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Thread: 50HP (Tot) Twin Engine Briggs VTwins on Jon Boat

  1. #1

    50HP (Tot) Twin Engine Briggs VTwins on Jon Boat

    This offers some twin engine redundancy to get you home when an engine might fail.
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  2. #2
    Super Moderator Corky's Avatar
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    Re: 50HP (Tot) Twin Engine Briggs VTwins on Jon Boat

    Amazing !! It might be the angle of the pic but it appears to be a big prop...Looks like they both run to get that prop to spin...I see in the other mini pics you've posted the fuel tanks are up front to help balance the boats out... I like the low mount engines I bet that makes the center of gravity so much better for sliding into the corners...

    Aluminum .120 14' X 76" hull
    Teledyne 4a084-4 engine
    Circle S 1.69:1 reduction
    67" Whirlwind "Razor X" prop



  3. #3

    Re: 50HP (Tot) Twin Engine Briggs VTwins on Jon Boat

    Yes both engines were spinning the same large prop. The belt wrapped around like a triangle.

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    Re: 50HP (Tot) Twin Engine Briggs VTwins on Jon Boat

    Do you use Cen clutch or one way bearings on the drive pulleys? Curious how you speed/power match the engines.

  5. #5

    Re: 50HP (Tot) Twin Engine Briggs VTwins on Jon Boat

    Quote Originally Posted by TLL View Post
    Do you use Cen clutch or one way bearings on the drive pulleys? Curious how you speed/power match the engines.
    No one way clutches or centrifugal clutches were used in the original prototype ( pic shown ) what happened was that
    if one engine died the other engine would not turn the dead engine and the prop.

    What we did first was add another pulley to the prop so that each engine drove the prop with its own belt. Then if an engine died
    all we had to do was remove the belt to the dead engine. This allow the remaining engine to spin the prop though much slower.

    If we had a long long way to get back home it also helped to repitch the blades in the prop for the now reduced hp driving the prop.

    Speed is relevant. We thought the single engine boat was damned fast ... or at least exciting to us.... and then the dual engine
    boat seemed like a jet in comparison. Again we are talking basically 25 hp to 50 hp for two engines and I know that does not
    compare to hot rod big block turboed V8s etc.

  6. #6
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    Re: 50HP (Tot) Twin Engine Briggs VTwins on Jon Boat

    Quote Originally Posted by preventec47 View Post
    No one way clutches or centrifugal clutches were used in the original prototype ( pic shown ) what happened was that
    if one engine died the other engine would not turn the dead engine and the prop.

    What we did first was add another pulley to the prop so that each engine drove the prop with its own belt. Then if an engine died
    all we had to do was remove the belt to the dead engine. This allow the remaining engine to spin the prop though much slower.

    If we had a long long way to get back home it also helped to repitch the blades in the prop for the now reduced hp driving the prop.

    Speed is relevant. We thought the single engine boat was damned fast ... or at least exciting to us.... and then the dual engine
    boat seemed like a jet in comparison. Again we are talking basically 25 hp to 50 hp for two engines and I know that does not
    compare to hot rod big block turboed V8s etc.

    It's a rare event that one of these engines will quit running, slightly more likely one might not start for some reason I've used a lot of these on para-flyers..not bulletproof but ultra reliable/TLL

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