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Old 05-05-2015, 08:39   #106
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Re: Cheeki Rafiki loss report

And another diversion, this is a video of a Maxi cruiser racer that grounded and needed a tow off by the local lifeboat in Weymouth UK at the end of race, does the owner need a precautionary keel drop and check or should he just wait until it drops off miles offshore and can be photographed upside down and critiqued by the experts on here ?


U tube video here
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Old 05-05-2015, 08:57   #107
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Re: Cheeki Rafiki loss report

Robin3:
The HR looks like it can be repaired quite easily. Keel looks like it is solidly attached. This was not a "light" grounding and yet it doesn't appear that the boat sank. Completely different hull structure and keel attachment structure so I'm not sure what your comments are contributing to this topic.
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Old 05-05-2015, 09:04   #108
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Re: Cheeki Rafiki loss report

Quote:
Originally Posted by DeepFrz View Post
Robin3:
The HR looks like it can be repaired quite easily. Keel looks like it is solidly attached. This was not a "light" grounding and yet it doesn't appear that the boat sank. Completely different hull structure and keel attachment structure so I'm not sure what your comments are contributing to this topic.
It did not sink and was dried out against a wall, patched and then sailed to the mainland, around 100 mls for repairs'

I made no comments at all, actually said 'a diversion' and folks can/will make of it what they will, most probably using it to prove whatever views they personally support as always.
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Old 05-05-2015, 09:09   #109
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Re: Cheeki Rafiki loss report

Quote:
Originally Posted by europaflyer View Post
I'm not so sure about the small backing plate theory. If that was the problem, we would have seen the bolts pull through the hull with their plates, leaving holes in way of the bolts. What I see is:

1) first two bolts (single) sheared cleanly
2) next three bolts (double) pulled out through hull with backing plates, removing a substantial amount of both the grid and hull laminate
3) aftermost bolt (single) sheared, possible corrosion



Exactly what caused the initial movement we will never know. The order in which the bolts failed or started to work we won't know. However, the final failure mode seems relatively apparent from this: of the nine bolts, three are sheared and presumably their backing plates are still inside the hull, and six are still attached to the keel, along with the failed laminate section.

The initial cause may well be debonding of the grid and the hull following grounding. This shouldn't have happened in the first place, and that we can argue about for a long time, but it did. This is almost irrelevant. What matters is that the majority of the keelbolts and all the backing plates are intact, but it was laminate failure caused probably by repeated flexing which allowed the final separation.

Even with two, perhaps three of the nine bolts seriously compromised, even with the hull and grid to some extent debonded, if the hull and liner had been sufficiently strong it would have held. This is a critical point. There is no secret on how to make these things strong - more fibreglass. For literally no more than £50 worth of fibreglass and resin, and half an hour of labour, that whole area could have been twice as strong, or more, and it would have held. And that is the fundamental problem with Beneteau and others like them - for the sake of a tiny cost saving, they will happily compromise critical areas of the boat as long as the standards they are working to allow it. And that is why these cheap, lightweight boats will never be as safe for offshore sailing as what people here call 'proper bluewater boats', whatever some diehard enthusiasts of mass-market production on here say. A boat which is so damn flimsy that the keel, with most of the bolts intact, can rip out a whole section of the hull laminate, is not a seaworthy boat.
A bolt on keel is a great manufacturing cost optimisation but a dreadful engineering solution. It concentrates load on two mission critical components. The keel and the hull. Feeding those attachment loads back into the hull is not a trivial engineering and manufacturing quality challenge.

A bolt on keel is also a good engineering solution for a well maintained race boat.

There is no scenario where a bolt on keel is an optimum solution for a boat where durability is important. Like a cruising boat or amateur race boat.

The other nasty of bolt on keels is their inability to fail gracefully. A key characteristic of enduring designs and something few manufacturers understand or care about.




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Old 05-05-2015, 09:15   #110
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Re: Cheeki Rafiki loss report

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Originally Posted by boatman61 View Post
Ahhhh... the good old Peen Hammer and Screwdriver test..
Ultrasound is typically used for one side access and large area surveys. Its good for void inspection. As is a knockometer.

Xray will give a more detailed through thickness image but requires access on both sides for the emitter and imaging plate. In aircraft and missile composite analysis the focus is often on crack detection and measurement of critical crack length.

Deflection and torsional testing is also effective if you have a good baseline and very consistent build. Probably the exception rather than the rule in most recreational vessels.

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Old 05-05-2015, 10:28   #111
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Re: Cheeki Rafiki loss report

Quote:
Originally Posted by leftbrainstuff View Post
A bolt on keel is a great manufacturing cost optimisation but a dreadful engineering solution. It concentrates load on two mission critical components. The keel and the hull. Feeding those attachment loads back into the hull is not a trivial engineering and manufacturing quality challenge.

A bolt on keel is also a good engineering solution for a well maintained race boat.

There is no scenario where a bolt on keel is an optimum solution for a boat where durability is important. Like a cruising boat or amateur race boat.

The other nasty of bolt on keels is their inability to fail gracefully. A key characteristic of enduring designs and something few manufacturers understand or care about.




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I agree but the part pointing that bolt on keels is not a optimal solution for cruising or racing where durability is important is not true in my opinión, bolt on keels are a optimal solution is they are well designed , proper keel stubs , wide enough keel roots, strong and tough interior structures make a huge diference, now the enginering problem come when they try to bolt a 3 tons narrow foil hig aspect keel to a flat 9 mm solid hull with a hollow plastic in built grid liner ,, whats the diference in terms of cost and perfomance, i guess not much but those Vampires with neckties in their offices are just looking at how they can squeeze more profit from a single hull production run,,, my 2 cents...
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Old 05-05-2015, 11:00   #112
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Re: Cheeki Rafiki loss report

Quote:
Originally Posted by neilpride View Post
I agree but the part pointing that bolt on keels is not a optimal solution for cruising or racing where durability is important is not true in my opinión, bolt on keels are a optimal solution is they are well designed , proper keel stubs , wide enough keel roots, strong and tough interior structures make a huge diference, now the enginering problem come when they try to bolt a 3 tons narrow foil hig aspect keel to a flat 9 mm solid hull with a hollow plastic in built grid liner ,, whats the diference in terms of cost and perfomance, i guess not much but those Vampires with neckties in their offices are just looking at how they can squeeze more profit from a single hull production run,,, my 2 cents...


Agree. Encapsulated keels come with their own set of problems. Lead bolt on wins hands down. Cast iron is for suckers who don't know any better.
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Old 05-05-2015, 11:39   #113
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Re: Cheeki Rafiki loss report

Folks, a bolt-on keel can be engineered to the exact same tolerances as a full keel. The Golden-Gate bridge is "bolted on". It's not going anywhere.

The problem isn't the method of manufacture, its the loosening of standards and tolerances that is the problem, and manufacturing to a minimum specification rather than a wide margin for error. The bolts on my keel are some of the largest I've ever seen. Clearly Beneteau has learned a lesson.

What does bother me however are these "sail drives" that have replaced shafts. What's going to happen when I back onto a rock accidentally and open up that 6" hole in the floor that the gear-case goes through? I feel like the entire engine compartment should be in a fiberglass bathtub just in case.
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Old 06-05-2015, 07:08   #114
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Re: Cheeki Rafiki loss report

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Originally Posted by minaret View Post
If your boat had a full hull liner, you wouldn't even be able to inspect it. Nor would anyone else. The methods of inspection that keep being mentioned here are cost prohibitive for anything but large boats and/or large repairs. Ultrasound is extremely expensive, and not very reliable. It can only scan relatively small areas at a time, and can be difficult to decipher and misleading. X Ray radiography can be a more helpful form of NDT, especially where keels and bolts are concerned. Of course, it's absolutely useless for detecting a failed liner bond. So is ultrasound. Thermal imaging, however, is the bee's knee's. I have been involved with a pretty fair amount, now. Started doing it before 2000. A few cogent points:


The typical method involves tenting the entire boat, then using a very large heater, such as a Tuco (10k), to evenly heat the entire structure of the boat to about 110-120 F. This can be quite pricey.


Then, as the boat cools, multiple images are taken, both of the entire vessel, and of problem areas. Dissimilar rates of cooling are what reveals information about the structure. Often, not enough images can be taken before the boat is too cool, and reheating must occur. Often, this must be done a number of times. Often, the tent must be large enough to allow large scale imaging. Often, the tent requires extra consideration to ensure no hot spots due to ambient conditions. This can be quite pricey.


Prices for thermal imaging have come down quite a bit. Entry level units capable of doing this sort of work start at 20k. Actual schooling is required to learn to use it. The school is not cheap. Our surveyor who does this has not mastered it in fifteen years of fairly regular use. If it costs $800 for a one day survey, how much do you think it costs to have him do a multiple day imaging with very expensive equipment. I'll tell you; it can be quite pricey.


To the point where this sort of thing is almost exclusively done in large insurance situations, and paid for by the insurance company. I have never ever seen anyone do this sort of NDT unless insurance was covering it. Because the bill is huge.
So, you would not be able to inspect it or it will be expensive?

As others have stated on this thread ultrasound and ecographie is the way to go. Much better than thermos images. As that top surveyor stated it is the best way to detect a bondage defect. It is used in aviation and on the space Industry and it evolved a lot. Now you have not only the image of sound waves but real images.



Top surveying companies when referring to methods to detect a bondage defect or a flaw on a a cored hull refer the use of ultrasounds or ecographie, not thermo imaging:

CND BATEAUX

Composites
Marine inspections built on proven and accepted Aerospace inspection techniques and procedures for composite structures during manufacture and in-service


"Key technologies:
Low frequency ultrasound testing (UT) - for Wet lay-up, Nomex, Glass Fibre
High frequency ultrasound testing (UT) – for Autoclaved laminate, thin skins
Ultrasound Phased array (PA) – for high and low frequency for large area scanning of masts and hulls – and – for Solid carbon fibre rigging (new technology)
Acoustic (generically known as bond testing) – for pitch catch resonance, bond testing
Mechanical – digital tap testing, tap hammer (working to aerospace specifications)
Other technologies if requested:
Shearography
Thermal imaging (passive and active)"


Ultrasonic Testing | Marine Results

Yes if you really want they can do Thermal imaging but it is obviously that it is not what they believe to be the best diagnostic techniques.

Another top company talking about the diagnostic tools:

Q.I. Composites - the NDT choice when things get serious | NDT

As I have said not everything is alright. The tolls exist but the boat manufacturers have a role that they are not performing in what regards to provide with the boat information about the inspection of bonds and the maps (regarding bond location and base line) that would make that inspection much less time consuming and less costly.

There is also a need of upgrading technologies from the part of most surveyors and a established protocol regarding how those inspections should be performed and the frequency.
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Old 06-05-2015, 07:29   #115
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Re: Cheeki Rafiki loss report

Quote:
Originally Posted by leftbrainstuff View Post
A bolt on keel is a great manufacturing cost optimisation but a dreadful engineering solution. It concentrates load on two mission critical components. The keel and the hull. Feeding those attachment loads back into the hull is not a trivial engineering and manufacturing quality challenge.

A bolt on keel is also a good engineering solution for a well maintained race boat.

There is no scenario where a bolt on keel is an optimum solution for a boat where durability is important. Like a cruising boat or amateur race boat.

The other nasty of bolt on keels is their inability to fail gracefully. A key characteristic of enduring designs and something few manufacturers understand or care about.
It all depends to what the keel is bolt too and how the efforts are distributed to the hull. It is only an engineering problem that can be well solved or poorly solved. Some performance cruisers use carbon or steel structures where the keel is bolted (some not even much expensive).

Regarding durability there are top racing boats that use that principle, with huge keels and lot's of ballast that transmit huge loads to the hull, used in racing mode at speed on the nastier waters of the planet, with more than 20 years, having done several racing circumnavigations and that are in such good shape that they invented a kind of second rate circumnavigation race for them, to allow amateurs and professionals with low budget to race around the globe.

They are not cruiser racers, where the safety margins in what regards scantlings are bigger but top racing machines that have by definition safe but lower margin scantlings (to be lighter). Those were not designed for sure to last 20 or more years and yet here they are, sound and safe in what regards keels and keel structures.
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Old 06-05-2015, 07:29   #116
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Re: Cheeki Rafiki loss report

Seems to me that the only real answer is that if you do a hard grounding the keel needs to be dropped for inspection.

I doubt many people do that, so the need real answer is to not get a boat has had a bunch of owners, where the chances are the boat has hard grounded more than once, yet the current owner has no knowledge of them.
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Old 06-05-2015, 07:47   #117
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Re: Cheeki Rafiki loss report

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This tragedy did not happen on a bespoke boat built for one knowledgeable owner. It happened in a very common scenario of charter. These boats are built en masse to a price point for that market. The design is fine for some charter service. But we should keep in mind what happens in charter. Crew constantly change and for sure they ground boats. The person paying for the charter has a huge financial incentive to "forget" about that soft grounding on day 2 of a 10 day charter.

The idea that this crew was knowledgeable about CR's design and repair history is simply not true based on the MAIB report. A huge percentage of these pan liner boats are or were in charter service and not sailed by knowledgeable buyers familiar with the shortcomings and full history of each boat. In the aftermarket they are sold to people with even less money and probably less experience than the original charter company buyer. It seems pretty clear then that a lot (most?) of these boats are in the command of sailors who have no idea about the damage history and what the limitations of the design really entail. And as long as no one tells them then this kind of thing will keep happening as the fleet ages.

The contention that these boats all wind up in the hands of people that know what they are getting in the economic bargain is simply not valid. The more likely scenario is that the majority of sailors don't know. It seems high time more people called out that the emperor's clothing is scant and stop making excuses. People are needlessly dying here. ....
I agree with part of what you say but I don't think for the same reasons.

Yes the boat being a charter boat with the typical charter boat maintenance and misuse by casual sailors had in my opinion a major role on the tragedy: The lack of proper repairs and the bad maintenance has its origins there.

But contrary to what you say the First 40.7 is not designed for the charter business, yes there are some in charter business (as almost any not very expensive sailboat) but it is not certainly the type of boat that charter companies buy, except the very few and small ones that are specialized in chartering performance boats.

Just a very small number of the more than 800 boats made went in charter business. Even boats more suitable for charter, like the Oceanis 400, are not designed for charter. The percentage of Oceanis 400 sold for charter is way less than 25% (and even that is a very exaggerated percentage).

Sure there are special versions for charter with more cabins and more heads to explore that market that is no way the main market neither the main design criteria of the boat. The boat is designed to suit those 75% of owners and a boat that pleases them and is a success, with more cabins and heads will be a success in charter too since what pleases charter sailors (beside more cabins) is not very different then what pleases most owners.
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Old 06-05-2015, 07:51   #118
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Re: Cheeki Rafiki loss report

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Seems to me that the only real answer is that if you do a hard grounding the keel needs to be dropped for inspection.

I doubt many people do that, so the need real answer is to not get a boat has had a bunch of owners, where the chances are the boat has hard grounded more than once, yet the current owner has no knowledge of them.
Yes, I certainly agree with that. Not only the keel dropped but the boat structure thoroughly inspected as well all the bonds and (or) lamination. More easy to sell the boat as it is
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Old 06-05-2015, 23:31   #119
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Re: Cheeki Rafiki loss report

This is a true unrestricted service Ocean boat with a good keel structure. The captain was saved by AMSA well into the event, but first and foremost, he was saved by his boat. Had this been the sort of craft being critiqued on this thread, the boat's disappearance would still be a mystery. Some wreckage may have been found some time later, but probably not.

Happened 3 days ago. From AMSA's website:

"AMSA coordinated the rescue of a solo yachtsman from rocks off the West Australian coast today.
AMSA responded after detecting a distress beacon about 9am AEST. In bad weather, the yacht had become grounded on rocks near Miles Island, about 125km east of Esperance.
AMSA tasked its Dornier fixed wing aircraft and a rescue helicopter from Perth to respond. AMSA also tasked a helicopter from Esperance to respond.
The helicopter from Esperance was able to land on nearby rocks around midday AEDT and the yachtsman climbed on board. The man was uninjured and transported back to Esperance."
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Old 07-05-2015, 04:01   #120
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Re: Cheeki Rafiki loss report

It seems that the prudent answer is to drop your keel twice a week to check just in case. Or summit (ok, I skipped a few pages. Lol).

One of the things about boats is "you" get to suck up the consequences of OWN actions and decisions....whether that is a good thing or not is a personal matter. For me it is a major part of the attraction - including my dumb assed decisions! Lol.
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