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mpg Re: Re: Boat with no name

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  • Lincoln Ross
    I bet you could get 100 mpg if you took the smallest 4 stroke engine you could find and ran it through a gearbox mounted on a single scull. You d probably make
    Message 1 of 2 , Oct 4, 2004
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      I bet you could get 100 mpg if you took the smallest 4 stroke engine you
      could find and ran it through a gearbox mounted on a single scull. You'd
      probably make 6 or 7 knots, too.

      Or you could go for something like this:
      http://www.stillwaterdesign.com/Pics/older25c.jpg
      which is supposed to go 18 knots on 10hp, I think. I'll bet it would go
      10 knots on 2hp. Maybe even better, since the wake might not be just a
      function of cube of speed. Assuming .5 pounds per horsepower per hour
      specific fuel consumption (well, ok, lets say .75 since this will be
      outboard motors) and guessing that gas weighs 7 lbs/gal, and
      approximating a nautical mile at 6000 feet, since I don't remember the
      real figure, I guess that's about 50mpg (statute miles). Don't trust
      these figures to be really accurate, they contain too many assumptions.
      Especially the SWAG about specific fuel consumption, which could be 50%
      high or low, I'm guessing.

      Probably these boats are optimised to minimize wake without thinking
      about wetted surface, but I'm sure they do better than most. (I'm
      biased, I helped lay up a couple of these a few years ago.)

      >Message: 8
      > Date: Sun, 3 Oct 2004 20:26:41 -0400
      > From: "Roger Derby" <derbyrm@...>
      >Subject: Re: Re: Boat with no name
      >
      >That is amazing. I guess I calibrated all power boats on my friend's
      >houseboat. He took it up river to the hydroplane races (Miss Budweiser et.
      >al.) and while I forget the exact numbers, it was gallons per mile and
      >refilling the tanks was a major budget item.
      >
    • Roger Derby
      Back in the 1950s when I was messing with sports cars, there were such things as economy runs. Mileage of 60 or more miles per gallon was needed to be
      Message 2 of 2 , Oct 4, 2004
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        Back in the 1950s when I was messing with sports cars, there were such
        things as economy runs. Mileage of 60 or more miles per gallon was needed
        to be competitive, BUT the Morris Minors etc had their tyres pumped up to 60
        psi or more and the tread cut away to leave only a 1/2" strip in the center.
        Transmissions and differentials were filled with kerosene and everything
        non-essential was left behind. The driver's foot was locked on the
        accelerator pedal so that never moved. The engine was started and the car
        accelerated to 60 mph or so at which point it was put in neutral and the
        engine shut off. When the speed had decayed to some 20 mph, the engine was
        restarted with the starter, the clutch engaged and the cycle repeated.

        What I'm talking about are useful boats with engines capable of clawing off
        a lee shore.

        Roger (although an "economy run" for boats might be fun)
        derbyrm@...
        http://derbyrm.mystarband.net/default.htm

        ----- Original Message -----
        From: "Lincoln Ross" <lincolnr@...>


        > I bet you could get 100 mpg if you took the smallest 4 stroke engine you
        > could find and ran it through a gearbox mounted on a single scull. You'd
        > probably make 6 or 7 knots, too.
        >
        > Or you could go for something like this:
        > http://www.stillwaterdesign.com/Pics/older25c.jpg
        > which is supposed to go 18 knots on 10hp, I think. I'll bet it would go
        > 10 knots on 2hp. Maybe even better, since the wake might not be just a
        > function of cube of speed. Assuming .5 pounds per horsepower per hour
        > specific fuel consumption (well, ok, lets say .75 since this will be
        > outboard motors) and guessing that gas weighs 7 lbs/gal, and
        > approximating a nautical mile at 6000 feet, since I don't remember the
        > real figure, I guess that's about 50mpg (statute miles). Don't trust
        > these figures to be really accurate, they contain too many assumptions.
        > Especially the SWAG about specific fuel consumption, which could be 50%
        > high or low, I'm guessing.
        >
        > Probably these boats are optimised to minimize wake without thinking
        > about wetted surface, but I'm sure they do better than most. (I'm
        > biased, I helped lay up a couple of these a few years ago.)
        >
        >>Message: 8
        >> Date: Sun, 3 Oct 2004 20:26:41 -0400
        >> From: "Roger Derby" <derbyrm@...>
        >>Subject: Re: Re: Boat with no name
        >>
        >>That is amazing. I guess I calibrated all power boats on my friend's
        >>houseboat. He took it up river to the hydroplane races (Miss Budweiser
        >>et.
        >>al.) and while I forget the exact numbers, it was gallons per mile and
        >>refilling the tanks was a major budget item.
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