plywood fuel tank

Discussion in 'Boat Design' started by whitepointer23, Feb 1, 2014.

  1. whitepointer23

    whitepointer23 Previous Member

    just wondering if it is possible to make a petrol tank out of ply and epoxy. i have heard of diesel tanks made this way.
     
  2. rasorinc
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    rasorinc Senior Member

  3. Mr Efficiency
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    Mr Efficiency Senior Member

    Not sure that epoxy and petrol are compatible, isothalic Polyester is though.
     
  4. tom28571
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    tom28571 Senior Member

    Plywood/resin/glass makes a good diesel fuel tank. Iso resin is best. Ethanol has just about removed homebuilt gasoline tanks from consideration because of deterioration of most available resins, including isothalic polyester. The risk of serious damage to a motor from ingesting the products of the deterioration is also very real.
     
  5. Ike
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    Ike Senior Member

    Making your own gasoline tank may seem to be a good way to save a few bucks, or fit a tank into an unusual space, but its a sure recipe for disaster. Handling gasoline is no place to scrimp. You can get roto-molded polyethylene tanks that are safe, come in all kinds of shapes and sizes, and meet all safety and environmental standards. They are also not affected by ethanol. If you don't like the idea of a plastic tank - some people don't, but they are just as safe as metal and will last far longer - you can also get metal tanks in any shape and size you want.
     
  6. tom28571
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    tom28571 Senior Member

    All shapes and sizes? Nope. In fact, trying to get good volume efficiency in an existing space is very problematic. The only rotomolded plastic tanks available to the individual are made by Moeller and sizes and shapes are limited. Inca has dozens of plastic tanks in their catalog but they are only available in a large quantity order and not individually. Moeller tanks are not vapor proof and do tend to smell. I hear that Moeller is using a new material that is more impermeable but have not had experience with those. No rotomolded tanks have baffles to limit surface effects either.

    Home made fuel tanks are not beyond the abilities of the careful builder if they follow good practices and hundreds have been built without more problems than commercial models. I agree that plastic tanks can be very good but they are not without some negatives.

    Building your own fuel tank is not abut saving money but getting adequate fuel in the available space. Designing a boat has enough compromises with out having to add available tank sizes to the equation.
     
  7. Ike
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    Ike Senior Member

    Older roto-molded tanks did have those problems, but since 2011 they all have to meet new environmental regulations (not just in the USA either they a CE certified) The permeability rate has been lowered from 300 gram/24 hr to 15 grams/24 hour. To do this they have had to change the formulation of the material. It is far less permeable and smelly.

    Yes moeller is about the only one that consumers can buy direct. A few years back they bought Tempo and so you can't get a Tempo tank unless you happen to find one in someone's left over inventory I have a 28 gallon moeller in my boat, but then I don't have the shape problem. If I leave the cover on the boat it does tend to have a faint odor of gas but mine was made before the new regs and has the higher permeability rate. But if the boat is left open there is no smell at all.

    I have visited hundreds of boat factories (it was part of my job) and about half the US manufacturers use roto-molded tanks with no significant problems. I can count the number of recalls (another part of my job) on one hand. Metal tanks were unfortunately often recalled. And we have all seen the reports on fiberglass tanks disintegrating.

    Yes, shape of the space is a problem and no they are not baffled. I think the largest roto molded tank I have seen were 110 US gals. I checked the Moeller site and the largest was 58 US gals.

    No I do not work for Moeller LOL
     
  8. Mr Efficiency
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    Mr Efficiency Senior Member

    Is ethanol content mandated in US gasoline ? That is not (yet) the case in Australia, but that may change. I have had no trouble with iso polyester tanks I have made, that were "odd" shapes, but never used fuel with ethanol or methanol content.
     
  9. groper
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    groper Senior Member

    The most chemically resistant resin available, especially to ethanol and the other ingredients in gasoline , is a novolac vinylester resin. I studied this for quite some time before choosing it to make my own integral tanks, using foam core not plywood tho.

    I would completely seal the ply in epoxy first, with a layer of glass included, then go over the entire thing with more glass but using the novolac vinylester. This should last many years trouble free. Once complete, don't forget to pressure test it and make sure it's leak free.
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    Foam core would be a better choice than ply, for sure.
     
  11. tom28571
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    tom28571 Senior Member

    Ike, you confirm what I said about plastic tanks. I am a fan of the smaller ones but not the really big ones that do not have baffles. I have one of he earlier ones although bought in 2011 and felt forced to remove my home made fiberglass/Isothalic resin tank after ethanol was introduced. Did not have a problem yet but have seen deterioration due to ethanol and did not want that. The smell from my tank is certainly objectionable if the boat is closed and stored inside. Leaving the boat open and tolerating the critters that can get in makes it tolerable.

    If the sheath and resin is proper for the fuel (diesel), I see no difference in using plywood or proper foam for a homebuilt tank. After all, if the plywood could give a problem, then the resin must be at fault.

    The tank volume remains the greatest negative to a stock plastic tank. If that is not an issue, the newer Moeller tanks are probably the best solution. Just make sure the tank is made from the newer low perm plastic formulation.

    Ethanol is boondoggle in many ways from crop subsidies to higher food and other commodity costs in addition to the obvious physical problems with older machines. Politics stink more than the fuel tanks.
     
  12. rasorinc
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    rasorinc Senior Member

    Here is Moellers complete offering for fuel tanks upto over 100 gallons and no smell as they corrected the mix 2 years ago. http://www.moellermarine.com/oem/fuel_tanks/fuel-tanks/ Includes tech drawings. Moeller makes their own valves and shutoffs also. USCC approved. Tanks up to 230 gallons.
     
  13. Westfield 11
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    Westfield 11 Senior Member

    Do the new Moeller tanks still have to be pre-filled with fuel to let them expand before installation? If so, does not this imply that their new barrier coating is less than effective.....?

    I cannot imagine being able to leave a boat in a marina or storage yard not only unlocked, but with windows or doors open for ventilation, nor can I see myself smelling fuel all the time either.... What a mess.
     
  14. rasorinc
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    rasorinc Senior Member

    Nothing on their website about prefilling and nothing when I called them. you do have to allow 2 more inches (2") to the depth to allow for the top fittings. vent hose and fill hose..
     

  15. whitepointer23

    whitepointer23 Previous Member

    thahks for the great replys. i think i will buy a plastic tank . sounds like the quickest and safest way.
     
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