Fumes and Sparks

Discussion in 'DIY Marinizing' started by Grebbo, May 8, 2006.

  1. Grebbo
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    Grebbo Junior Member

    Hi all,:)

    Before I start I would like to apologize for any repeated questions that you senior member might have heard before.
    I have spent the last couple of days just searching through past threads, links, Google etc looking at how to Marinize a standard automobile engine.

    I sensed a clear divide between people thinking it was possible and affordable and those who thought that a purpose built marine engine was the only way to go.

    My project currently involves a construction of 15 foot Flyer (1937 hydroplane wood raging boat)
    The engine will be a Lexus 4L V8 or a Buick 3.8L V6, commonly used in open ski boats, as a mater of fact a good friend of mine has a supercharged Lexus motor on in his ski boat that leaves the chevs for dead. Any how since mine will be under a hood, I was quite interested in the “Sparks” will fly comments from some of the members, should you not change the alternator and starter motor? I guess the guys in the open engine bay scenarios don’t have to worry about that.

    So my question is that, if you have enough ventilation to the engine bay (via air scoops etc and have adequate discharge vents) would it still be a problem??

    Also, How frequent are explosions caused by vapors igniting in the engine bay caused by standard alternators and starter motors?

    Also the boat will be used in Sydney Harbour etc so WOT periods will be limited.
  2. Bergalia
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    Bergalia Senior Member

    Fumes and sparks....

    I've seen through your diguise Grebbo...You're Rupert Murdoch aren't you. I mean, marinising a V8 engine with Aussie lead-free fuel costs at $1.40 a litre and set to go higher.

    But with regard to your spark query - I can only repeat a suggestion I made some time back. Visit your local lawn-mower or tractor dealer. They sell spark retardant gismos for machines which are employed in 'inflamable risk' areas (fuel depots, ammunition dumps etc).
    And marinising auto-engines is feasible - but expensive for alloy blocks. Sea water is corrosively cruel. Mind you, puttering about the Parramatta is even more corrosive judging by Press reports, thanks to Union Carbide...:mad:
  3. Poida
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    Poida Senior Member

    We were out fishing a couple of weeks ago when I said the guys, "the oceans on fire." The fire was a launch that I think was timber, the fire according to the news started in the engine.

    There is no law as far as I know about the need to have a marine alternator or starter motor in this state as laws are only made here for the purpose of making money.

    But reading threads here have made me very aware of the risk. I have a bilge blower, which is really a sucker that has ducting from the engine to an exhaust fan out of the side of the boat (that I sometimes remember to turn on).

    I don't think anyone can say maranising an auto engine is too expensive in relation to buying a marine engine as there are too many variables in the expense of the modifications that anyone making such a statement could possibly take into account.
  4. Grebbo
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    Grebbo Junior Member

    True Bergalia,:)
    Corrosive as may the salt water may, be a lot of the members forget that a lot of the boats out there are trailer boats that spent most of their time out off the water , I mean that, sure if you boat, regardless what it is, spends 24 hours in salt water, 7 days a week in the sea water, then sure, it will obviously need materials that are suited for the environment, however if you put your treasured boat in salt once a week and meticulously clean and service it each time you go out, then corrosion and leaks etc should be no problem, I think people spend too much time worrying about what could go wrong and not enough time marinating, servicing and understanding their hobby, I mean in the end that’s what its all about?! Or am I missing something, I mean I for one do not have an unlimited bank account or a wife that’s willing for me to spend 100’s of thousands of dollars just to have marine engines specifically built for my application, and NO, not everyone lives in USA (I wish I did) :rolleyes: where there are boat wreakers selling marine engines and parts for next to nothing. The rest of the world as bad as it may be (compared to the US) still needs to survive on modifying quite reliable and powerful automotive power plants, and there it is, innovation, experimentation, where do you think the big marine engine builders got their ideas from? From people like you and me, not afraid to experiment, driven by desire to go out there and have fun, obviously safety plays a big party, however reading some of the previous posts, everyone seams to be “lawyer conscious” with their “California rules this and that” and “ I would not do that if I were you”
    I mean the US may have more boats then the rest of the world, and have more stringent rules and regulations, however coming from one of the largest islands in the world, we have a long history of boating in our country, (New Zealand inclusive, not to include NZ as part of Australia or any thing) we have a long history of marinazing automobile engines for use in boats, and it seems that we are looked down upon for even considering the thought of such a thing, perhaps this forums should be called, ”if you are thinking of marinazing your boat then you are an idiot!” or something?
    Perhaps some of the members will be annoyed by me speaking out about their forum, don’t get me wrong, I have learnt more on this wed side then anywhere else, however I find it hard to get past the “ No, the automobile engine simply will not do” attitude:?:
    Not everyone goes out there and goes flat stick (WOT) for 7 hours at a time! The whole” its like pulling a 1500 pound trailer up a 45 degrees hill for 5 hours straight!?”
    “The automotive engine will simply not do!” attitude is simply not right for the budget boat builders, we are not thinking of breaking any speed records, or spending next 20 years out in open seas, all we need is some good advice from experienced boat builders and drivers, that’s all,

    I’m sorry I’m going to pop a valium or something now…:(
  5. Grebbo
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    Grebbo Junior Member

    Hi Poida
    That would have been a problem for the boat owner,:(
    But again I wonder was it a bad selection of parts (standard alternator or starter motor) or just lack of understanding and maintenance that caused a fire?:confused:
    I mean I live in Canberra, and each time I take my car to Sydney, (2.5 hour drive on the highway) I check the oil level, tire condition and pressure etc, even thought my car is 1 year old, I still like to check. I’m confident that there is little that can go wrong with the vehicle, like you say, good ventilation, be it a blower etc can go a long way. Thus my question how necessary is it to have a marine accessories?
    And thanks for that info Bergalia, re: flame arrestors from farming supplier, I will most definitively look in to it.:)
  6. Bergalia
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    Bergalia Senior Member

    Relax, Grebba. You say: "I mean the US may have more boats then the rest of the world..." True, my friend. But ask yourself this; Do they know what to do with them ? Stands to reason, you'd think that with all those boats they'd at least have some sense of nautical adventure... But as history shows, it was Britain which colonised America, and not the other way around....I rest my case....;)
  7. marshmat
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    marshmat Senior Member

    In a car, gasoline vapour (heavier than air) drops out harmlessly under the vehicle. In a boat it will pool in the bilge. Hence why you need the blower, to get the fuel vapour out of there before you crank the starter. You also have hydrogen gas coming off your battery as it charges; this rises- again, in a car, it goes right out the wiper plenum but in a boat it collects under the engine hatch.
    But those vapours can still build up underway, so you need a good underway ventilation system as well. With blower and good ventilation, you will probably not blow up your engine bay.
    Marine-grade alternators, starters, etc. add an extra measure of safety. Where a standard alternator throws sparks all over the place inside it, a marine unit does not. It is possible to use the car alternator, but the marine one is far safer. Many of the other marine components- special freeze plugs, etc.- are mainly for corrosion resistance, since the boat engine cools on water instead of propylene glycol. The marine flame arrestor is a must-have, the car air filter will not do the job on the water.
  8. antonfourie
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    antonfourie Senior Member

    Yes but then the British were still throwing sh*& into the street when the rest of the world used flushing toilets, and I have never lived in a country more resistant to change so I would not take them as a "good" example of progress or modernisation.
  9. Bergalia
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    Bergalia Senior Member

    Common mistake sir, confusing the 'English' as being the only 'British'. Britain is four nations, Scots, Welsh, Irish - and finally English. Whereas I accept that the English may have been throwing their sh*t into the street, as you claim, the Welsh disposed of it by digging deep holes (under the pretext of coal mining) and formed choirs to cover the noise of their communal bowel movements (in Welsh this is known as - eistedfodd); The Irish used the shoreline for their evacuations, the results of which were naturally washed out to sea and carried on the prevailing current towards the USA were, bleached and stiffened by salt the palid stools were recruited into the Boston Police Force;
    Finally we Scots, being anally retentive, placed our 'wee jobbies' in small bags manufactured from the stomach lining of a sheep and when times proved hard sold them to English and US tourists as haggis.
    That, Antonfourie, is the truth of it... Ask anyone, I would not lie....:D
  10. SheetWise
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    SheetWise All Beach -- No Water.

    I'd always wondered about the Boston police, and I'm happy to have that cleared up -- but your comment "when times proved hard" seems a bad choice of words. Unless I misunderstand "sold".
  11. Grebbo
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    Grebbo Junior Member

    Thank you Matt,
    that’s an interesting point, I guess the cars engine bay is no where as air tight as a boats engine bay, thus venting all of the potentially dangerous gasses quite quickly and without any external help (blowers etc)

    Is there any type of electronic warning system that can be installed in the engine bay, that would alert you of any explosive gasses? Just like a smoke alarm?:confused:

    I mean the boat that I’m building has a large forward facing scoop and two rearward facing scoops on top of the hood, plus a firewall (if you can call it that) that does not go all the way to the bottom of the boat, allowing air to circulate to the open cockpit.
    I will be fitting a blower only as a security measure (for the times when you are stationary for prolonged periods of time) so there should be plenty of fresh air movement in the engine compartment?

    Also, thanks all for the history lessons:p
  12. tom kane
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    tom kane Senior Member

    No need to worry about volatile fuels in boats if you install a Safe Remote Fuel System for Boats (thread) Keep all fuel related accessories out of the interior of the boat (even if it`s an inboard),seperated from inside,vented and drained overboard,do the same with fuel tanks.Luxury is a safe boat,what a wonder full life with no worries about fuel leaks,enjoy boating now.
    1 person likes this.
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    FAST FRED Senior Member

    If you troll a diesel engine site you find the SAME engine has 3 or 4 ratings.

    A really high short term rating and as the hours of service grow the "rated" hp drops till the most conservative 24/7 specks for work bosats.

    Gasoline engines are similar ,
    if you need an engine to go flat out for 10 hours , its NO problem ,
    just the HP and RPM will not resemble that of a dragster.

    Many auto engines are factory built as truck engines, using parts more suitable for a cont. load.

    Forged crankshafts , salt cooled valves and valve seat inserts , larger oil pump and water pumps are all part of the truck inventory.

    For a gasoline boat that worked hard the TRUCK version would be the better choice for marinization.
    Using the truck hp and rpm limits.

    A truck engine would stand a better chance of surviving long hours at FLANK SPEED.

  14. Ike
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    Ike Senior Member

    First off If you really check out your friends Lexus engine in his ski boat you will find out that other than the block it bears very little resemblance to the engine in the car. Outwardly it may even look the same but it's not. Marine engines are under much heavier loads than car engines. They are run at constant RPMs most of the time under heavy loads. So for the most part marine engines have much more heavy duty components. The fuel system is set up differently, The ignition system is set up to provide peak performance at a specific RPM rating whereas cars are designed to provide optimum performance over a range of rpms. The exhaust system is different. The engine probably had the water passages enlarged to increase cooling, and it probably has a different cam and hardened valves. There are more than likely other differences as well. Basically it is the same engine just like you and I are both men. That's where the similarities end.

    Second. To eliminate explosions and fires three things are done. The first is to make sure that the vapors are gotten rid of. Thus a good blower and ventilation system. Two, the source of fuel vapors is eliminated by using proper marine fuel hoses and fittings and pressure testing the system so there are no leaks. Third, eliminating sources of ignition by using electrical components that are ignition protected. (this is not the same as ignition proof) This means that alternators, starters, electric motors, relays etc are all designed and built to prevent any sparks from igniting any fuel vapors that may be in the engine compartment, or any other compartment where fuel vapors may be present such as the compartment where the fuel tank is.

    Yes boats blow up. Happens all too frequently but, studies in the US have shown that now, since putting laws in place to eliminate explosions, that most occur when someone has made a change to the fuel or electrical system, or has not properly maintained these systems. The commonest is replacing alternators and starters with automotive versions. Another that doesn't apply to fuel injected engines, is replacing the marine carburetor with an automotive carburetor. They may look the same but they are not.

    And last, Yes, in Australia and New Zealand they have laws controlling the manufacturer of recreational boats. These are basically the same as in the US, Canada, Europe and elsewhere.

  15. gonzo
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    gonzo Senior Member

    Speaking of fuel injection, there is a marked difference between an automotive system with a return line and a single line marine version.
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