Rubberizit to fix holding tank????

K

KenCamp

.
Nov 20, 2014
4
C&C 51 Annapolis
Hi all,

I was wondering if anyone had used a product called "Rubberizit" to seal a holding tank. I have an epoxy holding tank that was built directly into the boat with a hard-foam surround. The tank has never been used, but when I looked through the inspection port recently, I noticed that there was what appears to be a crack running along the seam at the bottom of the tank, otherwise the tank appears to be in good order.

What I wanted to know is if there is a reasonable way of sealing this crack (possibly caused by the boat flexing or, it may be, that the seam at the bottom wasn't properly sealed in the first place. I noticed this product called "Rubberizit" on the internet. It is a water-based rubbery substance and the manufacturers claim it can seal holding tanks and is flexible enough so that some stress will not crack it. I was proposing to line the entire tank with it, with particular emphasis on the seam at the bottom. The manufacturers recommend that some form of cloth is imbedded in the rubberiest where there is a crack that needs to be filled.

Anyone ever try this? And does it make sense that this stuff might work?
 
justsomeguy

justsomeguy

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Feb 20, 2011
8,060
Island Packet 35 Tucson, AZ/San Carlos, MX
I've not used such a product, but would be concerned about compatibility.

If your inspection port is large enough to get your hand into the tank, what about a good scrubbing with a cleaner/solvent, then a thinned epoxy repair?

And have you confirmed that the crack is, in fact, a "leaker"?
 
Anonymous 121765

Anonymous 121765

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Jan 6, 2010
1,520
Justsomeguy's advice is sound.

I don't know what an epoxy tank is but, I would bet you mean polyethylene tank.

If so, epoxy is a good fix. If in a corner, I would look for a molded corner piece for added integrity. Like a 1" x 1" 90° angle of a plastic material. this would add extra support & corner integrity to your fix, PVC would do. Follow the manuf.'s application instructions if you can work from the tank interior.

You can also make this work on the tank exterior if you can cover a greater distance than the crack itself. I made a tank fix like yours before & it has been working for twenty years now, good luck.

CR
 
centerline

centerline

.
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
I wouldnt use that product for any repair that was not an emergency repair, and especially not for a permanent repair.

you will be much better off cutting a large circle out of the top of the tank so you can get inside to work on the problem.... (very easy to cover the access hole)

probable a bit of grinding and a couple coats of coat of cloth and epoxy, and maybe a stiffener...

or there is a product called "por 51" which ive used numerous times for tank repairs, on my own equipment and for customers. it remains flexible, but if there is flexing going on, the structure of the tank will continue to flex, and in time ANYTHING will fatigue, weaken and then fail.

if you can get to the inside of the tank, its easy to paint on... either in place of the epoxy and cloth, or over the top of it after the repair....

but you really need to make sure the tank and hull is not flexing and causing the problem, because you maybe able to mask the symptom for awhile, but if the underlying problem is still there, the symptoms WILL return...
 
centerline

centerline

.
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
captnron said:
Justsomeguy's advice is sound.

I don't know what an epoxy tank is but, I would bet you mean polyethylene tank.

If so, epoxy is a good fix. If in a corner, I would look for a molded corner piece for added integrity. Like a 1" x 1" 90° angle of a plastic material. this would add extra support & corner integrity to your fix, PVC would do. Follow the manuf.'s application instructions if you can work from the tank interior.

You can also make this work on the tank exterior if you can cover a greater distance than the crack itself. I made a tank fix like yours before & it has been working for twenty years now, good luck.

CR
Click to expand
Capt,
i think, from post, the OP has custom built a tank integrated into the hull of his boat, out of epoxy. epoxy would NOT be my first choice for a tank, due to the problems associated with repairing over the top of epoxy... but it is what it is now:D....
 
kito

kito

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Sep 13, 2012
2,011
1979 Hunter Cherubini 30 Clemmons
Is this the same stuff the moron on TV calls "Flex Steel" ?
 
Anonymous 121765

Anonymous 121765

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Jan 6, 2010
1,520
Centerline,

You may be correct, but he didn't say it was a molded fiberglass type tank.
I always mention that the more info given upfront, the better the answer to their questions.

I've seen alot of problems with these type tanks, if attached to a flexing hull or interior construction, yea it will eventually crack & guess where? At the corners.

Ronco has a large list of tank designs that will fit most boats. If not having access, maybe he should just cut off the top & add a bladder tank.

Oh well, thanks pal.

CR
 
centerline

centerline

.
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
captnron said:
If not having access, maybe he should just cut off the top & add a bladder tank.
CR
Click to expand
a perfectly viable option.... add some spray foam down near the crack so the bladder stays free of it, and let the hull flex all it wants to....
 
K

KenCamp

.
Nov 20, 2014
4
C&C 51 Annapolis
Thanks for all the advice

Thank you everyone for all the advice (with the possible exception of the thought that if it was done right in the first place, it would have been better. Da!). But all your thoughts were very helpful.

Yes, the tank was built in the boat. Stiff foam was first put in place around where the tank was to be built and then the foam was epoxied to form the tank. The bottom of the tank has a single seam as one side of the tank follows the side of the boat and the other side is vertical to match the interior furnishings of the boat (in this case the back of a shower compartment.

The idea that seemed to me to make the most sense was cutting away the top of the tank and putting in a bladder. Does anyone know if you can get a custom bladder for an odd space? Or can one build a bladder? If so, is there any site that might show how one goes about building one?

KenCamp
 
thinwater

thinwater

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Mar 26, 2011
3,718
Corsair F-24 MK I Deale, MD
I would re-build the tank. If you can cut enough space for a bladder, you can fair and lay in new glass. Well built, FRP holding tanks will last as long as the boat. It is all about the details, and too often builders skimp, but what is a boat, other than a tank in the water? If it has truly not been used, FRP is among the simplest materials to repair. But you have to read-up and follow the rules.

In my mind, a bladder is going to be prone to permeation before solid FRP. I'd rather do the job right, once.

On the other hand, this install may be SO BAD the person who built it was afraid to use it. You description sounded improbably poor. Pictures help.
 
centerline

centerline

.
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
the good thing about bladder tanks is that they dont need to fit the space exactly... if it is a bit big, it will have a few wrinkles in it when the space if full, and if its a bit small, just add some foam sheets in beside it so it doesnt roll around in the space when the boat rolls...

you didnt say how big the space is, but if you open the space up, you can try to repair the tank from the inside (which is commonly more successful than repairing from the outside), and would be cheaper than a bladder tank, and if that doesnt work, you still have the bladder option.... so its kind of a gamble with your dollars.
 
Anonymous 121765

Anonymous 121765

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Jan 6, 2010
1,520
Ken,

If going the bladder tank way, simple take the dimensions & sketch it up. calculate the numbers for volume. If unsure, call a friend that knows how. Once you have the volume, look for a bladder size close to this. I would be careful not to have it larger than the orig. tank outline, smaller would be better. You don't want it to hang over the sides. Make sure of no burrs or anything that can cut into the bladder tank.

There are some solvents that you can just wipe on to smoothen them. Ask for what to use. Remember to ventilate the area so as not to breath in the fumes while working in interior spaces.

You will be surprised how easy a project this can be. Go methodically thru with patience pal.

Here's a link with all the info you need for calculating volume. You just need to be close.

http://www.basic-mathematics.com/volume-formulas.html

CR
 
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