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Author Topic:   Fiberglass Fuel Tank Repair
bt posted 04-19-2008 02:20 PM ET (US)   Profile for bt   Send Email to bt  
I recently bought an 1987 Montauk 17. It has a [fiberglass on-deck] fuel tank. It appears that there may be a hairline fracture as I am noticing fuel residue on deck after cleaning. It appears [the manufacturer of the fiberglass tank] is out of business as their phone is disconnected. Does anyone know if they are still in business? If not, I really like the tank and would like to have it repaired and re-glassed. Any advice?
jimh posted 04-20-2008 09:18 AM ET (US)     Profile for jimh  Send Email to jimh     
The widespread use of gasoline fuels which have been diluted with ethanol have made the use of fiberglass as a marine fuel tank material problematic.

Fiberglass fuel tanks are still made for use in aircraft, but in that application the rules of the Federal Aviation Administration (FAA) prohibit the use of gasoline fuels containing any ethanol.

Prior to the use of gasoline fuels diluted with ethanol, fiberglass fuel tanks were in widespread use in marine applications. However, since the introduction of ethanol-gasoline blended fuels, varying results have been obtained with fiberglass tanks, and even those which employ a laminate using specialty resins claimed to be resistant to ethanol have been reported to be failures.

According to a manufacturer of fiberglass fuel tanks for aviation applications with whom I recently spoke about this problem, his current recommendation for fiberglass fuel tanks is to use them as flower planters.

bt posted 04-20-2008 12:17 PM ET (US)     Profile for bt  Send Email to bt     
Thanks. Any recommendations for replacement of the fiberglass tank? I know that newer models of the Montauk come with 2 smaller plastic tanks under the rps.
jojoscoot2000 posted 04-21-2008 01:53 PM ET (US)     Profile for jojoscoot2000  Send Email to jojoscoot2000     
From what I have read here on this site, the Moller 26gallon is a great plastic tank for the Montauk. I have an 86' Montauk with a Pate fiberglass tank and will be replacing it with the Moller. They are available through West Marine.
bt posted 04-22-2008 09:52 PM ET (US)     Profile for bt  Send Email to bt     
Great. Thanks. I just ordered the 26 gallon Moeller tank from West.
Bob of Glenburnie posted 04-28-2008 01:51 PM ET (US)     Profile for Bob of Glenburnie  Send Email to Bob of Glenburnie     
whatever happened to the great KBS coatings everyone was talking about. do they work or don't they? as I am one of those with a pate tank and would appreciate all clear and concise advice. all replys welcomed
SteadFast posted 04-30-2008 04:16 PM ET (US)     Profile for SteadFast  Send Email to SteadFast     
I did use the coating on my 27 gal and followed the instructions as best I could. After the first season of use I drained the tank again and the coating was pulling loose from the 'glas in many places so I junked the tank. I figured on getting a new one but now they are out of business.
davidmassi posted 04-30-2008 07:31 PM ET (US)     Profile for davidmassi    
I just did a metal tank with the KBS coating (don't have gas in it yet). KBS states "Not for Fiberglass Tanks"
Bob of Glenburnie posted 05-07-2008 11:17 PM ET (US)     Profile for Bob of Glenburnie  Send Email to Bob of Glenburnie     
last fall I spoke with the KBS rep and he had no problem using the product on fiberglass. are we talking the same product?
KBS Guy posted 05-18-2008 09:46 AM ET (US)     Profile for KBS Guy  Send Email to KBS Guy     
Just to clear things up here, KBS Gold Standard Tank Sealer MAY INDEED be used for fiberglass tanks. The same prep products are necessary (AquaKlean & RustBlast) however there is just a slight difference in procedure when using the RustBlast. You can view the instructions here:

And by the way...we are not "out of business" as stated above. Quite the contrary, we are growing stronger every day and are now in many countries around the world. Offer superior products at more affordable pricing. Thanks

HAPPYJIM posted 05-18-2008 05:16 PM ET (US)     Profile for HAPPYJIM  Send Email to HAPPYJIM Gold-Standard-Tank-Sealer-Information-Instructions_ep_39-1.html

I have a Pate tank (given to me by a good member here) that I am going to try it out on. No dealers near me so I will order it on line. Thanks for posting KBS Guy.

frb91864 posted 05-18-2008 09:24 PM ET (US)     Profile for frb91864  Send Email to frb91864     
I may have been the original pioneer of the KBS sealer for the ethanol problem. When I first looked in to a coating about three years ago the choices were Kreem, POR 15 and KBS. After a little over two years mine has failed over the winter. Last year I completely drained the tank for winter storage. This fall I left about 1/2 of a gallon of gas in over the winter. When i finally uncover the boat last weekend and checked out the tank the coating has bubbled up, pulled loose and ruptured.
Maybe others may have better luck but I think there was someone else on CW that had similar short term success.


KBS Guy posted 05-19-2008 08:01 PM ET (US)     Profile for KBS Guy  Send Email to KBS Guy     
Based on your stated time frame, what you used could not have been KBS. Possibly POR, but regardless, when it comes to prepping and sealing the inside of a tank, you MUST USE the prep products and use them correctly. Also, if a tank already has substantial damage from ethanol blended gasoline, the cleaning and drying process is critical. Fiberglass can be rather porous and will hold moisture and/or fuel residue. That's why you need to use the AquaKlean degreaser correctly and possibly multiple times to remove all the oily residue from the old fuel. Rinse completely and allow to dry thoroughly.
Proceed with the RustBlast which, although there is no rust in a fiberglass tank, adjusts the ph to a more acidic level. Just a quick slosh with the RustBlast, pour it out, then rinse thoroughly again with clear water.
Now again let the tank dry thoroughly, as you do not want to trap moisture under the sealer. Use a blow dryer or shop-vac on blower to keep the air moving inside the tank to help the drying process. We place the tank out in the sun, plug all inlets, and rubber band a piece of plastic wrap tightly over the largest outlet. If after a couple of hours, you see moisture forming under that plastic, you still have some drying to do.
When you're sure you're dry, stir up the sealer and pour it in the tank. Slosh it around being rather methodical as you want to be sure to coat the entire interior surface. Any exposed fiberglass can still be affected by the alcohol. Once you're sure you've coated everything, prop the tank up and allow any excess sealer to drain out. You do not want the sealer to puddle inside.
Now, allow the sealer to cure at least 3-4 days before adding fuel again. Heat does not cure the sealer any faster, and therefore placing the tank out in the hot sun will not help, and may in fact hamper the cure strength. Just let the open tank cure slowly.

This is not a one night project. Take your time and you'll get great, long lasting results.

These directions and more can be found at:

bt posted 05-19-2008 09:49 PM ET (US)     Profile for bt  Send Email to bt     
I have not installed the new plastic Moeller tank yet because I did not like the fit under the rps. I am definitely trying the KBS product on my Pate tank. Thanks KBS guy.
jimh posted 05-20-2008 08:40 AM ET (US)     Profile for jimh  Send Email to jimh     
With regard to the effect of gasoline blended with ethanol on marine fuel tanks made with fiberglass, there is recent news of a class-action lawsuit being pursued in California. Boaters with fiberglass fuel tanks are seeking a remedy for damage to their fuel tanks caused by gasoline blended with ethanol from the gasoline refiners.
frb91864 posted 05-20-2008 01:27 PM ET (US)     Profile for frb91864  Send Email to frb91864     
I did in fact use the KBS sealer with all three components. It was March or April 2006. I still have the empty bottle of "Rust Blast" in my shed.
I called you guys before I ordered to check about it's compatability with fiberglass.
I think mine failed because it did not get it dry enough.
I did not go through the thorough drying process that you have described.
I am not crying "sour grapes" but just passing on my experience.
I bought a plastic Moeller but have not installed yet.
Maybe this weekend.


L H G posted 05-20-2008 03:05 PM ET (US)     Profile for L H G    
When any Montauk owner here can just buy a new Moeller 26 gallon tank for about $150, why bother trying to save the old Pate tanks? If you value your engine investment, time and life on the water (at $5.00/gallon), the risk is not worth it.
CJM posted 06-02-2008 12:31 PM ET (US)     Profile for CJM  Send Email to CJM     
I just returned a Moeller 26/gal tank that I bought for my Montauk. I could not access the filler with it tucked under my seat. I have just started looking into fixes for my 24/gal fiberglass tank that is seeping from the botton seam. I love my tank for size and also the quick visual I can make for fuel quanity. I have bought a couple of 6/gal portabel tanks to get on the water and will continue to explore my options.
oilyamerican posted 06-28-2008 09:39 AM ET (US)     Profile for oilyamerican  Send Email to oilyamerican     
Hi Guys,
While not into boats,I am into motorcycles , and we do have something in common :FIBERGLASS FUEL TANKS
I found this link looking for answers to the same problem you guys have: failed fuel tank lining products.
I want to list one more product that claims to remedy ethanol fuel attacking fiberglass: Caswell Tank Sealer
I used it in a brand new,never had gas in it,fiberglass fuel tank imported from the UK(expensive).The liner has started to fail after about 2 1/2 weeks of use with 10% ethanol high octane fuel.
The lining didn't dissolve,it just started to blister and peel off.The only thing I deviated from on the instructions was that since the tank was new , I did not shake a bunch of nails ,screws,etc. around in it as there was no dirt etc. to knock loose.Maybe that caused the failure , I don't know; but others are having similar failures.I'm not categorically saying the product won't work, I'm just saying it didn't work for me;and I thought with a brand new tank , I would have a pretty good chance of success.Caveat Emptor!
PHILRAJOTTE posted 07-08-2008 07:40 AM ET (US)     Profile for PHILRAJOTTE  Send Email to PHILRAJOTTE     
HAPPYJIM posted 07-08-2008 08:59 AM ET (US)     Profile for HAPPYJIM  Send Email to HAPPYJIM     

I see in your profile that you build custom tanks. What would you charge for the same size Pate tank?

Gene in NC posted 06-26-2009 12:48 PM ET (US)     Profile for Gene in NC  Send Email to Gene in NC     
Read the KBS instructions VERY carefully.


IMPORTANT: It is also very critical to methodically coat the entire fiberglass tank completely & thoroughly with the Sealer. If any part of the fiberglass surface should accidentally be left exposed or unsealed, however, these unprotected areas will be very susceptible to deterioration by ... alcohol blended fuels and ... it is therefore highly recommended that these fuels not be used in fiberglass tanks even after sealing... After coating the tank, remember to drain well to avoid pooling and puddles."

No way in the hot place that you can be sure not to use fuel with ethanol, and probability of ethanol in will only increase over time.

REcd Moeller 26 today. Don't like anything about it ... except ethanol tolerance.

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