Fantail steam launches

Discussion in 'Boat Design' started by confused, Feb 18, 2009.

  1. PAR
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    PAR Yacht Designer/Builder

    Those Harbor Freight engines are about as poorly built as you'll find. That one you linked to is about $150 and you might get 1,000 continuous hours out of it if you're lucky (which isn't much). Though it's rated a 6 HP, I seriously doubt it'll pull that much. It's a slow turning, long stoke upgrade from the 3.5 HP of the same family line.

    I'm not sure what you what as far as an engine, but if you're going with low HP, low displacement, you'll need to spin up the little engine to have sufficient gearing room to pull what ever you're looking to pull (1,000 pounds). The other option is a bigger displacement engine with lower RPM capability, but swinging a fat torque curve.

    Gearing is pretty simple to figure out, easy math. You could get a pocket watch motor to pull a half ton with enough gears, but there is a point of diminishing returns, with friction, heat build up, weight, practicality, etc.

    I think you'll want a fair bit more then 6 HP, if you expect some life span out of this engine, tractor package. Harbor Freight sells a 12 or 13 HP engine for about twice the 6 HP. It's better to ask an engine to work at 60% of capacity most of the time and 90% some of the time, then ask a smaller engine to work 80% most of the time and 100% some times. Naturally the little engine will die much quicker.

    I'm an ale and amber kind of guy Richard.
     
  2. apex1

    apex1 Guest

    Maybe... Haha.. but you are a reliable source of some background info, and you can express them much easier than I could. And that is the value Mike is looking for, I guess.
    So, continue to share the burden please.
    Focusing on a real task, I assume, is worth if we have a final decision wether to build a boat, a steam engine, a launch, a plane or a tractor.

    Regards
    Richard
     
  3. apex1

    apex1 Guest

    Never............ and you did´nt specify it should,...! .. but PAR handled that subject already above.
     
  4. confused
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    confused New Member

  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    A small tractor is a fun build. Think about what it does, it's a work machine, so torque and the ability to pull power through different routes is important. Typical routes are hydraulic rams and PTO's for rotary, engine supplied torque. The transmission and final drive assembly (rear) are the keys to a good tractor, plus chassis strength.
     
  6. confused
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    confused New Member

  7. confused
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    confused New Member

  8. apex1

    apex1 Guest

    I would recommend the engine already installed in an old tractor. It will be easier to find such a old artefact in the next village, than to find all the stuff you need to build a real vessel from scrap. Think about a gearbox, bell housing, axles, clutch, steering gear, tank, fuel supply, wheels, tyres, all on top of just the engine! What a task.........................:confused: :(
    If I was asked to do that, I would calculate at least one year to get it done! But I have some advantage over you, I have two fully equipped shipyards disposable, one fully equipped blacksmith and metal working shop (my son), my pocket money is a bit higher amount than yours, my knowledge is at least a bit better than yours !
    You got it?
    Try to find such old tractor and disassemble, study, experiment, improve, and assemble again, its sheer fun (apart from dirty fingers). You will get a deeper insight in some very complex coherences by discovering how some things do actually work together, than if you get stuck in your own homebuilt without a clue why it does NOT function.
    Regards
    Richard
     
  9. confused
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    confused New Member

  10. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Just to move the weight of that old rig, you'll need a lot more then 2.5 HP, unless you burden the engine with a 12 speed gear box, which will likely need at more then 2.5 HP just to spin it. That old tractor probably needs 5 HP, just to spin the gears in the pumpkin. Of course you'll have to haul it home from Massachusetts too. Work with what's there instead of repowering and finding yourself lacking in the umph department.
     
  11. confused
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    confused New Member

  12. apex1

    apex1 Guest

    It is possible to run some compressors in a reverse mode, this one looks quite simple so it should work. But where to get the air from? Is your "gas station tyre refill hose" a very long one?
    And btw what sort of shop is that? The NCO* ?

    Regards
    Richard
    * NCO = National Crap Outlet
     
  13. confused
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    confused New Member

    Ok. NCO. haha. I get the idea, but where the 'ell am I supposed to buy stuff from?
    I don't want to have to pay for shipping!
    and I was thinking of putting the tank ON the vehicle
    me
    thanks
     
  14. confused
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    confused New Member

    all I need the tractor to REALLY pull is a small trailer, 8ft long, 4ft wide.
    You think 13 hp is good?
     

  15. confused
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    confused New Member

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