How is the size of a rudder determined?

Discussion in 'Boat Design' started by Sunny Parab, Aug 18, 2014.

  1. Petros
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    Petros Senior Member

    what do you mean by "efficient" least drag? move effective for its size? lightest weight? best at low speeds? or high speeds? Efficiency is a measure against a something: fuel burn, drag, weight, cost, capcity or rudder authority. You have to define what it is you want to measure.

    to optimize for each of these conditions means you sacrifice the performance in another. There is no such thing as "most efficient", as much as best design to achieve the primary objective. Like in all things, you can not have it all. good low speed rudder capacity and low drag, etc. A really low drag rudder would have poor low speed rudder authority, and also be easy to stall out, so it would not be good for rough waters or for a boat that operates in varying conditions. Typically you size the rudder based on the area of the operating envelope that puts the highest demand on it. which means when in all other usage it is larger and heavier than you need.
     
  2. wannadriveaboat
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    wannadriveaboat Junior Member

    Its very funny
     
  3. Sunny Parab
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    Sunny Parab Junior Member

    What are the types of rudder??
     
  4. jehardiman
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    jehardiman Senior Member

    Side mount (Egyptian, Greek, Chinese, Roman, Viking, steering oar, sometimes not considered a "true" rudder which is/was mounted symmetric to centerline), shoe, horn, kitchen, blade, contravane, plate...there are lots of them. Google it or study the texts.
     
  5. Sunny Parab
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    Sunny Parab Junior Member

    Thank you brother
     
  6. PAR
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    PAR Yacht Designer/Builder

    I guess no one has figured the new NA courses have fired up again in India and they're looking to get their assignments completed?
     
  7. Sunny Parab
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    Sunny Parab Junior Member

    I am doing a project on FEASIBILITY STUDY OF DIFFERENT TYPES OF RUDDER....can anyone help me where can i find information
     
  8. TANSL
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    TANSL Senior Member

    Sunny Parab, I can not believe you can not get information on types of rudders and operation. Can not find any book or regulation that addresses these issues ?. Do not you have no choice but to use this forum to get information ?. If so, please do not adopt such a belligerent tone, nobody is obliged to help. The favors are requested, not required. If I have misunderstood you beg your pardon but the phrase you typed, in capital letters, suggests (to me it seems) a tone of voice unsuitable.
     
  9. JSL
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    JSL Senior Member

    Rudder size & shape go hand in hand with the boat/ship type. There is a lot on info out there. To steer you in the right direction check out SNAME, International Marine, Cornell Maritime and don't forget the aeronautical connection like aspect ratio, foil section.
    If you are in university or a school, talk with the teachers and tell them to do their job - teaching you how to learn & do research.
     
  10. Jammer Six

    Jammer Six Previous Member

    Tone of voice makes no difference here. Those who are going to help will help, those who aren't won't.
     
  11. PAR
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    PAR Yacht Designer/Builder

    It's not a matter of help Jammer, so much as the time of year. After a few years, you'll see the trends we (well at least me anyway) do and take a wild hair guess about what's really happening here. There are a few parts of the world where this sort of thing comes in cycles, usually at the beginning of a semester or come finals time. The real question should be why aren't his texts sufficient enough for this information, why isn't his instructor capable of supplying this understanding or most importantly of all, the name of the school itself, because I probably don't want to find myself aboard a vessel, from the hands of one of it's graduates.

    As has been suggested in most of the previous posts on this thread, there's no "rudder" book, nor a best rudder type, though some understanding of flow dynamics, might clue this fellow in a bit.
     
  12. daiquiri
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    daiquiri Engineering and Design

    What PAR says is pretty true. It was pretty interesting for me to observe in these years that some 75-80% (a rough, intuitive estimate) of similar requests come from students in India and in Philippines.

    Would be curious to hear why it is so, from somebody who has attended a university in these countries.
     
  13. Petros
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    Petros Senior Member

    I think there is a tendancy these days for young people to go to the internt for information, rather than look it up themselves. In India usually only the more afflent families, most of which are well connected politically, can send their children to a University. So these might be privileged kids have never had to do things for themselves.

    Or the other extreme possibility is he attends a trade school for low income families, and they have no books, printed materials, not even a library, all they have is an internet connection.
     
  14. Jammer Six

    Jammer Six Previous Member

    The generalizations here amaze me.
     

  15. philSweet
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    philSweet Senior Member

    I tend to sift through my pile of offcuts ...
     
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