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CliveG
16-08-07, 07:57
The MAIB Have issued their report on the investigation of the keel failure, capsize, and loss of one crew member from the Max Fun 35 yacht Hooligan V 10 miles south of Prawle Point on 3 February 2007.

My fellow Ely Sailing Club member Jamie Butcher was killed in this incident.

It appears the the keel has been made by an inexperienced subcontractor who changed the design to save money.
The keel had an additional 160Kg added to it the year before the incident.

How many other yachts of this sort of design are there out there.

rallyveteran
16-08-07, 08:02
I think you missed this paragraph from the two page synopsis:
As a result of the MAIB investigation, the Max Fun 35 yacht keel has been redesigned and now exceeds the minimum required safety factor. New keels have been fitted to 7 out of the 9 remaining boats.

CliveG
16-08-07, 08:10
It is not the Max Fun 35 I was asking about but all the other yachts with this type of keel configuration.
I can't believe that these 9 boats are the only ones that have been compromise by cost cutting and subsequent design improvements.

Eygthene
16-08-07, 08:22
Could anyone possibly post a link here to the MAIB report on Hooligan V keel loss.

Thanks

Skyva_2
16-08-07, 08:25
RYA report with link here:

http://www.rya.org.uk/NewsAndEvents/newsroom/news/hooliganv.htm

fireball
16-08-07, 08:26
http://www.maib.gov.uk/publications/investigation_reports/2007/hooligan_v.cfm

tome
16-08-07, 08:36
The keel design was altered to make the manufacturing easier by an inexperienced sub-contractor. However, the report shows that the original design was already flawed with a very marginal safety factor as a result of using ultimate tensile strength in the calculations

AngusMcDoon
16-08-07, 09:21
Although the original design calculations were flawed, I think that is less significant than the fundamental design change the subcontractor made. At least the original design with the keel side plates running all the way to the top of the taperbox looks strong. The as-built design where the keel was just fillet welded to the taper box at the point of highest bending stress gives me the creeps - it was just asking to fail sooner or later.

I expect that design change was authorised by someone who had never been on a boat and had no idea of the loads boats are subjected to. Maybe he should be sent out into the North Sea on a Maxfun 35 in a Force 8 with 4m waves with one of his dodgy welded keels keeping him from a cold wet death to see if he still thinks it was a good idea.

kds
16-08-07, 09:30
"I think that is less significant "

Perhaps you do - but the company that put the boat together should have made themselves aware of the change to the keel and the fact that they were already on the limits. What happened to quality control ?
Ken

wotayottie
16-08-07, 09:34
[ QUOTE ]
It is not the Max Fun 35 I was asking about but all the other yachts with this type of keel configuration.
I can't believe that these 9 boats are the only ones that have been compromise by cost cutting and subsequent design improvements.

[/ QUOTE ]

That applies to every boat ever built commercially. No manufacturer will build to the best possible quality standard without regard to cost - or at least wont do so and stay in business.

Am I the only one that feels uncomfortable when the MAIB talks about "likely cause of failure" and "possible hairline cracking". We know that the keel was inadequate - thats proven by its failure. Sounds to me like the MAIB report is to some degree speculation. Wonder how it will fare in court if it ever gets there.

savageseadog
16-08-07, 09:44
I think anyone commenting on this should be aware of there might be legal actions of various kinds either forthcoming or ongoing.

The one thing I will say without prejudice is that having seen many yacht keel roots is there are few that don't show some signs of rust and cracked filler ie at least some movement.

AngusMcDoon
16-08-07, 10:04
[ QUOTE ]
the company that put the boat together should have made themselves aware of the change to the keel

[/ QUOTE ]

I totally agree - I was only commenting on the engineering aspect. The subcontractor should not have made the change, but neither should they have been allowed to get away with it. It seems that there have been 2 cockups, the technical one where the engineering was wrong, and a management/quality control one, where the technical one was allowed to slip through.

16-08-07, 10:20
I vote with AngusMcDoon. These boats are marginal in all aspects but that keel fabrication has to be the worst mechanical alteration I have seen.

Going from a box with 4 longitudinal walls and 3 stiffening webs to a empty box with the stiffening not reaching, never mind welded to, the box base is a disaster.

Figure 11 shows that it broke the steel below the welds but above the shortened stiffening plates.

In light of the recent comments of trust in manufacturers about masts ...

The current world can not even make sure children's toys are safe.

marksaab
16-08-07, 11:23
Leaving aside the obvious technical details. With various posts on this site about importing boats from the USA and the CE/RCD compliance required isnt it a bit staggering that this boat didnt have CE/RCD marking and that no COC could be supplied by the manufacturer! Also that this was not picked up by Trading Standards (I guess lack of resources) or the UK seller of the boat when it was new.

hairbox
16-08-07, 11:26
Hi all
you lot make me laugh. when a keel falls off a BAVARIA and there is loss of life you slag the manufacturer off and make snide comments, now just listen to yourselves!!!!!!

cnh
16-08-07, 12:08
What interests me more is that it was designed as a RCD Category B.

Regs for this are:
B - Offshore; Wave height - Up to & including 4m; Beaufort - Up to & including 8

If you're racing a boat like that, then you may well find yourself in such conditions. Cruising is a different matter - racers press on at times when cruisers prudently retire to harbour.

Whislt I'm not convinced that some of the distinctions between the classes are terrribly meaningful, I certainly would hesitate before racing a Cat B boat hard.

Nicholas Hill

moondancer
16-08-07, 13:43
I am a big believer in the rule that good design looks right and bad design doesn't. Whenever I look at a very thin skeg keel and a heavy bulb it always gives me a shudder and I think about the loadings it has to take. To me they just do not look right.

DRANNIE
16-08-07, 14:19
I suspect unless the unfortunate crew member has dependants there will not be the financial incentive to bring legal action except perhaps by the owner for the loss of the boat.

I will be interested to see of there be a prosecution case brought for manslaughter.

16-08-07, 15:36
Hairbox, I was in your words: "slag[ging] the manufacturer". Its like buying a car with no grease in the wheel hubs, you can not tell until the wheel breaks off. (Ref Volvo incidents) We rely on their integrity and gross errors, like these, sadly result in the loss of life.

I will continue hammering bad professional engineering and quality until more see how little we are getting for our money. As for Bavarias I would keep quiet after counting how many made it to the Fastnet. Very disappointing entry number and success rate. Or does it just reflect the crews of that type of craft only.

misterg
20-08-07, 01:39
I can only agree with tome-

Coming late to this, and having just read the report twice, I believe the design is more deeply flawed than the MAIB report suggests. Let me explain:

The marginal safety factor figures that the MAIB quotes come from the Wolfson Unit Report (annexe L) which creates a spurious figure of 357 MPa as the yield strength of the steel used. In actual fact, the yield strength for the steel used is specified by the standard and the manufacturer's data as 235 MPa (annexe F, and 1.11.2) - i.e. 34% less, so when safety factors of 1.38 are cited from the corrected analysis of the original design (section 2.4.2), that should be 0.91 i.e. the keel, as designed, will fail (through bending) at 10% below the load needed to simply hold the bulb out horizontally.

Whether the Wolfson unit made such a crude error, or whether there was a mis-match between what the MAIB thought they'd asked for, and what the got, I don't know, but the root of the problem is in the following paragraph from the Wolfson Unit report in annexe L:

[ QUOTE ]
The ABS Guide also states the yield strength is not to be taken as greater than 70% of the ultimate tensile strength of the material and not greater than 390 MPa where steel is used. The steel used in the design is quoted as having a maximum ultimate tensile strength of 510 MPa, therefore the ABS Guide value for the yield strength is 357 MPa and the allowable bending stress is 178.5 MPa.

[/ QUOTE ]

This seems to be a howling "school-boy error" in interpreting the requirements of the ABS guide. What matters is the yield strength [sic] - where this might be unreasonably high (e.g. in high strength alloys), the ABS guide places further restrictions on the value that can be used, and it is these restrictions which have been re-interpreted into a fictitious stress limits.

The issue of the keel bolt fatigue failures (not relevant to this incident, but worrying, none the less) is not adequately addressed - their size satisfied the code, but still broke despite being made of a superior material (from the point of view of fatigue) than that specified.

Having read the report, my feelings go out to the family and friends of the lad that was killed. This incident should never have happened - IMHO (got to put that in) this is a failure of grossly inadequate design, compounded by 'on the fly' modification during production, the designer's lack of ability / opportunity / nouse to look critically at those modifications when he had the opportunity, and the company's acceptance of this.

It should also sound warnings as to whether the RCD will ever be an appropriate vehicle to control this sort of thing.

No connection to anyone or anything involved, just an erstwhile engineer with a bit of knowledge about metallurgy.

Andy

misterg
20-08-07, 01:49
[ QUOTE ]
The one thing I will say without prejudice is that having seen many yacht keel roots is there are few that don't show some signs of rust and cracked filler ie at least some movement.

[/ QUOTE ]

Would you mind clarifying what you mean by 'keel roots' in the context of your comment, please?

(I would normally think of this as the place where metal meets GRP, etc, but the comments in the report refer to what is effectively a change in section of the steel keel - from a position of near ignorance, I would expect 'cracking' / movement in the former, but not the latter.)

No connections / involvement, etc.

Andy

alant
20-08-07, 11:51
"As for Bavarias I would keep quiet after counting how many made it to the Fastnet. Very disappointing entry number and success rate."

Can you expand on these statements please.
I'm still trying to work out if you'r knocking or applauding them.

How many entered?
How many retired & where did they get to down course?
How many completed?
How many keels dropped off or any other major gear failure? /forums/images/graemlins/tongue.gif
etc.

Eygthene
20-08-07, 12:02
Andy (Misterg) has got much closer to a realistic analysis of the circumstances surrounding this failure.

At the time of this design, (and still at present as far as I can tell), the ISO standard for keels is in draft form, so the designer was able to adopt the American guidelines, which require only that the keel should be capable of supporting its own weight when heeled at 90 degrees, with a safety factor of 2:1 over the yield strength of the material.

As Andy pointed out, the yield strength figure used in the report was not actually appropriate to the material involved and the true factor of safety worked out to less than 1 as a result. The keel was bound to bend at high angles of heel and fatigue failure would be expected to occur sooner rather than later.

The draft ISO standard follows a similar line, though there is an allowance for dynamic loads included.

However, the yield strength of the material quoted in the standards is for rolled steel and when there is a weld in the highly stressed region near the root of the keel, this introduces material of a reduced yield strength as well as concentrating the stresses along the weld.

For this reason, the design of the welded joint and its effect on the dynamic properties of the structure will further reduce the safety factor and ought be taken into account in the design. There is no indication that this aspect has been considered in the draft that I have read.

Until a satisfactory standard for a fabricated fin is agreed, I think the designers should be constrained to using a cast steel fin. How many more keel failures will it take before this is recognised?

misterg
20-08-07, 16:50
[ QUOTE ]
However, the yield strength of the material quoted in the standards is for rolled steel and when there is a weld in the highly stressed region near the root of the keel, this introduces material of a reduced yield strength as well as concentrating the stresses along the weld.

[/ QUOTE ]

John,

Does this comment apply to the 'as designed' keel as well as the 'as made' version? (I think it does, but I'm not clear whether you mean it to)

[ QUOTE ]

For this reason, the design of the welded joint and its effect on the dynamic properties of the structure will further reduce the safety factor and ought be taken into account in the design. There is no indication that this aspect has been considered in the draft that I have read.

[/ QUOTE ]

I was surprised how simplistic the American design code was (as quoted in the report). I am also surprised that there seems to be an expectation of a common standard for lightly build racing machines, and for production 'cruisers'. This is akin to a common set of rules for Formula1 racing cars and granny's little run-about. Either racing development is stifled by conservative design rules, or mass production drifts towards the same narrow margins of safety (weaker is cheaper) while claiming that the boat "meets the standards" - We have already heard of manufacturers of production boats claiming that their construction "meets the draft ISO standard" when discussing structural failures.

I think when we take out all the experienced supervising surveyors required to verify a boat is built 'to code' (from whichever country), it will open the floodgates to such minimum standards engineering.

Andy

Eygthene
23-08-07, 09:53
Andy,

The drawing of the as designed keel shown in the MAIB report (Fig 14) does not show where the welds are, nor what is welded to what (such welds must be shown on any proper design drawing), but the schematic (Fig18) does show a couple of small fillet welds where the keel enters the bottom of the taper box.

I would be very surprised if the as-designed keel would be manufactured without these welds. As soon as welds are placed there, they would have a deleterious effects on the fatigue strength of the structure. Also, whether welded there or not, the point where the keel enters the bottom of the taper box would be a point of high stress concentration which also needs to be factored in to the design calculation, as this further significantly reduces the "safety margin". You have already shown that in fact there was no safety margin in this design, even without adding these particular considerations.

The sooner the Draft ISO standard is agreed and put into effect the better, but there were still a lot of items awaiting clarification/drafting, in the 2004 draft version that I was able to download off the web.

John

misterg
23-08-07, 17:38
Thanks John.

I have emailed the MAIB about my concerns, and have included the point about taking fatigue into consideration, too.

Andy

Eygthene
28-08-07, 10:33
Well done Andy. I am trying to trace an ISO standard that I referred to a few years ago, concerning welds and the appropriate design factors. I think that standard was related to factory chimneys, though we were using it in relation to wind turbine towers. I should have a reference to it somewhere. When I do find it, I will put together something to send to the people working on this ISO standard about keels.

John

Duffer
03-09-07, 12:01
I was very saddened by Mr Butcher's death. The other crew members did remarkably well to raise the alarm and get themselves rescued at night at that time of year.

Sailfree
03-09-07, 13:40
As a non practising structural engineer I find these discussions very interesting.

When I did practise designing bridges it was shortly after the Westgate and Milford Haven bridge collapses. I remember new additional checks being bought in very quickly by the Morrison committee. I also remember that you always tried to avoid welding to a tension face as it induced fatigue. With stress reversals on a keel I would have thought this a given for a boat and that welding on stressed parts should be avoided unless a fatigue analysis was completed.

In previous threads I have expressed concern that yacht design still appears to be based on "rules of thumb" and empirical design that is revised only after something fails. I can understand this better for racing boats (in F1 Colin Chapman was not beyond beefing a component up until it did not fail!) With boat costs being driven down by sales volume competition I believe its only a matter of time before some serious underdesigns occur on production boats (I believe the Bavaria match boats are the only ones so far to have an "alleged" underdesign that required post build modification).