Origami steel yacht construction

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

Thread Status:
Not open for further replies.
  1. pdwiley
    Joined: Jun 2008
    Posts: 1,004
    Likes: 86, Points: 48, Legacy Rep: 933
    Location: Hobart

    pdwiley Senior Member

    You don't read very well, do you? I clearly stated that the Colvin Witch design, in its 34' version, had a design displacement of 14,104 lbs and that the stretched 38' version had a design displacement of 15,740 lbs.

    Note: design displacement. Would you like me to post some photos of the designer's title block and signature, where the basic sizes & weights are specified?

    BTW the designer also specifies what the expected increase in draft is when the hull is loaded with a tonne of stores. How much does your 36' design displace when loaded with a tonne of stores? You can't actually tell, because you don't have the lines & offsets to calculate the actual displacement and increase in displacement with load.

    My hull plate isn't 10 gauge either, it's 4mm. As for posting its weight, sure, when it's done, I'm happy to do that. I'm willing to bet that it comes in at less than 10% variation from the design weight (but, if you have the 'huevos' to accept the bet, I want someone independent to hold the stakes). Not sure exactly what you think it'll prove though. How over design weight would I need to be, before it got to be as heavy as your design?

    Your own book says your 36' design displaces well over 17,000 lbs and at least 2 builders say the as-built versions displace over 20,000 lbs. That shoots really big holes in your assertion that a framed hull is heavier than a Swain origami one. I could use your own behaviour here and call you an outright liar, but I won't. You might be honestly mistaken. Once.

    Tom's Witch designs (and the Gazelles) are pretty distinctive in terms of their profile and it's relatively simple to tell if they're floating more or less on their DWL by looking at the amount of clearance between the bottom of the transom and the water line. There have been over 120 Witches built, mostly by amateurs, and over 700 Gazelles built.

    Tom numbers all his designs and the plans for ANTELOPE (probably close to the last new design he's done I think) show design number 203. That's 199 more than you and I'll ignore the minor variants of Tom's, such as my stretched Witch.

    Bernie Harberts did a circumnavigation in a Witch. Here's a URL for the curious:


    Here's his account of hitting a wreck all standing.


    I've got accounts of other ones hitting rocks in the Great Lakes and other places, none of them got holed or took on water. There was an aluminium Witch washed up on a rocky beach in Nova Scotia after its owner was taken off by the Coast Guard, it had a dented in chine but no holes or tears. I've been aboard a Ganley 29' single chine design that got put on the beach by its owner and it had a dented port side along the chine, no hull tears. That one was really weakly built too, the plate was 1/8" and the longs 1/2" square bar set as a diamond profile. It suffered bad frame buckling - the frames weren't welded to the hull plate.

    Metal is inherently forgiving of navigational errors, nothing special about the origami hull.

    As I've posted in the past there's a Van De Stadt design in steel that displaces 5.4 tonnes according to the Web site.


    Perhaps these people actually know how to use materials to best advantage and minimise excess weight rather than load it into the hull plating?

    It's apparent that what you have is a hull shape that sails well, but you don't know why, you can't answer any questions about how it works in any engineering terms, you can't show any math at all and you can't produce any changes to it (except maybe by trial and error). It's also apparent that while the 36' hull shape has remained more or less static, the interior reinforcements & structures have changed over time in response to as-built problems, and the 'new' design becomes 'the' design, negating any & all past issues. You can say what you like about the mast support design in MOM, nobody with even a basic idea of loads and fatigue would EVER put those loads directly on the shell plating. It's stupid.

    I contrast that with the design that I've decided to build, where the scantlings and build plan have remained relatively unchanged from the original design - the only changes have been in minor material sizes to reflect what one can buy today (eg, 32x6 flat bar rather than 35x6 flat bar). I've never built a boat before in my life and this design is going together just as the plans said it would. I'm not an engineer, I just build to the plans. I'm happy.

    Show some huevos, Brent - as you say. Allow Mike Johns to analyse your plans and see how they stack up structurally. What are you afraid of?

    I predict another totally off-point rant now rather than addressing what I've written. Ho hum.

    1 person likes this.
  2. terhohalme
    Joined: Jun 2003
    Posts: 512
    Likes: 39, Points: 28, Legacy Rep: 506
    Location: Kotka, Finland

    terhohalme BEng Boat Technology

    This is deck stepped mast. The mast arc is supported only by this pillar (and its pair on the other side). There are no strong beams across the boat at the mast. After this there is a picture of painted inside just before foaming, and it looks like there is no other structure here. There isn't also any mark of the strut welded to frame.



    Attached Files:

  3. LyndonJ
    Joined: May 2008
    Posts: 295
    Likes: 19, Points: 0, Legacy Rep: 233
    Location: Australia

    LyndonJ Senior Member

    Not the technology, it's just a building method and you should know the difference.

    Since your conversion to admitting errors and saying it makes you a Napolean no less you'll have no trouble seeing your errors now eh?

    12% ...............common knowledge to whom? 12% is an increase of 1.12 and if the mass and loads go up approximately proportional to the length squared....... 1.12 times 1.12 is 1.25 which is around 25% more load on the structure.
    25% Lets play nicely and say 20%

    You'd better be real sure you had that extra to start with.

    How did you ensure the factor of safety when you hate calculations and math and engineers and can't use computers except for spamming forums, and won't follow guides written explicitly for people like you ?

    The answer is of course that you can't, you havn't and you will never be able too, you've got no more idea of the collapse depth of your hull for example than the people you convince to hand over their $$$

    You cant even give them a stability curve or table of offsets, and every engineering argument you used turned to mush, now you're clinging to potential wreckage.

    Trial and error.....you said it :mad: The error occurs when the error occurs right? Then and only then do you admit it.
  4. junk2lee
    Joined: Jul 2010
    Posts: 76
    Likes: 2, Points: 0, Legacy Rep: 18
    Location: Canada

    junk2lee Junior Member

    Thanks for the link and the better picture,terhohalme.Again,I don't like the LOOK of that myself.If I were building this I wouldn't do it thataways.But whether it'll buckle or dimple the hull or sink the ship is unknown to me.Maybe nothing at all.It agrees with the aforementioned difficulty of a homebuild design.They are uncontrollable.Anyone can do anything with a Swain,a Colvin,a Hannah,foam it over,and then the designer gets the heat because the boat looks like theirs.What about the Builder who Interprets the plan?...There's plenty of grist in that mill but these folk apparently had coffee with Brent and not much more.
  5. Tad
    Joined: Mar 2002
    Posts: 2,309
    Likes: 192, Points: 73, Legacy Rep: 2281
    Location: Flattop Islands

    Tad Boat Designer

    Francis Kinney has been dead for 15 years....it's time to let it go.....

    Calculating the real weight of any boat....use the Naval Architect's method

    You do this by measuring the flotation.....assuming the boat is built to plan....measure from the sheer to waterline at stem, stern (P&S), and amidships (also P&S). Draw this new (actual) waterline on your lines drawing. And using the Trapezoidal Rule, or Simpson's Multipliers, or a computer, calculate the actual displacement. Then measure the specific gravity of the water the boat is floating in and calculate what she really weighs.....don't trust any scales, don't believe stories from others...do your own work. Make sure to note the load condition when you measure flotation....how much fuel in the tank, water, gear, people aboard, dinghy aboard, etc.
    1 person likes this.
  6. bearflag
    Joined: May 2010
    Posts: 227
    Likes: 17, Points: 0, Legacy Rep: 195
    Location: Thousand Oaks, California

    bearflag Inventor/Fabricator

    Integral calculus, algebra, known volumes and mouse clicks

    I'm not sure if Brent has the (rudimentary) Math or Engineering skills to follow Archimedes Principle... you would after-all have to know the know the volume of the hull to figure out the weight in open water. And to do that you would need to have the lines...
  7. LyndonJ
    Joined: May 2008
    Posts: 295
    Likes: 19, Points: 0, Legacy Rep: 233
    Location: Australia

    LyndonJ Senior Member

    That part (the posts landing directly on the plate) is Brent's design 100% and built as designed.

    The continuous lower framing is actually Brents older design but people feel more comfortable with it than his newer one which is atrocious design since it has another in-built failure mechanism.

    There's numerous other cock ups in his plans too. And never any calculation of adequacy. He also made a few wrong assumptions on the strength of the longitudinals and got the whole arch curve analogy wrong.

    That's why the debate gets hot, people say to Brent "that's really poor" and he says it's perfect and that they should go back to kindergarden or that it's new technology. So they prove it's poor and he attacks engineering as a process. Even lies to cover his ***. He likes to say they are too stupid to understand his structure:rolleyes:

    He never says " you got a point oops" he just points to the Titanic or the space shuttle and says he knows better than to use an engineering process.

    So it's great that even a neophyte with common sense thinks it's poor ;)
  8. Brent Swain
    Joined: Mar 2002
    Posts: 951
    Likes: 35, Points: 0, Legacy Rep: -12
    Location: British Columbia

    Brent Swain Member

  9. Brent Swain
    Joined: Mar 2002
    Posts: 951
    Likes: 35, Points: 0, Legacy Rep: -12
    Location: British Columbia

    Brent Swain Member

    I just posted along reply. 90% was deleted
  10. junk2lee
    Joined: Jul 2010
    Posts: 76
    Likes: 2, Points: 0, Legacy Rep: 18
    Location: Canada

    junk2lee Junior Member

    words in my mouth?

    whoa.I said I didn't like the look of it and that I would do it differently but I also that I can't imagine the condition of failure for the pictured strut+pad.

    Because nobody has had a failure there that I've heard of.
  11. Jeff
    Joined: Jun 2001
    Posts: 1,368
    Likes: 71, Points: 58, Legacy Rep: 923
    Location: Great Lakes

    Jeff Moderator

    (Just to be clear, your 7:53 post was not moderated in any way. It's always possible a technical glitch occurred, and if so, I am sorry. It should not be possible to truncate a post due to tag errors, but possibly if you went back in your browser and edited a previous version, or possibly if you posted at the very moment when a server was being restarted.)
  12. Ad Hoc
    Joined: Oct 2008
    Posts: 7,276
    Likes: 1,165, Points: 113, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    I wouldn't hold your breath waiting!!

    Now do you see the point..?
  13. Brent Swain
    Joined: Mar 2002
    Posts: 951
    Likes: 35, Points: 0, Legacy Rep: -12
    Location: British Columbia

    Brent Swain Member

    While my past posts repeatedly state that my smallest design is a 26 footer the reference to a 21 footer keeps coming up. I believe that is called Dyslexia. So how reliable is the math and judgement of a dyslexic?
    I have never been critical of Dudley Dix as I have never seen any of his designs.
    Mike Johns keeps asking questions that I have repeatedly answered in my posts. It appears when he reads a post , he only sees about 20%, if that , the rest he misses. I've repeatedly stated that I begin with a set of lines , yet he continues to be unable to read that part, stating that I don't start with a set of lines. If we apply the same logic to his designs then neither does he use a set of lines, as, given that they are not posted here, they don't exist.
    Mike also has a mental block in understanding that the greatest load on a rig is only as great as the breaking strength of the three windward shroud, plus the weigh of the mast and rig and a little help form the forestay and backstay, altho they wont keep the mast up, without the three windward shrouds. Some have problems understanding how the mast support , 4 inches of 1/2 inch plate, with a compression strength of 120,000 lbs, suppoprted by a couple of four foo tlong 2 inch sch 40 pipes, is stronger than three windward ,shrouds with a total breaking strength of 36,000 lbs.
    I believe that is called attention deficit disorder, or ADD For short. So how reliable are calculations by someone with a mental affliction like ADD?

    <removed - personal attacks are not called for>

    While we are at it, could you give us a rough estimate of what you charge your clients for a 36 ft hull and decks with wheelhouse ,keel , rudder and skeg, tacked together with handrails, tankage , lifelines, deck detail, engine mounts,hatches , mooring bits chocks etc. Maybe Mike and some of the others could also give that info.
    Could you also tell us how many of your clients have been able to get a 36 sailing for under 15K, or under 30K for that matter.
    Its interesting that the keel supports in the photos which you advocate are the ones that proved inadequate, and the ones in the drawing, with which the green 36 in the photo has hit rocks at hull speed, without any damage , is the one you are so critical of. Proves your claim that you haven't learned anything in the last 26 years.
    Is it wise to hire a designer or builder who claims he hasn't learned anything in the last 26 years?
    The offer, by the guy with ADD, and the guys who claim they haven't learned anything in the last 26 years, to do a structural analysis , reminds me of a story about three people in a room debating the old formula, 1 plus 1 equals 2.
    The mathematician said "Absolutely true , 100% of the time. The lawyer said "Well, it would depend on the circumstances." The accountant ran to the window, pulled the blind shut , ran to the door and locked it, then turned around and said"What would you like it to be?"
    Any analysis done by Mike would be modified to match what he would want it to say.
    It has been stated that the mast should not be supported by hull plate.
    When there is no keel under the mast, as in twin keelers, what supports it , when it is stepped below decks . Water? No. Air?No. Faith in allah? No, Karma? No. The hull plate? Bingo! You got it right on the fifth try.
    You say floors. What supports the floors? Hull plate? Bingo again! Man you are getting good at this!
  14. Bubblehead
    Joined: Jul 2010
    Posts: 7
    Likes: 1, Points: 0, Legacy Rep: 30
    Location: Southlake TX

    Bubblehead Junior Member

    Perhaps you could enlighten us with your punch-through calculation for this support

  15. Brent Swain
    Joined: Mar 2002
    Posts: 951
    Likes: 35, Points: 0, Legacy Rep: -12
    Location: British Columbia

    Brent Swain Member

    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.
    We have put the side decks of a 36 under water ,without the lee shrouds slackening in any way. Not many boats can do that. The maximum loads you can put on it, before the shrouds break, are nowhere near the strength of that mast support.
    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.
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.
Thread Status:
Not open for further replies.