Epoxy Diesel Tanks

[Paul G.]

Anyone know if you can effectively make make epoxy/ply diesel tanks using run of the mill epoxy boatbuilding resins?

Seems like a nice way to make a small easily fitted tank.

[capt jake]

Devlin has made them in the past this way, though he no longer does. I am not sure if they are coated on the inside with another product though. I will try to remember to ask.

[RonW]

Eventually the epoxy turns into goo that start plugging up the injectors.....Another poor use of the miracle goodge.....

[Gary E]

Make your tank first out of cardboard and duct tape to get the shape the way you want it. Then take that to a sheetmetal shop and have it made from black iron or aluminum. Make it ONCE and it will last forever.

Dont forget to plan very carefully for the Fill. Vent, Fuel Out, Fuel Return and Drain connections.
You may as well privide a cleanout access so you can get your arm in there.

[John B]

I'm trying to remember where I saw a polyethelene?/ P.E.T food grade drum being used as fuel tanks recently. I'll let you know when it dawns on me.

[Uncle Duke]

Gougeon Brothers "bible" talks about this a little:
"We have made fuel tanks using the same basic tank construction techniques. Up to this point they have been very successful. However, we do not feel that we have enough experience with them yet to recommend them unconditionally. West System resin is resistant to gasoline and fuel oil, so this does not seem to pose a problem."
Then they talk for a little, reassuringly, about fire and heat issues (the summary being that this isn't a big problem, since wood insulates better than steel or iron, besides which your hoses will melt before any tank fails...). Then they say:
"We repeat that we have had limited experience with wood fuel tanks. No serious testing programs have been entered into, nor are there any existing safety standards. We do, however, feel that there is good potential for wood tanks."
Two notes:
1) This is from the 4th edition - there is a newer edition which may have better information
2) They strongly recommend making the tanks removable, instead of "built-in".

[raymacke]

No experience on diesel tanks but if using "auto gas" epoxy tanks can a problem because of the growing use of ethonal. Check out this link - http://www.boatus.com/seaworthy/fueltest.asp

[Northernguy59]

why would someone take this chance.................. of failure?

[kc8pql]

why would someone take this chance.................. of failure?

I agree. I have ply/epoxy water tanks and so far they're just fine, but I did what Gary E suggests and had my fuel tanks fabed at a sheetmetal shop. A leaky water tank wouldn't be nearly as much trouble as a bilge full of diesel.:eek:

[Dave Fleming]

Fuel Tanks are not something I would experiment with.


As Gary E, mentioned, get thee to a good ALUMINUM fab shop and have them make the tanks to your templates.

Probably 6000 series AL.

Good sumps, cleanouts, TIG welded outlet/inlet stubs.
But above all a good CG approved pressure test!

[JimConlin]

The fifth edition of the Gougeon book is no more encouraging. Sounds like they had a 'Come to Jesus' moment with their lawyers and promised never to do another tank.
What Dave said.

[plyboat]

The tanks we built at Devlin were drop in, I don't think you are supposed to build integral fuel tanks. After 10 years there have been no problems. We used a "special" epoxy (can't remember what it was) and each coat was post cured to about 140 degrees. I don't think they were cost effective to build so we went to having tanks made for us.
---Joel---
www.boatbuilder.org

[paladin]

epoxy ain't good, no matter whose, aluminum fuel tanks, black iron and stainless are now recommended to be sealed internally with a neoprene like substance.....I'll see if I can find the stuff tomorrow....

[mmd]

ABS and DNV regulations state that no gasoline tanks are to be integral with the hull structure. Integral diesel tanks constructed of fibre-reinforced plastics are not to be fitted in way of nor employ sandwich construction. A plywood tank sheathed in 'glass and epoxy is a form of sandwich construction.

Use metal, and have it pressure tested using approved procedures prior to installation. You'll sleep better for it.

[plyboat]

MMD
If you don't glass it is it considered sandwich construction? If you have a diesel tank that is a drop-in and not integral then do the sandwich and fiber reinforced rules apply.
---Joel---

[mmd]

My understanding of the regs (and this is certainly not absolute - regulatory interpretations are known to vary considerably, even among those agencies charged with enforcing them) is that to build a fuel tank in Fibre-Reinforced Plastic (FRP), the tank structure must be a solid laminate of resin and reinforcing fibres, no foam core, plywood core, honeycomb core, etc. This does not discriminate between integral or drop-in tanks. The reasoning behind this was explained to me as if there is a leak in a solid FRP tank, you can detect the leak; if the inner FRP shell leaks in a cored structure, it is undetectable until the structural integrity of the core is compromised which may result in catastrophic failure.

[BFR]

One of the boats I worked on at ydl used intergral composite fuel tanks... glass foam glass the only problem suffered was when the tanks were preasured tested the baffles didn't allow for the escape of air so the tanks had some seperation along seems.
Most boat's i've done seem to have stainless or ally tanks but there are arguements for and against on both of those aswell.
The major problem same as black water and gray water tanks is getting all internal seams glassed or atleast coved so there are no leaks.... diesel will always find a leak no matter how small.
personally I would go with plastic tanks... roto moulded or welded ones.... try someone like hercules tanks (http://www.herculestanks.co.nz).
just design it so you can get it in and out without having to rip apart the whole boat.

[capt jake]

With the new configuration of fuels, I would be hesitant. In some bio-diesel mixes, they do add a bit of ethanol. Ethanol is what will eat the epoxy.

The Devlin tanks were not sealed with anything but epoxy. He hasn't had any problems with the 'yet'. They are 10 years old. He said he would not make them again as it is too risky. ;)

[Stu Fyfe]

Had a voltage leak from a frayed wire that disolved the aluminum tank of Redwing. Rowed out to the boat at the Hyannis Yacht Club and started to smell diesel a good distance away. When I arrived I had a bilge full of 15 gallons of fuel. Used a manual bilge pump to get it into some jerry cans. Not a pleasant experience. Took years to get the smell out of the bilge, not to mention the rainbow skirt around the hull in calm weather. Try using rubber pads under it where it rests on the supports just in case this ever happens.

[Bo Curtis]

I had a similar, less dramatic experience last summer... smell of diesel in the boat, traced to a weepy aluminum tank. No frayed wire, just (I believe) galvanic action involving water in the tank, and some copper/brass fittings in electrical contact. The tank is 20 years old, looks great on the outside, but honeycombed inside.

Read Nigel Calder. He recommends polyethylene tanks, if you can find an off-the-shelf one that fits and does the job. Tempo makes a good variety of shapes. That's the way I'm going, but I admit if you're the least bit worried about a fire that might melt the tank, well, it might be enough to sway you to metal. But think twice about aluminum... it's overrated. Stainless is actually not ideal either. Black iron is a good choice, if you keep it filled on the inside and painted on the outside.

I thought about wood/epoxy. I think the new edition Gougeon book admits defeat on the subject, and that's enough for me.

[capt jake]

I have hear that the CG is not in favor of polyethylene tanks and that they may move towards not allowing them. Polyethylene does allow permiation of the vapors through it. This is more evident with gasoline (and that is their major concern).

[sdowney717]

Instead of epoxy use
POLYESTER RESIN

I have coated gasoline tanks on the inside with polyester and never had any trouble.
I once repaired steel saddle tanks by,
cutting off the rusted bottom
Cleaning the inside
Sanded off all the paint to shiny metal
Coating the inside and outside with polyester resin using a brush.

Then, draped 2 layers of heavy woven roving over the bottom to create a new bottom for the tank.
They have not had a problem for over 10 years, the gas has no effect on cured polyester resin, so I assume diesel would be even less of a problem.
The boat slammed thru the waves never had any trouble with leaking cracking separation etc...

Anyone else?