ISO 12215-5: 2019

Discussion in 'Class Societies' started by TANSL, Oct 12, 2019.

  1. JotM
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    JotM Junior Member

    You did issue your comments during the public review period then, did you?
     
  2. JotM
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    JotM Junior Member

    I'm under the impression ISO/TC 188/WG18 has gone in the same direction the Eurodes on construction have gone: there still is a possibility to use the (now called "simplified") method in Annex A, but when needed a more elaborated (and more costly) method is available for optimization of the design.
     
  3. TANSL
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    TANSL Senior Member

    There is no doubt that the "practicality" of the standard has completely disappeared. As an example you can see the procedure to calculate the dimensions of the panels, in Annex A: it is a real nightmare.
    I have not been able to detect the errors that Alik comments, although I have differences in formulas that apparently should be the same (see pressure on the side for a sailboat). I have seen, however, that in the Spanish version there are even translation errors. It therefore seems that the standard has been written with total disregard or neglect of the end user.
    The bad thing is that the organization, very satisfied with Mr. Soupez's work, continues to commission him work :(
     
  4. Alik
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    Alik Senior Member

    Yes I did, but probably should have insisted more.
    Interesting to note, that Wolfson Unit still did not release the update of HullScant to the -5:2019 version, I suspect due to the problems they have with making it work.

    Actually I was in the group for ISO12215-7 for multihulls and I did detailed review on that standard. Thus, now -7 it has been dropped, because there were way too many problems, namely detected by us for power catamarans calculations.
     
  5. Alik
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    Alik Senior Member

    In fact, number of manhours required to design a recreational boat has increased dramatically. Say, for stability under ISO12217 now we have to analyze 7-8 load cases; while on commercial boat of that size only 3 cases. The Clients are not willing to pay extensive engineering fees. For us, being in Asia it is getting more and more difficult to convince the Clients that they should invest in design and build certified boats. European Clients are also looking for shortcuts. At the end of the days these are just small craft where design budgets are limited by value of the boats. In these terms, heavily sophisticated standards reduce the safety, not improve the safety.

    I also believe ISO is interested in selling more standards, again and again. This is why they change them so often!
     
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  6. JotM
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    JotM Junior Member

    I was wondering about that. You are referring to the ISO/FDIS versions of 12217 that have been published for comments I presume, right?
    Have you by any change seen 12215-10, that is supposed to have been published last month?
     
  7. Alik
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    Alik Senior Member

    Regarding stability, I have published a paper:
    Nazarov A. Small craft freeboard and stability: approaches to assessment and perspective improvements// Transactions of RINA, Vol 159, Part B1, Intl Journal of Small Craft Technology, Jan-Jun 2017
    Most of problems are indicated there; standard writers can read and act (if they wish!).

    Regarding 12215-10, I am not into that. Of sailing boats, we are designing only catamarans now.

    Actually, presently I am not keen on joining the workgroups or involve in lenthy discussions and verification of the standards. It takes a lot of time, and there is little or no revenue. We concentrate to practical design work, and findings and proposals for improvement we publish in research papers/conferences. Yes, often classification societies and other organizations ask us to review the rules.

    On other side, once we receive rules and standards for review (especially for structure), I always require calculated samples from the rule developers, so we can check them without guessing what is what, and searching the omitted values and formulas. In most of cases, they will not provide calculated samples - so, check it yourself first, guys! My attitude now is: 'no samples - no review, sorry!' Or it should be paid work to check...
     
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  8. Ad Hoc
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    Ad Hoc Naval Architect

    All standards/rules no matter who produces them (ISO/LR/DNV-GL etc etc) require real-world input. Since the rules are only as good as those that can review and evaluate them for errors/omissions/unworkable solutions. Any changes/modifications require this real-world feedback from either in service experiences and/or errors being noted by others using the rules. Just like any computer programme - it requires a dedugging from actual users.

    If you're unwilling to particulate in the review and critique of the rules, prior to publication, you can't really criticise them for not "listening" to real-world usage.
    Change can only occur if you are willing to participate in the discussions and debates.

    That's perfectly fine...but you can't then in the same breath criticise them if you're unwilling to assist the reviews.
    One provides the critiquing and reviews out of a sense of for the greater-good of advancement, so to speak, rather than for any personal gain or profit..
     
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  9. Alik
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    Alik Senior Member

    Why I can't criticize? I perfectly can, irrespective I participated in the review or not. This is my natural right.

    The problem with reviews is: they give bare text with all errors, and most of them never give theoretical background and calculated samples. DNVGL sending out HSLC rules, where some formulas and values are 'forgotten'. How one is supposed to review it, if we can't even calculate the sample ourselves?? Review of complex rules, such as for composite structures, would require us to program the calc methods, validate and see what is happening - huge job!

    The writers get paid for writing the rules. Why the reviewers should not? ;) I have other things to do for fun, rather then review rules and standards with plenty of errors, and also guessing the 'hidden' formulas and values.
     
  10. Ad Hoc
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    Ad Hoc Naval Architect

    No one is saying or even suggesting you can't. I've no idea where you get that position from.
    Anyone can criticise anything.. that's rather obvious i'd say. :rolleyes:

    However, there is a difference when one criticises and actively participates to correct what they consider to be inaccurate or wrong, and those that just merely wish to criticise for the sake of it.
    One leads to progress and refinement the other, ... does not.

    If one is starting from scratch, then yes it is... no one is suggesting it is not.
    If one has experience and knowledge of said rules and their application ... much less so. And that is the MO of reviewing new rules.

    You know full well why not :D... it leads to the obvious bias and nullifies the Independence and impartiality of the reviews! :(
     
  11. Alik
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    Alik Senior Member

    So, look at joint HSLC Rules of DNVGL, they are basically written 'from scratch', so we have to program all these complex matrix operations for composite analysis first... And they never came up with calculated samples, so reviewers can't really see the results are. So, the rules remain quite crappy, I don't think anyone is using them for composite boat design, and they are NOT usable for fast small craft.
     
  12. Ad Hoc
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    Ad Hoc Naval Architect

    Ive been using the "new" DNV and now DNV-GL rules since they were first introduced back in 1991. The rules have subtly changed over the years the major one being in 1996 and 2016 in terms of derivation of pressures - but ostensibly the same format... they are certainly not - from scratch. Just minor mods over the years, from in-service feedback. Which is the point of reviews and to critique by others...

    In terms of the composite section, this has changed since the DNV-GL link up. But at their core (no pun :D) the basis of the rules remain the same.
    The only difference is, in the absence of coupon testing and actual values, you just need to do more leg work up front..

    No one is forcing you to use them...that is your natural right :p
     
  13. Alik
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    Alik Senior Member

    We are designing advanced composite craft fast and for those boats the new Rules are not workable, in terms of loads, too. Composite analysis method introduced in 2016 is completely new for DNV.
    I have official letter from DNVGL office advising against using those new rules for fast craft...
     
  14. Alik
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    Alik Senior Member

    This is exactly what we are doing. Rules not workable - bye-bye to this class, they lost the client :p
     
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  15. rxcomposite
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    rxcomposite Senior Member

    I guess this question should be directed towards Tansl and Alik who are practitioners of ISO.

    1. In the bending moment formula, the unit is expressed in Nmm.mm2 (table H2). The derived unit is N.cm.

    2. In the in plane modulus G for WR, it is given as 5100 N/mm2 (5.1 GPa), just about right. For UD, the formula gives 37.5 N/mm2 (0.037 GPa), quite low. Typical values for EGlass is 5-6 GPa.

    While this value is not used in the tabulated sheet, it is critical in predicting the values of off axis fibers such as biax,

    3. In the Biax tables, it is listed as in plane modulus, it is calculated as 0.45 of WR tensile modulus (6300 N/mm2). In Engineering Constant method it is usually referred to In Plane shear modulus and is a multiple of G. Typical values are 1.2 to 2.5X depending on fiber type and weave. Thus if G is 5 GPa, value should be between 6.0 to 12.5. The G goes UP (so does the Poisson’s ratio) as the fiber is rotated from 0 degrees.

    I am interested how this was rationalized.
     
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