The perils of edgy design offshore

Discussion in 'Sailboats' started by CutOnce, Jul 18, 2011.

  1. Willallison
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    Willallison Senior Member

    Gary.. I think the point you are missing here (well, one of them anyway) is that it's not so much that we (assuming it's not just me of course..) object to those who want to tear off into the distance in whatever craft they choose. In fact I would be the 1st to vehemently defend their right to do so.
    It's the fact that others are put into a life threatening situation in order to come to their rescue when it all goes pear-shaped.
    It's a bit like the bushwalker who wanders off into the distance with nothing on but a pair of shorts and thongs and then expects others to come to his rescue when he gets cold and lost....
     
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  2. Gary Baigent
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    Gary Baigent Senior Member

    That is fair comment Williamson ... but the lore of the sea, the unwritten code, is that you look after someone in trouble ... and that can go two ways, or more, because plenty of people on light displacement boats, like me for example, have picked up crew in the water, fallen/thrown from wildly oscillating heavy displacement boats getting out of control downwind. If ever there was an unsafe boat, it is that type. Just IMO of course.
    Having said that, I'm not advocating people sailing offshore expecting others to come to their rescue if they do foolish things; in fact just the opposite ... and Ad Hoc's comments regarding Mini-Transat boats sailing off willy nilly, relying on technology and other vessels at sea if they get into strife, is just smoke screen nonsense.
     
  3. Willallison
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    Willallison Senior Member

    Nothing unwritten about it....it's international maritime law.
     
  4. Ad Hoc
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    Ad Hoc Naval Architect

    Ok…in your designs what sea and wind conditions do you design to??

    And once you have done this, how do you then confirm that the boat satisfies these conditions?
     
  5. Gary Baigent
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    Gary Baigent Senior Member

    By sailing them and observing how they handle the conditions, of course. I've broken foils and rudders (hitting the bottom at speed) and dropped masts when rigging stays gave way, learned the hard way, empirical knowledge, beefed up this and that, sucked and seen. My stuff is experimental but I've done enough miles to know what is going to work or not. Also, in no way do I design and build for the populace - if someone wants one of my designs, they're warned that the boats are light and definitely edgy.
    Having said that, the Kiwi 35 is actually a pretty old design now, and obviously the boats have done plenty of miles for them to be understood, their good, and not so good points being revealed. All boats are a compromise ... and if you race, you definitely gravitate towards "edginess." I've done some miles on the ahead-of-its-time Young Rocket 31 Positive Touch and Jim designed this boat for harbour and close to shore sailing with almost a league team for crew weight (not dissimilar to K35)... but owners have done hard Coastal Classics and Auckland/Tauranga races plus a couple of trips to New Caledonia. And his more extreme Extreme version with 17 foot beam has a similar life CV. Also there are numbers of Greg Elliott designs of similar ilk here. And the point I'm making is that they are all edgy but they are handled by expert kiwis ... and like the Mini-Transat designs, they have stood the test of time; there have been problems but nothing seriously bad has occurred. That is why I defend the K35 crew; it was their choice of boat type, they knew it well ... and I believe they were "unlucky" to be in the horrendous climatic position that they found themselves in. This could happen to anyone ... safe, heavy boats too; we all know that numbers of them have disappeared.
     
  6. Ad Hoc
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    Ad Hoc Naval Architect

    Ok….i understand, it is a trial by error based design, rather than a technical based validated at sea.

    Nowt wrong with this approach but…the trouble with this approach is, you haven’t a clue what is the maximum conditions your design can put up with before failure, until you encounter it, and by then it is too late. And then you cannot say design XX is good or bad, nor compare one design against another on this basis, because it is all personal opinion and subjectively based not a rational stochastic and engineering based approach, ie naval architecture!

    Naval Architecture is the foundation of a design knowing before you even get the bottom wet (not just drawing and hoping for the best), whether the boat is at least half safe or not...and what is the expected maximum conditions. Sea trials are simply to validate the design SOR.

    A simple GZ curve for example, will tell you if you put the boat in the water will it float will it float up right and will it be able to right itself under a heeling moment. This is not rocket science and nor is it “awe shucks, you’re taking the fun out of this “edgy” design lark”. Without a few basic checks you’re playing with fire, in the name of “gambling” and “edgy designs”..when you haven’t a clue what it is your gambling with.

    As this guy found out to his peril:
    http://www.bbc.co.uk/news/world-asia-pacific-14386092

    Hubris and pride come before fall.

    Without an SOR you’re wallowing around like a leaf on the breeze hoping it sticks to something to say hey…this is it! With such a lackadaisical attitude you have no grounds to pontificate to others about gambling with their own lives based upon your own misplaced sense of fun and gambling and trial by error of a limited sample of your "design" experience.
     
  7. MikeJohns
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    MikeJohns Senior Member

    The following is smoke screen nonsense


    All you are observing is that a poorly designed uncontrollable heavy boats are uncontrollable! Then the grand fallacy you extrapolate based on that observation is that since they were heavy that must be why they were uncontrollable! Why not because of the color of the hull? It would be just as sensible as your theory.

    Unsafe poorly controlled boats of any displacement result from racing designs driven by rule cheats. I have no doubt you've encountered them in light as well as heavy forms.

    The Sparkman and stephens rainbow 2 was a good illustration of a heavy monster you'd agree? Certianly by the time the owner had bastardized it from Rod’s design it was a monster but a clear winner on its allowed rating.

    Is this really the sort of boat you would hold up to illustrate characteristics related to displacement ? .....Apparently it is. http://outrig.org/multihull-stories/light-brigade.html

    You shouldn't take a poor example and ignorantly extrapolate generalizations. This just compounds ignorance. You are basing your opinion on a statistically limited sample of abysmal designs, chosen to suit your viewpoint and that’s just not sufficient. Then you lack the knowledge to see why your observations really are flawed.

    So are you really interested in learning anything that might differ with your preconceptions, or are you entrenched in a belief system?

    Unless you either specifically learn what makes a boat controllable ( AKA Naval architecture ) or directly experience a controllable heavy displacement boat you won’t know otherwise. You will continue to lack any basic understanding of the subject outside of a very myopic view and apparently a very limited experience.

    It's important that you realsie that simply because you might be a self taught expert on a very narrow range of craft types doesn’t make you an expert on anything else, and you are definitely not an expert on heavier displacement hullforms. The sooner you realise this the sooner you’ll stop misleading people

    Belief systems have no place in Naval Architecture nor does willful ignorance.
     
  8. Paul B

    Paul B Previous Member

    It appears Wingnuts had a SI of 100.7 after the mods (shows with the Asy).
     

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  9. Guillermo
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    Guillermo Ingeniero Naval

    Yeap! :)

    Rules are never totally perfect but are conceived to increase safety and they always evolve from experience.... usually sad experience related to disasters, may I say. This is how it has always been and will keep on being in this growingly crowded world.

    Of course one should be allowed to design and build whatever one wants and sail it at his/her own risk, but one should not be easily allowed to put the life of others in risk, including the life of rescuers. This last point of view should not be forgotten.
     
  10. MikeJohns
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    MikeJohns Senior Member

    Thanks for that.

    So the limit of positive stability (LPS\AVS) is as designed, at just a touch over 100 degrees ?
     
  11. Doug Lord
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    Doug Lord Flight Ready

    Perils of Edgy Weather in Any Boat

    ===============
    "B", where did you get that info? How current is it? Does it reflect the added ballast and carbon mast?* Thanks.

    * There have been at least two mods mentioned in various threads:
    1) removal of ballast and added SA,
    2) addition of ballast and added carbon mast.

    ===================
    See post 190: Wingnuts was required to have a valid ORR certificate in her race category. The ORR regulations state that entry "may be limited on the basis of her stability index at the option of the race organizer".
    I've written the Chi Mac authority regarding this because if the above SI is accurate for the boat in the race then the ChiMac authority must have
    waived the stability index requirement for Wingnuts since under ORR:
    Offshore Race Categories(SI)
    0-120
    1-115
    2-110
    --------------------
    My effort here and in post 190 is to try to ascertain facts , as much as possible, and to differentiate them from the rampant speculation abounding in this thread and other threads. Thats why it is important to have links to information such as the quoted SI for Wingnuts and for other information as well regarding purported modifications.
     

    Attached Files:

  12. CutOnce

    CutOnce Previous Member

    Doug:

    The Internet is just not a reliable enough source of information to be able to further investigate this tragic event and reach conclusions. It's like trying to reconstruct a complete dinosaur from digital pictures of random tiny bone fragments from random dig web sites. It may be possible to guess what the dinosaur looks like, but in all likelihood the rendering is wrong.

    Asking the CYC for information on an open investigation where their own liability is a question is going to produce zero results. Especially regarding specific exemptions from NOR rules. Their lawyers will have instructed all staff to not respond to anyone except the appointed review committee and law enforcement at this point.

    I think the speculation that Wingnuts was on or across the line regarding safety/stability criteria is probably right, but the likelihood of anyone clearly admitting that is low. Since the crew, club and race all probably have little interest in apportioning blame and seeking financial damages it may never be spelled out. The Morley family and friends don't want to blame the club or race. The Club and race aren't looking to punish the Morleys.

    --
    CutOnce
     
  13. BATAAN
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    BATAAN Senior Member

    I'm very glad the point has come up about "need to be rescued". In my USCG small boat time we were forced every weekend to tow at least one, and sometimes many, racing sailboats from the open ocean to safety, due to downed masts, broken rudders etc. They used to treat us like a tow truck financed by the city, just call at the least problem, and we risked our lives to save them from their folly brought on by boredom, poor preparation, need for speed and desire to impress others. Present CG policy no longer gives a tow but they call an expensive towing service for you. Big improvement I think. Still, if you go racing, cover your own butt and don't make others risk life and property for your hobby.
     
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  14. CutOnce

    CutOnce Previous Member

    AdHoc:

    Your posts are right on, although a few words of defense for trial by error design. Trial by error is what I like to refer to as reality-based, and adhering to design standards is best described as theory-based.

    Theory is accepted practice, and forms the foundation for professional designs that follow. That is good, but you have to acknowledge that most mathematical equations are developed forensically from observations of real world behavior. Document enough data, derive the patterns of that behavior and develop an equation that fits the behavior and reproduces the results across a range of conditions. Validate equations against the real world, and then use the equations to predict behavior of new designs.

    The problem with theory-based design is that very few to no breakthroughs happen to change design paradigms. By staying inside the safety fences of the equations and theory, potential for discovering problems with those theories is also eliminated.

    Here in Canada, the designers of the Avro Arrow encountered control issues with delta shaped wing leading edge designs - as they were working within the established design theory and practice of the day. The theoretical/mathematical tools to experiment were lacking, and the equations of the day lacked sufficient sophistication to predict and solve the turbulence and drag issues demonstrated. The lead engineer at the time tried various designs that radically departed from accepted theory - and with testing one of these designs showed breakthrough gains in performance and stability. Reality-based design succeeded where theory-based design failed. Once the new designs proved a success, new equations were developed to fit the new hypothesis, and future developments have moved forward from that point.

    Notably, just about all ground breaking designs come from amateurs - as professionals generally tread on ground already broken by amateurs.

    That being said, my money goes to professionals as the risk level and failure percentage is much lower.

    In this particular case, an originally edgy design had evolved over many years to incorporate new materials (carbon spars, asym, carbon prod, sails etc.) and greater familiarity with sportboat performance. It would be interesting to see if the original designer was consulted regarding the cumulative updates - and given the opportunity to evaluate their effects on the original design premise and numbers.

    --
    CutOnce
     

  15. Paul B

    Paul B Previous Member

    SI is not LPS. LPS is a component of SI. To get LPS from the stated SI you would have to have the input measurements for the formulas and work backward.

    I don't plan to do this. I don't have the measurement form for this boat. But given the formula for SI I would imagine the LPS is less than 100 in measurement trim.

    Sailing trim would drop that number even more, especially with things like a headsail furled on the headstay.
     
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