The use of computers in boat design

Discussion in 'General Computing' started by Stumble, Aug 12, 2011.

  1. Leo Lazauskas
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    Leo Lazauskas Senior Member

    I've attached two of my favourites.
    The ITTC purports to be setting some form of best practice, and they serve up nonsense like that.
    And it was signed off by one full Prof and 8 experts with PhD's! :rolleyes:

    Attached Files:

    • z1.gif
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    • z2.gif
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  2. tunnels

    tunnels Previous Member

    Thats the truth for sure !!
    Biggest problem is the computer person is not a enthusist and the enthusist is not a computer person .
    Just because you can draw fancy lines does not mean they are what they really should be !!
    Button pusher designers have little or no imagination of nautical things of beauty that are functional and practical and work well .
    One of the best and cleverest designers of Americas cup boats always used to use his set of batterns to check and redraw by hand some of the hull lines after they came off the computer .
    Even a builder with a eye for fine detail and understandin can see computer mistakes that can be seen when making a plug for a glass boat .
    But is it the computer thats the probelm or the driver ??

    Does the car have an accident or is it the driver ??
    Maybe computers need better drivers that understand better the computer capabilities and a better understanding of what they are meant to be doing and what they should be looking for ! After all a computer is it just a tool !!:(
  3. gonzo
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    gonzo Senior Member

    The number crunching of computers is something that is a great advantage. The formula for aesthetics has not been discovered yet. Also, the limitations of programming have to be taken in consideration. In an earlier post, a spiral was mentioned. There is no computer able to draw a peerfect spiral. It is posible to do it with a stick a string and a pencil. The same can be said of an oval. CAD may be within operational parameters, but still look ugly. I firmly believe that lofting by hand full or at least half size is worth the effort.
  4. Alik
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    Alik Senior Member

    I used to sketch the outline of boat by hand prior to computer modelling. We scan this napkin hand sketch, trace it and start developing 3D model using soft natural lines of hand drawing. Just one sample:

    Attached Files:

    1 person likes this.
  5. Leo Lazauskas
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    Leo Lazauskas Senior Member

    Reading this, you could imagine that all people who design without computers never make mistakes or build ugly unsafe boats.

    There are as many fools who can't use computers at all, as there are people who use them foolishly. :p
  6. Leo Lazauskas
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    Leo Lazauskas Senior Member

    Complete nonsense!
    Just as there are limits on the accuracy of a computer line drawing of a
    spiral, there are also limits on what can be done with a stick and string.
    Or do you use an unstretchable string and an infinitely thin pencil to draw the lines? :p
  7. DCockey
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    DCockey Senior Member

    I completely agree with Leo on this one. Tell me how accurate you want the spiral or oval and I'll draw it on the computer to that accuracy or better.
  8. jehardiman
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    jehardiman Senior Member

    There, fixed it for you....:D

    Really though, computers are just like a power tool, they can't do anything better than a hand tool, they can just screw it up a lot faster, so it takes more skill, not less to set it up so that it will run correctly. A chain saw and an ax will both fell a tree, but neither will make sure that it falls in the right direction.

    From my perspective, all computers have done is confuse the issue of "truth". You will spend 90% of your time and money getting the last 10% of the answer, and then lose 20% of performance to seaway, fabrication, and fouling so just do the hand calculation, add 20% seaway reserve, and call it good. As I pointed out in a thread long ago, the economics of fuel costs to design time don't make continued analysis worth it. Running 100 cases with a "truth" difference of +/-1% is deliberate obsfucation...the real skill is knowing when to stop playing with yourself and just build it.
  9. jehardiman
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    jehardiman Senior Member

    The point I was trying to make with the spiral was that it was a continuous function. A digital system, by definition, cannot produce a continuous output, it must discretize. So both you and gonzo are somewhat correct, on one hand a computer cannot output a continuous function and cannot deal with real world variations, on the other hand it can within certain accuracy limits and perhaps better than a gross physical model because in the real world we cannot control that absolute materials and environment. This is the thrust of the argument that I wish to make about computers…computers solutions exist is a limited world…real world solutions comprise the limitless world…they are as different as night and day no matter how much they resemble each other.

    To paraphrase from a quote by Leo..All models are wrong, some models are useful
  10. Ad Hoc
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    Ad Hoc Naval Architect

    A friend of mine who is a serious mountaineer says when they are scaling a difficult ascent, they are reminded of the axiom:-

    A professional knows when to stop, and amateur does not.

    No different in naval architecture.
  11. BATAAN
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    BATAAN Senior Member

    And a friend of mine who is an old, not bold, pilot, says the professional knows when to NOT go on a flight due to weather or other factors, while the low-time pilot has sometimes too much faith in his equipment and ability and not enough awareness of his limitations.
  12. Leo Lazauskas
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    Leo Lazauskas Senior Member

    I think that some CAD programs could have difficulties in accurately approximating the slopes of spiral. As the spiral loops become smaller and smaller, more spline nodes are need to approximate it, and I have doubts that one could rely on the values of the slopes. The spiral itself might be very well approximated, but there could be quite a bit of waviness between nodes, depending on the type of approximating spline.

    It's a wise man who quotes a man who quotes wise men!
  13. PerCorell
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    PerCorell Junior Member

    Sorry but I can not read the intire folders and I just seen thei tread, after adding a new tread in the software section that explain my background, -- but I will say that much that software are perfect for just that and I think I proved it by building some 7 different designs of my own in various sizes each, just to prove the software.
    What you need to realise is that it allway's is a bad idea to just translate the old method into new software, that to do the same as you did by hand will be done better by hand, untill you know the software. Computers are much better than that. But they ask newthinking, there are the problem. Try a search on Google for CyberBoat. I left my homepage from when I stopped building woodenboats there on Yahoo Groups. There I also focus on the main important thing, the framework, and if you want to see what I mean by newthinking, then look at the framework with those designs the 3dh frame lattrice, that offer you ribs cut from sheet materials generated by a press of a button from a 3D model, and the basics for all of what you goy's want to do with software ; that can not be done with the old ribs but ask a new aproach and understanding of the build works.
    See as long as you want to build as they did 200 years ago it is better done by hand, unless you realise some of the concept behind CyberBoat. Sad thing about it are that I jettisoned the whole thing, as no one want wooden boats anymore.
  14. tunnels

    tunnels Previous Member

    no one want wooden boats anymore.

    Sorry not true !! Plenty people want all wooden boats built !!

  15. boradicus
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    boradicus Senior Member

    CUER & Python

    Computer analysis is actually proving to be beneficial for projects like CUER's (Cambridge University Eco Racing) solar race car design. They are a racing team, and so they try to get as accurate measurements for testing purposes as possible. After the initial construction of their monocoque body, they had it 3D scanned in order to account more accurately for the addition of remaining components and for simulation purposes.

    I agree about aesthetics, however, aesthetics are something that begin in the mind's eye and tools, whether electronic, manual, or theoretical/mathematical, or a combination of all of the above, are only tools. You can get as good a resolution as is needed using a computer as by any manual method, but the ability to design a curve manually is probably easier to do by hand (at least initially) than by using some piece of software to get the job done.

    I liked what I read earlier about designers needing to know programming or programmers needing to know something of design. Python is actually a very accessible programming language that is easy to use and free to download. It would be easy in my opinion for a designer to make his own tools using Python to augment the use of spreadsheets. Programming can make use of algorithms as well as linear equations, and Python can do this very easily and quickly with a minimum amount of code. I am currently looking at writing a small tool for initial design of a hull cross section. This probably isn't for everyone, but since I am currently stronger with programming than with boat design, it seems useful to help me understand the process better.
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