Hello folks, I was a new member a year ago, put my tools down for a bit but I’m getting back to work now :). I started a boat for my lady and I in mid- January of 2009, was making great progress and hit a significant speed bump in my life in March… getting things back on course now and need to build tanks for my project.
I’ve been getting my fingers sticky for over 30 years, repair, fabrication, industrial FRP maintenance and construction at a pulp mill ( tanks, piping, and corrosion barriers), built a few boats to 40 feet, etc… what’s got me concerned is the ethanol problems with our gasoline today.
I like Derakene’s 411-45 and I’m planning to use that, and-less somebody has a better suggestion.
Although I’m pretty set on the decision to use fiberglass reinforced tanks, I’m open to discussion if people have ideas as to whether or not it should be done.
Thank you, Gerald
FRP tanks are what most recreational boats down here in the lower 48 use. (Malibu’s, Mastercraft, Baja, Sea Ray, Four Winns, etc…) In my owners manual there is a warning about ethanol fuel. I’ll have to go dig it out and read it again so I get it right, but it says the ethanol will deteriorate your tank by pulling chemicals from the side walls. I don’t remember it saying NOT to use it.( I think it’s more of a warning cause in most areas theres no way around the ethanol) But like I said I’ll have to dig it out tonight and re-read it.
Thank you Rotorage,
Quite a few boat manufacturers used to use fiberglass fuel tanks but they have fallen out of favor in recent years due to the ethanol being added to fuel. The ethanol will dissolve and suspend most resins and those dissolved resins are distractive to the engines. I know some gas tanks are still being built ( lots of diesel tanks, even ortho resins get along with diesel ) but I don’t know with what resins.
I also know that some of the go fast boats are building fiberglass fuel tanks that are common to the structure ( built in place) and although the Coast Guard and the American yacht Council except that for diesel tanks, they frown on it for gasoline tanks… for this project I am considering building the tanks in place.
If I ever sell this boat I will warn the future owners that their water tanks have had fuel in them and they should not drink water from them. 
Actually, if you find an appropriate resin, please let me know! Ive been looking for 6 months now to find a resin for my fuel tank. The problem is, Im looking for one that will withstand the ethanol AND high heat as the tank will be over the motorcycle engine. Ive seen 100c on the temp indicator so I imagine the heat seen on the underside of the tank will be that high or higher. I think Ive resolved myself to get a resin that will take the heat and then put in a tank liner that will take the ethanol.
Ray
I think I’ve found my resin ( pending a better suggestion) but I don’t think it would work for your application, the chemical resistance of the resin is reduced as the temperature increases. If I remember correctly the Derakene’s 411-45 will tolerate 50% ethanol at 150°F. I think it’s thermal distortion limit is around 240°, have you considered a heat shield may be a thin piece of stainless steel and a quarter inch air gap?
Gerald
I dont have a link but there is a product specifically made as a heat shield for the underside of motorcycle tanks. It is self-adhesive foam with a thin reflective aluminum barrier on it.
I had forgotten about that product. That may help deflect some of the heat and prevent softening or distortion of the resin. Ill have to look into the Derakane again. I had sent some emails a while ago and if I remember right they either dont deal with individuals or only sell in bulk, neither of which help me!