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Jackdaw

Eco power capsized!

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Upwind in 15 knots?!?!? Keel gone?

 

03/02/2013 - 20:20

 

At 1049hrs UTC the boat was positioned at 31° 59.00 N 27 26.24 W, so 500 miles west of Madeira and 360 miles south of the Azores island of Sao Miguel

 

 

 

Weather conditions in the area that Sanso was sailing were a NE’ly wind of 15kts. The boat was racing upwind in a moderate trade winds swell. Prior to the incident all was reported to be well on board, only minutes before Sanso had e-mailed a daily report to Race Direction.

 

 

 

At 1110hrs UTC (1210hrs local time Les Sables d’Olonne, France) Vendée Globe Race Direction were alerted by Ricardo Maldonado, the manager of ACCIONA sailing team, who informed Vendee Globe Race Direction that MRCC Madrid had received the warning that two EPIRB distress beacons (COSPAS/SARSAT) had been activated.

 

 

 

Immediately Race Direction in Les Sables d’Olonne, the MRCC Ponta Delgada (Azores) and CROSS Griz Nez tried to contact the IMOCA Open 60 ACCIONA but received no reply.

 

 

 

MRCC Ponta Delgada then requested an aerial reconnaissance of the area by plane. A C295 plane was on zone by 1630hrs UTC. On arrival they found Javier Sanso in his liferaft. Sanso made hand signals and smoke signals (smoke hand flare) next to his capsized boat.

 

 

 

At 1650hrs UTC this information was confirmed to Race Direction by MRCC Ponta Delgada.

 

 

 

At 1750hrs UTC an EH101 helicopter was dispatched from the Azores island of Terceira heading to the zone to effect the rescue of Javier Sanso and is expected to be in the area by 2300hrs UTC.

 

 

 

Ends

 

 

 

Official Press Release of ACCIONA 100% EcoPowered Team

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FFS!!! Surely the management of the IMOCA 60 class should be charged with bringing the sport into direpute or something? This whole shambles is doing our sport no good whatsoever. What sane Marketing director would put money into this? Crazy. Are they just waiting until someone dies before they do something?

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Nothing new here. Keels have been falling off racing yachts with regularity ever since the fin keel became de rigeur.

 

Evidently basic naval architecture is not something practised by yacht designers, and / or fundamental structural assembly techinques are not adhered to by yacht builders.

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You guys seem to have it sorted out. You should team up to develop your own round the world single handed race with the largest audience in the sport by a wide margin. You could use your brilliant minds to design the boats too. I'm sure you could do it better, and I'm sure everyone would watch since this Vendee and all that preceded have been such unmitigated failures. Go for it Dane and Fastyacht!... oh, you should built the boats, keels, rudders, spars, rigging etc. too, since it appears that nobody is "following the fundementals" anymore.

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In other words, don't think of sailing the Vendee Globe unless you are prepared to accept a 15% chance of losing your keel.

 

gotta say, 3 out of 20 is just wrong.

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It is obvious there is a significant advantage to skinny keels. This is just engineers pushing the safety factors down.

The fix is simple. Make a set of rules defining the keel design which is to be checked, inspected and approved by the race management. Job done.

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In other words, don't think of sailing the Vendee Globe unless you are prepared to accept a 15% chance of losing your keel.

 

gotta say, 3 out of 20 is just wrong.

 

Maitre Coq also had keel problems. Yeah, not losing it, but still.

 

It is real bummer that Acciona had keel problems. Acciona was one of the newest builts and haven't sailed much and it wasn't built to be fastest/lightest boat. Really surprising problem.

 

Hopefully Jesus Renedo can give some insights after Bubi's rescue.

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Haven't the results of the Safran teams analysis of their keel failure already explained this? Essentially engineering based on inaccurate assumptions:-

 

'The analysis confirms that the loads experienced by the keel were undoubtedly far higher than the standard values used by the design teams, as well as the values calculated from the shock recordings during the Transat Jacques Vabre 2009.'

 

'The shocks experienced by the boat and its appendages were also more violent, in particular exceeding the estimates used by the design team.'

 

What would be interesting is to see if the actual loads required to cause the Safran failure were ever calculated, then applied to the keels that were still in use to see what sort of safety factor was actually in place. I suspect we'll be seeing a lot of new IMOCA keels in the not too distant future.

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It is obvious there is a significant advantage to skinny keels. This is just engineers pushing the safety factors down.

The fix is simple. Make a set of rules defining the keel design which is to be checked, inspected and approved by the race management. Job done.

 

That puts way way way too much responsibility on an organization which is not equipped to handle it.

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Ill be happier discussing this when I hear that Javier is safe and sound on dry land. Last news report is that he was still in his life raft awaiting rescue. Anyone got an update?

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Simple fix to keel problem, governments start charging for the total cost rescue and sinking the damn POS boat since it's a navigation hazard. Taxpayers don't need to subsidize people going out in boats with a 15 percent chance of loosing a keel on boats and capsizing.

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Rigs used to fall down - enter carbon, PBO, etc.

Sails used to blow up - enter 3Di.

Halyards used to break - enter vectran, dyneema, PBO etc.

Deck fitting used to pull out or break - enter soft attachments, titanium, carbon.

 

All these 'shock absorbers' are now almost indestructible and stiff as all buggery.

What's the next bit down the chain that will load up...

Keels. (and rudders again).

 

Rinse and repeat.

 

The engineering load assumptions have changed because the loads being handles by the other components in the boat, have now got to a new reliability level and are sending great shock waves through the rest of the structure.

They will sort it out with the new reference loads - until we start breaking rigs again.

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It is obvious there is a significant advantage to skinny keels. This is just engineers pushing the safety factors down.

The fix is simple. Make a set of rules defining the keel design which is to be checked, inspected and approved by the race management. Job done.

 

The thing is : there is already such a rule. See annex A of the IMOCA yearbook 2012. It says, among other things, that there has to be a safety factor of 5 in transversal bending. If the keel properly is designed, it should be largely enough. The ISO norm asks for 3.2 only ! It is interesting to note that this rule has been added to the IMOCA rules under the pressure of designers in 2010 (it has been somewhat loosened since : there used to be a ratio between the first bending and torsional frequencies).

 

Most keels that break (with the notable exception of safran's titanium keel) are made of welded plates. These keels are interesting, because they are light and small. But their design and fabrication is highly critical because welds have very adverse effects on the metal's fatigue strength. The high safety factors will not save a faulty design or fabrication.

As for titanium, it is inherent to the material to be sensitive to fatigue and to break suddenly as soon as the smallest crack appears.

 

Looking at facts, the fix is to go carbon keels for everyone : Team Plastique is in her 4th Vendee Globe, plus contless transatlantics, with her original, solid carbon keel.

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I find keels falling off embarrassing for the industry but not surprising.

 

To engineer something you only need three things. The loads, the material properties and the geometry.

 

Geometry is easy with 3D CAD. I hope they use non-destructive testing after the keel has been made to verify that the assumptions they made during the design in regards to weld penetration was correct. If not that is just negligent and not really excusable. I also hope that they use good paint systems to protect the metal from corrosion. Corrosion pits can easily initiate fatigue cracks.

 

Material properties are also simple. They should be in datasheets. By the way I have no idea why they use high strength steel for keels that fail in fatigue. The fatigue performance of brittle, high strength steel is worse than that of lower strength ductile steels. Its not like keels bend into bananas because of low strength. They fall off suddenly because of fatigue.

 

By far the worst are the loads. I recon there are only a hand full of people who know what the loads on a canting keel actually are. You would have to record that data during many miles under different conditions. ABS offshore racing yacht guide is going to be useless. If a boat goes up and down a wave at zero heel with a standard keel you are only going to produce more or less tension in the keel. With a canting keel the same motion produces a bending moment (which is far worse). Under certain conditions the bending moment could be reversed. That is the same as a tack or jibe on a regular yacht. So potentially a canting keel yacht sees the equivalent of a tack at every wave.

Even if somebody has the load data it is unlikely that the data is shared between different teams. It is secret stuff but that secret stuff could save the life of a sailing mate. The aircraft industry shares accident data so that the same accident doesn't happen again. I'm not aware that the sailing industry does this.

 

Then there are misconceptions like "The keel has performed great for the last 30,000 miles. I have a lot of faith in it. It will be good for a circumnavigation". That is just BS. It only shows that an identical keel used in the same conditions might also be good for 30,000 miles if you are lucky. There is a large statistical spread for fatigue data so you would have to sail at least a few identical keels in the same conditions to be reasonably sure that the design is in fact good for the distance claimed. It doesn't say anything about the amount of fatigue damage the keel has accumulated. It might fail at 30,001 miles. Fatigue is a bit like water dripping into a bucket. Every mile adds a few drops of water into the bucket. It is just a matter of time before the bucket is full and the keel falls off. I would do a very through NDT inspection of the keel before going single handed around the world to make sure that there are no corrosion or small cracks in the critical area. No idea if they do this. Best would be to replace it with a new keel to a proven design before the race (start with an empty bucket of known capacity).

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>>>>Looking at facts, the fix is to go carbon keels for everyone : Team Plastique is in her 4th Vendee Globe, plus contless transatlantics, with her original, solid carbon keel.

 

Isn't the keel on Team Plastique the only fixed keel? If so, the loads are totally different than a canting keel and you can't compare the two....

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From #22 karsten

" By the way I have no idea why they use high strength steel for keels that fail in fatigue. The fatigue performance of brittle, high strength steel is worse than that of lower strength ductile steels."

 

As another generalization: BS.

 

You can get 'good fatigue strength' and 'high strength' if the specification for the steel aims high enough. Not cheap, but not uncommon.

 

So far, this thread lacks technical depth.

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The forces are incredible......think of how hard the water feels when you are barefoot waterskiing or wipe out when you fall waterskiing. These boats can go at the same kind of speeds. The force on a keel moving through the water at 20 or 30 knots with a constantly changing angle of attack must be unbelievable.

 

Maybe the designers should be forced to go on a few overnight trips in 30 knots of wind with the boats crashing to windward and with no radio or epirb. Nothing adds safety factor better than a designer having to risk his own life and getting scared.

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Well, where welding is involved, HY steel is significantly inferior in fatigue compared to mild and weld strength is lower than base metal. HSLA while generally better than HY for fatigue, is a significantly more challenging material to work with than mild steel for achieving acceptable welds, and for engineering a fatigue resistant structure.

 

A generally immutable fact of steels is that the higher the yield, the less elongation to failure. The way around this is with very special alloys and treatments. Within any given class, you generally give up toughness as you ratchet up the strength.

 

The corrosion aspect is not to be ignored.

 

What I don't know is where this failed. Or any of the others. In reading about the failures of the past I have not ever seen a detailed technical discussion. Mike Plant's bulb fell off his fixed keel. Some have had failures of the hydraulic systems. What specifically failed and why is unknown to me.

 

Unless there is comprehensive knowledge of the mechanisms and details of past failures, there is very little if anything at all that a designer can get out of those experiences, except the understanding that someone underestimated a load. Frankly considering the track record, I don't think there has been much information sharing at all. And what would the mechanism for sharing be? ABS rules are totally inappropriate and inapplicable. Unless a class society gets involved, or IACS, or SNAME, or RINA (the Royal Institute of Naval Arch. or indeed the Italian class as well), how will we all learn from these? And they go back 20 years! And some of the information may be lost.

 

On the other hand, there's no shortage of opportunity for data gathering. And no reason this can't be shared more effectively. Accelerometer data gathering could be required and made public.

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Considering the light weights of these boats, the essentially horizontal projection of the ballast bulb, and the wide flat sections of the hullform, all the traditional "righting moment" evaluations for keel strength are going to be ridiculously inadequate. The inertial forces could easily dominate the situation. And the combination of inertial forces with hydrodynamic forces, and the reversals ever few seconds, adds up to a severe fatigue machine. One with I daresay no good fatigue model. You can try to design to the fatigue limit stress but clearly something in the system is taking more than that and fatigue is happening.

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So.... Rubber keels. Wiggley instead of canting. Problem solved. Glad he is safe.

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We don't know enough about Acciona's keel, it's mode of failure or those of all the other easily-cited but not so easily understood failed keels to be shoveling all these generalized proclamations. No, it's not as clear and easy as has been spewed. Fatigue isn't linear nor in inherent relationship to tensile yield. The loads aren't obvious and there's way more going on than a slab of steel and a weld. This race has seen failed halyards, deck fittings and sails and you don't have to look far for examples of failed cost-is-no-object masts. I share everybody's indignation on Bubi's behalf, but we don't know what happened or how to guarantee that it will never happen again. These boats are incredibly complex systems and thousands of elements have to perform and interact perfectly to circle the globe as fast as a man can sail. Not one of the skippers started the race thinking that nothing could go wrong.

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We don't know enough about Acciona's keel, it's mode of failure or those of all the other easily-cited but not so easily understood failed keels to be shoveling all these generalized proclamations. No, it's not as clear and easy as has been spewed. Fatigue isn't linear nor in inherent relationship to tensile yield. The loads aren't obvious and there's way more going on than a slab of steel and a weld. This race has seen failed halyards, deck fittings and sails and you don't have to look far for examples of failed cost-is-no-object masts. I share everybody's indignation on Bubi's behalf, but we don't know what happened or how to guarantee that it will never happen again. These boats are incredibly complex systems and thousands of elements have to perform and interact perfectly to circle the globe as fast as a man can sail. Not one of the skippers started the race thinking that nothing could go wrong.

 

Perhaps the moral of the story is that when you make a keel into an active discrete element system, rather than a fixed fin, much less a integrated portion of the shell, it is bound to have the same statistical trouble you see with rigs and rudders. Although I have a problem with the frequency. Seems to me you've just got to be conservative with the keel! (but how? is the immediate question in response...)

 

I agree with you (as stated above) that we simply don't know enough to know what happened.

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Thanks everybody. the team is moving to Azores and now focusing on the boat, tomorrow they will make decisions.. the most important thing is that he is ok.

 

Thats good news! Thank you for information.

Hope team can manage to save to boat, but it still very far from islands.

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Simple fix to keel problem, governments start charging for the total cost rescue and sinking the damn POS boat since it's a navigation hazard. Taxpayers don't need to subsidize people going out in boats with a 15 percent chance of loosing a keel on boats and capsizing.

Since the old time & everywhere around the world, THE rule is that anyone has to do whatever he can to save life and do it for free!

No one is thinking about breaking this rule... I hope!

But you should remember that saving the boat has always be charged by the rescuers and it should stay the same!

Would you think not to save a family crossing to Hawaï just because you can't check the validity of their insurance policy?

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The forces are incredible......think of how hard the water feels when you are barefoot waterskiing or wipe out when you fall waterskiing. These boats can go at the same kind of speeds. The force on a keel moving through the water at 20 or 30 knots with a constantly changing angle of attack must be unbelievable.

 

Maybe the designers should be forced to go on a few overnight trips in 30 knots of wind with the boats crashing to windward and with no radio or epirb. Nothing adds safety factor better than a designer having to risk his own life and getting scared.

quite st...d remark!

Dont you think?

Are F1 or Nascar designers racing?

How can you became a yacht designer without practicing?

How can you build a team without checking your designer know how?

How can you reach limit without playing with limitations?

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Maybe the designers should be forced to go on a few overnight trips in 30 knots of wind with the boats crashing to windward and with no radio or epirb. Nothing adds safety factor better than a designer having to risk his own life and getting scared.

Merf has sailed a lot further than just a few offshore nights on many of the boats he has designed. Stop being so ignorant, a lot of the information required is just a google search away.

IMOCA standards on keel loads are the highest in the industry. However they are also the only monohulls that consistently sail all the way around the world.

 

THis VG has seen the greatest number of keel failures, and yet this is the first VG with the higher keel design safety factors. WHat does this tell you? Basically there is something going on that all of JuanK's, Verdiers, Safran's, Merfyns, Farr's and all of the skippers experience and computer power is not picking up. SO if you honestly think that that anyone on this site knows better then you are having a laugh.

None of the skippers ask for the design of the keel to be pushed to a level that will put them at risk.

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I have to admit keels falling off sailboats is pretty frigging unbelievable. Who the hell takes that kind of risk designing by computer. It is very apparent that yacht designers do not know how to engineer. Look at the results. I wonder if anyone has ever created a test fixture a life sized keel and performed some basic and not so basic loading along with shock loading on the structure. Some engineers actually test to failure to understand what the structure can take using many different loads- shock, cyclical and then 10x max load . It's sad but telling when some tells you but the computer told me its good enough. This quest for weight savings is fucking insane some one is going to die.

Frankly this shit is killing sailing.

 

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who I must say that this video freezes all my spine !

So keel completely gone, no fin left ...

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I have to admit keels falling off sailboats is pretty frigging unbelievable. Who the hell takes that kind of risk designing by computer. It is very apparent that yacht designers do not know how to engineer. Look at the results. I wonder if anyone has ever created a test fixture a life sized keel and performed some basic and not so basic loading along with shock loading on the structure. Some engineers actually test to failure to understand what the structure can take using many different loads- shock, cyclical and then 10x max load . It's sad but telling when some tells you but the computer told me its good enough. This quest for weight savings is fucking insane some one is going to die.

Frankly this shit is killing sailing.

Step back from the keyboard

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Ill be happier discussing this when I hear that Javier is safe and sound on dry land. Last news report is that he was still in his life raft awaiting rescue. Anyone got an update?

he is one tough bastard. he could drift to the caribbean on eco-power, eating raw seagulls and mahi he pulls out of the ocean with his teeth. "Goony Goo Goo"

 

Go get 'em bubi!

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Daggerboard sticking out. Keel entirely gone.

 

Anybody else shocked by the fact that the Vendee Globe official communication won't admit having lost yet another keel ?

 

[ As for technical discussions, I'll just refrain from now on... The level of misinformation and finger pointing from most people here is just frightening... ]

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THis VG has seen the greatest number of keel failures, and yet this is the first VG with the higher keel design safety factors. WHat does this tell you? Basically there is something going on that all of JuanK's, Verdiers, Safran's, Merfyns, Farr's and all of the skippers experience and computer power is not picking up. SO if you honestly think that that anyone on this site knows better then you are having a laugh.

None of the skippers ask for the design of the keel to be pushed to a level that will put them at risk.

 

Is there enough funding somewhere for a salvage vessel to go and get Acciona? Check out the stub and see if there are any clues? And have any boats had (calibrated?) accelerometers onboard - maybe that data could be published?

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THis VG has seen the greatest number of keel failures, and yet this is the first VG with the higher keel design safety factors. WHat does this tell you? Basically there is something going on that all of JuanK's, Verdiers, Safran's, Merfyns, Farr's and all of the skippers experience and computer power is not picking up. SO if you honestly think that that anyone on this site knows better then you are having a laugh.

None of the skippers ask for the design of the keel to be pushed to a level that will put them at risk.

 

Is there enough funding somewhere for a salvage vessel to go and get Acciona? Check out the stub and see if there are any clues? And have any boats had (calibrated?) accelerometers onboard - maybe that data could be published?

 

Yacht owners are under obligations to try and organize a salvage operation of the drifting vessel, you can be sure they are working it, but that usually is not too easy (reference: Poujoulat, BT and PRB past abandons).

 

Edit: Azorean tugs have already successfully retrieved both Poujoulat and BT

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Safran had accelerometers onboard prior to designing the titanium keel.

 

accelerations equal net unbalanced force, not force on one particular component.

 

to the people going on at length about how the designers and engineers are obviously incompetent and/or stupid, just shut the fuck up. Yes keels shouldn't fall off. No you have no fucking idea how complicated an engineering problem that is. expounding your ignorance ad nauseum is in no way going to improve anything.

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No, I do understand how "complicated" this problem is. And that's the problem! Making a keel this complicated--making the stability and safety depend on this complicated ill-understood system--without having the resources to properly engineer it, is crazy. But these guys racing these things see risk differently than ordinary folks. Not that they are risk-seekers, but that they seem to accept the fact that more than one percent of them will die at sea in this race, never mind that 15% will go turtle.

 

The reason these things fall off is that the engineering is inadequate. Period. Sure, it is complicated. Whose fault is that?

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You guys seem to have it sorted out. You should team up to develop your own round the world single handed race with the largest audience in the sport by a wide margin. You could use your brilliant minds to design the boats too. I'm sure you could do it better, and I'm sure everyone would watch since this Vendee and all that preceded have been such unmitigated failures. Go for it Dane and Fastyacht!... oh, you should built the boats, keels, rudders, spars, rigging etc. too, since it appears that nobody is "following the fundementals" anymore.

 

My point EliBot is that this has been going on for years and is still happening. Its dangerous and is bad for the sport.

F1 realised that having half the field not finish due to mechanical failures meant that the sport was failing so they fixed it. They realised people dying was not acceptable so they fixed it. The Volvo Ocean race realised that keel ram failures etc were not acceptable so they fixed it. Its all fixable. what will not be fixable is if someone dies. what would take a very long time to fix is if sponsors start walking away in their droves because the risks are not acceptable.

This is all fixable. I have built boats and the keels have not fallen off so dont get all on yer high horse with me. If we were talking about cars here and 3 in 20 flipped over randomly whilst driving along there would be a massive outcry. How come there are hundreds of thousands of yachts already out there whose keels dont fall off? If a sport or section of sport thinks that they have to build these kind of risks in (for that is effectively what they are doing by acepting this ongoing state of affairs) to be able to get an audience then there is something terribly wrong with their offering.

The engineering capability is there to ensure this does not happen again. Thousands of planes cross our skies every day without wings falling off. They simply build in a level of safety that means it wont happen.

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You guys seem to have it sorted out. You should team up to develop your own round the world single handed race with the largest audience in the sport by a wide margin. You could use your brilliant minds to design the boats too. I'm sure you could do it better, and I'm sure everyone would watch since this Vendee and all that preceded have been such unmitigated failures. Go for it Dane and Fastyacht!... oh, you should built the boats, keels, rudders, spars, rigging etc. too, since it appears that nobody is "following the fundementals" anymore.

 

My point EliBot is that this has been going on for years and is still happening. Its dangerous and is bad for the sport.

F1 realised that having half the field not finish due to mechanical failures meant that the sport was failing so they fixed it. They realised people dying was not acceptable so they fixed it. The Volvo Ocean race realised that keel ram failures etc were not acceptable so they fixed it. Its all fixable. what will not be fixable is if someone dies. what would take a very long time to fix is if sponsors start walking away in their droves because the risks are not acceptable.

This is all fixable. I have built boats and the keels have not fallen off so dont get all on yer high horse with me. If we were talking about cars here and 3 in 20 flipped over randomly whilst driving along there would be a massive outcry. How come there are hundreds of thousands of yachts already out there whose keels dont fall off? If a sport or section of sport thinks that they have to build these kind of risks in (for that is effectively what they are doing by acepting this ongoing state of affairs) to be able to get an audience then there is something terribly wrong with their offering.

The engineering capability is there to ensure this does not happen again. Thousands of planes cross our skies every day without wings falling off. They simply build in a level of safety that means it wont happen.

How many were open 60's?

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You guys seem to have it sorted out. You should team up to develop your own round the world single handed race with the largest audience in the sport by a wide margin. You could use your brilliant minds to design the boats too. I'm sure you could do it better, and I'm sure everyone would watch since this Vendee and all that preceded have been such unmitigated failures. Go for it Dane and Fastyacht!... oh, you should built the boats, keels, rudders, spars, rigging etc. too, since it appears that nobody is "following the fundementals" anymore.

 

My point EliBot is that this has been going on for years and is still happening. Its dangerous and is bad for the sport.

F1 realised that having half the field not finish due to mechanical failures meant that the sport was failing so they fixed it. They realised people dying was not acceptable so they fixed it. The Volvo Ocean race realised that keel ram failures etc were not acceptable so they fixed it. Its all fixable. what will not be fixable is if someone dies. what would take a very long time to fix is if sponsors start walking away in their droves because the risks are not acceptable.

This is all fixable. I have built boats and the keels have not fallen off so dont get all on yer high horse with me. If we were talking about cars here and 3 in 20 flipped over randomly whilst driving along there would be a massive outcry. How come there are hundreds of thousands of yachts already out there whose keels dont fall off? If a sport or section of sport thinks that they have to build these kind of risks in (for that is effectively what they are doing by acepting this ongoing state of affairs) to be able to get an audience then there is something terribly wrong with their offering.

The engineering capability is there to ensure this does not happen again. Thousands of planes cross our skies every day without wings falling off. They simply build in a level of safety that means it wont happen.

How many were open 60's?

 

Relevance??? Its an engineering problem. Stop trying to make out as if its some special case. If the Volvo 70s can do it when they are being pushed even harder then why cant the 60's? Answer, they can but they dont, not enough anyway.

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First: He fell off the boat and managed to SWIM back to it, then got in his liferaft. Man, this is the most frightening story I´ve ever heard. I mean, the moment he fell off he was 90% dead. No Harness on. These guys always say harnesses are rubbish because with these things on they can´t move. But When you look at the early videos of Alessandro you see that he nearly always is wearing one. So?

Second: This is like the VOR a race at the limits, also technically, It´s like Formula 1 racing. In F1 30 years back cars broke in nearly every race. If the drivers were lucky enough to survive they stepped into the next car, designed just like the other one. You had corpses every three months. Still they kept on, still the whole thing didn´t lose it´s fascination until some of the drivers stepped up and said that things had to be changed (first Jackie Stewart then Niki Lauda)

Nowadays they are still loosing wheels and wings because of extreme constructions. But nowadays they are hitting walls at 250km/h and step out of the car just like that. It´s all about the evolution. In extreme sports you always will have victims be it sailing, motor racing or climbing.

I Think this is part of the game. Nobody´s gonna change it even if everybody involved is trying to do so.

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You guys seem to have it sorted out. You should team up to develop your own round the world single handed race with the largest audience in the sport by a wide margin. You could use your brilliant minds to design the boats too. I'm sure you could do it better, and I'm sure everyone would watch since this Vendee and all that preceded have been such unmitigated failures. Go for it Dane and Fastyacht!... oh, you should built the boats, keels, rudders, spars, rigging etc. too, since it appears that nobody is "following the fundementals" anymore.

 

My point EliBot is that this has been going on for years and is still happening. Its dangerous and is bad for the sport.

F1 realised that having half the field not finish due to mechanical failures meant that the sport was failing so they fixed it. They realised people dying was not acceptable so they fixed it. The Volvo Ocean race realised that keel ram failures etc were not acceptable so they fixed it. Its all fixable. what will not be fixable is if someone dies. what would take a very long time to fix is if sponsors start walking away in their droves because the risks are not acceptable.

This is all fixable. I have built boats and the keels have not fallen off so dont get all on yer high horse with me. If we were talking about cars here and 3 in 20 flipped over randomly whilst driving along there would be a massive outcry. How come there are hundreds of thousands of yachts already out there whose keels dont fall off? If a sport or section of sport thinks that they have to build these kind of risks in (for that is effectively what they are doing by acepting this ongoing state of affairs) to be able to get an audience then there is something terribly wrong with their offering.

The engineering capability is there to ensure this does not happen again. Thousands of planes cross our skies every day without wings falling off. They simply build in a level of safety that means it wont happen.

How many were open 60's?

 

Relevance??? Its an engineering problem. Stop trying to make out as if its some special case. If the Volvo 70s can do it when they are being pushed even harder then why cant the 60's? Answer, they can but they dont, not enough anyway.

No need to be obtuse Dane, big differance in the engineering of a fixed keel versus a canting keel. But you knew that, didn't you?

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APPENDIX A. RULES FOR KEEL DESIGN

Minimum safety factors to be respected:

Keel horizontal, 1g on the bulb + keel fin

- Factor of 5 for the whole keel

The value of 5 corresponds to the multiplicative factor of load for the breaking point (or permanent

deformation) of FRP (fiber reinforced plastic), or the overall loss of elastic behaviour of metals which

generally equates to exceeding the elastic limit (see note 1).

- Grounding, Keel canted to the maximum, with 3 x the weight of the boat excluding the bulb weight,

applied to the end of the bulb, and with all the ballast tanks filled on the same side.

- factor of 1 for the free part (keel and fin)

- Check that the elastic limits of the bearings and attachments of the keel are not exceeded.

Note 1

 

: for ductile metals (ie elongation at break greater than 3%), the criteria required is an overall elastic behaviour, ie no permanent deformation (such as residual bend of the keel fin) once unloaded.

Exceeding the elastic limit locally (at a fillet for example) is permitted.

Material properties to be used:

- Metals: Use the mean values guaranteed by the manufacturer.

- FRP: Apply a factor of 0.7 to the manufacturer’s mean data (target value)

Materials shall be delivered accompanied by their certificates of conformity. Taking measurements of the mechanical properties of samples of the materials is recommended.

Frequencies of keels:

Keel fitted to the boat, rotation bearing and hydraulic system attached and locked in the central position, the frequencies of the keel in torsion must be greater or equal to:

- 3.2Hz for torsion

- 1.07Hz for flexion

Centre of gravity:

The CG of the bulb shall be forward of the axis of torsion of the fin.

NB

This design rule does not impose a particular method of analysis on the structural engineer (software, method of analysis, finite element calculation, type of mesh, size of mesh…).

The structural engineer must choose the tools for his analysis and understanding. .

 

As you said Fastyacht......

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Look at the IMOCA "yearbook" annex A. Not a document to be particularly impressed by.

 

Well, considering that before this annex got written, some keels were scantled with safety factors of 3, anyone in their right mind would agree that this is a major progress. And that it is not the IMOCA rule's role to teach engineers how to do their job...

 

Of course, if you're so well informed, you carefuly avoid mentionning the fact that some of the keels that failed in the history of the IMOCA class did, because skippers didn't follow their designer's advice to replace the keel after a certain number of miles sailed. Maybe this is also at play in this Vendee...

 

Still, I grant you that it appears that some people manage to design keels that last longer than others...

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APPENDIX A. RULES FOR KEEL DESIGN

Minimum safety factors to be respected:

Keel horizontal, 1g on the bulb + keel fin

- Factor of 5 for the whole keel

The value of 5 corresponds to the multiplicative factor of load for the breaking point (or permanent

deformation) of FRP (fiber reinforced plastic), or the overall loss of elastic behaviour of metals which

generally equates to exceeding the elastic limit (see note 1).

- Grounding, Keel canted to the maximum, with 3 x the weight of the boat excluding the bulb weight,

applied to the end of the bulb, and with all the ballast tanks filled on the same side.

- factor of 1 for the free part (keel and fin)

- Check that the elastic limits of the bearings and attachments of the keel are not exceeded.

Note 1

 

: for ductile metals (ie elongation at break greater than 3%), the criteria required is an overall elastic behaviour, ie no permanent deformation (such as residual bend of the keel fin) once unloaded.

Exceeding the elastic limit locally (at a fillet for example) is permitted.

Material properties to be used:

- Metals: Use the mean values guaranteed by the manufacturer.

- FRP: Apply a factor of 0.7 to the manufacturer’s mean data (target value)

Materials shall be delivered accompanied by their certificates of conformity. Taking measurements of the mechanical properties of samples of the materials is recommended.

Frequencies of keels:

Keel fitted to the boat, rotation bearing and hydraulic system attached and locked in the central position, the frequencies of the keel in torsion must be greater or equal to:

- 3.2Hz for torsion

- 1.07Hz for flexion

Centre of gravity:

The CG of the bulb shall be forward of the axis of torsion of the fin.

NB

This design rule does not impose a particular method of analysis on the structural engineer (software, method of analysis, finite element calculation, type of mesh, size of mesh…).

The structural engineer must choose the tools for his analysis and understanding. .

 

As you said Fastyacht......

 

Exactly. Not much there.

 

What's with the plastic deformation prohibited except at fillets?

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Considering that this has been happening with some regularity, for 20 years, I'd say that no, the problem is not understood and that the IMOCA document is useless. In fact if is more like a "it's not our responsibility" thing. Frankly I think IMOCA would be better off with nothing at all. Bad guidance is worse than no guidance. Designers always get sucked into doing the minimum required by the guidance document. When the document sucks, you get sucky results. Happens in boats, happens in ferries (why the fuck do you think the ESTONIA killed people?) happens in buildings, happens in aeroplanes etc.

 

OK that's cynical and churlish.

 

The reality is that you need *good* guidance.

 

Engineers are intelligent. They cannot be expected to be geniuses and omniscient.

 

There is nothing in that document about how and what loads are to be analyzed. It looks nothing like a well-developed engineering rule. You need loads. You need acceptable methods of analysis.

 

I suspect that the competitive pressures have prevented information exchange over the past 20 years. That doesn't work. You don't advance the state of the art by bottling it up. If these canting keels are to be part of the mix, they need to work. If that means that there needs to be a joint engineering task force, then that is what it takes.

 

Budgets for racing campaigns are slim. You know that engineering suffers in this situation. Look at what it takes. Clearly the 1st principles approach hasn't worked. Neither has any empirical analysis because the boats advance too much. If anyone has ever strain gaged these systems in detail and taken them out in real conditions, that information has not been made public. The hydrofoils are more or less 60 degrees apart. taken together with the fact that the CG of the system is nowhere near the center of the boat, and the speeds through the waves, you've got all kinds of potential for loading that is impossible to know without measuring it directly. Foils working against each other. Inertial effects. Heave being damped by the ballast foil while going through waves. Heave/yaw coupling, surge/yaw coupling, the list goes on. This problem will not get solved until there is a concerted effort to do so in an open manner. That's my opinion.

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APPENDIX A. RULES FOR KEEL DESIGN

Minimum safety factors to be respected:

Keel horizontal, 1g on the bulb + keel fin

- Factor of 5 for the whole keel

The value of 5 corresponds to the multiplicative factor of load for the breaking point (or permanent

deformation) of FRP (fiber reinforced plastic), or the overall loss of elastic behaviour of metals which

generally equates to exceeding the elastic limit (see note 1).

- Grounding, Keel canted to the maximum, with 3 x the weight of the boat excluding the bulb weight,

applied to the end of the bulb, and with all the ballast tanks filled on the same side.

- factor of 1 for the free part (keel and fin)

- Check that the elastic limits of the bearings and attachments of the keel are not exceeded.

Note 1

 

: for ductile metals (ie elongation at break greater than 3%), the criteria required is an overall elastic behaviour, ie no permanent deformation (such as residual bend of the keel fin) once unloaded.

Exceeding the elastic limit locally (at a fillet for example) is permitted.

Material properties to be used:

- Metals: Use the mean values guaranteed by the manufacturer.

- FRP: Apply a factor of 0.7 to the manufacturer’s mean data (target value)

Materials shall be delivered accompanied by their certificates of conformity. Taking measurements of the mechanical properties of samples of the materials is recommended.

Frequencies of keels:

Keel fitted to the boat, rotation bearing and hydraulic system attached and locked in the central position, the frequencies of the keel in torsion must be greater or equal to:

- 3.2Hz for torsion

- 1.07Hz for flexion

Centre of gravity:

The CG of the bulb shall be forward of the axis of torsion of the fin.

NB

This design rule does not impose a particular method of analysis on the structural engineer (software, method of analysis, finite element calculation, type of mesh, size of mesh…).

The structural engineer must choose the tools for his analysis and understanding. .

 

As you said Fastyacht......

 

Exactly. Not much there.

 

What's with the plastic deformation prohibited except at fillets?

 

That's about the same as saying if your bumper can withstand the weight of your car 5 times you are good to hit a wall at any speed (and as often as you want)....

 

....I guess that's why they are called naval architects, not naval engineers.

 

Just glad Bubi got lucky and manged to swim back to the boat.

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I hate to even bring this up, but maybe the Canada keel sponsorship was TRUE?

As for Acciona, I would think the biggest shame of all of this is all the technology on board, and how it was going to change the industry for the positive.

yarrow

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Damn impressive helo rescue . . . long way over open water, and a hard to see raft floating free from the vessel. Terrific job.

 

I had understood that the USCG helos had a 400nm range - so only a 200nm radius (for a 2-way trip). Interesting this portuguese helo went out twice that distance. This helo could cover all the way out to Bermuda . . . which the current USCG helos apparently can't.

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Very sad. Glad Bubi is safe! I am sure the other teams will be looking at the 100% eco-powered option for the next cycle regardless if Acciona finished or not. Too many hydrogenerator problems to skip alternative energy sources like solar going forward.

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Damn impressive helo rescue . . . long way over open water, and a hard to see raft floating free from the vessel. Terrific job.

 

I had understood that the USCG helos had a 400nm range - so only a 200nm radius (for a 2-way trip). Interesting this portuguese helo went out twice that distance. This helo could cover all the way out to Bermuda . . . which the current USCG helos apparently can't.

The EU101 (Merlin) is the standard helo fro european navies and coastguard. It is a pretty big unit. There are still lots of others out there (eg Lynx) but the Merlin is coming into service more and more.

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APPENDIX A. RULES FOR KEEL DESIGN

Minimum safety factors to be respected:

Keel horizontal, 1g on the bulb + keel fin

- Factor of 5 for the whole keel

The value of 5 corresponds to the multiplicative factor of load for the breaking point (or permanent

deformation) of FRP (fiber reinforced plastic), or the overall loss of elastic behaviour of metals which

generally equates to exceeding the elastic limit (see note 1).

- Grounding, Keel canted to the maximum, with 3 x the weight of the boat excluding the bulb weight,

applied to the end of the bulb, and with all the ballast tanks filled on the same side.

- factor of 1 for the free part (keel and fin)

- Check that the elastic limits of the bearings and attachments of the keel are not exceeded.

Note 1

 

: for ductile metals (ie elongation at break greater than 3%), the criteria required is an overall elastic behaviour, ie no permanent deformation (such as residual bend of the keel fin) once unloaded.

Exceeding the elastic limit locally (at a fillet for example) is permitted.

Material properties to be used:

- Metals: Use the mean values guaranteed by the manufacturer.

- FRP: Apply a factor of 0.7 to the manufacturer’s mean data (target value)

Materials shall be delivered accompanied by their certificates of conformity. Taking measurements of the mechanical properties of samples of the materials is recommended.

Frequencies of keels:

Keel fitted to the boat, rotation bearing and hydraulic system attached and locked in the central position, the frequencies of the keel in torsion must be greater or equal to:

- 3.2Hz for torsion

- 1.07Hz for flexion

Centre of gravity:

The CG of the bulb shall be forward of the axis of torsion of the fin.

NB

This design rule does not impose a particular method of analysis on the structural engineer (software, method of analysis, finite element calculation, type of mesh, size of mesh…).

The structural engineer must choose the tools for his analysis and understanding. .

 

As you said Fastyacht......

 

Exactly. Not much there.

 

What's with the plastic deformation prohibited except at fillets?

Bleah. Is that all? Not a word on fatigue, either low-cycle or limit? And plastic design at the fillet? Or a word about material deratings for things like heat affected zones, casting or bar stock quality, temperatures, etc. No word on corrosion properties. Granted, in aerospace, we don't have the luxury of large nominal stress margins, but we do account for as many known factors as possible, and negative elastic margin anywhere in the analysis is cause for extensive concern and review. People may say, yeah, but aerospace standards are so expensive, yadda, yadda. Hey, pay me now or pay me later. That level of design assurance wouldn't come close to satisfying even a preliminary design review and it isn't that difficult using modern tools.

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[Reposted once I figured out how to correctly attach an image...]

 

See below a screenshot from the video taken from the recon plane. Granted it's blurry but you can't even see a hint of a keel stub there.

 

post-72237-0-32960600-1359995946_thumb.jpg

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Damn impressive helo rescue . . . long way over open water, and a hard to see raft floating free from the vessel. Terrific job.

 

I had understood that the USCG helos had a 400nm range - so only a 200nm radius (for a 2-way trip). Interesting this portuguese helo went out twice that distance. This helo could cover all the way out to Bermuda . . . which the current USCG helos apparently can't.

 

This is a bit incorrect. The AugustaWestland EH101 used in Sanso's rescue has a typical range of 750nm: http://www.agustawes...product/aw101-1 and it's a monster (It was also the heli shown in the final scene of Skyfall). The Coast Guard operates a helo with a very similar 700nm range, the MH-60: http://www.uscg.mil/.../cg711/h60s.asp.

 

Bermuda is 635nm from Newport, meaning its on the ragged edge. They don't keep helicopters in Bermuda ($$$). Even halfway in between you are out of helicopter range for them performing a rescue and getting back to shore. There is no real solution to this problem, other than placing a Coast Guard cutter on the race course ($$$). There's a reason its a Cat 1 offshore race and you prepare as such.

 

We should be extremely grateful that the Coast Guard's and Navy's of the world are willing to undertake these rescue missions at all, given the jeopardy the fine flight crews and rescue divers put themselves in all because we wanted to have some fun.

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Looks like the bottom fell off. Good thing he was sstill in the environment when it happened.

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In other words, don't think of sailing the Vendee Globe unless you are prepared to accept a 15% chance of losing your keel.

 

gotta say, 3 out of 20 is just wrong.

 

Clean,

 

Any idea how many keels were lost in the Vendee Globe GAME???

 

Inquiring minds wanna know. If mine came off, I'd want a credit on what I paid for the AP and extra sails.

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The IMOCA appendix is worse than useless. The high safety factor for a static load forces the designer to specify a high static strength, relatively brittle steel which is difficult to weld. Otherwise the root seciton of the keel will be very fat. The type of steel, the difficult welding and likely the susceptibility of the steel to corrosion will make it a bad choice for fatigue in this environment. If the safety factor was lower one could possibly use a stainless steel which is easier to weld and has lower notch sensitivity (imperfections are less likely to initiate cracking). Unfortunately such a more sensible material choice would not meet the IMOCA static strength rule.

I would expect that the person who signs the keel drawing will notice the complete lack of fatigue requirements in the IMOCA rule and do his own investigations. Measuring the actual ram loads is not that difficult. Then there is a wonderful standard EN 1993-1-9 Eurocode 3: Design of steel structures: Fatigue (it costs only a few $). It basically tells you how many cycles a structure would withstand if you know the stress range. The cycles do not depend on the material as long as a ductility requirement is met. The standard has a table showing the connection detail and the allowable stress range at 2,000,000 cycles. A flat plate without any disturbances can withstand 160 MPa. So this is the best case scenario. A perfect butt weld (same thickness plates, NDT inspected, welded from both sides, run on and offs cut away) reduces this to 112 MPa. A full penetration T fillet weld reduces this to about 71 MPa, if you have a partial penetration T fillet weld the allowable stress range is only 36 MPa.

So potentially you have a 800 MPa material where the weld is only good for 36 MPa for 2,000,000 cycles and all your analysis is based on is 5g and these 800 MPa. Scary stuff. I'm quite sure if you did a proper analysis of the keel at the pivot pin you would come to the conclusion that only a forged, milled out of solid block or composite keel fin will do. Any weld has to be pretty fancy. There is no way you can get away without regular NDT.

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As this is an Open Class, new this year: according to MichDes:

 

An example of the changes that have occurred with the most recent boats?

MD: "The angle that has been given to the axis of rotation for the keel. The front part is higher up, which means that the keel is angled and can be seen as a foil, which helps lift the boat up. On the Farr designed boats this angle was 2 degrees, but 5 on Safran and now we're up to 7.5." *

 

I know Safran had loaded the boat with sensors, at least the acceleration in 3 axes etc. Did not helped them a lot :)

And the only way to know the forces is to load a boat with sensors, and do a VG with it. The Southern Ocean is something else then the North Atlantic.

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As this is an Open Class, new this year: according to MichDes:

 

An example of the changes that have occurred with the most recent boats?

MD: "The angle that has been given to the axis of rotation for the keel. The front part is higher up, which means that the keel is angled and can be seen as a foil, which helps lift the boat up. On the Farr designed boats this angle was 2 degrees, but 5 on Safran and now we're up to 7.5." *

 

I know Safran had loaded the boat with sensors, at least the acceleration in 3 axes etc. Did not helped them a lot :)

And the only way to know the forces is to load a boat with sensors, and do a VG with it. The Southern Ocean is something else then the North Atlantic.

 

Agreed Leo. Was that what the wiring in Acciona's keel was - strain sensors? If so, recovery of the boat and data becomes even more important.

 

Glad Bubi is safe and sad that a brave experiment didn't make it all the way around. I think they made their point, however.

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I was just wondering. If they manage to recover the boat. Will all the computers be destroyed by the water, or are they going to be able to salvage some data ?

Otherwise on a personal matter, it sucks for Bubi who would have lost all his photos, videos, etc, that he didn't sent.

I know this is not the most important topic here, but still feel sorry for him if this is the case !

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Will all the computers be destroyed by the water, or are they going to be able to salvage some data ?

 

If the boat is recovered before it breaks up I suspect the computers will be hardened enough (to survive the sort of exposure to water that they'd receive on a Vendée) to be recoverable, at the very least I'd expect them to be watertight enough to allow the hard disks to be restored.

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Regarding the design process for these keels, we design similarly loaded and complex structures for the offshore energy industries, and simulation is one of the best tool to do this, but we will spend probably ten IMOCA budgets just doing the simulation, and another ten in testing. That is one of the differences. The other is we can take as long as we need.

 

To expect IMOCA as an organisation to undertake such a development process, and underwrite the result, and complete it in time for the teams to be able to build and install it within the next cycle, is unrealistic.

 

Just adding material is not a solution, and can be detrimental as the structural response will be counter-intuitive. Personally I'm not a fan of a one design element, such as just the keel, as this will constrain other design elements and ultimately limit development, but I think there has to be a pooling of available data and experience (both IMOCA and VOR) if the class wants to solve this within the next cycle.

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Ill be happier discussing this when I hear that Javier is safe and sound on dry land. Last news report is that he was still in his life raft awaiting rescue. Anyone got an update?

he is one tough bastard. he could drift to the caribbean on eco-power, eating raw seagulls and mahi he pulls out of the ocean with his teeth. "Goony Goo Goo"

 

Go get 'em bubi!

 

He is certainly the master of understatement.

 

In 20 knots, he gets thrown off the boat. The boat rolls over.

HE SWIMS OVER. This is the bit where I am trying to visualize chasing down a capsized Open 60 in 20 knots, on your own in the middle of the Atlantic. Kicking off seaboots, PFD inflated . For most off us this would be fucking terrifying.

Then he sorts out a life raft from the transom.

HE SPENDS THE REMAINING daylight hours trying to dry his clothes. No survival suit. He is trying to stay warm in the clothes he was wearing when he swam after the boat.

Heli arrives at night looking for him 2 miles from his position. that's okay, down to his one last flare and it does the trick.

Doc checks him out. He's fine. His message reads as if its all in a day's work.

 

But he looks pretty exhausted in the video.

 

Again, so glad he made it. He is one tough SOB. Fortunately, because he was separated from the boat in the middle of the Atlantic and I reckon it took nerves of steel tp sort that out.

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For most off us this would be fucking terrifying.

 

I feel queasy just thinking about it. He was so so close to not making it. Sometimes everything lines up against you, and sometimes it lines up for you. Seems this time both happened. A lot of pure bad things all in a row, and then a lot of pure good to recover and be rescued. So so glad.

 

In the end, I agree with some of the sentiments above. 3 out of 20 is worse than just bad, and after 20 years of this, and getting no better, I have no confidence that the current attitudes to the design will ever fix it. There are other aspects to the rules for an IMOCA 60 that are mandatory safety and detract from performance. A trivial one is the AIS antenna. The rules put it at the top of the mast. This makes a huge difference to the range, and thus the visibility of the craft. But putting anything way up there is a clear performance issue. But everyone agrees it is a good thing, and they all do it. Similarly there are all the rules about safety gear. In a race where some boats remain carbon black inside to save a kilo or two of paint they still carry all the safety gear.

 

The keel integrity is just going to have to be regarded as covered by a mandatory safety rule. And, well, we do already know what the rule probably needs to be. Machined solid steel. No welds, no voids. The VO70s managed to wreck just about every part of the boats, even tearing a keel out of the boat, but they never broke a keel fin.

 

Yes IMOCA is a development class, and we love the developments they have created over the years. However there are times when you just have to admit that the technology is beyond your capability or resources, and you have to man up to that. If Saffran can't get it right, there is zero chance that lesser funded designers or engineers can bridge the gap.

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As this is an Open Class, new this year: according to MichDes:

 

An example of the changes that have occurred with the most recent boats?

MD: "The angle that has been given to the axis of rotation for the keel. The front part is higher up, which means that the keel is angled and can be seen as a foil, which helps lift the boat up. On the Farr designed boats this angle was 2 degrees, but 5 on Safran and now we're up to 7.5." *

 

I know Safran had loaded the boat with sensors, at least the acceleration in 3 axes etc. Did not helped them a lot :)

And the only way to know the forces is to load a boat with sensors, and do a VG with it. The Southern Ocean is something else then the North Atlantic.

 

Excellent post, at all counts, Leo !

 

Yes, playing with the rotation axis angle to the horizontal is adding further unknown factors to the keel behaviour and resulting tests.

 

Yes, there is a need for a (full VG course) sensors-monitoring of keel(s), unfortunately nobody has yet shown any interest in funding suggested research, and .... I believe it should be done concurrently on different keel configurations to compare which does not help !

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As this is an Open Class, new this year: according to MichDes:

 

An example of the changes that have occurred with the most recent boats?

MD: "The angle that has been given to the axis of rotation for the keel. The front part is higher up, which means that the keel is angled and can be seen as a foil, which helps lift the boat up. On the Farr designed boats this angle was 2 degrees, but 5 on Safran and now we're up to 7.5." *

 

I know Safran had loaded the boat with sensors, at least the acceleration in 3 axes etc. Did not helped them a lot :)

And the only way to know the forces is to load a boat with sensors, and do a VG with it. The Southern Ocean is something else then the North Atlantic.

 

Excellent post, at all counts, Leo !

 

Yes, playing with the rotation axis angle to the horizontal is adding further unknown factors to the keel behaviour and resulting tests.

 

Yes, there is a need for a (full VG course) sensors-monitoring of keel(s), unfortunately nobody has yet shown any interest in funding suggested research, and .... I believe it should be done concurrently on different keel configurations to compare which does not help !

 

It's being done.

I seem to recall reading that the first instrumented boats were 2 Finot's in the Vendee 2000.

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Regarding the design process for these keels, we design similarly loaded and complex structures for the offshore energy industries, and simulation is one of the best tool to do this, but we will spend probably ten IMOCA budgets just doing the simulation, and another ten in testing. That is one of the differences. The other is we can take as long as we need.

 

To expect IMOCA as an organisation to undertake such a development process, and underwrite the result, and complete it in time for the teams to be able to build and install it within the next cycle, is unrealistic.

 

Just adding material is not a solution, and can be detrimental as the structural response will be counter-intuitive. Personally I'm not a fan of a one design element, such as just the keel, as this will constrain other design elements and ultimately limit development, but I think there has to be a pooling of available data and experience (both IMOCA and VOR) if the class wants to solve this within the next cycle.

 

The money is a major point

 

http://forums.sailinganarchy.com/index.php?showtopic=132017&st=3600#entry4034813

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The details of these keels look awful in terms of fatigue.

Designing simply to some "safety factor" means nothing.

Let's take a swag at the cycles experience.

Say 100 days X 24 hours X 60 min * 60 seconds = 8.6 X 10^6 seconds. What is the frequency of the major stress cylcing? Wave encounter? Mostly downwind in long 14 to 18 second period waves, some upwind in to 8 second waves. Let's just say the frequency is somewhere between 15 and 45 seconds.

 

Cycles for 100 days is somewhere around 200,000 to 600,000 cycles. This assumes no hydroelastic vibration of any significance. (You better have designed that out of it!) This is not good. This is medium cycle fatigue. Not surprising considering that the rule allows yielding at fillets?

 

Let's look at the stress range. Pitch induced hydrodynamic loading may increase the bending moment on the keel to something significantly greater than the Righting Arm induced. Take the boat going 20 knots and getting 5 degrees of AOA. Figure out the moment. Add that to the righting arm induced moment.

 

Consider combined stresses of torsion on both Z and Y axes simultaneously. Twisting the bulb and also fore-aft surging of ballast.

 

This is just quick talk. But if you thought experiment this through, you get some pretty good ideas. Take the load cell data already gathered and you should be able to engineer this thing better. But you'd have to be pretty conservative. Like the cycles. Figure the frequency is high for design. Figure it is low for analysis. Assume the fin broke off at the most likely stress concentration from earlier FEA. Note that the sharp fin edge going to a boss is a terrible design detail to deal with! Consider the cycles to failure to be around 100,000 cycles. Look up the KIC for the material. Do some fatigue calculations. You back out a stress range. Then go forward through the assumptions again with that. See where it goes.

 

I would be curious to know what approach had been taken in design. Some teams may have done it differently from others. How have they used the past hard experience to come to some better understanding? I suppose it will never get published but I'd love to see it in private even with an NDA signed.

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Hum101, thanks for your info, I thought so it was that expensive.

 

Finot research, I thought that failed in getting good data, but that is my memory.

Moody you remember it ?

 

Potter, youre right, lots of good info on the internet:

A good one:

http://www.gurit.com/files/documents/Sink_or_Swing_-_The_Fuindamentals_of_canting_keel_structures.pdf

 

 

And:

There have been failures in every keel material - carbon, fabricated steel and milled steel - and the failures have related to material flaws, structural engineering calculations and construction.

 

But,

 

nobody build there own masts from scratch any more, in the future a package deal from one constructor like Caraboni offers could merge all the knowledge to a few companies. But they should include the keel too :)

http://www.cariboni-italy.it/public/caritec/products/datasheets/CantingKeel.pdf

 

Etc:

why do you not see curtain designers back in the Vendee, I have the feeling at least one of them is a bit scared by the weight loss program, delicacy of modern keels and the possible liability. Why put your name again in peril... you have now a nice client base to grow old on...

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nobody build there own masts from scratch any more, in the future a package deal from one constructor like Caraboni offers could merge all the knowledge to a few companies. But they should include the keel too :)

http://www.cariboni-...CantingKeel.pdf

My reservation with a single OD keel is that the loads imposed on the keel will be very different depending on other design factors, such as the hull shape. A full bow can create instantaneous shock loads on a canted keel an order of magnitude higher than a slender bow. Similarly, with 50% displacement in water tanks, the loads would change dramatically depending on how the sailors set the boat up in given conditions.

 

Enforcing a single OD keel, with presumably a warranty based on a limiting load and cycle envelope, would either constrain the boat design and operation to try and stay within this envelope, or place each team in a position where the keel warranty will be invalid, because they can't quantify the loads their boat is applying to the keel. Alternatively the keel supplier will simply not warrant the product, the most likely scenario.

 

As a purest, I would like to see the teams retain the responsibility to develop solutions to this. Unfortunately this will be very expensive for all concerned, and maybe the class can't afford further contraction.

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