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mac 19 propeller pitch question

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  • sailhard1964
    re: Incidentally – to the group -, my 93 Mac 19 has been in dry dock (on the trailer in the back yard) awaiting my finishing some modifications for going
    Message 1 of 1 , Jun 22, 2008
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      re: Incidentally – to the group -, my '93 Mac 19 has been "in dry
      dock" (on the trailer in the back yard) awaiting my finishing some
      modifications for going on two years. The biggest one being
      installation of a 2 stroke Merc. 50 and EZStick steering and the
      fiberglass work of waterproofing the holes made in the motor well
      when the steering went in. If you've a 50hp too, can you please tell
      me what prop pitch works best and what speeds you top out at?

      I got my mac 19 with an almost new looking Tohatsu m40c ( 2 stroke )
      with a 10 pitch 3 blade fairlu dinged up prop. It seemed to move the
      the boat well with the tank empty, ( sorry no speedo ) but really
      struggled to get up on a plane with the tank full.

      I got this chart ( I'm sure your 2 stroke has similar rpm )


      and ordered the 7.1 pitch 4 blade prop ( the one for the heaviest
      load ) and the difference was ammazing. It planes with a full tank no
      problem, and it "felt" much faster with the tank empty. Worth noting
      is that with this prop the motor mount/transom "creak" a little going
      from dead slow to faster. A little unnerving. I have video on youtube
      of my mac with this prop tank empty on a flat day.


      I have a digital windspeed meter, so I'll try and get a ball park top
      speed. Macgregor says 25mph ( with an empty boat 1 person and no mast
      attached and no extra wieght) So I bet the top speed is less for my
      boat with 2 batteries, 2 gas tanks, anchor/chain etc.

      I also picked up a brand new "hustler" 3 blade 8 pitch prop for 40
      bucks on ebay and will give that a try soon if I get the chance.
      I assume it will be a little faster with the tank empty and slower
      with the tank full.

      I keep the tank full with my wife and 2 kids aboard mostly, but I'll
      empty it if I'm by myself and want to freak out the local "yachties"
      by blasting by.

      I really hate the noise of the 2 stroke 40 at full speed...And also
      the limited steering of the side mounted tillar. ( no right turns
      allowed )

      I'd like to get a 4 stroke 50 hp honda or suzuki ( with a center
      mounted tiller ) but they cost too damn much. 7 to 10 grand!!
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