Shaft angle change at strut

Discussion in 'Inboards' started by 67-LS1, Jul 24, 2022.

  1. 67-LS1
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    67-LS1 Junior Member

    Apropo of nothing, has there ever been a strut or ?? that allows the shaft angle to change before the prop on an inboard? Something that could be used to lessen a shaft angle to (hopefully) get better forward thrust. Not so much something that could be trimmed, just a fixed angle.
    Anything?
     
  2. Ad Hoc
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    Ad Hoc Naval Architect

  3. 67-LS1
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    67-LS1 Junior Member

    Those look like they would go inside the hull. I’m wondering if there is or has ever been anything that would change the angle of the shaft below the hull so under water. The shaft would come out through a standard packing box and there would be some kind of a bevel gear or ?? at the strut.
     
  4. bajansailor
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    bajansailor Marine Surveyor

    I think that if you had something like a universal joint to change the angle of the shaft, and it is outside the hull, in the water, then the weed / fouling and shells / barnacles would play merry havoc with it - this is probably why you do not see any boats fitted with propulsion arrangements like this.
     
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  5. 67-LS1
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    67-LS1 Junior Member

    I was thinking something more streamlined. Like if the u joint or cordon joint were in some kind of a hydrodynamical case.
     
  6. bajansailor
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    bajansailor Marine Surveyor

    That would be a terribly complicated component, as there would have to be water-tight seals on each end to keep the sea water out of the hydrodynamical case.

    Building a tunnel in the hull in order to reduce the angle of the shaft would be much simpler, and much less to potentially go wrong.
     
  7. gonzo
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    gonzo Senior Member

    There are Vee-drives to accomplish that.
     
  8. DogCavalry
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    DogCavalry Soy Soylent Green: I can't believe it's not people

    It would be an awful thing to drag through the water too. Give terrible water to the prop.
     
  9. kapnD
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    kapnD Senior Member

    That is a common item nowadays, Volvo and Zeus make them, and heavy commercial models are made to drive large ships, barges and tugs.
    z drive boat - Google Search
     
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  10. Barry
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    Barry Senior Member

  11. rxcomposite
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    rxcomposite Senior Member

    In the early days of Arneson drive press releases, they talked about the development of the angled shaft. They said that universal joints could not handle the power and CV joints have problem with having too much diameter and seal problem. I think they settled with pinned ball joint.
     

  12. kapnD
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    kapnD Senior Member

    If the shaft angle is kept at 12* or less, the losses are negligible, water is a very forgiving medium in this respect, especially when the rocking of the boat and fluctuating sea surface are factored in.
    Test tank results will show some improvement with linear drive angles, but not so much in the ocean.
     
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