Fuel Tanks, Batteries etc in same compartment

Discussion in 'Boat Design' started by Mat-C, Dec 5, 2012.

  1. jonr
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    jonr Senior Member

    And use fume detectors.
  2. viking north
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    viking north VINLAND

    The regulations have spoken and answered the OP's question. End of Story
    Last edited: Dec 5, 2012
  3. Mat-C
    Joined: May 2007
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    Mat-C Senior Member

    Thanks guys - logic tells me it's not a good idea, but when I look at all the production boats (of which I've owned a couple myself) that have the fuel tank located located in the same compartment as the engine, battery(s), bilge pumps, etc, etc, I wondered what the difference is...
    Hence the question regarding regs - if Searay etc do it, then why not me....

    The reason for moving the tank fwd is to shift some weight. The boat is a bit light in the bow. I realise it's not ideal as the trim will be affected by fuel load, but it will be better than the current situation.
  4. watchkeeper

    watchkeeper Previous Member

    Still waiting for you to post evidence of cars having fuel tanks mounted with the batteries as per your assertion that this would then disprove my assertion that:
    1. Its an extremely risky business to combine fuel storage with any electrical equipment in a boat
    2. Its illegal
    3. Fuel produces vapours that settle forming a highly comustible mixture within confines of a bilge
    4. Bilge gas alarm will probably activate just as the deck is blown twenty feet up and the bow off if there is a current leak
    5. Electric thrusters have electric motors and control switching than can spark igniting vapours

    ...but I guess I'll be waiting a long time because there are no cars with fuel tanks and batteries combined, another of your off the cuff assumptions
  5. watchkeeper

    watchkeeper Previous Member

    The posts have got away from the main reason for a bow tank not being ideal being effects on trim and bow attitude.
    If you need to get bow heavy using ballast you could use a sea water (or extra fresh water) ballast tank that would remain constant or pumped out to suit conditions.

    Regarding gasoline tanks I have very little experience with gasonline inboard engine powered boats. If it helps the few aluminium OB driven boats I have built used EU EC rules for fuel tanks (buyers were EU) and EC rules state that tanks must be a tank within a tank and separated from all other equipment.
  6. jonr
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    jonr Senior Member

    Vapor alarms are capable of detecting fuel/air ratios well below the combustible limit.
  7. philSweet
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    philSweet Senior Member

    but, but, um, wait a second;)

    There might just be a method to Frosty's madness-

    the flashpoint of gasoline is -44 deg F
    the temp at which bad things can happen is about 20 degrees warmer as a general rule of thumb. I would expect a spark triggered BANG to be possible at temps above -24 deg F. So if there is a chance your fuel and air temp might get warmer than this, please take precautions.

    Now considering the above, Why does it matter where you put it?

    It's not a rhetorical question. The rules are there for a reason, but I don't think we've figured out what they are yet. The ability to service both the fuel system and the electrical device safely comes to mind. Incidental vapors, spills, and wet rags when changing out a fuel line or fill hose or filter need to be accommodated.

    I wouldn't install anything other than explosionproof rated equipment in a compartment with a gasoline tank, and a sample of boat sized thrusters I looked at on line all provided a warning. See page two of here- http://great-water.com/store/PDF/manuals/Thrusters.pdf

    And I'd be real worried if there were interchangeable explosion proof and non explosion proof models. I'd want one that can't be swapped to a substandard motor later. I'd be strongly disinclined to install a battery or any other object that requires routine electrical work down there. Windlass solenoid, battery switch, fuses - no thanks. The rules aren't sufficient to keep you safe. They assume that the materials, procedures and workmanship exist to compliment them.
  8. tunnels

    tunnels Previous Member

  9. Frosty

    Frosty Previous Member

    The mini had battery in the trunk where the fuel tank and pump is.

    Rolls Royce had too Rover 3liter and 3,5 and many cars with full engine compartments.

    Fuel injection engines have the fuel pump' inside' the fuel tank, as does Harley motorcycle and many many others.

    Ever heard of inline fuel pumps. A electric 12 v pump that has fuel inside it.

    And your worried about it in the same compartment. Time has left you behind has'nt it?

    The silliest ever was when I worked at an airfield years ago and we had a couple of old Lancasters from the war. You could not smoke within 200yds I think it was. We had DC3 too.

    When the Lanc was started it spit out flames as long as 1 foot licking the engine cowl and wing.

    The RR Merlin was carburettor and with a rich mix would fire enormous flames. When all fired it was all you could do to stop yourself from running away.

    Then you had to go 200yds away to have a cigarette!!!!!!
  10. watchkeeper

    watchkeeper Previous Member

    Frosty - As is so often the case someone posts a question about best practise or alternatives to solving a problem.
    Posters many having suitable and or professional experience respond with suggestions that you immediately challange.
    The above posters including me reply to your posts with sound reasons for our suggestions, recomendations whatever.
    You then go on to reject and disagree, thats fine but there is a pattern - you post destructive rather than constructive posts
    Perhaps you should consider why
  11. rxcomposite
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    rxcomposite Senior Member

    As far as I can remember ABS requires that batteries needs to be enclosed in a sealed box with a vent leading outside the boat. There is no distinction even if the batteries are sealed type.

    This is to protect the batteries from itself. Non sealed batteries emits hydrogen gas and can be ignited by a spark due to a loose connection or during servicing.
  12. tunnels

    tunnels Previous Member

    Im my own small boat electrics are one side if the boat and fuel the other and they only meet when they get to the outboard motor at the back !! plus the under floor area is totally vented at each end plus it all gets washed out after each trip when the inside floor is rinced with a hose and fresh water , !!:D:p:p
  13. watchkeeper

    watchkeeper Previous Member

    All the above cars are past, no modern builder makes the same mistake, todays industry standards don't allow old practices because they were proven dangerous.

    A pump submerged in liquid does not present a hazard as does an external electric pump exposed to fumes/vapours.

    My father flew a Lancaster bomber on 1000 bomber raids with RNZAF, he also flew Wellingtons on convoy duty and Bristol Blenheims in South Pacific
  14. Frosty

    Frosty Previous Member

    You are correct I always question everything I don't give up until I have answers and I thoroughly accept the theories given to me . As an engineer and have engineer friends I dont find this unusual.

    You read things from a book and accept them without question.

    Thats your perrogative. Your simple acceptance of everything put before you spreads to this forum and your misunderstanding of engineering practice means that any questions or queries not on your note book you find disruptive .

    I thought you might have said something about fuel pumps in fuel tanks. Did that disrupt your plans.

  15. FMS
    Joined: Jul 2011
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    FMS Senior Member

    Consider the potential risks involved and the result of a failure.
    In 2011 the USCG reported 135 accidents involving 154 vessels
    5 deaths
    99 injuries
    $3,344,516 damages
    from Explosion (fuel)
    Source http://www.uscgboating.org/statistics/accident_statistics.aspx

    Most recreational boats have bilge drains that connect compartments. Gasoline fume or fuel leaks would settle to the lowest point, the stern and engine compartment where the bilge blower and also the engine, starter, and battery are. This relies on the bilge blower to suck out any fumes from the low point.
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