explosion proofing the engine compartment?

Discussion in 'Boatbuilding' started by richard gray, Apr 16, 2014.

  1. richard gray
    Joined: Mar 2013
    Posts: 64
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: port coquitlam

    richard gray Junior Member

    I am trying to understand the need for explosion proof alternators and starters in gas engine compartment, when there are so many other sources of spark, wiring spark plugs electric pumps etc?is good ventilation and detectors an alternative?
     
  2. gonzo
    Joined: Aug 2002
    Posts: 15,494
    Likes: 1,037, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    No ventilation is not the same. It isn't legal either. Spark plugs only spark inside the cylinders, where they create an explosion. Plug wires don't spark, unless they are damaged which means they should've been changed. All switches have to be explosion proof too if they are in the engine compartment.
     
  3. richard gray
    Joined: Mar 2013
    Posts: 64
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: port coquitlam

    richard gray Junior Member

    explosion

    SO!!! thanks!!! will need explosion prove starter and alternator. not that coast guard checks?? so many 12 volt exposed cables ,it makes you wonder? will isolate any relays,switches and wiring as possible.loose fittings can spark,so risks at every turn. i could wrap thinks in woven glass cloth to dampen things smaller sparks,lower risk. ventilate and watch or vapours.
     
  4. Navygate

    Navygate Previous Member

    Richard,
    It is a preventative measure.
    It helps reduce the risk of an explosion.
    Redundancy is key in marine land.
    Eliminate fuel leaks, no fuel for an explosion.
    Eliminate sources of ignition, no explosions.
    Introduce sensor alarms to detect explosive vapours, reduced chance for an explosion.
    Ventilate well, reduced risk.
    The list goes on and on.
    Then, complacency becomes the villain...
    If it/you really want to blow-up, eventually it/you will.
    :)
     
  5. FMS
    Joined: Jul 2011
    Posts: 611
    Likes: 22, Points: 18, Legacy Rep: 227
    Location: united states

    FMS Senior Member

    It's important to have at least two levels of safety when a failure can kill or seriously injure you.

    At least once a year I inspect every connection in the engine compartment. I check that every connection is tight and not corroded. I check that there is no visible chafing of insulation. And finally that every switch works and there is nothing intermittent.

    I open the engine hatch at the start of each day to do a quick visual inspection and I always run the blower for a minute before starting and a few minutes after fueling.
     
  6. gonzo
    Joined: Aug 2002
    Posts: 15,494
    Likes: 1,037, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    You also need a flame arrestor in the carburetor, one of the most important items.
     
  7. CDK
    Joined: Aug 2007
    Posts: 3,324
    Likes: 148, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    There is no real need for explosion proof devices. In fact what is factory installed isn't truly explosion proof, it just looks that way to justify the steep price.

    No engine bay explosions are possible if:
    A. Fuel lines and fittings are correctly installed
    B. Sufficient airflow is ensured to maintain a non combustible air/fuel ratio.
     
  8. Jim Caldwell
    Joined: Aug 2013
    Posts: 267
    Likes: 8, Points: 18, Legacy Rep: 48
    Location: Cleveland, Ohio

    Jim Caldwell Senior Member

    Explosion Proof means it will not set off an explosion or fire, not that it will survive an explosion.
     
  9. richard gray
    Joined: Mar 2013
    Posts: 64
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: port coquitlam

    richard gray Junior Member

    explosion prevention

    thanks for input. i can start to plan out my preventative measures as some replies have suggested. thanks all !!! Rick
     
  10. tom kane
    Joined: Nov 2003
    Posts: 1,767
    Likes: 48, Points: 58, Legacy Rep: 389
    Location: Hamilton.New Zealand.

    tom kane Senior Member

    You can build a boat that runs on volatile fuels that is completely safe and I ran my boat worry free and it was wonderful.

    The solution is to isolate all of the fuel components from the inside of the hull so that there is no chance of spillage or fuel vapours. EFI and carburettor systems all work better and more efficient. It is just a matter of getting away from the traditions of the past and realy knowing how things realy function and build accodingly.
    Remote safe fuel systems for powerboats.
     
  11. richard gray
    Joined: Mar 2013
    Posts: 64
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: port coquitlam

    richard gray Junior Member

    see photo of engine on hull, and drive train will guid a held down aluminium cover over engine and drive train, build in gas tanks in double bottom at sides. isolate wiring, cover starter and alt with woven glass cloth(?) the tips help
     

    Attached Files:

  12. JSL
    Joined: Nov 2012
    Posts: 811
    Likes: 62, Points: 28, Legacy Rep: 41
    Location: Delta BC

    JSL Senior Member

    Built in gas tanks~double bottom? Are these integral??? If so, may not be legal.
     
  13. richard gray
    Joined: Mar 2013
    Posts: 64
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: port coquitlam

    richard gray Junior Member

    tanks

    you mean tanks that are not independent are not legal?
     
  14. Ike
    Joined: Apr 2006
    Posts: 2,542
    Likes: 377, Points: 83, Legacy Rep: 1669
    Location: Washington

    Ike Senior Member

    Richard you really need to do your homework before you continue.

    If you look at the USCG Web site http://www.uscgboating.org/regulations/boat_builders_handbook_and_regulations.aspx or my website, See my signature you will find the regulations for recreational boats.

    First lets's start with "explosion proof" Equipment on recreational boats are not required to be "explosion proof". They are required to be ignition protected. There is a significant difference between the two and explosion proof is a much higher level than ignition protected. What ignition protected means is that an electrical item will not allow a spark to ignite an explosive mixture. This does not mean that an electrical item cannot create a spark. The simplest way to accomplish this is a flame screen. Alternators, starters and other items make sparks. But if you look at the ones that are marine, they are either sealed so no vapors can enter them or they have flame screens which prevent a spark from igniting the vapors. This works exactly the way a flame arrestor on a carburetor works. You will also find these screens in the vent for fuel tanks, and on other items on boats. What these screens do is in the case of a spark igniting vapor inside the carburetor (say a backfire) or inside the alternator, the screen cools the flame front to the point where it won't ignite the vapors outside the carburetor or other equipment. And that is exactly how these items are tested to make sure they work. hey are put in a compartment contain an explosive mixture, and a tiny explosion is set off inside the item of equipment. If the test compartment explodes, well it didn't work. But they do work and this is really old tried and tested technology that works and is relatively cheap compared to explosion proof.

    Spark plugs, wires and other items that do not make sparks that are open to the atmosphere in the engine compartment are not required to be ignition protected. One of these is the battery. Batteries when properly hooked up and protected with a box or rubber caps on the terminals, do not make sparks and so are not required to be ignition protected. But they are required to have the rubber caps on the terminals or be protected against contact by metal tools by a box or other means and they are not allowed to move around. they have to be secured in place.

    But do not think the lack of a requirement for ignition protection means it is ok to use automotive parts. Marine parts are made to different standards than auto parts, including electrical wiring, ignition wires and hoses.

    The regulations are designed to eliminate the fire triangle. The fire triangle is a source of ignition, a source of fuel, and the right amount of oxygen to allow an explosion. The electrical regulations are designed to eliminate the source of ignition. The fuel regulations are designed to eliminate leaks (fuel) and ventilation is designed to remove fuel vapors from a compartment while at the same time keeping the fuel/oxygen mixture too lean to allow an explosion ( too much air not enough fuel vapor)

    All of these apply to gasoline powered boats with permanently installed engines (the law) and the industry standards (voluntary but followed by everyone building and selling boats) also apply to outboard powered boats.

    Yes, on recreational gasoline powered boats the tanks are not allowed to be integral with the hull. You can do this on diesel boats but it isn't a good idea. Even so some manufacturers do make integral diesel tanks.
     
    1 person likes this.

  15. tom kane
    Joined: Nov 2003
    Posts: 1,767
    Likes: 48, Points: 58, Legacy Rep: 389
    Location: Hamilton.New Zealand.

    tom kane Senior Member

    Dont`t tell me that I can`t I have told you how you can and you can use all of the approved marine fittings and comply with the Regulations.
    Google " Remote Safe Fuel System for boats Tutorial "
    " Safe Remote Fuel System for boats "
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.