MAIB Investigating Keel Loss - Tygar

Tranona said:
One way of resolving this with racing boats and particularly dual purpose boats like the First is change the rules to either reward more robust keels or penalise what might be considered less robust. Not sure that would go down well with owners, designers or builders!
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Already happening. This is a current "state of the art" IRC keel.

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And this is "old thinking" IRC keel

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Tranona said:
I am not dismissing them. That is why I use the term systemic. If you are trying to claim that there is a failure in design and manufacture then that is systemic, and in that case you would see commonalities in the causes of failure. So far the main commonality (particularly if you read the full ISAF report) is GROUNDING, closely followed by the boats also being involved in racing. So, ignoring those two factors is indeed putting your head in the sand.
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I am not stating there is a failure in design or manufacturer. I'm stating that there is reason to suspect there is. The absence of proof of a problem is not proof on the absence of it.

So let's start with your two main causes.

Racing can not per se be the cause of keel loss. Categorising it as a cause just comes across as another example of them and us amongst yachtsmen. So let's talk about racing keel failures. I'll come back to cruiser racers as I go along with the RCD (even though it is only European and the issue has to be considered worldwide) that a cruiser racer is not a racer. So racers suffer keel loss. The loss of cantilevered keels does seem notable, within the proviso where I think we agree that the numbers are small. I would argue even here that is a competent designer can't design a steel structure that handles the required loads then there is something lacking in the understanding of those loads. So that's the first question mark over keel design. Not proof, question mark.

Hooligan V was a racer, albeit not racing at the time, I hope we can agree to dismiss this one as being mainly down to very poor practice at an individual fabricator.

So next is grounding. Of course if you hit the rocks hard enough the keel is going to come off. Yes they are down to user error and can be pretty much dismissed from any suspicion of design or manufacturing failures.

However I have, IMHO, very reasonable and very serious concerns about dismiss keel losses due to grounding.

Firstly, there is a very big difference between keel loss during a hard grounding and keel loss where the boat has touched the sea bed at some stage in the past. I'm not attempting to define the dividing line, but there has to be one.

Having a boat sailing around with lethal hidden damage after a grounding that leaves no outward signs, of which CR was an example, should not be considered an acceptable situation. That's why I was so against putting the blame on Doug Innes, even though I didn't think him blameless, because he ended up with the sole blame and the event is dismissed as user error (e.g dismissed by you, amongst many).

Secondly, it appears the default response of manufacturers to blame grounding in the absence of evidence. e.g Match 42 and Polina Star III.

In IT it is pretty much the norm to a) pin the blame on the users b) dismiss it as a unique occurrence that will never happen again. Time after time after time I've seen the approach delay the identification and resolution of problems. It must be a normal human reaction as the same thing is happening with keel loss.

I'm not even attempting to prove there is a problem, simply trying to demonstrate that there is a reasonable suspicion that there is a problem. One think that seemed obvious to me with CR, regardless of any direct grounding damage, is that she had a pattern of usage that probably place her well into the top 1% of the 800-odd 40.7s that were built. That to me says at least think about fatigue as a factor in the keel loss. It is noticeable that as a school boat Tygar of London appears to have been heavily used, but given we know next to nothing about the loss that would have to go to the back of my mind until the report comes out.

Tranona said:
It is perfectly possible to build more robust keels and supporting structures as Swedish builders (among others) have demonstrated but it invariably involves a performance penalty. Those looking for performance advantages have to accept the compromises or suffer the performance penalty. One way of resolving this with racing boats and particularly dual purpose boats like the First is change the rules to either reward more robust keels or penalise what might be considered less robust. Not sure that would go down well with owners, designers or builders!
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I'm not attempting to propose a solution either. However there are quite performant designs with the steel frames the Swedes and others around the Baltic favour. But let's understand the problem first, maybe such a radical solution isn't necessary. Maybe for example, saying you can't count the inner moulding in the hull thickness calculation for the keel area because you can't prove it will always remain bonded would be sufficient, but I don't want to stray that far off my main argument.

Tranona said:
So far there has been sufficient explanation of the small number of keel losses on production cruising boats and none of these suggest a serious systemic issue in design or manufacture. This does not mean as you say that there are not issues in using these boats, but they are very firmly the responsibility of owners - that is the way the boats are used, maintained and repaired if damaged. I recognise that grid reinforcing structures present new potential problems, but that does not mean that previous methods were trouble free as many owners of some well known boats will testify.
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I don't accept those arguments as discussed above. One thing I would point out though is that I'm not trying to advocate that a return to traditional or old-fashioned design as the solution. Modern keel design offers so much that the way forward is to continue to challenge the design and build practices to ensure the keels stay on or at least it is obvious when repair is necessary. I believe the RCD, Harmonised Standards engineering approach is right. I'm arguing that failures need to be closely monitoring and investigated, not dismissed, so it can be improved where it is not good enough.

Tranona said:
The reality is that you are never going to eliminate failures, but I would suggest that the vast majority of boat owners will never experience problems with the keels on their boats.
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We agree on something. The vast majority of keels will stay on. Having flown on business on quite a few of the dodgiest domestic airlines in the world I always tried to re-assure any colleagues travelling with me that we had a >99% chance of making it off the plane alive. For some reason they weren't always re-assured.
 
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I think some of the problem may be counterintuitive.
Modern construction is stronger.
Therefore damage may be more subtle and less obvious.

In the old days, you ran a Sigma33 aground at speed, you'd push the back of the keel up, probably cracking a floor.
Damage contained to a limited area, easy to inspect and repair.
Introduce more efficient 'floor' matrices, they are stronger, harder to damage but damage may be subtle and hidden.
 
lw395 said:
I think some of the problem may be counterintuitive.
Modern construction is stronger.
Therefore damage may be more subtle and less obvious.

In the old days, you ran a Sigma33 aground at speed, you'd push the back of the keel up, probably cracking a floor.
Damage contained to a limited area, easy to inspect and repair.
Introduce more efficient 'floor' matrices, they are stronger, harder to damage but damage may be subtle and hidden.
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Good point.
 
About this comparison with aircraft, I can only think of a very few keel-off incidents. But there appear to be plenty of aircraft crashes. I wonder how many people died sailing in 2016? Perhaps that is not a fair comparison as many more people fly than sail ...

"A report by the Airline Safety Network said there were a total of ten fatal accidents, resulting in 79 deaths last year. That compared with 16 accidents and 303 lives lost in 2016."
 
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