Catastrophic failure

[Robin]

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I think you'll struggle on this one. Cat capsize on cruising size vessels is largely a leftover reputation from the very early days and old boats like the Apache. Its way harder to turn over a modern cat than a modern mono of the same length. If you doubt it, look at the area under the stability curves to see the energy involved.


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My 'Cat' comment was a bit tongue in cheek knowing that Boatmike has a Cat. That said the AVS figs and stability curves are IMO somewhat irrelevant in the practical reality that capsizes are caused by wave action not by wind pressure, dinghies excepted of course. Given a wave of the right size, any vessel will capsize and as I understand it that is not influenced much if at all by ballast ratios or hull shape. How quickly a capsized mono will right itself is another question, but irrelevant in this discussion because a capsized mono with no keel left attached is going nowhere but glug glug glug!

 

[boatmike]

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We are all guilty of having our own hobby horses - my own is AVS. On a priority basis I would prefer more boats to have an AVS in excess of 130deg than a stronger keel. I wonder which aspect would contribute to saving more lives?
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The angle of vanishing stability of a boat which has had its keel knocked off is depressingly low
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I respectfully suggest you consider who would be prepared to pay the extra for a boat built to withstand the impact you suggest and if you say we should all be compelled by law then really you are saying that you are so right in your view that it should be legally imposed on others and their free choice taken away.
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No because the difference between designing a boat properly and doing so without consideration for safety is not in fact as large a cost penalty as people think. Perhaps such legislation would increase the price of the cheapest boats but not drastically. Legislation to control the emissions of cars and trucks has resulted in better engineering without a drastic increase in cost. Without legislation though it would never have happened.

 

[retsina]

During my years as a structural engineer in the aircraft industry, in the 70's the specifications for light aeroplanes was fairly low and many crashes were due to low spec. Nowdays, the design spec is much higher as a result the cause of cashes due to material and design failure has been reduced drastically. Same should apply in the yacht leisure industry; the minimum requirement should be elevated in certail areas of the boat to maximise safety; in most cases it is a design issue rather than workmanship.

 

[Sailfree]

I am begining to change my mind on this one!

I know cars are crash tested but wonder how they can prove an impact resistance on boats without testing and with small production volumn at great additional expense.

As I wrote on another thread the 43DS that was commissioned only 2 weeks before mine was inadvertantly crash tested against the cill of Hythe Marina at quite a speed (sufficient for one to break a few ribs) and surprisingly suffered only a dented keel but the impact was sufficient to cause them to lift it out immediately to check for hull damage but to their surprisethere was none.

 

[bbg]

Just to be clear, what is the problem you think needs to be legislated for? I haven't heard of a rash of keels falling off due to hull-speed groundings, so what is the problem that you think needs fixing?

I agree with your sentiment that a keel should not fall off following a hull-speed grounding. But I don't hear of it happening.