Tragic Accident

Norman_E

Norman_E

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Photos here of the upturned Max Fun 35 that was the subject of speculation a few days ago, before it sank. No sign of any marks on the hull so it does not look as if it hit anything. A tragedy that one crew member lost his life, and I hope the cause is quickly determined and lessons learned.
 
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That said - very impressed by the clean bottom in the pics.

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Poor taste /forums/images/graemlins/frown.gif
 
A very sad story.
It looks like the keel fractured cleanly an inch or two above the base.
I hope that the authorities will be able to carry out tests in order to effectively determine what caused such catastrophic failure.
 
More unhelpful speculation...

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It looks like the keel fractured cleanly an inch or two above the base.

[/ QUOTE ] This is just more unhelpful speculation - you can't possibly make that judgement based on the photos. What you can see is the slot into which the keel fitted. Take the trouble to find out a bit about the yacht, see here for starters.
 
Re: More unhelpful speculation...

Thank you for posting that most useful link - I did take the trouble to try and find out more, but I just looked at the Builder's web-page, and that does not have a lot of information.
Sorry, I should have thought of looking at the Designer's webpage.
I copied and saved the photo, and enlarged it, and that appeared to indicate a stub, but I realise now that this is actually the slot for the keel.

The designer's webpage notes :
"The steel keelfin slots into a recess in the hull and with the keelbolts as well as with the mainchainplate bolts also a mechanical fastening is achieved between hull shell and interior liner".

Sorry, but I am just a sad pedantic engineer who is interested in the possible causes of such catastrophic failure. And it was that, for sure.
 
Re: More unhelpful speculation...

Noted your Bio. Can you comment on the discussion on structural requirements for yachts that the Thread "Questions to be asked again" has drifted on to (it started discussing the same sad incident).
 
Re: Questions to be asked again

Thank you Dylan for that link to the other thread - I had not seen it before.
And thank you Roger Sailfree for your most interesting and informative thoughts and observations in this other thread.
Re my comments.... ummm, I think everybody else (including yourself) has said everything (and a lot more) that I might have been tempted to say, and they have expressed these opinions re structure and strength in a much better manner than I could have.

The bottom line is that the yacht was apparently sailing along in relatively calm conditions, offshore, with no known underwater obstructions (like rocks, shoals etc) in the way, when sudden catastrophic failure of the keel, or its method of attachment to the hull, occured. We do not know what caused this, but experienced engineers have put forward some very plausible theories.
My current thought is that maybe the pointy front of the bulb at the bottom of the keel hit some obstruction underwater (it could be anything floating partially submerged).
If the front of the bulb hits an object first, this will put a much greater bending moment on the hull / keel joint (with consequent extreme deceleration and high stresses) than (say) if the vessel was to ride up over the object - in the latter instance the vessel decelerate less rapidly, the forces involved will be smaller, and the bending moments from impact in way of the root of the keel will be much less.

But I will stress that this is all just speculation by an itinerant engineer.
And the information available so far clearly indicates (to me at least) that no fault can be levelled at the crew.
 
Re: Questions to be asked again

Just from the p-o-v of an ex-racer, and not as a specific comment about Hooligan, most racing yachts touch bottom several times a season when trying to cheat tide in shallow water. Maybe this imposes some cumulative stresses on the keel attachment points?
 
Re: Questions to be asked again

I thought to revisit the terms of The Recreational Craft Directive, as in here.....

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3. INTEGRITY AND STRUCTURAL REQUIREMENTS
3.1. Structure
The choice and combination of materials and its construction shall ensure that the craft is strong enough in all respects.

Special attention shall be paid to the design category according to section 1, and the manufacturer's maximum recommended load in accordance with section 3.6.

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Then I recalled that craft designed principally for racing - which is how the MaxFun 35 is described on the designer's website - are exempt from the Essential Safety Requirements in all respects.

.....Not wanting to start another hare. Just to keep it in mind.....




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Re: Questions to be asked again

Following on from my previous note, after posting it I was going to add a comment about fatigue, but then I had to go out in a hurry on a job.
And Ken has commented above about how racing boats do touch the bottom occasionally - it is only fair and reasonable to expect them to do so, as none of us are perfect, and racers take calculated risks when racing, and can take greater risks if they know the bottom is soft mud rather than say hard rock.

Was thinking about it all from a fatigue point of view while I was driving along earlier...... as we are all aware, metals like steel are very prone to fatigue - you can break a piece of steel rod by simply bending it back and forth until it fractures.
(But was Hooligan's keel made of steel? We dont know. Sorry, more speculation).

Cyclic loadings on a steel item can also cause failure when the number of cycles approach the fatigue life of the material.
The Hooligan has been around Britain, and I am assuming that she has been raced fairly hard.
I am wondering if there was fatigue in either (some of) the keel bolts, or in the top section of the keel, perhaps in way of the joint between the keel and the flange for securing the bolts (if it is of fairly 'conventional' construction).

If there is no keel left at all, and quite possibly no bolts left, then that would imply that all the bolts failed catastrophically, perhaps as a result of 1 or 2 failing earlier (as a result of fatigue / cyclic loadings / corrosion etc) and then the loads having to be absorbed by the remaining bolts being greater than what they were capable of sustaining.

If the bolts are all intact (perhaps even a bit loose), and the keel has fractured in way of the root, then the exact cause should be possible to determine from analysis of the portion left behind.

If the whole keel disappeared, bolts and all, then the bolts (and backing washers / plates) would have had to 'tear through' the hull, and the hull damages as a result of this happening would be fairly apparent.

So, we shall just have to await what the official findings are. Might well turn out to be something totally different to what has been mooted above!
 
Re: Questions to be asked again

As posted elsewhere, the structural standard likely to be required by RCD is ISO 12215-5 (personally I doubt that the racing exemption would apply to a boat being offered for general use).

Only thing is, this standard hasn't been agreed yet. When it is agreed, it might not be all it needs to be. Fairly damning ABS paper here .

Andy
 
Just shows that you cannot always trust what you read. The report I linked to said that it sank and even commented on the difficulty of recovery, but showed photos of it floating upside down. I just took their word for it that it had sunk later. If it stayed afloat it should be easier to recover.
 
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