Origami steel yacht construction

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

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  1. LyndonJ
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    LyndonJ Senior Member

    Properly, with a frame continuing into either a floor or running through to the opposite member. It's an appalling constructed and welded part of an abysmally designed keel support.

    Like the mast supports.

    Structural strength a priority over everything else :p :p :p Thats something you just haven't gotten. It's something you've tried to spin away.

    Thats' why minimum standards exist, to stop that sort of design and construction.
  2. LyndonJ
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    LyndonJ Senior Member

    Stability is derived from a known COG and a 3d model which includes the cabin trunk the raised ends, the wheelhouse etc they are all counted. You are completely wrong ...again and again even when youre told youre wrong you still dish up the same lines.

    Who is some ??? Nebulous claims to authenticity typical of your posts. You are implying your critics here said that, would you like to show a link.....

    USA girl not Aussie, the Aussie made it comfortably in a more suitable boat.

    How did you determine COG when you can't even give your clients weights and moment info?

    The creative accounting, the spin the deceit the distortion is all yours, it always has been. The realities at sea are that you have some dangerous design features that could fail nastily and they need improving. And don't just say well it hasn't happened yet.
  3. Ad Hoc
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    Ad Hoc Naval Architect

    Well, it is nice to see Brent asking his friends to support him, always good to have friends, no matter how misguided their loyalty is to someone they consider a craftsman.

    Ok, lets put some of this into perspective and recap, again!!!

    Brent has no lines plan, no stability book no data. He refuses to post lines saying it is his lively hood and will lose money blah blah blah. (So much for helping others save money).

    So, lets see what others promoting origami are doing. Here is one site:


    Oh look, and here are some lines:

    Lines Plan.JPG Lines Plan-1.JPG

    Brent refuses to to understand basic structural mechanics and cannot even answer a simple question, which according to Sheetwise, is easy anyone can. Draw your own conclusions.

    Here they address frames and structure and stiffening and what they call ‘strength’:


    They are trying and I do emphasis trying, to address the issues which have been raised endlessly on this and the other thread:

    ..which it seems many of those in favour of supporting Brent blindly, have yet to read in full. They should do so before commenting.

    Unfortunately in this ‘strength’ they fail to point out that this only addresses tensile uniaxial loading. It does not address displacement, instability and fatigue, nor multiaxial loading, which all boats must account for in structural design. But, they are trying…

    Brent refuses to allow several posters who are willing to provide their FEA services for free, yes, free, to address his structural philosophy. What do these guys do, well, look here:


    Unfortunately, the import aspects such as the magnitude of the load, the boundary conditions, the method of applying the loads and where it is applied, for example, are missing. This sadly reduces the images to just nice pretty pictures and no basis for real comparison. BUT, they are trying…

    Brent constantly states how quick and easy it is to build, yet only he has built them that fast. (Not difficult when you have no respect for quality and things which ‘can’t be seen’).

    These guys reckon around 14 months to build….wow, simple answer to a simple question. Getting the picture yet???

    Whenever anyone asks Brent for simple clarification to simple questions, rather than getting replies or answers, as noted in the “origamimagic” website, how does Brent reply?

    So, you have to ask yourself this question if you are sold on the origami approach. Would you buy your plans and dream from people that try and address your questions, are open with the data they have, or from someone who always responds in his time honoured fashion when asked to clarify a question with:

    Troy summed up pretty well Brent’s whole attitude to quality, professionalism and work:

    But of course all we get to judge the value of a man by his replies:

  4. TeddyDiver
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    TeddyDiver Gollywobbler

    Again.. it's not ignored! and again how are the "school bus windows" secured?

    ps. and as I have stated before I'm a fan of high cabins, wheelhouses and narrow hulls among other things I agree with Brent. And in my own buildings sometimes go with the feeling rather than calcs (despite the fact that I can do the math) but, but I'm not pushing the same sloppynes to others nor trying to make a buck out of it..
  5. welder/fitter
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    welder/fitter Senior Member

    For those who missed the point of post #410

    Post #410 of this thread was written to illustrate a point, though that point - as I expected it to be - was missed by some. Perhaps, a few members will recall that I have done this before, and that I waited a day, or so, before explaining why I made the post, as I am doing so now. The only thing that was missing this time, unless I missed it, was Brent's predictable ballistic response.

    Post #410 was to make the point to Brent that no one likes to be called names, nor have their integrity questioned. It was also to make the point to those who are friends or fans of Brent, that members, such as myself, become angry when Brent calls someone whom we respect a less than favourable name, or makes personal attacks, simply because they do not share his views.

    I had expected to search for an example - it wouldn't have taken long - but Brent has, himself, supplied one that illustrates my point better than anything I could have found:

    Correct me if wrong, but the Van de Stadt 34 is 4mm steel and the Brent36 is 3/8" which is 9mm.

    My 26 is ten gauge hull plate, my 31, 36 and 40 are all 3/16th. I only suggested 3/8th for a 60 footer.

    "What's the problem?", you're thinking, "this is an harmless post."
    Two points:

    1) When a post quotes another post, if there is no form of separation, it seems to read as if both sentences are being stated by Brent. There is no way of knowing that "goodwilltoall" is the author of the first sentence, unless one goes back & searches previous posts to Brent's response. When Brent's posts contain multiple quotes, it's just too damn much work to go back & find each quote. I figure that Brent may have the same problem that I do, which is that I still haven't figured out how to multi-quote. Still, there are other ways to remove the confusion; by italicizing, underlining, etc., as I have done above.

    2) If I recall correctly - if wrong, please don't call me a liar;) - "goodwilltoall" stated that he has known Brent for over a year and has bought Brent's book and/or Alex's video, and seems to be on favourable terms with Brent. So, Brent corrects the misunderstanding over the BS36 hull plate thickness. Now, if "pdw", myself, or another - who had had a disagreement with Brent in the past or was in the middle of an argument with Brent - had erred as "goodwilltoall" did, it is far more probable that Brent would have, either; Called that person a liar, or; not corrected the misunderstanding and waited for a future opportunity to call that person a liar, when they made another post that was based on the incorrect understanding. There are examples of this throughout these forums, spare me having to dig one up.

    So, do I really believe that Brent is a liar, thief, scammer, and all of the other awful words I used to describe him? No. I do believe that Brent does mislead, at times, and that he allows others to misinterpret, without correcting them. I know that Brent shows a lack of respect for anyone who disagrees with him, as well as, those he is in competition with. Perhaps, the most maligned of the latter, would be Thomas Colvin, who Brent appears to have some deep dislike for. I also do feel that Brent tends to bully people. No excuse for this. As Brent has no issues with being disrespectful to others, I feel no reluctance to treat him in the same manner.

    Yes, it would be more enjoyable to read posts about & discuss boat design & boat building. Yes, it would have been nice to see the transverse framing thread answer the OP's question, rather than see Brent try to push his concept of building without them - which is what originally lit the fuse, imho - and I'd like to think that Brent might, in the future, send a private message to someone if his sole determination is to sell his plans, rather than to answer a question.

    My final point: On the steelwork; not acceptable, but if Brent doesn't feel the need to improve, it will remain that way. However, he does not have the knowledge to give advice on welding & should get himself a few books from the library shelf, so he can research the information before offering his opinion. While this will probably be taken as a major criticism, by some, it is not. No man or woman can be all things to all people. No one is perfect and "knows all", and we all have our limitations. It is in humble recognition of these limitations and the desire to improve on them where we experience our greatest growth.

    Last edited: Aug 1, 2010
  6. Wynand N
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    Wynand N Retired Steelboatbuilder

    I did my apprenticeship as a Boilermaker and worked in a refinery (Sasol) as well as power stations where only top welds (X Ray) are performed by qualified welders and still I had seen a few of those weld failed where the pipes were sheared off on the weld. I spent a lot of time in the construction field and also seen welds failed, but never in my 35 years as a Boilermaker seen a plate sheared and the weld stayed intact....
    A chain is as strong as its weakest link and when steel is joined by whatever method, that would be the weak link.

    Most welds done by amateurs on boats are very suspect with only partial or no penetration at all, slag filled etc and with very high caps that makes welds in fact weaker and in NDT procedures would be rejected, even when done faultlessly by a professional welder. More worrisome is the fact that most of the welds are grind smooth leaving very little left.

    But perhaps Mike (WF), Ad Hoc and MikeJohns give us all more insight into welds as they are more qualified to do so rather than listening to the crap BS dish up. Im only a Boilermaker speaking from experience.

    Over 76800 views and still counting....
  7. magwas
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    magwas Senior Member

    Not exactly. Rules have been given us to make sure that the boats built to them are seaworthy. One can choose not to build for rules, going on one of the following two ways:

    1. Do the calculations which have been done behind the rules for himself, and choose safety factors to optimize for the design goal. I guess really serious racing boats are built this way. This way one will have a boat with known strength and stability, with a carefully decided risk built in.

    2. Do not do any calculations, just use common sense and rules of thumb. This is the way boats have been built for milennia. This way you can have strong and sturdy boats, but you will never know how strong are they actually. And common sense can also mislead you, especially when using a relatively new material (metal) with a new boat building technique (origami).(Of course "new" here is a very relative term, contrasting with the tradition of wood boat building.) When you take this road, you won't have any scientific evidence regarding to the strength of your boat, and you will have no arguments when hard facts are demanded.

    You have choosen the latter road, so heat from NAs who have been taught for many long years only to believe hard facts is understandable. However I don't think that name calling is appropriate from either side.

    This is why I strongly suggest to accept the offer for structural analysis. Everyone would learn from it.

    It is also interesting to note when I have decided to learn applying scantling rules in this forum, the same NAs were calling me names who now mocking Brent.

    (And when I wanted to apply them to a kayak, there were builders whom I truly respect who did not understand my motive.)
  8. Ad Hoc
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    Ad Hoc Naval Architect

    A jolly good experienced boiler maker i might add!:cool:

    MikeJ may be more qualified than I, since my expertise is in aluminium, not steel. However certain aspects remain.

    Some assumptions are required, to “generalise”, and I do stress “generalise”. For example, the steel is basic low carbon grade A type, it is not thermally or mechanically treated to improve its properties. It is also assumed that the correct filler wire is selected for the correct grade of steel to produce the same metallurgical steel as the parent metal, ie not a ‘composite’ as such.

    Additionally, it is worth noting even before you weld, that a rolled steel plate will generally have different properties in the longitudinal, transverse and through thickness directions. This affects the results too.

    Also assuming the welder is following correct procedures and that the welder is properly trained, thus the resulting weld is considered to be “sound”.

    Given the caveats above, testing is then conducted at what is called cross joint, or CJ tensile test. This is a test across the joint, from parent metal to HAZ to weld and back to the parent metal the other side, ie transverse to the weld. The cross joint strength is usually required to exceed the minimum specified UTS of the parent metal. In most situations the weld metal is stronger than the parent metal - it is oversized - so that failure occurs in the parent metal or the HAZ at a stress above the specified minimum.

    What this “oversized” means is that a weld that is not machine flat to the same thickness of the parent metal. Why is this important?

    Stress = Force / Area

    So, the more area, the lower the stress.

    Thus, if a plate is 6mm thick, but the deposited weld at the joint gives a total thickness of say 9mm thick, the total “area” of the weld is greater than that of just the plate, by 3mm or a 50% increase!. Therefore for a given applied load, the weld (assuming a quality sound weld) will be stronger, simply because there is more “area”. In simple terms, the local plate thickness has increased!

    The failure region is therefore in the HAZ – parent metal region. The reason being is the temperature increase during welding affects the final grain structure, it changes size and that the HAZ edge furthest away from the weld, has a lower cooling rate. Since the rate of cooling of this region is not the same as the original parent plate.

    So, going back to the Stress = Force / Area

    Whilst the HAZ-parent metal has the same thickness as the parent metal, it has lower hardness owing to the low cooling rate which in turn is shown by a minor change in the grain structure. Hardness is directly proportional to the yield stress. In other words, this outer edge of the HAZ has a slightly lower yield stress or UTS than the surrounding plate and weld. The welded joint shall crack here for the same applied force.

    (There is the CE or carbon equivalent forumla. This calculates the rate of cooling and thus predicts the hardening effcts during welding and is based upon the chemical composition. This is then affected by the: heat sink, heat input and metal temparture).

    Several points to note:

    A longitudinal weld test, the force is shared more equally over a constant strength of the steel, and produces different results.

    If the weld was ground flat, so the whole plate thickness remained the same, the failure is more than likely in the weld and/or weld-HAZ region. The reason being that all welds contain flaws be they minor or major, this cannot be avoided (this too is a whole subject in itself). It is only the shear “bulk” of the weld, ie increasing the “area” that saves the weld from failing first and thus failing in the HAZ-parent metal region. Unless of course the welding procedure is poor and the resultant weld is poor quality. In which case, no amount of “area” shall save it!

    But an over sized weld bead is generally not favourable….this gets into fatigue rather than normal static tensile stresses…again, a whole subject in itself.

    Basically welds crack owing to 3 main reasons:

    3…stress level and/or amount of restraint.

    And then that goes into another ever increasing field of explanations….

    Also worth noting that aluminium is different from steel, owing to the mechanical and thermal treatments that are readily used in aluminium plate/extrusions for fabrication. This has a significant affect on the weld strengths.
  9. Wynand N
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    Wynand N Retired Steelboatbuilder

    Thanks Ad Hoc.

    This is the type of reply that is informative and we can all gain from. A far cry from the explanations of BS or for that matter myself :eek:
  10. tazmann
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    tazmann Senior Member

    This reminds me of when I was a youngin and we were havin a family squable, Dear ol ma would jump in and say , you know son the more you
    stir sh** the more it stinks:)

    On the keel support and tank arangment you have in the drawing. The old system with the 1/2" x 4" flatbar webs you said after a hard solid grounding it got bent up into the hull. Your new setup IMHO you have added more support from the inside edge of the keels out to the chines but if you look at the end view drawing the inside edges of the keels and support angles stop, there is no support till you get down into the sides of tanks where the webs get wider. Now if you emagine the same forses that bent up the old design in the new one, Rather than being bent up into the hull it looks more like the hul skins will shear at the tank top along the inside edges where the angle supports stop?


    You mention the mast support. The one previos picture the support pipes were not tied into the webs and I agree it would be better tied in. Other than that it seams to me a pretty stout setup, I'm open for a friendy descussion on the subject pros cons

    Attached Files:

  11. junk2lee
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    junk2lee Junior Member

    Wow!That's perfect!'Way better than the wikopedia stuff I've been trying.
  12. wardd
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    wardd Senior Member

    No one here is allowed to die before this thread dies
  13. junk2lee
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    junk2lee Junior Member

    The gist I'm still interested in is the "I'm open for a friendy descussion on the subject pros cons" of this post I've quoted above
    The background I've gleaned:
    #221.Terholme posted photos of twin compression posts .Later,he added clearer pictures post #242.

    #255 Brent responds,
    "Each 2 inch sch 40 pipe is over 6 inches in circumfrence, which gives us over 12 inches of 3/16tgh plate, total, supporting the mast ,which at 60,000 PSI gives us over 132,000lbs tensile strength on the plate around the mast supports, far more than the 5/16th rigging, at a tensile strength of 12,000 each, plus the weight of mast rig and sails.
    .....etc then
    Tying the pipes into the topsides would make it a shear strength with the load spread over an even greater area, drasticaly increasing the strength , which as the above figures point out would be redundant."

    #257 Bubblehead...
    "First, AISC will have an allowable shear of about 20% of Fu if I recall. So you need to derate your material for that, unless you're OK with the yielding/deflections. This already puts you well below the loads you describe, even before 20-30 years of corrosion reduces the plate thickness further.

    Second, this is clearly a cyclic/fatigue loading condition and I suspect there should be further strength derating for that. It appears that the connection has this shear being applied entirely in the HAZ of the weld (and your calculations indicate likewise) and I believe this would cause unfavorable performance under fatigue loading."

    #259 MikeJohns
    "Just look up distributed load verses point load and then go and calculate the shear stress in that plate. Post back here what that stress is and I'll tell you how many cycles you'll have to failure "

    So, I assume that the column or columns are not of concern and that these as described will not buckle. Also can't the 20-30 years corrosion mentioned above be ignored for now...the HAZ is also about RESIDUAL stress too,I've read.I don't know how great that would be in steel or how large HAZ would be so close to the hull but whichever,I see that Bubblehead is mainly concerned with a shear load failure and MikeJohns says" calculate the shear stress in that plate"

    My most important question boils down to whether real-life cracks would show after "x" fatiguing cycles-does this appear as a crack in the hull near the weld of the pad?.The water will come in!Would dye show these beforehand??or if there'd be an easier-to-spot deformation of the hull?
    Further argument naturally might ensue:
    The cyclic load is a hard one for me-Which circumstance comprises a fatiguing load? (being "beyond the material's elasticity to return to full strength")-There'd be a lot of this-and that about wind,wave and all so Wouldn't it be easiest to just figuratively drop the boat on her masthead "x"times because the forces would then be agreeably large and since the concern here is only about the posts+pad+hull,the direction of force through these can only be along it's vector,whatever is happening outside...edit add-although this idea is a bit of a stretch because it involves BOTH struts !a sailboat motoring..
  14. troy2000
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    troy2000 Senior Member

    We'll live forever......

  15. wardd
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    wardd Senior Member

    As a non boat builder I have a question, can origami boats be built fundamentally sound and what would it take?
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