Fuel Tank Sealant

[Hermit Scott]

My fuel tank was designed to sit with the bottom flat and touching the boat inside the whatever you call the hatch by the transom.(I guess I would call it the trunk)lol Water has made corrosion pits on the bottom of the tank.
I made an access panel and had it TIGGed to the top of my fuel tank. I think it is 15 gal. I cleaned it out with acetone and brake parts cleaner(I love that stuff). Spic n span. I also had a leak tigged that the PO had circled on the bottom.
I bought a gal. of fiberglass resin today. For future use. I have only fiberglassed one thing before so I am not experienced with it yet.
I want to coat the bottom of the tank on the outside, in some epoxy like coating or urethane. Will fiberglass resin do well in this application?
I took my rebuilt engine to my boat lat weekend. Sunday I am going to drop it into the compartment connect everything and try to start it. I need my fuel tank on Sunday. So whatever I do I want to be able to accomplish it Saturday and be ready to take it and install it and use it on Sunday.
If there is something better than fiberglass let me know, but I hear that some fuel tanks are made of fiberglass, is that the same type of resin?

 

[RichH]

For metal tanks, you can apply a thickened epoxy lining (w/ cloth if desired) to either the outside or inside. Several epoxy manufactuers (Interlux Commercial Div., etc.) offer 'lining epoxies' for this purpose (and for potable metallic water tanks)

 

[frank balcer]

Don't know about lining a tank with fiberglass but 15 years ago i had a center cockpit boat that developed a leak in the aluminum fuel tank where the tank rubbed against some rough fiberglass mat. I pulled the tank, acetone washed, sanded, acetone washed again and then glassed the leak. I ran into the current owner this summer and he said tank still is doing good. On the other hand he is getting ready to repower again.

 

[RAD]

West System

quick & easy and within an hour it'll be dry

 

[Hermit Scott]

tank FrankBalcer

Rad- unfortunately there is no west marine near where I live in San Antonio. I need to try to fix it today. Also they will be closed tomorrow when I arrive in the town where my boat is. Plus I have a gal of fiberglass waiting on me downstairs.

Frank - Could you give me some details about how you glassed the leak? Did you put a small patch (less than 3"), did you use any firberglass cloth weave, or did you just use the resin?
I think the same thing happened to my tank that happened to yours; where the tank rubber and water corroded simultaneously a hole developed.
I want to coat the whole bottom from the outside, then build stand-off-feet so the rubbing doesn't happen again. I do not want to put anything inside the tank. There are some questionable areas from water corrosion so I want to fix it right. There is alot so I can't have my welder cover the whole bottom, I would just cut another aluminium sheet and cover and weld to the bottom if fiberglassing wasn't an option.

 

[frank balcer]

Hermit

I used the unidirectional mat. i ground down the area and had a hole the size of a nickel. I cut 7 or 8 pieces each a little larger than the last. I mixed my resin, weted the area, then applied the layers one on top of the other. let it cure over night, sanded the rough edges and put it back in my boat. It still is holding gas to this day.

 

[Hermit Scott]

JB Weld

Thanks for the info on the fiberglass. I am not confident enough with fiberglass yet to bank on it working for me. I used a punch to dent the tank where any suspicious looking spots were and then skim coated it with JB Weld. I will be able to powder coat right over top of JB Weld if I decide to do that later.
I need to practice with the fiberglass before I use it on anything critical.