Australian National Standard for Buoyancy and Stability after Flooding

Discussion in 'Stability' started by mflapan, Oct 23, 2008.

  1. Ad Hoc
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    Ad Hoc Naval Architect

    Mori

    If i had time i would, hence the quick review i gave. I have far too much to do between now and submission date. NO time to even eat!!

    Designing vessels that are "above" 12g is a matter of interpretation and making good representation tot he regulatory authority that is administring the vessel. Some Flag sates are very accommodating some are not. Some naval architects can provide sufficient "arguments" to allow dispensations and others are not. I'm not saying it is easy, but a reasoned and a sensible approach, not a heated one, usually works best. BUT, as i said before, all this must be done pre-contract. Doing it post-contract will lead to disaster. However, if, at the end of the day all avenues have been exhausted and a seat for 12g with a harness is required, then so be it. (Just make allowances pre-contrcat should this end up to be the case!!) Would you drive your car at speed and not wear a seat belt??....the rules are for passenger safety, not for the whims of the naval architect.

    The "hovercraft designers" were always to most vocal in these committee meetings, for obvious reasons. Not having to design to the HSC code previously (under CAA) came as a shock to them! However, given the number of "units" made compared to the "norm"; what is being done, listening to the minority and giving it a majority voice, does that make sense? There are always going to be losers, in any set of prescriptive rules. So long as those of the vast majority are well "serviced" the objective is achieved, passenger safety.
     
  2. mflapan
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    mflapan Junior Member

    Dear Ad Hoc

    Thanks for the response. I think we have mutual understanding even if not agreement.

    One of the vexing questions regarding seat belts and small high speed craft is the concern that you are strapped in should the vessel flip over, etc. I think you would need to be careful to balance the potential benefits of seat belts against the protential risks. There is an interesting paper presented by a colleague of mine that describes such an occurrence at http://www.nmsc.gov.au/documents/Lugg David- paperThrill_Rides5.pdf. The result had persons been wearing seat belts would almost certainly have been fatal. By the same token, I have heard of incidents where people have been thrown from high speed vessels as they passed over the wake of another boat, and then run over by their own boat as it circled. The question of seat belts needs more in-depth analysis, possibly on a vessel by vessel basis.

    Best regards
    Mori
     
  3. Ad Hoc
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    Ad Hoc Naval Architect

    Mori
    This is where the 2 issues are being blurred when they should not.
    "...the concern that you are strapped in should the vessel flip over, .." Well, which is the concern here??...it seems you are focusing on the passenger in the seat belt. What about the vessel??..if there is a possibility of the vessel flipping, it shouldn't be allowed.
    Remember the "Elk test", for the Mercedes A-class car?...a small magazine performed a simple tight turn test and it flipped....so Merc redesigned it to prevent it.
    If there is a real concern that the vessel will flip, the vessel should not be allowed anywhere near the sea!
    Your focus on a problem is wrong!

    Secondly, there are many citings of people in car crashes who say "I would have died if i wore a seat belt"..i know of several myself. YET, there is a significantly higher number whose lives have been SAVED by wearing a seat belt.
    I think you really need to address the philosophy of where the risk is, the risk, on what you have cited, is the vessel itself. It is considered risky for people/passengers in such a vessel, do not let the vessel touch the water!
     
  4. mflapan
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    mflapan Junior Member

    Dear Ad hoc

    If I understand your reasoning correctly, vessels should never sink, so lifesaving equipment is superfluous!

    Safety is not black or white but shades of grey. We cannot guarantee safety. The best we can do is provide for relative safety. The standards use the concept of defence in depth to reduce to acceptable levels the probability of catastrophic consequence. An expressed example of defence in depth is contained in Clause 1.6.2 of the NSCV fire safety standard at: http://www.nmsc.gov.au/documents/NSCV/NSCV Part C Section 4 - Edition 2 V3.pdf

    If you look at the Fast Craft standard, it does contain provisions intended to reduce the probability of flipping, however, they cannot guarantee this will never happen.

    The philosophy we apply is to focus on safety outcomes rather than prescribed solutions. That means that we try to look at the issue on its merits rather than just assuming that the prescriptive solution for a motor vehicle is the best solution for the maritime environment. But please note that just because I am prepared to entertain rational arguments against a prescriptive solution does not mean that I reject the prescriptive solution, or that the arguments against it will prevail. It just means that I have an open mind.


    Regards
    Mori
     
  5. Ad Hoc
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    Ad Hoc Naval Architect

    The role of a Flag state is ostensibly to stop ANY vessel going to sea...why?..if it doesn't go to sea, there is no safety risk. Simple.
    So, rules are set to prevent a vessel going to sea....but a vessel does of course go to sea. Therefore such rules are made to ensure all risks are mitigated as much as possible.
    So, as a flag state is must ask itself this very simple question. Which is greater risk, a vessel flipping or a passenger strapped in, when a vessel flips.
    It is as simple as that.
    If the concern is the vessel, then what do you do about this risk, have measures that prevent it 100% or 70% or 50% and so on...this is where representations to the Flag state are made and sensible approach taken..is the vessel inherently risky?..if the bottom line is yes, it should not go to sea. If the risks have been mitigated as much as possible, then the flag state and its rules, have done their job, to protect the passenger.
    Prescriptive rules are for guidance...how a flag state administers them is a different matter. Ego, address the way your flag sate administers such rules. Yet you are going down an every increasing set of prescriptive rules, rather than a proper "equivalence based" philosophy, as the HSC Code is slowly doing. Problem with this is requires approval officers as being very educated and knowedgable, not computer programmers who tick boxes off in a check list of rules.
     
  6. mflapan
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    mflapan Junior Member

    Dear Ad hoc

    You are correct in saying that the HSC Code represents significant progresss towards a more performance-based approach relative to SOLAS.

    Workable standards need a balance between performance and prescription. The two concepts are not mutually exclusive. We are drawing from both prescriptive and performance based approaches in the NSCV, hopefully combining the best aspects of prescription (convenience) with the best aspects of performance (flexibility). To this end, we have adopted a number of the performance characteristics of the HSC Code and modified them to reflect a performance-based structure pioneered by the Building Code of Australia that has been refined in the light of their experiences over a 15 year period.

    An observation that I might make on the HSC Code is that it appears to still be in a state of development. My impression is that it is becoming more prescriptive over time relative to earlier editions and the DSC Code. I understand this is in response to concerns that the threshold for compliance with performance-based 'motherhood' statements is sometimes difficult to establish and can be inconsistently interpreted. Prescription in itself is not a bad thing, as it provides a tangible statement of what is hopefully agreed good practice. Prescription only becomes a problem when compliance can only be measured against the prescribed solution rather than the safety outcome. Likewise, reliance on performance approaches alone tends to be inefficient as everyone has to re-invent the wheel each time they use it. That is why we are taking a hybrid approach.

    Yes, you are right that performance based approaches require higher levels of competence in both proponents and approvers. This is discussed in my paper on equivalent solutions.

    Regards
    Mori
     
  7. mflapan
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    mflapan Junior Member

    Dear all

    This is to say that the final version of the National Standard for Commercial Vessels Part C Subsection 6B Buoyancy and Stability after Flooding has been approved by the Australian Transport Council and can be viewed at:

    http://www.nmsc.gov.au/media/pages_media_files/files/NSCV%20Part%20C%20Section%206b%20-%20ATC%20endorsed.pdf

    The standard will be applicable to new commercial vessels in Australia from the 1 October 2010.

    Thank you to those who contributed to its development

    Regards
    Mori
     
  8. wardd
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    wardd Senior Member

    does this mean a boat has to settle on the bottom right side up?
     
  9. mflapan
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    mflapan Junior Member

    Hi Wardd

    Thanks for the question. There is a difference between flooding and sinking. Flooding may or may not lead to sinking, depending on the nature of protection.

    But that is why we don't just use the old terminology subdivision and damaged stability - to get people to think about the safety outcome.

    Hope this helps.

    Regards
    Mori
     
  10. Landlubber
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    Landlubber Senior Member

    Mori..


    Universal across australia rules, yeah sure, just like the Gun Laws eh, (different in every state already).......in ya dreams.
     
  11. MikeJohns
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    MikeJohns Senior Member

    Thanks Mori

    Just looking at the crash bulkhead guidelines and you have a typo page 42 in table 16
    "The collision bulkhead shall be located sufficiently forward to enable the vessel shall meet a........."

    that would get the solicitors running to the Barristers for a determination in their clients favor !

    Cheers
     
  12. mflapan
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    mflapan Junior Member

    Thanks very much Mike.

    I have made a note of the error. It should read "vessel to meet" and not "vessel shall meet".

    For problems of a more technical nature that any of you might identify (i.e. other than these simple typos), we have a process in place that requires a "Proposal for amendment of the NSCV" to be submitted by one of the Commonwealth, State or Territory jurisdictions. So at first instance, discuss any such matters with the relevant Maritime Authority.

    In response to Landlubber's comment, all this is now rather temporary as moves are well advanced to have a Single National Regulator under the Commonwealth Maritime Agency AMSA. Refer to: http://www.amsa.gov.au/Maritime_Reform/maritime_safety_reforms.asp for more information. Hopefully that will go some way towards improving national uniformity.

    Regards
    Mori
     
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  13. Landlubber
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    Landlubber Senior Member

    ...Mori, hope you are right, but the states seem to do what they like after all anyhow, fingers crossed eh.
     
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