Origami steel yacht construction

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

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  1. Wynand N
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    Wynand N Retired Steelboatbuilder

    And just how do you determine / calculate that magic fracture point :?: You definitely does not have the mathematical ability or knowledge to do that, period.
    I recommended you read and study this: http://www.boatdesign.net/forums/sailboats/euler-factors-mast-design-33882-2.html

    Brent, for once stop your ignorance and get wise to what people are trying to educate you.
    I mentioned in the post where the quote was taken that a boat should have adequate scantling at least to handle the mast compression that may easily exceeds displacement (weight) of boat and the same pull exerted on chainplates. Obviously your design does not have that scantling - just read your replies again in this thread - and you hit back with this ridiculous argument with rigging breaking before max loads are exerted on mast.

    In fact, what you are saying is that in a real blow or storm when the mast is really put to the test and before it is really loaded, your rigging will snap, dropping the expensive mast and sails, damaging the boat and if the skipper/crew are lucky, escape injury...:confused:
    Hail you Brent, what a designerr you are. Boats with 175 degree positive stability, no decent calculated scantling to handle stress loads, snap off masts when the going gets tough, jeez, what else have I left out:D

    Gentleman of the board, I came to the conclusion that all the well respected designers, engineers, people in the know and boatbuilders contributing to this
    thread was indeed wrong all the time. Perhaps all the naval architects and engineers in the world it seems. Brent Swain is the new super hero of boat design; Mr know it all; with the following credentials - all others are stupid, origami (totally frameless) is king, well built boats are rubbish and monstrosities, derby demolition king, welder par excellence to name but a few...
    If only he can start with the basics like Simpson multipliers to get some hydrostatic figures, be able to calculate righting moments which is a simple affair with boat lines, maybe standing rigging as well, do some research on scantling rules for steel boats and incorporate it into his designs may he be then consider a boat designer of sort and maybe just then start to be taken seriously.

    Brent, I am 54 years old and still I learn every day of my life. I have built boats - small to large for a very long time, have a three year diploma in small boat design and still I listen and look to what others say with an open mind - not that I would necessarily approve, but most of the time I gain from that positively.
    Criticism can be constructive or destructive - really depends on you.
    OTOH, ignorance is the hallmark of a fool......
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  2. pdwiley
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    pdwiley Senior Member

    I quoted Euler's formula on the origami group years ago & got ignored.

    Brent doesn't understand dynamic loading. The compression load on the mast support is only static WHILE THE BOAT IS ALONGSIDE A WHARF (or in other flat water. In open water with any sort of swell you need to consider kinetic energy loadings and momentum and that is a whole new animal to static loadings.

    As I have posted before, David Lewis' boat was fine alongside but in open water the mast punched a hole through the hull. On Brent's view of the world this couldn't ever happen because the rigging would snap first. Didn't happen.

  3. MikeJohns
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    MikeJohns Senior Member

    PDW was talking about your designs not scaling over 36 feet.

    Don't deliberately confuse your frameless Origami builds with plate first framing and bulkheads second builds. Which is what you are referring to above.

    Plate first construction has been used on many vessels even 70' barges that I have seen. But substantial framing was added after the hull was pulled together.

    I've explained before that framing considerably reduces damage and limits buckling of the plate and lets it yield rather than buckle. Something very obvious in the infamous Gringo collision.

    It's a buckling analysis I want to do on your hullform to show you just how it collapses without frames and then another analysis with frames to show you the difference. But this belongs on the Origami thread.
  4. junk2lee
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    junk2lee Junior Member

    To field several kicks....
    MikeJohns confirmed that trunkcabins are included in the inversion so my question was answered,really.
    -to TeddyDiver,I haven't done all this properly for my own (40-45% ballast ratio,full keel,narrowish hull)boat since 1984 when I didn't even have a calculator that did square roots,I bet...I think you are meaning moment? But yes I try to calculate everything in 3 dimensions,for sure and as you say,find the average,as I said elsewhere in the thread.......a good idea to refresh this,because all kinds of things can happen between drawing board and the buyer of a second hand boat twenty years later!as per Tads post and my experience...Surveyors are supposed to do this but that's another kettle of fish..

    - just a thought per wave tank capsizes;My own wooden mast has Buoyancy with the boat inverting and , dynamic resistance to motion underwater(being very large in section but rigging and sailbundles have some considerable too),per MikeJohns mention of the tanktest,beam-on capsize. but how much,etc,etc ...static and dynamic are still two separate movies to run..the latter being an evolution of the former including calculations of TIME (and therefore acceleration etc etc... I sure can't be sure WHAT I've missed from my rough sketches ... oh,I'd sure like a good model in a good tank too!my boat,ofBrents boat,your boat too,
    but 'til then,must make do with climbing aboard and going from there ...anecdotally...
    Last edited: Aug 14, 2010
  5. junk2lee
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    junk2lee Junior Member

    well,I have trouble thinking thataway myself.... sorry,more anecdote!but motoring against a head sea?is that your meaning? But the forestay and backstay's be surging to the mast's rocking load ......Brent sails when he can,I know,but the motoring conditions you might be thinking about are not uncommon where Brent spends time -big ,short chops and no wind- It'd amount to something cumulatively over the 30 years I've known him.Most other boats I see hereabouts do it a lot.I have heard some awful KRANGS from these so I sure agree with the forces involved!Oh,I'm sure Brent has banged along sailing too when he must though a good helmsman will mitigate the jerking (if able) inany case.
    Last edited: Aug 14, 2010
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  6. Brent Swain
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    Brent Swain Member

    David Lewises boat had 10 gauge hull plate , and I don't remember any thing he said about his mast punching a hole in his hull. I do rememebr him talking about a cabin side being bent inwards, without him showing any photos of that side of the cabin, nor metioning any ports broken,or leaking, which would have inevitably happened if that were true. I don't think he would have missed the opportunity to show the dammage had there been any.
    How dense does one have to be to believe three 5/16th shrouds are strong enough to push a couple of two inch sch 40 pipes thru 3/16th plate?
    How dense does one have to be to believe that which hasn't happened in 30 years of cruising all over the world in all conditions , just may happen in the first 4 hours?
  7. Brent Swain
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    Brent Swain Member

    Past experience over many boats over several decades, in sometimes extreme conditions, is a far beter, and more reliable predictor than any mathematical formula.
    I just met a couple who bought a Colvin Gazelle for $10K . I guess from this point, on the resale price of a Gazzele is $10K.
    While people returning from offshore cruises keep telling people to keep it simple , cruising boats keep on getting more complicated and more needlessly expensive.
    Only me, Van de Stadt and Beuhler have made any attempt to keep things simple.

    If your goal is to get off the treadmill, then it would be foolish to get your advice from anyone who has never accomplised that for any length of time, especially anyone who believes no one should be allowed off the treadmill.
  8. Brent Swain
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    Brent Swain Member

    90% of the added weight is below the VCB, and increases ultimate stablity as long as you arrange for the lockers to remain shut. That is easy to do. I always do it when heading offshore..
    My boat is available for any test, as I'm sure any of my 36 ft owners would agree to.
  9. Brent Swain
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    Brent Swain Member

    Think of origami boats as longitudinally framed , which, due to the longitudinal curves, are far more effective than transverse framing.
  10. LyndonJ
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    LyndonJ Senior Member

    ! ! !

    Attached Files:

  11. LyndonJ
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    LyndonJ Senior Member

    How dense do you have to be to have to make up arguments you can win:rolleyes: :rolleyes: . It's really dumb to put up a straw man and knock it down. Makes you feel good perhaps since you got so much else wrong so often.

    Heres some other threads worth reading



    And this thread in its rotund fullness.

    <this line removed in response to http://www.boatdesign.net/forums/metal-boat-building/origami-steel-yacht-construction-248-47.html#post389276>

    :!: :!: :!: Warning {Brent Swain says that Naval architects say that his boat will fail in 4 hours of heavy use} :!: :!: :!:
    So stop the distortions please and try and get some dignity back by sensible posting. If we all started playing your games it would be a farce.

    Your behavior is just so pathetic at times. Lies, distortions, made up facts and trading on deliberate misunderstandings all rolled into marketing hype.
    Nothing you say can be taken at face value when you post like that, and the above post on stability is just another made up BS fact with no calculation to show it otherwise.

    I know you hate calculations because they interfere with your beliefs. But you are really dangerously naive at times dude.
  12. peter radclyffe
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    peter radclyffe Senior Member

    My boat is available for any test,
  13. WestVanHan
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    WestVanHan Not a Senior Member

    Listen- I don't know Brent,I don't know his style of boats,and pay little attention to this thread.

    BUT Lyndon...you are the one posting a distortion.

    Brent never said his boats fail..... yet you go on and post that NA's say they do.

    Maybe you misunderstood his rhetorical question,but I don't think you did though because you immediately try to start acting all preachy and deprecating.

    So why not "get some dignity back by sensible posting"

    And while you're at it why not tell us all how "three 5/16th shrouds are strong enough to push a couple of two inch sch 40 pipes thru 3/16th plate?"

    Easy,you can't and it won't-so you go on the attack and try to misdirect the statement.
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  14. M&M Ovenden
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    M&M Ovenden Senior Member

    Hi WestVanHan,

    I agree that at face value sometimes it does seem like members of this board are a vigilant gang attempting to lynch Brent. I do find the personal attacks disagreeable also; in all fairness the negative comments seem to come from Brent Swain the majority of the time.

    If you spend some time reading the Realistic scantilings, Transverse frame calculation and this complete thread you may choose to edit or delete your last post.


  15. raw
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    raw Senior Member


    I asked this once before, but it seems you missed it....

    To get all (>90%) of the owners belongings (added weight as you call it) below the VCB would require you to put right down in the bilge. If I am not mistaken, Don't you have a tanks down there? If so, then the above statement is simply false. You may attempt to load all your belongings low in the boat, which is a good idea, but the majority of it is never going to be below the VCB. If you said that 90% of it was loaded below the VCG, then this would be believeable.

    To illustrate for yourself and others here, I have attached a midship section of a real cruising yacht I designed a few years back. FYI, This boat has been built and has somewhere in the vicinity of 10-15k NM of international cruising under its belt. Since actual dimensions of the yacht are irrelevant to this conversation, I will only say that it is larger than most you will see and certainly larger than any Swain design I have heard of. I will also say that I have removed >90% of the detail from this drawing for obvious reasons and that the image shown is not to any particular scale though is in proportion..

    You will note that it also has underfloor tanks amidships which combined with other systems/piping and the internal hull structure leaves very little space available for storage under the sole. Quite simply, there is now way the owner is going to add gear below the CB. How do you do it? A midship section like I have shown would help.

    The position of the CB has been calculated using one of the well known hydro packages around and the CG was determined from an inclining experiment of the completed vessel and has been adjusted for full tanks as an expected "departure" condition. I say this because this is the lowest CG for this boat. Emptying tanks will raise the CG slightly. At least one person a few post earlier, questioned whether the CG could be above the CB. I trust this clarifies for everybody here (not all are pros afterall).

    Attached Files:

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