Cummins Marine Diesel Repower Specialists › Forums › General Discussion › General Feedback on Propeller slip

  • Creator
    Topic
  • September 30, 2021 at 5:42 am #121320

    rconover
    Participant

    I have a 40ft boat with a 2003 cummins 450 diamond. 1.34 gear ratio. I believe the prop currently on it is a 22×20 4 blade but I need to have that pulled and checked. But if the pitch is correct I am calculating a prop slip of 42% at 2300rpm, 19mph. Boat is currently over propped and plan on pulling soon. Going to take a couple maybe 3″ if possible out of the pitch. At least that was my initial plan. But if a different size and or shape of propeller may be a better fit I would consider buying a new one. See pic of boat its got a tunnel drive and appears to have room for a little larger wheel if that is warranted. Would welcome any feedback.

    https://photos.app.goo.gl/aHe8FuRrRcc1p9DfA

  • Creator
    Topic
Viewing 4 replies - 1 through 4 (of 4 total)
  • Author
    Replies
  • October 22, 2021 at 11:47 am #122221

    Clark Leighs
    Participant

    Try talking to a company called Accutech Marine Propellor.

    He has acted as a consultant several times that I am aware of.

    Home

    October 13, 2021 at 11:59 am #121857

    Mike Uliasz
    Participant
    Vessel Name: Runnin' Down a Dream
    Engines: Cummins 6bta-M3 370hp
    Location: Mathews, VA
    Country: United States

    You can go out to this link, plug in the numbers and it will come back with a prop recommendation.

    https://www.vicprop.com/free-propeller-sizing-calculators

    October 13, 2021 at 5:57 am #121824

    rconover
    Participant

    I have talked to several shops but have not gotten any actionable feedback. Only suggestion has been cup, which the prop already has. I am hours from any major metropolitan area with a shop. Only small operations that deal in outboards in my area. So no way to ask for a loaner to test. I was hoping to stumble across someone with expertise in this area. To me the slip numbers above are way up there, but maybe thats how it is with a tunnel. And if so there might not be much room for improvement. Thanks for the reply.

    October 12, 2021 at 6:43 pm #121816

    Clark Leighs
    Participant

    I am no expert under any circumstances but I would sort out this prop. as far as you can. It will only cost you the time for testing and the cost of the prop changes.
    The closer you get to a working unit the better the chances are of choosing the next prop with less fooling around after you get it.

    Pitch changes as mentioned and maybe some cup which should help reduce slip.

    Are you talking to a prop shop now? The tunnel will limit what you can do so find out from your prop shop now what they suggest.

  • Author
    Replies
Viewing 4 replies - 1 through 4 (of 4 total)

You must be logged in to reply to this topic.