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Ocean 40 prop pitch

Discussion in 'Ocean Yacht' started by ShionMcIntosh, Jun 22, 2021.

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  1. ShionMcIntosh

    ShionMcIntosh New Member

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    Can anyone point me in the right direction as pitch suggestions. I have a 2001 40' with Cat 3126 420 hp. Props are Hy Torq 23x28.I bought the boat last year and didn't have much time to get to know the boat before the props had to be reworked.
  2. VetteLT193

    VetteLT193 New Member

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    Those are factory props assuming medium cup. Considering it is 20 years old I'd probably bang around .5 to 1 inch out of them. You will lose speed but they will better handle any extra weight you add and take some pressure off the engines
  3. ShionMcIntosh

    ShionMcIntosh New Member

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  4. ShionMcIntosh

    ShionMcIntosh New Member

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    Thanks for the reply. Would you happen to know what is a fair cruise to ask out of her at 2400rpm?
  5. VetteLT193

    VetteLT193 New Member

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    New was 25 knots+ at that rpm, 30k+ WOT.

    These boats REALLY respond to weight and to clean bottoms and running gear. A freshly hauled and cleaned boat with little to zero owners gear on it, light fuel and about zero water will run much better than one with a ton of gear on it.
  6. ShionMcIntosh

    ShionMcIntosh New Member

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    I've been only seeing 18 to 21 with all gear removed. When I bought it I was getting 24 to 25 at that RPM just can't figure out what the issue is yet. I also have had the fuel rack adjusted so I'm thinking maybe now down on power possibly. Is there any way the mechanic could have maybe accidentally detuned it?
  7. Capt Ralph

    Capt Ralph Senior Member

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    What RPM were you turning for 25 (KTS or MPH) @ WOT?
    What RPM are you turning now? Really the same boat and weight @ WOT?
    Why were your injectors adjusted?
    Turn your syncro off. Both engines suffering?

    Your ships bottom baby's-ass smooth? Your props have not been damaged? If you are spinning the same RPM and lost speed, then you forgot to throw the mother in law overboard with her junk.

    If you are really not making the same WOT RPM as before, after ditching all the weight with clean bottom, remember ruel #13;
    The rack on a 3126 takes special Cat tools. There is a rather large inventory just to make up this complete special tool kit.
    Missing one of these tools for your higher (than trucks) HP ratings could have de-tuned your motor.
    Rule #13, truck techs can't touch marine engines.

    Oh, Loosing diameter will reduce speed also.
    After grinding on props a few times for previous repairs, diameter is lost. No mater what the numbers on the hub say.

    Prop scanned lately? Reports from previous owner?
  8. VetteLT193

    VetteLT193 New Member

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    What capt Ralph is saying is everything I would... this is a basic math problem and something doesn't add up. If your RPM is correct, props are what you say they are (could they have been swapped? Bought the wrong set?) Then the speed should not change that much at the same rpm
  9. ShionMcIntosh

    ShionMcIntosh New Member

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    So as long as I'm making the same RPMs no matter horsepower rating with the same pitch and diameter propellers and weight I should be moving the same speed correct?
  10. cleanslate

    cleanslate Senior Member

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    I have a 42 foot Ocean.
    A bit different than yours . Mine is older, less power etc.

    Bottom has to be super clean and smooth for your top speed. You probably had a clean bottom when you got those higher speeds.
    Mine is the same way.
    Only takes two or so weeks in the salt water to get growth on the bottom of the boat to slow it down.
    This includes a little slime etc…

    Yes this boat is sensitive to weight and growth as said already.

    Again how much fuel did you have in the boat and your water tank etc. when you achieve those higher speeds it all comes in the play.
    Also were you running with the tide when you got those high speeds that makes a huge difference!
  11. cleanslate

    cleanslate Senior Member

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    Observe the tides and currents while looking at your speeds .
    Current , as we know is everywhere even miles out in the ocean. You maybe bucking the tide more than you think.
    This will mess with your speeds for sure.
  12. Capt Ralph

    Capt Ralph Senior Member

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    Mostly correct.
  13. DOCKMASTER

    DOCKMASTER Senior Member

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    As Capt Ralph mentioned, this is mostly correct. If your engines somehow got detuned or were loosing appreciable horsepower you would not be able to turn the same props at the same RPM. However, your speed can be affected by current and wind as others suggested. You can also be loosing speed due to inoperable trim tabs. How did you run previously to get 25 knots? Were you full tab down? Are you certain your tabs are working? The trim tabs lift the stern so if they are not working you can lose a lot of speed.
  14. ShionMcIntosh

    ShionMcIntosh New Member

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    I've been running with the trim tabs all the way up I spoke with the previous owner this morning and he also mentioned tabs I didn't realize that made a difference thank everybody for their help.
  15. DOCKMASTER

    DOCKMASTER Senior Member

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    Let us know your results when you run with your trim tabs down. You will want to play around with them. Some boats, like mine, want every bit of tab down I have. Others like some % between up and down. If you can find some smooth water and play with them while watching your speed you can get a good sense of how your boat reacts to the tabs.
  16. DOCKMASTER

    DOCKMASTER Senior Member

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    Also, forgot to mention, unless you have indicators telling you your tab position (doubtful) you will want to get a good idea of how long your tabs take to go from full up to full down and vice versa. You can simply do a mental time count as you cycle them back and forth. Mine are about 10-12 seconds to cycle full. Yours will be different I'm sure.
    Capt Ralph likes this.
  17. CaboFly

    CaboFly Member

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    Had a 40 SS back a few years. Same props and Cat 3126's. Took 1/2 inch of pitch out of wheels. That resulted in cleaner running engines and improved longevity but at the price of some performance. Once the props were worked it was a 29.5 knot WOT and a 23 to 24 knot cruise at 2400 rpm.
  18. ShionMcIntosh

    ShionMcIntosh New Member

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    What a difference trim tabs make!! I seen anywhere from 22.5 to 25 knots depending on current. Thanks for you guys help.
  19. cleanslate

    cleanslate Senior Member

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    Yes they do make huge a difference.
    Tab away !
  20. ShionMcIntosh

    ShionMcIntosh New Member

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    Do you guys think the Humphree tabs would adding performance?