why builders ever use aluminum for potable water tanks is really boggling - preferably plastic, or even 300 series stainless, should be used. Maybe in this case it was to get the custom "V" shape to fit the that specific area with maximum capacity so plastic wasn't able to be custom fitted and the stainless was too pricey. Chlorine in potable water is just too corrosive for aluminum. That's a good fix for now but if she were mine at some point I'd scrap the aluminum tanks and fit in new plastic tanks as big as possible for that space.

[Carl]

It almost looks like electrolysis reaction going on in the tank. I had an aluminum gas tank in my previous boat that had that v in the bottom. It would sit in any bilge water that accumulated, and actually acted as a damn. It became pitted just like that, but on the outside and began to leak. Not good. I took it out and had a new one made from heavier gauge, and had them square off the bottom of the V, so the water could flow under it. Only lost about 6 gallons, no big deal. Before I put the new tank in, I put 3 coats of barrier coat on the underside of the tank. Only had the boat for 3 yr after replacement, but all was good. Just wanted to share this in case you have to replace later.

[Nancy]

Nice repair. Thanks for posting.

[Deedee]

We did talk about taking the tank out and replacing with plastic but this seemed to work for now. Thanks for the feedback.

[DougSea]

Nicely done Deedee! What I would have given for top of tank access when I went at it!!

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