Origami steel yacht construction

Discussion in 'Metal Boat Building' started by origamiboats, Nov 30, 2001.

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  1. Bubblehead
    Joined: Jul 2010
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    Bubblehead Junior Member

    For a newbie like me, this is an interesting thread on a number of dimensions.
    Here's my question:
    For one of these designs, how does one go about calculating the margin to skin buckling? I can see how (1) a tensile load on a portion of the stresskin must be offset by a compressive load elsewhere, (2) the moments generating these compressive loads would increase linearly with, say hull length, and (3) the critical skin buckling load would plummet with an increase in hull size (e.g., a simply supported column's critical buckling load drops with the square of the length).
    Obviously, frames increase the resistance to skin buckling dramatically.
    But is there any method other than empirical to get at the answer?
     
  2. bearflag
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    bearflag Inventor/Fabricator

    Umnnn.... its right here..... under Class Societies. Its #3 right now....

    http://www.boatdesign.net/forums/classification/

    I imagine over time it will be lower though unless he puts a sticky on it.

    direct link is:
    http://www.boatdesign.net/forums/classification/transverse-frame-calculation-32584.html
     
  3. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    Wow, you really are paranoid and delusional.

    Not only do you ignore advice and comments you are incapable of finding a simple thread that has been pointed out to you that the thread is STILL THERE!

    One more time, it is here:

    http://www.boatdesign.net/forums/classification/transverse-frame-calculation-32584.html

    But as with everything in that thread above, and this one, you steadfastly refuse to accept anything other than your own word and belief based world order, because that suits you. Sorry Brent, the world does not revolve around You…nor does it pander to your delusions.

    If you are incapable of clicking a link, or using a search engine on a website, it comes as no surprise that your replies and snake oil spin in the Transverse Frame thread drag on for 40 pages and go nowhere and are just meaningless nonsense. Comprehension is so under rated these days!
     
  4. bearflag
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    bearflag Inventor/Fabricator


    And in case you were REAAAALLY wondering.... the "demolition derby" bits are still there too. As far as I can tell, nothing was deleted.

    But I think Jeff (the moderator) said as much as that.

    http://www.boatdesign.net/forums/cl...se-frame-calculation-32584-27.html#post378382 <--- link to the Richard/Apex1 and Brent Swain boat challenge.
     
  5. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    So, just as a thought, you could start a thread, and ask, how shall we do this derby challenge?
    Or
    Just as a thought,
    you could click on the persons name that took up your challenge and send them a PM…just a though! It is a wild thought I admit, as it is a radical way of obtaining a solution to a truly vexing problem of how to contact somone for information.:eek:

    Or is it that it is much easier to throw mud at others and claim “others have chickened” than actually carry out your threat/challenge? Ignore what is there, then make bold statements that others have chickened out and then say see… I am right

    Is this your usual MO for convincing people that your ways are the only way and best?
     
  6. MikeJohns
    Joined: Aug 2004
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    MikeJohns Senior Member

    I asked this question:
    After all the attempts to actually engage you sensibly on structural issues and your reply is again based on selective limited statistics :

    But they haven't. When you scaled your 21 footer up to 36 feet the keels were inadequately supported, tore welds and damaged the hulls from groundings. Anyone knowledgeable could have told you the design was inadequate...................and your response would have been the same!


    Using statistics of all your 21 to 35.5 foot boats and excluding the failures doesn't prove anything.

    While at the same time Your engineering knowledge is abysmal and demonstrably proven so by your own design failures.

    On the other thread where we were trying to get you to discuss structures, it was clearly stated that your 36 design has inherant unecessary weakness, and severe stress raisers which are likely to cause fatigue failure at some stage in the vessels life if it's used at sea.

    You can't determine when that failure occurs or what the extent of the damage will be. Since there is no redundancy in your structure it could be seriously catastrophic, for example, if it's in the middle of a severe storm.

    I have said repeatedly that you can add a day or two and a hundred or two dollars worth of material and do the job properly. But your response is this:

    While you disregard all concern about safety, couldn't give a toss about the people and their safety. And won't even look at the very serious structural issues raised.

    I just cannot believe this response. It is delusional. Or would a better term be criminally egotistically based negligence ?
     
  7. MikeJohns
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    MikeJohns Senior Member

    Not only that, Brent's advocating a design for the challenge that's not even his!
    What does that say.:)
     
  8. MikeJohns
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    MikeJohns Senior Member

    The subject is called elastic instability, the analysis requires a lot of expertise and understanding. The traditional method is a long and non-trivial mathematical approach that has to make assumptions and simplifications.

    The other better more accurate approach is a computer based buckling analysis. Class societies incorporate panel buckling criteria based on FE analysis in their rules.

    It's a good call because if you scale a boat you should have an idea of both the loads and the structural response to those loads.

    Brent already scaled a 21 foot to a 36 foot and had major problems he didn't forsee (but should have) . The keel supporting structure buckled from groundings.

    To scale to 40 or even as he claimed to 60 feet is daft without a proper analysis.

    Buckling has nothing to do with tensile or compressive strengths it's just about a structure where displacement is induced at a greater rate than the applied stress within the linear part of the materials stress strain curve. In other-words it lacks sufficient stiffness. Frames stiffen the structure and let the plating work in tensile strength mode from a collision, without the frames there's nothing restraining the shape and it can collapse easily once the collapse is started.

    You should have a look at the Transverse frame thread too( lots of links to it in the above posts) I posted some shape buckling pics and talked about it there too.


    PS
    we have offered to Brent to do such an analysis on his design for free ( normally a fee of several thousand dollars) this was for his clients sake and to show him once and for all where his limits were.
    But he didn't want to know.
     
  9. LyndonJ
    Joined: May 2008
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    LyndonJ Senior Member

    It was against your 36 remember :(
    Just go ram the harbor wall at 7 knots, it's what you implied your T boning could survive. But you know it'll crumple like tissue paper with compression-buckling ridges all the way up to the mast.

    Can't do that?


    I offered to analyze the hull too. FEA is one of my specialties. Then it turned out that Brent was lying wholesale about having the lines. Sheesh there's attitude and there's attitude but you put lives before your ego, you are one sick little puppy.
     
  10. CatBuilder

    CatBuilder Previous Member

    Good GOD this thread is entertaining.

    I would buy tickets for the steel vs epoxy demolition derby

    [​IMG]



    AND the BC Beatdown!

    [​IMG]

    I've tried to resist posting, but I think you guys need to cash in and sell some tickets for these events!
     

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  11. bearflag
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    bearflag Inventor/Fabricator

    I offered my event management skillz.

    Right down my alley. I used to produce and promote auto racing, rock concerts, motocross, and similar events.

    :)
     
  12. bearflag
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    bearflag Inventor/Fabricator

    Proposed Event Outline

    I think the derby should be something that would more replicate Brent's claims than the original derby as proposed by Richard.

    Say....



    1: Both boats should motor their "yachts" into a pier going 15 knots. EDIT: Or we could get an old derelict steel barge.

    2. Boat should be dropped on its side from sufficient height into "deep" water such as to simulate getting struck broadside my a large breaking ocean wave. (Alternatively several shipping containers of water could be simultaneously dropped from 30-60 feet on the boats). Ideally the boat should be induced to rolling over and self-rigthing.

    3: They should be "dropped" from a crane from sufficient height into shallow water of depth such that the collision represents being slammed on ground or reef in a storm and the keel slamming onto terra-firma.

    4: A wrecking ball will be swung from a uniform distance into the midpoint of the side of the hull, to simulate a collision.

    Boats will be judged by an independent panel of experts and mariners but the final vote will be given to a live "studio" audience.

    The boat deemed to be the "biggest floating (or non floating piece) of junk" will be scrapped with a irreverence (lots of options, explosives, machineguns, fire, bulldozers, etc etc).

    If the votes are reasonably close (say 10-15 percent of each other) the boats will have to "duel it out". Boat owners will flip coins and take turns ramming the others vessel until one side's sinks or admits to defeat.


    (working suggestion in progress)


    ::gets popcorn::


    EDIT:

    Ideally the event will take place somewhere where gambling is legal. And the "action" can be either given to the winner/promoters or to a charity established for the education of aspiring naval architects/engineers/designers.
     
    Last edited: Jul 17, 2010
  13. welder/fitter
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    welder/fitter Senior Member

    Brent,
    You may have others fooled, but I know that you are intelligent enough to differentiate between a physical and a verbal coward. It is one thing when you counter sound points with anecdotes, it takes us nowhere and is only acceptable to one whom buys into stories over science, much like a discussion between creationists & evolutionists. But, when you take parts of a person's statement & use it in a way that is not in context with the original post, or when you push a design as being "better", then steadfastly refuse to offer proofs for this, rather, begin attacking the detractor on a personal level, you show verbal cowardice.

    From what I read on origamiboats, only one of your apostles disputed Daniel's concerns with any serious attempt at science, most, rather like their leader in these forums, attacked Daniel on personal grounds & gave the same anecdotes as you have used so often. This is typical & is why I use the "orwellian sheep" reference to describe some, not all, of the members of that group. Maybe, "apostles" is a more fitting term? Yes, the subject of origamiboats on the cruisers & sailing forums seems to be, to one moderator, a sancrosanct topic. Considering members of those forums discuss monohull vs. multihull & the good/bad of materials, boat designs, manufacturers & other construction methods, it seems "odd" that your boats are not to be questioned.

    Mike
     
  14. SheetWise
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    SheetWise All Beach -- No Water.

    I don't believe that's the argument I'm reading. Maybe your detractors here were simply trying to throw you a bone -- but it seemed like a silly, obvious, and intuitive problem (i.e., A < B). Obviously, the exact relative properties are a bit more complicated. Your responses have been less than direct ... So, even though that is a simple problem, why don't you explain the physical relationships between these two forms of steel, as you've described them, just to prove you can.

    Edit: This was my summary from post #154. Forgive me if I've misinterpreted this softball claim and challenge.
     

  15. LyndonJ
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    LyndonJ Senior Member

    BS is the one with beliefs. The whole idea of regulations and design guides/rules is to let someone ignorant of the engineering process do a decent job of designing something. Whether its a house or a boat.

    I think to get your head around the BS approach you need to understand that he designed and built a 21 footer. It was up to the job strong robust but tiny.

    From then on he's been stretching that 21 footer and adding to try and stop the failures after they appear as the boat is used.

    The so called structural arguments he's just made up, and got them wrong, Looking at BS reasoning about structural strength it's laughable. Where did he get it from, all his attempts at explaining structure are either not applicable or just plain wrong.

    There's no belief systems in engineering, it's an absolute discipline. So the basis for BS arguments is belief and his 'detractors' are trying to be his educators. But if you know A>B and BS calls you all the insults under the sun because he has hung his marketing on B>A and won't change then you get the picture.

    The structural design for his 36 footer is perilously flawed and needs to be corrected. His response is moronic, words fail to describe how dumb he's being. Design based on delusion, and it's not like he doesn't know by now.

    I think there should be a recall of boats built to his design and flaws corrected. The nice little cottage industry should stop immediately and sort itself out.

    Anyone caught up in the scam should get some help, go see a professional and get the framing added and sorted before the interior goes in. And don't worry about offending BS it's your life and assets at risk.

    Where's Alex Christie? He started this thread didn't he? He's involved in this fiasco too. What do you think Alex? You should be aware of the BS in these boats by now.
     
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