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1984 46 viking 3 or 4 blade props

Discussion in 'Viking Yacht' started by Waytofast79, Dec 13, 2019.

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  1. Waytofast79, Dec 13, 2019
    #1
    Waytofast79

    Waytofast79 New Member

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    Hey got a question for you guys I have 3 blade props on the boat now and I’m contemplating going to 4 so got a question what is everyone else running on your 46 3 or 4 blade
  2. MBevins, Dec 13, 2019
    #2
    MBevins

    MBevins Senior Member

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    My 44 runs 4blade 24x26 dynaquads. With 6-71s
  3. Capt Ralph, Dec 13, 2019
    #3
    Capt Ralph

    Capt Ralph Senior Member

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    If your making good speed and proper rpm with the 3 blades I'd stay with that.

    My rule of thumb; 3 blades are faster, 4 blades are quieter.
    Upfront cost and cost to repair also goes to the 3 blade wheel.
  4. Capt Ralph, Dec 13, 2019
    #4
    Capt Ralph

    Capt Ralph Senior Member

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    One sad part of getting props repaired, many times you loose diameter and proper performance.
    Check your factory specs.

    The factory usually has done the home work to deliver the best running package already.
  5. Waytofast79, Dec 13, 2019
    #5
    Waytofast79

    Waytofast79 New Member

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    Yea I want change to 4 blades because I need more lift I need a ton of tab to run the boat and get any speed
  6. MBevins, Dec 13, 2019
    #6
    MBevins

    MBevins Senior Member

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    Then look at the ACME props.
    Just put them on my Viking. A ton more aft lift with them. Actually took an inch of pitch away.
  7. PacBlue, Dec 13, 2019
    #7
    PacBlue

    PacBlue Senior Member

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    I prefer 4 blades over 3, even though a 3 blade prop may see a higher wide open throttle speed due to lower drag (less number of blades).

    The reason you see 3 blades is because the builder wants that higher wot speed for marketing and he gets to save a little money. But in the long run, the extra blade area of the 4 blade prop handles the extra weight gain better, gives some more lift on the stern, especially with some cup, and can get you a better cruise speed.
  8. MBevins, Dec 13, 2019
    #8
    MBevins

    MBevins Senior Member

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    Can't argue with that position.
  9. Capt Ralph, Dec 13, 2019
    #9
    Capt Ralph

    Capt Ralph Senior Member

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    Is your (or mine) mother in law sitting on the stern?
    BBQ and play toys in the aft storage?
    Does your wheels have full diameter per factory design? This is a serious point..
  10. SeaLion, Dec 14, 2019
    #10
    SeaLion

    SeaLion Senior Member

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    A slight tangent but... What about the pros and cons of 5 blades vs. 4?
  11. Waytofast79, Dec 14, 2019
    #11
    Waytofast79

    Waytofast79 New Member

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    Not a lot of weight in stern even just when going out for a short cruise have to use a lot of tab unless the back tank is low also I’m changing my fridge how do you fit a full-size fridge down in the galley
  12. Beau, Dec 14, 2019
    #12
    Beau

    Beau Senior Member

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    What make hull? Some just squat no matter what you do. You may have to run off the forward tank unless you're on a longer trip since that seems to help. Are your tabs large enough? When at rest does the water line parallel the water surface?

    Move some people around as a ballast test as you run. Do two people standing forward help the planning? How does the boat run with that extra weight forward- maybe a couple of hundred pounds of forward ballast is the trick?
    Last edited: Dec 14, 2019
  13. Beau, Dec 14, 2019
    #13
    Beau

    Beau Senior Member

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    certainly the door mays have to come off....when you purchase don't exceed the outside dimensions of the existing
  14. PacBlue, Dec 14, 2019
    #14
    PacBlue

    PacBlue Senior Member

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    As you go up in blade area you can achieve a smoother feel, less vibration. 5 blades come into play when the hp is higher than these DD engines, as a 4 blade can have plenty of blade area for this hp class.

    For this application, a 5 blade would probably have lower speed and possibly lower cruise at the same rpm as a 4 blade.
  15. Capt Ralph, Dec 14, 2019
    #15
    Capt Ralph

    Capt Ralph Senior Member

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    The 5th blade just added more weted surface and really slowed you down.
    Un like 1500+ HP and reduction that needs the grip of the water, all you doing is producing more drag.

    Remember, race boats run 2 blades because nobody can fix a one blade.
  16. Waytofast79, Dec 14, 2019
    #16
    Waytofast79

    Waytofast79 New Member

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    Ya I put extensions on the tabs they are plenty big once I drop the tabs I get plenty of lift I just want more prop lift and less tab
  17. Beau, Dec 14, 2019
    #17
    Beau

    Beau Senior Member

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    Is it a MY or a SF
  18. Capt Ralph, Dec 14, 2019
    #18
    Capt Ralph

    Capt Ralph Senior Member

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    Where do you keep getting this gross prop lift idea from? There may be some on certain designs but you are not going to find much if any changing blades on a prop on an old boat.
    Diameter, rpm, tab and no weight make good old boats move. No magic, just sense.
  19. Waytofast79, Dec 15, 2019
    #19
    Waytofast79

    Waytofast79 New Member

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    It’s a sportfish and I talked to a few prop shops around here and they said the 4 blades will give lift and also be a smoother ride
  20. PacBlue, Dec 16, 2019
    #20
    PacBlue

    PacBlue Senior Member

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    There are certain props that creat
    They are correct, each propeller has a Thrust and Lift component, some are better than others, not to get to technical but a basic diagram below for a visual aid:

    [​IMG]
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