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5189Re: Speed under motoring (4.7 knots at 2.000 rpm)

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  • tom1us2001a
    Jul 3, 2010
      JF,

      Your speed sounds about right for 2K rpm. I usually motor at 2100 rpm and move along at a blistering 5 knots. I used to have a fixed 2 blade and now have a feathering 3 blade. My speeds did not change (while motoring) with the change in props.

      A little more HP and less reduction in the transmission would help with motoring speeds. Its the 3:1 reduction in forward that limits our speed. Just not getting enough revs on the prop to push you faster. I've thought about changing the transmission to a higher ratio such as 2:1 (which would match the reduction in reverse) but I don't think the motor has enough HP to handle the extra stress and thus could not reach full power if needed. For now I will live with what it is, but if the engine ever needs rebuilding I would consider making some changes. It would be interesting to hear what others have changed (engine, trans) that improved speed and maneuvering power.

      Regards,

      Tom
      CN35-199 Dream


      --- In campernicholson@yahoogroups.com, "JFR" <jfregnard@...> wrote:
      >
      > My CN has a 35hp Piranha engine with a two-blade folding propeller. With revs at 2.000 rpm, she sails at 4.7 knots in a flat sea and virtually no-wind. Such a speed seems quite slow to me. Would anyone have figures that I can use as a benchmark ? Should I put in a 3-blade regular propeller ?
      > Any advice will be welcome,
      >
      > JF Regnard
      > CN35#207
      >
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