Testing fiberglass fuel tanks

Gypsy Soul

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Duffy 26
I'm currently converting a 26 Duffy from gas to diesel. The tanks that were in the boat seem to be good shape. Is there somehere I can send the tanks to have them inspected, tested, and cleaned out? Or should I just have new ones made? I want to complete the project right, but why spend the the money if the tanks are good?
 

hntrss

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31 Duffy
Fiberglass tanks usually hold up well. If concerened about ethanol damage, i would visually inspect and pressure test before you drill for return lines and cleanout. If it holds pressure you should be golden
 

Gypsy Soul

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Duffy 26
If there is ethanol damage will the inner lining be soft? Are there places I can send the tanks to have them certified.
 

phil

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fiberglass tanks

Hello all: I have read quite a bit about this issue in various places. Actually, ethanol driven decomposition of fiberglass resins in these tanks may not take the form of particles trappable by fuel filters. Instead (or in addition) ethanol may actually dissolve some portion of the resin and allow it to pass any filter (its in solution) and wind up in the cylinders and be combusted. From what I have read, in a short time, solubilized fiberglass resins can ruin an engine. Its not only a pressure test thats required here; this is only for tank integrity at the time of the test, but a very close visual inspection (at least) of the tank interior to assess possible damage to the resin. In addition, I would take a sample of the contents and have it analyzed for resin or its components. That way, this would confirm whether resin that has gone into solution (which would indicate degradation of the tank), or not. I dont know if this is done routinely, but if it can be done, sounds like cheap insurance to me.
 

Gypsy Soul

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My other thought is to just have two new aluminum tanks fabricated and coated. Any thoughts on aluminum tanks for diesel fuel. My thought is that they may sweat more causing moisture in the tank. Should I stick with fiberglass if possible?
 

tunaorlater

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What year was the boat built? Was there any issues with the tank while running the gasser?
 

captainlarry84

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KristenFormer Charter Captain
No tanks

With all the repowers that have been done in my area from gas to diesel the fiberglass tanks were never changed or had any problems. If those tanks have survived 10 years of gas then they are most likely A…OK. Once the diesel goes in any damage from ethanol will stop. I would leave the tanks as is. Aluminum tanks…..no tanks. I would not buy a boat with aluminum tanks. The max life of aluminum tanks is 20 years. I have seen to many boat in my area go through the invasive process of aluminum tank replacement after 10 years. If you do decide on aluminum, which I would not do 3/16 is the minimum gauge I would use along with a powder coat or cold tar protective coating.
 
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