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Thread: Fuel tank installation

  1. #1
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    Default Fuel tank installation

    I'm planning the fuel tank layout and install for a 27' power boat. I decided upon a plastic tank because I found that one that nearly fits perfect, as opposed to paying someone to weld a stainless tank.

    My question: how much space should I leave around the tank so it can breath? Is 3/8" or 10 mm enough?

    Thanks for any feedback. I'm guessing that this issue must have been covered extensively before.

  2. #2
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    Default Re: Fuel tank installation

    Wooden hull or fibreglass?
    Hope for the best, but plan for the worst.

  3. #3
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    Gas or diesel? gas & diesel grounding is critically important with plastic tanks! (Especially gas tanks)
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...0-Ducker-Resto

  4. #4
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    Default Re: Fuel tank installation

    Gas. It would be sitting on the bilge stringers with 3/4" of air below, plenty on the ends, 3/8" on either side and room on top. If needed, I could add another 3/8"...

  5. #5
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    Default Re: Fuel tank installation

    Wooden... reinforced with Xynole.

  6. #6
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    Default Re: Fuel tank installation

    I was just looking at plastic tanks even though my boat is not built yet...
    Seems to me I remember seeing something like 3% for expansion...
    Maybe it was on the Moeller site - or on one of their spec sheets...

  7. #7
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    Default Re: Fuel tank installation

    Here's something I found:

    FEDERAL LAW
    183.572 - Grounding
    Each metallic component of the fuel fill system and fuel tank which is in contact with fuel must be statically grounded so that the resistance between the ground and each metallic component of the fuel fill system and fuel tank is less than 100 ohms.

    Fuel flowing from the dispensing nozzle into a fuel tank is a potential source of a static electric charge which could cause a spark between the dispensing nozzle and metal component of the fuel tank fill system. To prevent such a spark from occurring, metallic components of the fuel tank fill system and metallic fuel tanks must be grounded.
    Grounding or bonding may be accomplished by connecting the metallic components electrically by running a wire from one component to the next, and so forth to the boat’s ground. Grounding can usually be accomplished by a connection to the common bonding conductor or the engine negative terminal.
    If the fuel tank deck fill fitting is nonmetallic, and nonconductive hose is used as a fill pipe, there is no need for grounding the fill fitting. Chrome-plated plastic fill fittings are treated the same as metallic fittings.

    And (more detail): https://www.fs.fed.us/t-d/pubs/pdfpubs/pdf95512323.pdf
    "If it ain't broke, you're not trying." - Red Green

  8. #8
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    Default Re: Fuel tank installation

    That is a tighter fit than I would specify, but I'm sure that someone will come along in the next few posts to say differently.
    Hope for the best, but plan for the worst.

  9. #9
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    Default Re: Fuel tank installation

    ABYC wants 1/4-inch minimum all around for metallic tanks. Silent on the space surrounding for non-metallic tanks AFAIK.

    I do know that plastic gasoline tanks swell quite a bit when first put into use. Might want to ask the maker how much to expect and factor it into your installation and hold-down plans.

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  10. #10
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    Default Re: Fuel tank installation

    Quote Originally Posted by mmd View Post
    That is a tighter fit than I would specify, but I'm sure that someone will come along in the next few posts to say differently.

    I, for one, would be interested in hearing your reasons for a looser fit.

    Jeff

  11. #11
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    Default Re: Fuel tank installation

    Jeff, I am a firm believer that there is never too much ventilation in a wooden hull. Fuel tanks should be sized to the engine consumption and desired range, then fitted in the largest compartment available for tankage, not sized to fill the maximum volume of the allotted space. Space around a tank should be measured in full inches, not fractions of an inch. I realize that space is always at a premium in yachts, but frequent fill-ups are so much easier than repairing rot in hidden places.
    Hope for the best, but plan for the worst.

  12. #12
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    Default Re: Fuel tank installation

    Gas. It would sit on the bilge stringers with 3/4" of air underneath, bounty on the closures, 3/8" on either side and room on top.

  13. #13
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    Default Re: Fuel tank installation

    Quote Originally Posted by mmd View Post
    Jeff, I am a firm believer that there is never too much ventilation in a wooden hull. Fuel tanks should be sized to the engine consumption and desired range, then fitted in the largest compartment available for tankage, not sized to fill the maximum volume of the allotted space. Space around a tank should be measured in full inches, not fractions of an inch. I realize that space is always at a premium in yachts, but frequent fill-ups are so much easier than repairing rot in hidden places.

    Thank you. What you say here makes a lot of sense. Tank manufacturers and fire officials are likely not thinking about wood maintenance when stating clearance requirements.

    Jeff

  14. #14
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    Default Re: Fuel tank installation

    Quote Originally Posted by Garret View Post
    Here's something I found:

    FEDERAL LAW
    183.572 - Grounding
    Each metallic component of the fuel fill system and fuel tank which is in contact with fuel must be statically grounded so that the resistance between the ground and each metallic component of the fuel fill system and fuel tank is less than 100 ohms.
    Thread Hijack warning.

    Reading this with interest. Will soon be putting the galvanized steel tank back in my Sea Skiff. It is all metal obviously. Someone had a make shift ground on it, hose clamp around filler neck with a wire under it and I assume it ran to a ground. I never checked it and if I am honest I never thought about it needed to be grounds. Obviously I need to fix this proper while it is all apart.

    Simplest thing is probably to put a stud in the filler neck. It removable and I could just welding a stud on there without worrying about gas fumes.Then I can clamp a proper cable on the stud. Easy access if I need to clean it or check the connection too.

    Just want to make sure I reading this correctly. I need a line run back to the ground, as in the negative post on the battery, correct? I may just run it to the engine block but just want to make sure I understand this. Fresh water, dry stored boat so never dealt with bonding systems. Did not realize that was an issue. So glad I ran up on this.
    Jeff
    Kudzu Craft Skin boats
    SoF boat kits, supplies and plans

  15. #15
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    Default Re: Fuel tank installation

    Engine block or negative terminal strip would be fine.
    "If it ain't broke, you're not trying." - Red Green

  16. #16
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    Tanks often have s small tab welded on, maybe 1/2 wide and an inch long with a hole drilled through. Its welded on at one end and the hole is bored through the other. A ring terminal is crimped on the wire and a machine screw secures it to the tab.

    Is the boat inboard ( or any variant thereof) or out outboard? If inboard the block is fine, but there will be a ground buss somewhere. Secure other end there. If its an outboard do that too.

    Kevin


    Sent from my iPhone using Tapatalk Pro
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  17. #17
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    Default Re: Fuel tank installation

    Quote Originally Posted by Garret View Post
    Engine block or negative terminal strip would be fine.
    Perfect, thanks!

    It is a 20' inboard. There is no provision for and appears is never was grounded but it is an easy fix. Looking at the tank there is a jam nut where the filler neck screws into the tank. It is perfect place to drill and tap a small hole and attach a screw. No messing with the integrity of the tank and no risk of creating a leak point.
    Jeff
    Kudzu Craft Skin boats
    SoF boat kits, supplies and plans

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