Plywood Fuel Tanks

Discussion in 'Fiberglass and Composite Boat Building' started by DogCavalry, Jan 26, 2022.

  1. DogCavalry
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    DogCavalry Soy Soylent Green: I can't believe it's not people

    This used to be an excellent way to make a tank: a strong plywood box, glassed and coated liberally and carefully with the resin of your choice. Then the corrupt and incompetent b-tards in Washington mandated corn ethanol in gasoline, simultaneously wrecking boats, damaging the environment, and robbing honest working fellows of more tax dollars.

    However, there are now a number of resins formulated to be impervious to ethanol. Thanks @BlueBell , this never occurred to me.

    And my fuel tank guy takes about a year to complete a new project. It turns out that people who are really good at things are quite busy. On the other hand, you can hire a useless knob immediately. No waiting. I'm not waiting a year for tanks.

    So I mean to make my own tanks. On the even less typical side, I read that lexan is fine with gasoline. How about a lexan lid? Talk about your inspection port. No need for a sender either.
     
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  2. fallguy
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    fallguy Senior Member

    Make sure the Canadian coasties don't/can't ever hang you on that idea first.

    It'd suck to make a tank that you can pressure test to 3psi and get boarded and be told you have a problem. I'm still worried about the stupid charcoal canisters.
     
  3. DogCavalry
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    DogCavalry Soy Soylent Green: I can't believe it's not people

    Thankfully we don't have that yet.
     
  4. Rumars
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    Rumars Senior Member

    You can always try your hand at HDPE welding.
     
  5. DogCavalry
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    DogCavalry Soy Soylent Green: I can't believe it's not people

    Is that something I might realistically do? I know I can do a proper job of ply boxes, then glass them. But I know nothing of HDPE welding.
     
  6. fallguy
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    fallguy Senior Member

    What epoxy?
     
  7. DogCavalry
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    DogCavalry Soy Soylent Green: I can't believe it's not people

  8. Barry
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    Barry Senior Member

    Construction Standards for Small Vessels (2010) - TP 1332 E https://tc.canada.ca/en/marine-transportation/marine-safety/construction-standards-small-vessels-2010-tp-1332-e#wb113

    This is Canada's Construction Requirements for Small Vessels. The pertinent fuel tank construction section is 7.3. The section says that the construction methods etc must meet ABYC H24? I would doubt that an insurance surveyor would pass a wood fuel tank. Not sure if it would pass the non combustible requirement.

    Also note that inspection plates are not allowed on gasoline fuel tanks.
     
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  9. Rumars
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    Rumars Senior Member

    It's doable if you dedicate some time for practice and some money for the welder. Of course you could just as well ask around to see who does plastic welding and have them do it, maybe you don't have to wait a year. Are good metal welders so thin on the ground over there? Since you are contemplating making it out of glassed ply you don't need crazy shaping techniques, cut and bend the metal yourself and find someone to weld it.
    If I wanted a metal tank without welding I would have absolutely no problems using angle iron, screws, rivets, gaskets, solder, JB Weld, etc. For example glavanized steel with flat locked seams soldered over, Al sheet riveted on angle profile sealed either with a gasket (solid or from a tube) or with epoxy paste (plenty made for the exact purpose of sealing a gas tank).
     
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  10. fallguy
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    fallguy Senior Member

    what does the last sentence mean? Can you expound?
     
  11. Barry
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    Barry Senior Member

    7.3.1.5 A GASOLINE fuel tank shall have no openings in the bottom, sides, or ends.

    7.3.1.6 Clean-out plates shall not be installed in GASOLINE fuel tanks; clean-out plates may be installed in the top or sides of DIESEL fuel tanks.
     
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  12. DogCavalry
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    DogCavalry Soy Soylent Green: I can't believe it's not people

    Gotcha. No cleanouts.

    I find in the literature, requirements for cores in frp tanks above 20 gallons. They give, as examples, balsa and pvc. I don't think plywood has inferior fire resistance to balsa.

    But if a welded HDPE tank can be as good as a spun cast tank, that's promising.
     
    Last edited: Jan 27, 2022
  13. DogCavalry
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    DogCavalry Soy Soylent Green: I can't believe it's not people

    @Rumars , it's the combination of the hand skills, technical knowledge of regulation, and time to do the work that's thin on the ground. If I design every last detail I can get it fabricated by a competent shop.
     
  14. Rumars
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    Rumars Senior Member

    A gas tank is just an airtight box. Unless you need compound curves (wich involve an english wheel) all a fabricator does is cut and fold some metal. Any halfway competent metal roof installer or auto body mechanic can make you one, and if they can't weld themselves to the required standard they usually have a buddy who can. Fittings are all available online. You just make a pattern out of cardboard and ducktape and give it to them.

    If correctly done a welded HDPE tank is as good as any, entire speedboats are made this way. Quickest way to find someone is to ask the local plastics distributors, they know what their customers do.

    Google "riveted gas tank" you will find plenty of examples and tutorials from the homemade aircraft crowd (they also make fiberglass tanks, usually with vinylester). Materials of choice are under 1mm Al sheets (can be bent by hand), solid and blind sealed rivets and a polysulfide goo. The same techniques can be used with stainless steel, monel and bronze sheet if you don't like Al.
     

  15. DogCavalry
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    DogCavalry Soy Soylent Green: I can't believe it's not people

    Thanks @Rumars . Every conversation with you is educational.
     
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