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Old 25-05-2014, 10:15   #391
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Re: UK yacht Cheeki Rafiki missing in mid-Atlantic

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Originally Posted by Brob2 View Post
Because of the high aspect ratio fin keel / rig combination?

Yes, in my limited experience, A very difficult boat to keep Hove to in.


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Old 25-05-2014, 10:17   #392
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Re: UK yacht Cheeki Rafiki missing in mid-Atlantic

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Originally Posted by Cavalier View Post
If I remember rightly, that's also very close to the delineation between YM Offshore and YM ocean.

RYA YM Offshore, is stated at 150nm , BUt in reality the difference in reality between YM Ocean and Offshore distances are rather made up.


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Old 25-05-2014, 11:04   #393
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Re: UK yacht Cheeki Rafiki missing in mid-Atlantic

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Sir, I am not quite sure how we are in disagreement. If you read [way] back through the thread I believe I was the first one to postulate prior bolt failure from corrosion followed by individual failure, followed by progressive collapse (loosing and flooding), followed by the loss of the keel pulling through the remaining holes and taking part of the laminate with it (hence the peeling). Not that it makes a hero of deduction, more to the point that we are both most probably in agreement over the final stages of CR's capsize.

Pure speculation however, based on one medium resolution photograph from on angle. The only thing we know for sure is that the keel's gone and so is the poor crew.

May they rest is peace.
Very good. Particularly the last.
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Old 25-05-2014, 12:05   #394
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Re: UK yacht Cheeki Rafiki missing in mid-Atlantic

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Came across this site where a surveyor found some rusted keel bolts on a boat and yes it was a Beneteau!...
I find myself shaking my head in wonder - What does a 1988 Beneteau 345 and her badly rusted keelboats have to do with Cheeki Rafiki, a Beneteau First 40.7 built in 2006, 18 years later?
By the same extension of logic, if I see rust in the transmission of Model "T" Ford, should I assume that my Ford Taurus will have the same problems, since they both have transmissions and were built by Ford?
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Old 25-05-2014, 13:04   #395
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Re: UK yacht Cheeki Rafiki missing in mid-Atlantic

My Tuppenceworth,

The area where the keel separated from the hull shows delamination near the centre and virtually no damage fore and aft, suggesting the sikoflex, or 3500 or whatever bonding agent was used on the keel to hull seal had failed in those areas, allowing salt water to come into contact with the fore and aft keel bolts.

This would be a very oxygen deprived environment, which would cause fairly rapid (1-3 yrs) corrosion of the keel bolts fore and aft, also rocking motion would have further degraded the hull/keel bonding agent.

Most likely 1 of the bolts corroded so badly that it gave way, allowing further motion on the remaining keel bolts, which most likely the fore/aft bolts were also badly corroded. It appears the centre bolts/bonding were unaffected (which would further corroborate the theory)

There were reports of the boat taking on water hours before hand, most likely through the failed bolt/bolts.

The boat most likely suffered a hard grounding at some point in the last 3 years, maybe the hull keel join was later resealed or maybe not, but this would certainly fit in with the observed damage.

Certainly it appears that the bolts had been on the way out for some time and routine proper maintenance (ie a periodic pull of a keel bolt or two) may have shown up this issue.

The wind/wave condition at the time would not have the boat "falling off waves" nor would a side ways collision likely rip the keel off.

If i were a family member or friend of the lost ones, I would certainly be asking the owners of any recent recorded hard groundings or when if ever the keel bolts had been pulled or the keel /hull join had been inspected/resealed.

My deepest sympathy and condolence for the friends and family of the lost crew.

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Old 25-05-2014, 18:48   #396
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UK yacht Cheeki Rafiki missing in mid-Atlantic

I don't see the uk MAIB recovering that Hull for analysis by the way. They have no rescue/recovery assets anyway.

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Old 25-05-2014, 19:22   #397
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Re: UK yacht Cheeki Rafiki missing in mid-Atlantic

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Originally Posted by Zanshin View Post
I find myself shaking my head in wonder - What does a 1988 Beneteau 345 and her badly rusted keelboats have to do with Cheeki Rafiki, a Beneteau First 40.7 built in 2006, 18 years later?
By the same extension of logic, if I see rust in the transmission of Model "T" Ford, should I assume that my Ford Taurus will have the same problems, since they both have transmissions and were built by Ford?
No the question is how a 23 year old boat with severely rusted keel bolts still had it's keel. While an eight year old boat from the same manufacturer lost it.
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Old 25-05-2014, 20:23   #398
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Re: UK yacht Cheeki Rafiki missing in mid-Atlantic

This is most definitely not just a Beneteau problem. I'm sure every boat builder who bolts on keels is looking at these pictures and considering the engineering of their bolted keels. I expect there will be many changes (perhaps made quietly) Among the obvious questions:

What was the engineering decision to have only three bolts in the for and aft area? Plenty of room for more.

How is the center keel support constructed? It appears to have ripped out which would indicate that those center bolts did not break.

Why use a single line of bolts on the centerline instead of pairs of bolts offset left and right)? Maybe they did use pairs in the center section that ripped out.

.
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Old 25-05-2014, 23:37   #399
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Re: UK yacht Cheeki Rafiki missing in mid-Atlantic

I want to clarify one thing up front: I was the one the other day who said I thought my boat had around 10 keel boats (from memory). The actual number is 9: two in single-file fashion in the front, followed by three rows of two, and finally one solo bolt in back. I was thinking there were two bolts in back. I don't know the diameter. I'm going sailing tomorrow (and honestly not worrying about my keel falling off) so I'll break out the calipers and measure the bolt diameter.

The keel bolts run through the hull and the thinner part of the pan liner and are backed by 1/2 inch thick steel plates between the liner and nuts. Unfortunately I never photographed those openings when the boat was put together, but from memory the hull was probably an inch thick of more in this area, and the pan liner is itself probably 3/4 of an inch to an inch thick, so the material is pretty substantial. The pan liner is bonded to the hull with plexus. I hear a lot of complaining about that technique around the net, but any areas I've been able to see, including where it was cut through on my boat for the transducers and kelp window, the plexus layer is as solid as the fiberglass. The hull is solid non-cored glass. Only the deck is cored on the 40.7.

If you look at the high res version of the new photos you see some large scale hull damage: The center section with the 6 bolts in a 2x3 pattern is completely missing. That's water welling up through the hole. The remnants of the aft-most port hole are visible but otherwise that section is gone. The front two bolts appear to be sheared off, and I can't make out the back one other than the rust stain. Evans among others have speculated about a bolt failure, but I'm not so sure of that. The rust stain could point to a failure of the aft bolt. But even if it failed I don't see why that would cause a total structural failure of the center section of the hull AND pan liner all on it's own. This looks to me like structural failure. As I said in a previous post that could be the result of a build problem, but given the shear number of tough miles the more than 500 40.7's have done over the past 15 years that wouldn't be my first guess. I'd guess that some impact damage had happened to the hull previously which eventually caused delamination and failure in the big seas. Note that something which causes the pan liner to separate from the hull might do this, as would something that cracked either or both structures. That could have been a previous grounding, collision, or even improper yard work at some point if the keel had been removed at some point e.g. for shipping. It's pure speculation of course, and unfortunately may remain so.

As a final note, anyone who has a keel of this type should have the keel nuts torqued every time the boat is out of the water, and make sure the yard tells you if they're loose. This is especially important after a grounding. If the nuts are loose after a grounding you should be suspicious that the hull may be damaged and really you should have the keel dropped and the entire structure inspected in that case.
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Old 26-05-2014, 11:49   #400
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Re: UK yacht Cheeki Rafiki missing in mid-Atlantic

You have to wonder why a PANPAN was not issued when they first noticed the leak,ships in area could have been on scene sooner.Also,considering the conditions,why was the liferaft not readied in the cockpit?Is it possible they were thinking of returning to eastcoast considering their proximity?Questions aside,condolences to the families.
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Old 26-05-2014, 13:17   #401
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Re: UK yacht Cheeki Rafiki missing in mid-Atlantic

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Originally Posted by gjorgensen View Post
The actual number is 9: two in single-file fashion in the front, followed by three rows of two, and finally one solo bolt in back. I was thinking there were two bolts in back.
Thanks for the info. This is key to understanding what MAY have happened.

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Originally Posted by gjorgensen View Post
The pan liner is bonded to the hull with plexus. I hear a lot of complaining about that technique around the net, but any areas I've been able to see, including where it was cut through on my boat for the transducers and kelp window, the plexus layer is as solid as the fiberglass.
Just one caveat, the plexus bonding material may be appear to be as solid as Glass Reinforced Plastic ("fiberglass" in US dialect) but the plexus-hull and plexus-liner interfaces have to transmit a lot of shear (as anything in the middle of a flexed element) and IF THOSE INTERFACES HAVE CRACKED JUST A BIT IN A PRIOR GROUNDING they will (because there is no glass fiber going across the interface) not absorb that shear, drastically reducing the flex resistance and increasing flex deformation of the whole structure.

In a nutshell, the plexus bonding solution works great if there is no preexisting grounding damage, but it loses a lot of strength if there is prior damage. Therefore it is critical to monitor that the plexus is not cracked to ensure grid liner and hull work as one structure. Grounding damage does not need ot be the end of the world, because it is relatively easy to repair the damage with GRP and end up with a stronger structure than in a new boat (see for example the standard Moorings fix for grounding damage that breaks the plexus bond between grid liner and hull), but IF THE BOND IS NOT REPAIRED THEN THE STRUCTURE IS NOT STRONG ENOUGH.

If you ask a structural engineer (I confess I used to be one) they will tell you that the structure holding the keel should be "ductile" (ie capable of significant plastic deformation without loosing most strength) because when the boat runs aground (as when a car crashes, an earthquake hits a building or any loads driven by changes in speed of heavy things) you need plastic deformation to absorb energy without unacceptable stresses. When the hull and grid liner are secured with plexus instead of GRP the resulting interface is not ductile, it is fragile. For comparison, if grid and hull were held together by Glass Reinforced Plastic, the strength/stiffness of the system would probably not be that much higher, but the % LOSS OF STRENGTH/STIFFNESS FROM A GROUNDING WOULD BE MUCH SMALLER and you could probably keep sailing without repairing the damage.


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SNIP you look at the high res version of the new photos you see some large scale hull damage: The center section with the 6 bolts in a 2x3 pattern is completely missing. That's water welling up through the hole. The remnants of the aft-most port hole are visible but otherwise that section is gone. The front two bolts appear to be sheared off, and I can't make out the back one other than the rust stain. Evans among others have speculated about a bolt failure, but I'm not so sure of that. The rust stain could point to a failure of the aft bolt. But even if it failed I don't see why that would cause a total structural failure of the center section of the hull AND pan liner all on it's own.
+10 on your "not so sure". The two "single file" bots in the front and the one in the back are not important when dealing with the critical loads for a keel, which are the sideways loads due to weight and hydrodynamic lift. The bolts that matter are the 6 (=3x2) that are not in the fore-aft plane fo the boat, and those seem to be intact in the bottom of the sea now.

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Originally Posted by gjorgensen View Post
I'd guess that some impact damage had happened to the hull previously which eventually caused delamination and failure in the big seas. Note that something which causes the pan liner to separate from the hull might do this, as would something that cracked either or both structures. That could have been a previous grounding, collision, or even improper yard work at some point if the keel had been removed at some point e.g. for shipping. It's pure speculation of course, and unfortunately may remain so.
+100 on all that. Hopefully someone will come up wit a data point that will explain it all.

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Originally Posted by gjorgensen View Post
As a final note, anyone who has a keel of this type should have the keel nuts torqued every time the boat is out of the water, and make sure the yard tells you if they're loose. This is especially important after a grounding. If the nuts are loose after a grounding you should be suspicious that the hull may be damaged and really you should have the keel dropped and the entire structure inspected in that case.
I have my reservations about "bolts are still tight" being sufficient proof that everything is OK with the structure that holds the keel.

Granted, this will tell you if the bolts or threads have failed, but it will not tell you if the plexus bond has broken.

Unfortunately there are yards out there that think that you can fix the break between the liner and hull by tightening the bolts, and that is not the case. If the plexus bond is broken it needs not be fixed with GRP; end of story.
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Old 26-05-2014, 14:30   #402
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Re: UK yacht Cheeki Rafiki missing in mid-Atlantic

From ITWPlexus: (Red emphasis mine)

"Plexus "Fiberglass Fusion" Adhesives have revolutionized the way boats are designed and built. When applied to fiberglass and other composites, they dissolve a thin layer of each mating surface and actually fuse two composite surfaces into one, creating a chemically cross-linked bond so strong that the composites will delaminate before the bond fails.
In addition to unmatched bond strength, Plexus Adhesives offer:
Flexibility to absorb vibrations and withstand stresses caused by the pounding of wind, water, and high speed on performance boats
Excellent resistance to fuel, chemicals, UV, extreme temperatures, and repeated thermal cycling
Design freedom to replace wood (especially below the waterline) with composites, thereby preventing rot and warranty issues

By replacing heavy, unreliable marine putties, Plexus Adhesives:

Virtually eliminate surface preparation (no sanding, grinding, or primers required) and replace slow, labor-intensive assembly methods, reducing production times by up to 50%
Eliminate chlorinated solvents
Produce stronger, lighter, faster boats

By obsoleting mechanical fasteners such as bolts, rivets, and screws, Plexus Adhesives:

Distribute loads over a much greater area
Minimize fiberglass fatigue, wear, and failures
Eliminate potential leak points

ITW Plexus is ISO 9001 certified. Plexus Adhesives have been tested and certified by the world's most respected marine agencies, including Lloyd's of London, Det Norsk Veritas, Icelandic, and the American Bureau of Shipping."

Any comments on how your impressions differ and how you come by them?
In a previous life, I owned an advanced composites business. My experience is that secondary bonding of two GRP structures is dicey at best...
Plexus looks to be best available practice from where I sit.
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Old 26-05-2014, 14:56   #403
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Re: UK yacht Cheeki Rafiki missing in mid-Atlantic

Quote:
Originally Posted by KnuckleDragger View Post
From ITWPlexus: (Red emphasis mine)

"Plexus "Fiberglass Fusion" Adhesives have revolutionized the way boats are designed and built. When applied to fiberglass and other composites, they dissolve a thin layer of each mating surface and actually fuse two composite surfaces into one, creating a chemically cross-linked bond so strong that the composites will delaminate before the bond fails.
In addition to unmatched bond strength, Plexus Adhesives offer:
Flexibility to absorb vibrations and withstand stresses caused by the pounding of wind, water, and high speed on performance boats
Excellent resistance to fuel, chemicals, UV, extreme temperatures, and repeated thermal cycling
Design freedom to replace wood (especially below the waterline) with composites, thereby preventing rot and warranty issues

By replacing heavy, unreliable marine putties, Plexus Adhesives:

Virtually eliminate surface preparation (no sanding, grinding, or primers required) and replace slow, labor-intensive assembly methods, reducing production times by up to 50%
Eliminate chlorinated solvents
Produce stronger, lighter, faster boats

By obsoleting mechanical fasteners such as bolts, rivets, and screws, Plexus Adhesives:

Distribute loads over a much greater area
Minimize fiberglass fatigue, wear, and failures
Eliminate potential leak points

ITW Plexus is ISO 9001 certified. Plexus Adhesives have been tested and certified by the world's most respected marine agencies, including Lloyd's of London, Det Norsk Veritas, Icelandic, and the American Bureau of Shipping."

Any comments on how your impressions differ and how you come by them?
In a previous life, I owned an advanced composites business. My experience is that secondary bonding of two GRP structures is dicey at best...
Plexus looks to be best available practice from where I sit.

Humm , nice!! 50% of that statement is Marketing BS, Plexus its a really nice stuff but gluing a full grid liner inside of a bare hull have some kind of negative impact, in fact the liner never fit perfectly even with the hull , the plexus made contact uneven leaving dry gaps and voids everywhere,
in the right spot its a strong adhesive, i will say for liners there is no other choice at the moment , bulkheads its another history.

Lets see...

Distribute loads over a much greater area

BS.

Minimize fiberglass fatigue, wear, and failures.....................


Bs. i see some funny hull to deck joints glued with plexus and cracked inside due flex , plexus its not flex friendly. A beneteau 50 have the fwd last bulkhead glued with plexus , FG taped in one side and nothing in the cabins side

Eliminate potential leak points ........................

Now this is Funny, can someone enlight us how easy is to spot a hull leak with a full pan liner hiden the real hull ?? Grid liners need to be baned from the boat construction techniques , is just awful.
From the manufacture point of view , save cost, faster production and a overall clean looking interior , nothing else....

Plexus its another invention to make boats faster in the production line,
Stronger??? nahhhh
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Old 26-05-2014, 15:39   #404
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Re: UK yacht Cheeki Rafiki missing in mid-Atlantic

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Originally Posted by neilpride View Post
Humm , nice!! 50% of that statement is Marketing BS, Plexus its a really nice stuff but gluing a full grid liner inside of a bare hull have some kind of negative impact, in fact the liner never fit perfectly even with the hull , the plexus made contact uneven leaving dry gaps and voids everywhere,
in the right spot its a strong adhesive, i will say for liners there is no other choice at the moment , bulkheads its another history.

Lets see...

Distribute loads over a much greater area

BS.

Minimize fiberglass fatigue, wear, and failures.....................


Bs. i see some funny hull to deck joints glued with plexus and cracked inside due flex , plexus its not flex friendly. A beneteau 50 have the fwd last bulkhead glued with plexus , FG taped in one side and nothing in the cabins side

Eliminate potential leak points ........................

Now this is Funny, can someone enlight us how easy is to spot a hull leak with a full pan liner hiden the real hull ?? Grid liners need to be baned from the boat construction techniques , is just awful.
From the manufacture point of view , save cost, faster production and a overall clean looking interior , nothing else....

Plexus its another invention to make boats faster in the production line,
Stronger??? nahhhh
Good post, mate! I think that you have hit most of the high spots... especially the final paragraph.

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Old 26-05-2014, 16:51   #405
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Re: UK yacht Cheeki Rafiki missing in mid-Atlantic

it may be just me, but this thread has become the same old stuff from the usual suspects
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