The perils of edgy design offshore

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

  1. sharpii2
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    sharpii2 Senior Member

    Where did you get this quote?
     
  2. Ad Hoc
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    Ad Hoc Naval Architect

    Will

    May be so, BUT, If you look at the RORC, they make it clear the onus is on you, the owner. Ergo, if you want to race, get the boat checked out. Once done…it is clear where you can or can’t go. No need for chopping about with different race locations.

    ”..When the data is available, either as STIX assessed by a notified body or as IRC STIX calculated by the IRC Rating Authority following submission of data by a boat’s owner, STIX and AVS will be printed on each boat’s IRC certificate. In a similar manner to SSS, STIX or IRC STIX is a number representing the perceived 'seaworthiness' of the design, with again a higher value reflecting a more 'seaworthy' boat.

    Each boat's STIX or IRC STIX is calculated in accordance with ISO 12217 Part 2 by the combination of factors related to dynamic stability, inversion recovery, knockdown recovery, displacement-length, beam-displacement, wind moment and downflooding, using the following data and methods…... Owners are responsible for the supply of righting moment data from a source acceptable to the IRC Rating Authority in the form required by ISO 12217, Part 2, Paragraph 6. In addition to IRC STIX, certificates will show the angle of vanishing stability as calculated by the boat’s designer or other qualified person…”
     
  3. Willallison
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    Willallison Senior Member

    Yes... fair point... the solution is to adopt the correct regs in the 1st place....
     
  4. magwas
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    magwas Senior Member

    If you can design a monohull within the Mini rules which does not right itself in a sea which have capsized it, then my hats off to you.
    Note the rules for water tightness.
    And I think that any serious designer would design a boat this size and intended usage with the assumption that it WILL get breaking waves greater than the boat, and WILL capsize. So a design goal should be that a capsize should not be a serious issue: no one should be harmed, the inside of the boat should be dry, and the boat should right itself without any effort from the crew.
    These goals can be achieved with a conventional mono, but not with a cake pan. I believe this is a fundamental difference, and stability is a crucial ingredient here.

    With a big enough cake pan, you could go for the multihull way: accomodable when flipped. Although the facts that a significant proportion of the crew would probably be outside when the flip occurs and due to the design it can be a violent one, I still see a lot of risks here.

    Also notice that
    - there are rules meaning that you cannot just go out to an offshore race without experience with this class
    - there are a lot of flotation required
    - there is a requirement for a safety hatch which is above the waterline in al positions.

     
  5. CutOnce

    CutOnce Previous Member


    Here.
    Second comment down.

    --
    CutOnce
     
  6. daiquiri
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    daiquiri Engineering and Design

  7. Guillermo
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    Guillermo Ingeniero Naval

    This may bring us again to the debate about the validity of the STIX as a seaworthiness indicator. ;) :D
    http://www.boatdesign.net/forums/stability/sailing-boats-stability-stix-old-ratios-13569-24.html
     
  8. sharpii2
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    sharpii2 Senior Member

    Thanks.

    These comments may be unreliable as they seem to be either second or third person. The blog where these comment were supposedly made is not named.

    But when I think of the other evidence at hand, that is much more reliable, it appears this boat was altered considerably from its original design. How else to explain why Stumble's comments on how the one he sailed on behaved so contradicts what happened with this one. Perhaps that was the purpose of the large crew, living ballast to offset less ballast and a taller rig.

    When I guestimate the weight of the crew compared to the supposed weight of the boat (provided by Doug Lord), I come up with about one third the total weight of the vessel in crew weight alone. The crew weight, approximately 1300 lbs was even greater than the specified weight of the Ballast 1100 lbs, IIRC.

    It appears that a former owner added more ballast, which was then removed by the deceased owner. If this is the case, it would be a bad day in court for the owner (and possibly MA, if there was one involved) if one or two of the minors who were aboard ended up being killed instead of the owner and his girlfriend.

    I would not be surprised if they find evidence of an upward blow to the back of the skull on at least one of the victims. If I have the story straight (it seems to change on a daily bases), the crew jumped into the lake when the capsize was well under way. If that is the case, the two victims might have hit stanchions on the immersed wing.

    When it comes to athwartship shifting ballast I have always thought that it should be limited to one third the total ballast with Canting ballast boats being limited to a similar amount of weight shift (limiting the cant to one quarter of the boats Beam on either side.)
     
  9. Doug Lord
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    Doug Lord Flight Ready

    The Perils of Edgy Weather in Any Boat

    Sharpii, the most reliable information I have run across to date is in this quote below. The Morley's added ballast and they added a carbon mast in place of the original aluminum one:

     
  10. Doug Lord
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    Doug Lord Flight Ready

    The Perils of Edgy Weather in Any Boat

    -----------------------
    Sharpii, the crew is mandated by the Notice of Race to be at least 5(corrected 8-4-11-misread) people(and was 8 on Wingnuts)-see document below.
    I just discovered something very, very interesting. Wingnuts had a valid ORR certificate as required by the organizing authority.
    In the ORR rules(see below) this is written about stability:
    2.02 Stability
    2.02.1 Stability Index: a yachts eligibility for entry in ORR races of ORC Special Regulation Categories,0, 1 or 2 may be limited on the basis of her Stability Index, at the option of the race organizer
    --
    This seems like a big deal to me: Did Wingnuts meet the requirements of the Stability Index? Was Wingnuts given a waiver that she did not have to meet these criteria?
    I'm going to try to find out......If anybody knows more about this specifically in the case of Wingnuts, please speak up(with links or other corroboration).
    ---
    I just sent this message via the "contact us" form at the ChiMac website:
    Under the ORR rules under Stability, it says that a competitor may have to meet the stability criteria listed in Section
    2.02.01 at the discretion of the race organizer. Can you verify whether or not Wingnuts was required under the Chi Mac authority to meet the criteria of the Stability Index?
    Your response will be most appreciated!
    Doug Lord
     

    Attached Files:

  11. Paul B

    Paul B Previous Member

    The SI required for Cat 0 is 120, for Cat 1 it is 115, and for Cat 2 it is 110.

    The standard Kiwi 35 supposedly has an SI of right at 100. Whatever modifications and fit out the Wingnuts has had could make this better or worse.
     
  12. Ad Hoc
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    Ad Hoc Naval Architect

    Indeed.

    But with any set of prescriptive rules, there shall always be “winners” and “losers” and those saying it is not applicable/correct measure.

    Whichever side of the fence one is on…it is better to have some type of ‘measure’ in an attempt to provide“suitability” than having none and letting everyone “police” themselves.

    If enough voices say it is not a correct or suitable measure, with evidence to demonstrate, then an upgrade of the rule occurs to refine it. But if none exist to begin with, how is one going to be “measured” other than...”take my word for it matey..she’s a beaut..”, ”she’ll be right mate…I’ve sailed her for years”….or like those like GB :

     
  13. Gary Baigent
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    Gary Baigent Senior Member

    Well, here's one for you Ad Hoc (by the way your pseudonym doesn't actually relate that well to your adherence to rules):
    Very interesting latest (actually old) development in the Transat 6.5's: full volume scow bow on a total planing hull. Mind you, Transat 6.5's have always had full and plumb bows for decades. Also they are now ancient in terms of time in their flat dish/saucer development with a beam close to 50% of their length - 6.5 LOA x 3 metres beam, even more extreme than the Kiwi 35. Plus of course, very light displacement with deep, canting keels, anti derive daggers and numbers with rotating wing masts. Now you long winded traditionalists, are going to throw up your arms, "What horrors! should be banned etc") - but huge numbers of 6.5's having been crossing oceans, often in very hard conditions, for near 40 years now and achieving speeds and times way above what small boats are entitled to do. But that is racing ... not plodding along stolidly, with no joie de vie, in boats of huge weight. Leave it up to the individuals (just like our lassez faire monetary leaders advocate!! Works for them, eh matey?) to make their own choices and decisions on what boat type they want to sail.
     
  14. Ad Hoc
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    Ad Hoc Naval Architect

    So, it is clear where you are coming from, since your silence provides the answer.

    As for this:

    Still unable to offer a sensible riposte I see.

    Well, let them race without Internet, GPS, SatNav, weather fax, EPRIB and the usual “get out of jail” international rescue at hand. Then we’ll see how many wish to go out and race…
     

  15. Gary Baigent
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    Gary Baigent Senior Member

    Ad Hoc, old mate, you're carping on a bit ... but no, I'm not a registered naval architect, no, but I have designed and built a few boats - all unmentionables in your world; light displacement monohulls but worst of all, multuhulls, and foiling trimarans at that - you can check some of them out on this site.
     
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