Transmission ratios

Discussion in 'Propulsion' started by Upston, May 16, 2018.

  1. Upston
    Joined: May 2009
    Posts: 8
    Likes: 0, Points: 1, Legacy Rep: 10
    Location: Los Angeles

    Upston Junior Member

    Hi All,

    I have a 55 ft motor sailor with a IH 310 CI diesel through a Paragon 3 to 1 gear set. I have the opportunity to buy a nice rebuilt Paragon as spear for a good price but it is 2.5 to 1.
    Can I run a 2.5 ratio with the same prop ? Not worried about performance really but don't want to load up the motor. I never run above 80% rpm s if that matters.

    Thanks for any advice
     
  2. kapnD
    Joined: Jan 2003
    Posts: 323
    Likes: 10, Points: 18, Legacy Rep: 40
    Location: hawaii, usa

    kapnD Senior Member

    Your prop will likely need some adjustment.
    Boatdiesel.com has an excellent calculator section, the prop calculator will specify optimum prop and suggest other combinations that will also work.
    Accurate weight measurement is a huge help in determining your propeller/transmission needs.
    If you do indeed never run over 80% rpms, it might be a good idea to set your throttle lever to not exceed that number.
     
  3. Upston
    Joined: May 2009
    Posts: 8
    Likes: 0, Points: 1, Legacy Rep: 10
    Location: Los Angeles

    Upston Junior Member

    Hi Kapn,

    Thanks for taking the time, I wil look u the site you suggested.
     
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