Recent Content by johneck

  1. johneck
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    Rowing: blade travel extension through flow induced vibration

    Once the boat is moving, the relative velocities of the water past the oar are much lower, so many of the variables that you are looking at become...
    Post by: johneck, Dec 7, 2023 in forum: Hydrodynamics and Aerodynamics
  2. johneck
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    Defining propeller pitch

    It is very interesting to read all the different viewpoints on this. It is what makes propeller design such an interesting topic in my opinion....
    Post by: johneck, Feb 17, 2022 in forum: Props
  3. johneck
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    Propeller pitch on quad installations VS twins

    That is an interesting way of looking at the problem, unfortunately it is an oversimplification and not actually correct. If the boat were not...
    Post by: johneck, Jan 31, 2022 in forum: Props
  4. johneck
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    Electric hydrofoil prop

    Thanks for the update, very interesting. I did read the article. I agree with your statement that the only way to really make an improvement in...
    Post by: johneck, Jan 6, 2022 in forum: Props
  5. johneck
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    Electric hydrofoil prop

    The prop will produce out of plane forces if it is operating at an angle of attack. Angle of attack can come from tilting the drive, tilting the...
    Post by: johneck, Jan 1, 2022 in forum: Props
  6. johneck
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    Outboard prop modifications

    It is fun to build, but I think that Gonzo has it right. Adding blade area only helps if the prop is really overloaded, this one is not. Adding...
    Post by: johneck, Nov 30, 2021 in forum: Props
  7. johneck
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    Are my props too big? 22 by 20, 3 blades, a 1970 Eggharbor 37

    The short answer is no, the props are not too big. Even at only 8-10 kts they are probably only using about 120 HP/shaft. The problem is likely...
    Post by: johneck, Sep 8, 2021 in forum: Props
  8. johneck
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    DelftSHIP model to Solidworks

    here it is
    Post by: johneck, Mar 29, 2021 in forum: Software
  9. johneck
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    Flexible mast from iceboat on a racing dinghy

    Yeah, OK. I was not trying to say that you shouldn't ever ease the sheet, but the more you can sail without doing so, the better your chance of...
    Post by: johneck, Mar 15, 2021 in forum: Boat Design
  10. johneck
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    Flexible mast from iceboat on a racing dinghy

    The extreme flexibility helps the iceboat in a few ways which are not really needed for most sailboats. It allows the sails to be flattened...
    Post by: johneck, Mar 15, 2021 in forum: Boat Design
  11. johneck
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    Prop Questions

    Propellers are very sensitive to the inflow velocity, which means vessel speed. So when moving at a slower speed more power will be required to...
    Post by: johneck, Jan 12, 2021 in forum: Props
  12. johneck
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    Expert seeking expert to bounce prop design ideas off

    Sounds interesting, but why do you think that optimizing Cl/Cd of a blade section will produce a better propeller? It seems to me that more...
    Post by: johneck, Jul 31, 2020 in forum: Props
  13. johneck
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    Please help me with my school project

    The rule of thumb about right, so you need approx 2500 HP/shaft to get to 50 MT; maybe a bit less with a Tractor tug. How did you arrive at 273...
    Post by: johneck, Apr 16, 2020 in forum: Props
  14. johneck
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    Kaplan Propeller Drawing

    that came from sine(beta) and cos(beta). People usually use beta for pitch angle, but for various reasons used phi here Old guys used to try...
    Post by: johneck, Mar 4, 2020 in forum: Props
  15. johneck
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    Kaplan Propeller Drawing

    One thing I just noticed is that "skew" is projected skew in radians, not expanded skew as it says in the comments. "dtor" is simply the...
    Post by: johneck, Mar 4, 2020 in forum: Props