Help with Propulsion

Discussion in 'Boat Design' started by standman, Nov 27, 2021.

  1. tonipu
    Joined: Dec 2014
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    tonipu Senior Member

    yes, and the shaft can fail and brake, as i see it happen in few , espetialy planing boat
     
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  2. standman
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    standman Junior Member

    Single strut ok. 2.5 Inch 304 stainless with 6 ft with no support?
     
  3. tonipu
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    tonipu Senior Member

    keep in mind than i have more practical then teorethical knowlege.

    for my experience single strut for that lenght and shaft diameter is more than ok, but dont go out of the strut more than shaft diameter, and make strut about 20mm thick, and good solid base on the boat
     
  4. tonipu
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    tonipu Senior Member

    about my boat
    it is welded but i wait the design for a nice hardtop
     
  5. standman
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    standman Junior Member

    So your teacher is Mr. Experience. I hear he's one of the best. :) . Thanks. will post sea trial vids soon. Can you please run your prop software keeping the pitch at 34.8
     
  6. tonipu
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    tonipu Senior Member

    Pitch 34.8
     

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  7. tonipu
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    tonipu Senior Member

    With safety factor 3
    So i will dont go under 2.5inch
     

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  8. Barry
    Joined: Mar 2002
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    Barry Senior Member


    Grade 304, otherwise referred to as the UNS 30400, is the most popular of Austenitic or the 300 series. It is a primary alloy comprising 18 percent chromium and 8 percent nickel, hence the tag' 18-8 alloy'. Another variant, Grade 316 or UNS 31600, comes with an additional 2 percent molybdenum. That's why this metal displays a higher resistance to corrosion by salty water.

    Pulled of the net from a SS supplier. 304 is cheaper than 316 but 316 offers better corrosion resistance.

    https://stevedmarineconsulting.com/...tainless-Steel-ProBoat146-Stainless-Small.pdf

    Page 52 introduces a table as to the various SS for corrosion.
    There are other alloys to consider, Monel, etc.

    304 appears to be on the lower end of acceptability, probably due to cost
     
  9. standman
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    standman Junior Member

    Thanks Barry, Thanks Tonipu!
     
  10. standman
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    standman Junior Member

    Thoughts on rudder post diameter?
     
  11. tonipu
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    tonipu Senior Member

    i will go same as shaft diameter
     
  12. tonipu
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    tonipu Senior Member

    i like this design
     

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  13. standman
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    standman Junior Member

    Suffered a major setback as my place got hit with a massive storm (over 320kph winds with 15 foot water surge). Got left with nothing but our toilet. I've been through many hurricanes when I lived in Florida including hurricane Andrew but this was one tops them all. You'll see the boat top left thrown quite a distance
    received_595513161522552.jpeg
    received_304953754914276.jpeg
     
  14. DogCavalry
    Joined: Sep 2019
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    DogCavalry Soy Soylent Green: I can't believe it's not people

    @standman , my condolences. That is as you say, quite the setback. I lived in Nova Scotia, plenty of hurricanes, but weaker than that.
     

  15. tom kane
    Joined: Nov 2003
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    tom kane Senior Member

    https://www.boatdesign.net › gallery › pivotal-drive-ret...
     
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