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      A Few Simple Rules   05/22/2017

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Quagers

Cheeki Rafiki MAIB report published

866 posts in this topic

See it here,

 

https://www.gov.uk/government/news/cheeki-rafiki-accident-investigation-report-published

 

Obviously mainly speculation but highlights racers lax attitude to groundings and proper repair and inspection following them. Some discussion of the route chosen for the crossing and some issues around commercial coding. Surprisingly little discussion of crew experience.

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This is from the MAIB Safety flyer on the incident (attached)

 

Narrative

On 16 May 2014, an alert was received from the personal locator beacon of the skipper of the United Kingdom (UK) registered yacht Cheeki Rafiki, which was on passage from Antigua to the UK, and located approximately 720 miles east-south-east of Nova Scotia, Canada. Despite a major search effort, during which the yacht’s upturned hull was located but not recovered, Cheeki Rafiki’s four crew remain missing.

 

In the absence of survivors and material evidence, the causes of the accident remain a matter of some speculation. However it is concluded that the yacht capsized and inverted following a detachment of its keel. In the absence of any apparent damage to its hull or rudder other than that likely to have been directly associated with keel detachment, it is concluded unlikely that the vessel had struck a submerged object. Instead, a combined effect of previous groundings and subsequent repairs to its keel and matrix had possibly weakened the vessel’s structure where the keel was attached to the hull. It is also possible that one or more keel bolts had deteriorated. A consequent loss of structural strength may have allowed movement of the keel which would have been exacerbated by increased transverse loading through sailing in worsening sea conditions.

 

Safety Lessons

 

1. Matrix detachment is possible in yachts where a GRP matrix and hull are bonded together. The probability of this occurring will increase with longer and harder yacht usage. There is therefore a need for regular structural inspection by a nominated competent person as part of a formal verifiable procedure, as well as before embarking on an ocean passage.

 

2. Owing to the continuous nature of a matrix where solid floors are in place, particularly where the keel is attached to the hull, it may be difficult to readily identify areas where a detachment has occurred. There are differing opinions among surveyors and GRP repairers with regard to what are appropriate methods of inspection and repair, including the circumstances in which the keel should be removed. There is therefore a desire for best practice industry-wide guidance to be developed.

 

3. Any grounding has the potential to cause significantly more damage than may be subjectively assessed or visually apparent, including matrix detachment. It is therefore important that all groundings, including those perceived to be ‘light’, result in an inspection for possible damage by a suitably competent person.

 

4. Ocean passages require comprehensive risk assessment and contingency planning. A compromise needs to be made between planning a high latitude route, to pick up favourable winds and ensure a speedier passage, and a low latitude route, to avoid particularly adverse weather at the expense of a slower passage possibly necessitating additional port calls. Weather routing, vessel tracking and frequent communications from a shore-based support cell can significantly reduce the risks.

 

5. Attached keels are a feature of modern yacht design. Operators and crews therefore need to be aware of the associated danger of keel detachment, and have preventive procedures in place to reduce the risk, e.g regular inspection of the keel attachment area and checking of keel bolts, and documented actions to take in the event of flooding, including reducing the load on the keel and preparing for the yacht capsizing and inverting.

 

6. Search and Rescue mid-ocean is hampered both by the time it takes fixed-wing search aircraft to arrive and their ability to assist when on scene. Consideration therefore needs to be given to how the alarm will be raised, both by the quickest means and with an accurate position. Wearing a Personal Locator Beacon provides additional assurance that the alarm can be raised if it has not been possible to deploy the vessel’s EPIRB.

 

7. It is likely to take many hours or even days before SAR assistance can be provided midocean, during which time being able to board a liferaft will be key to survival. In small craft there will be a trade-off between positioning the liferaft so it will deploy automatically in the event of an emergency, and the risk of it deploying accidentally in heavy weather. Whatever solution is chosen, for long passages it might be necessary to make other compromises to ensure that the liferaft is located in the best possible position to ensure its availability in the event of a catastrophic event, such as a sudden capsize.

SafetyFlyerToMAIBInvReport08-2015_CheekiRafiki.pdf

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i'm part way through the report.., so maybe all will be explained.., but i'l ask my question anyway...

 

is what they call the "matrix" what some of us refer to as a hull liner?

 

it looks that way from the picture in the report.

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i'm part way through the report.., so maybe all will be explained.., but i'l ask my question anyway...

 

is what they call the "matrix" what some of us refer to as a hull liner?

 

it looks that way from the picture in the report.

I'm not sure, but since they refer to the GRP matrix as bonded to the hull, I infer that to be a reference to the floor members and structural grid that supports the keel and rig loads. I do not think it refers to the liner.

 

I could be wrong...

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3. Any grounding has the potential to cause significantly more damage than may be subjectively assessed or visually apparent, including matrix detachment. It is therefore important that all groundings, including those perceived to be ‘light’, result in an inspection for possible damage by a suitably competent person.

 

That will do wonders for insurance rates. Some years I would be running an inspection a month :o

3.1. Quit building fragile boats :rolleyes:

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I just wanted to say to the group here, that we assisted in the MAIB investigation, but were unable to review a draft of the document before it was published. I think there a few inconsistencies in the report, but on the whole it is a well written document.

 

The report does indicate that prior groundings were repaired in an unknown way. Just to be 100% clear, at FYD we have no knowledge of the Beneteau dealer recommended repair procedure. That by itself is a pretty worrying. Even if that was followed, we don't necessarily know that it would be sufficient.

 

We take safety very seriously and will issue an announcement/addendum to the MAIB report with some other considerations. The biggest thing I want to emphasize is, please contact your yacht designer if you have any questions. If you have an incident that potentially caused structural damage, contact your yacht designer. If you have an impending repair contact your yacht designer.

 

In this particular instance the hull liner laminate (do not call it a matrix), is not a trivial simple laminate. Replacing it with some unknown laminate to similar thickness would not necessarily be adequate. Please ask first. It almost incomprehensible that a repair could be made in a critical area like this without guidance. Please let us help you.

 

We will be back with more, after we've had a chance to fully digest the report. Stand by.

 

Patrick

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3. Any grounding has the potential to cause significantly more damage than may be subjectively assessed or visually apparent, including matrix detachment. It is therefore important that all groundings, including those perceived to be ‘light’, result in an inspection for possible damage by a suitably competent person.

 

That will do wonders for insurance rates. Some years I would be running an inspection a month :o

3.1. Quit building fragile boats :rolleyes:

With respect for the lost crew, I'm concerned if anyone thinks it is acceptable for a production racer/cruiser to be designed and constructed in a way that grossly normal useage may require a significant inspection regime and designer consultation on a regular basis. A custom GP boat? Perhaps.

 

Agree with 3.1.

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I don't see a whole lot of strength in that design and using splooge to hold the pan to the liner is a punters game. Worst of all there is no way to check the condition of the splooge holding the bits together after a grounding.

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Thanks for the visuals Proa.

Appreciate it.

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Anecdotal evidence collected throughout the investigation suggests that the frequency of grounding, particularly when racing, may be higher than reported.

No shit...

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Where would a person- Owner, Skipper, Crew Boss, even crew, report groundings? Most boats through the years I have raced on bumped the bottom short tacking the shore line to stay out of the current. When I experienced this, reporting it to whoever would seem silly. I have been on boat deliveries when some dumb ass thinks he knows what he's doing and smacked, rocks, sandbars, log booms so hard it actually sent me flying when down below. While off watch sleeping, a violent awakening. These groundings are reported to the Owner, if there is at least one crewman aboard with any respect for seamanship.

 

Who or what entity should serious groundings be reported to?

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It almost seems to me you'd need a yard that has a NA on retainer.

 

And sailboat owners are cheap....

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I just waded through the whole thing.

 

It is a bit worrying that Beneteu had a service bulletin detailing how to repair a detached matrix in this boat, and that the MAIB had no trouble finding multiple instances to look at, and multiple repair examples to study.

 

I would not want to own a boat with this method of construction. It is brittle, and has no means of inspection for manufacturing or damage related faults.

 

Regarding grounding, this was a charter boat with a hired captain. No charterer ever describes any grounding as other than "light", nor I suspect, does any hired captain.

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This is how airplanes are operated (in theory). An overstress/overspeed is logged and leads to big $$$ inspections and NDT.

Almost no boat owners would be willing to pay for this kind of thing.

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so, it seems like the GRP hull in the area of the keel is solid laminate

 

the liner (matrix) is apparently made in a similar fashion as the hull, so i am assuming it is also a solid GRP laminate - although Patrick Shaughnessy from FYD might be implying in his post above that there is something special about the construction of the liner...

 

the two pieces are glued together, but if the glue fails - which is known to happen after some groundings - the liner can move wrt the hull, and this movement can weaken the structure somehow allowing the keel to fall off.

 

clearly relative movement could lead to the keel bolt holes enlarging, and maybe some other holes forming, allowing water ingress

 

there is not much detail about exactly why the keel falls of - i could imagine a few scenarios..., but i am surprised they didn't speculate a bit more about this

 

so, one thing i have always wondered about this type of build.., is why the keel bolts only go through a "bay" of the liner, and not through the beams which are also part of the liner, and cross the keel...

 

this seems to me like it would be much stronger, as it would do a better job of distributing the keel loads over a large area than simply having backing plates on the liner bay.

 

Patrick - can you comment on this?

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so, one thing i have always wondered about this type of build.., is why the keel bolts only go through a "bay" of the liner, and not through the beams which are also part of the liner, and cross the keel...

 

this seems to me like it would be much stronger, as it would do a better job of distributing the keel loads over a large area than simply having backing plates on the liner bay.

 

Patrick - can you comment on this?

 

Because the beams are hollow.

 

You cannot bolt thru without crushing them.

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Not a fan of hull liners full stop. Makes construction cheaper but proper built in structure is surely a better answer? If you had a collision with something and water was leaking in from behind the liner, how the hell would you get at it to diagnose and try to limit flow? Maybe I'm missing something.

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Another issue, this includes many things other than keel/hull connections, is that many structural issues and rigging issues do not present themselves while the boat is moored or on the hard. Many problems that are hidden away while docked, can only come to light when the boat is sailing in a certain amount of breeze and a certain type or size of seaway. This makes finding some issues much harder and there is a need for some sort of inspection while in real world, real time sailing conditions.

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A glued in grid? I know there are some great adhesives these days but come on. I'd think that would do for a cost cutting/ease of installation not internal structure as much. Loose keel bolts because of it? Things that make you go.........hmmmm.

 

Some production builders need to take a page from X-Yachts with there fully bonded/integral in galvanized grids; these days - carbon. Not because it's easy or cheap but bloody strong & stiff.

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so, one thing i have always wondered about this type of build.., is why the keel bolts only go through a "bay" of the liner, and not through the beams which are also part of the liner, and cross the keel...

 

this seems to me like it would be much stronger, as it would do a better job of distributing the keel loads over a large area than simply having backing plates on the liner bay.

 

Patrick - can you comment on this?

 

Because the beams are hollow.

 

You cannot bolt thru without crushing them.

 

 

so make them capable of taking the load....

 

they probably wouldn't have to be completely solid.

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A glued in grid? I know there are some great adhesives these days but come on. I'd think that would do for a cost cutting/ease of installation not internal structure as much. Loose keel bolts because of it? Things that make you go.........hmmmm.

 

Some production builders need to take a page from X-Yachts with there fully bonded/integral in galvanized grids; these days - carbon. Not because it's easy or cheap but bloody strong & stiff.

 

in the older X-yachts, with the galvanized grid.., the keel bolts do go through the galvanized beams.

 

in the current boats, with the carbon grid, the keel bolts do not go through the beams - at least that's the way it looks from the diagrams

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Annex, page 19page_19.jpg

Annex, page 20page_20.jpg

Those hollow beams directly above the keel are nothing more than hull stiffeners. They are there to keep the bottom of the hull from flexing under the high loading of the keel. All there is for actual strength at the keel attachment point is the hull thickness and another layer of glass glued to the hull. What happened to actual floors (beams) the keel bolts used to be bolted through?

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Annex, page 19

Annex, page 20

Those hollow beams directly above the keel are nothing more than hull stiffeners. They are there to keep the bottom of the hull from flexing under the high loading of the keel. All there is for actual strength at the keel attachment point is the hull thickness and another layer of glass glued to the hull.

 

right - i understand that...

 

but why does it have to be that way?

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Annex, page 19

Annex, page 20

 

Those hollow beams directly above the keel are nothing more than hull stiffeners. They are there to keep the bottom of the hull from flexing under the high loading of the keel. All there is for actual strength at the keel attachment point is the hull thickness and another layer of glass glued to the hull.

right - i understand that...

 

but why does it have to be that way?

I don't think it should be that way. There should be more material built/layed up as one complete unit, or go back to keel bolts going through solid floors.

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A glued in grid? I know there are some great adhesives these days but come on. I'd think that would do for a cost cutting/ease of installation not internal structure as much. Loose keel bolts because of it? Things that make you go.........hmmmm.

 

Some production builders need to take a page from X-Yachts with there fully bonded/integral in galvanized grids; these days - carbon. Not because it's easy or cheap but bloody strong & stiff.

 

in the older X-yachts, with the galvanized grid.., the keel bolts do go through the galvanized beams.

 

in the current boats, with the carbon grid, the keel bolts do not go through the beams - at least that's the way it looks from the diagrams

 

I can't actually comment on the newer ones but their grid system is a landmark/hallmark system. I couldn't think of doing anything but doing it right.

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Dumb question - did the bolts break or wiggle back and forth enough to erode their way through the hull yanking the nuts right through? I can't recall.

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I don't think it should be that way. There should be more material built/layed up as one complete unit, or go back to keel bolts going through solid floors.

 

 

Perhaps, one can always guess and speculate.

 

I am laminator. How much more material. I know one layer, two, ... ten layers (or even more) . But I do not know how many is "enough that it does not break".

 

And who told you that some more material would NOT result in the same ending, only some monthes or years or simply some groundings later ?????

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From the pictures, it looks like the bolts and backing plates pulled through, ripping sections of laminate with it.

 

Nothing was said in the report, but the attachment needs to involve more than the small area of (substandard) laminate that surrounds the three bolts taking the load. If it had instead 8 smaller bolts, pulling on a larger area of laminate, it would have been quite a bit stronger. A hull built this way is kind of like a monocoque race car tub or fuselage. You don't just stick a couple of large bolts through the thin skins to resolve a large load. You use a bunch of small fasteners, because the load carrying ability of the skin locally is quite limited. Or you need to have a stiff enough backing plate well attached to accomplish the same thing. I guess they thought the liner served that purpose, but it sounds from the report that there was a known history of problems with them.

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I'm surprised at all the surprise. It all seems fairly obvious to me.

 

The design met all requirements of the ABS, the only source of scantlings at the time the design was put into production. With a relatively minor increase in the area and thickness of a few washers, it also me the requirements of the ISO standards published later. The yacht was constructed in this fashion because it met cost targets, performance targets, market requirements and applicable standards. Period.

 

Once built, the onus is clearly on the owner to maintain the yacht in a seaworthy condition or to remove it from service is such determination cannot be made - this was clearly not done and that is, in my opinion, the beginning and ending of the story regarding the loss of the keel and the loss of the crew. Period.

 

There is an interesting question about why one would purchase a yacht that is constructed in such a fashion that it becomes nearly impossible to tell whether it is damaged in the face of easily anticipated situations that arise from normal operation. But this question lies well outside the scope of both regulations and manufacturer responsibility.

 

We live in a caveat emptor world and passing this off as an ocean going yacht is no different than a Lada being passed off as a reliable automobile - a knowledgable end user is required to correctly identify the suitability of the product to the desired application. I do not believe any of us can honestly state that we wish for a sanctioning body or government agency to begin making that determination through a bureaucratic lens?

 

Surely owners of yachts constructed in this fashion now have some soul searching to do, some checks to write and possibly some boats to destroy. Other than that, while the outcome is unseemly, there's really nothing here to see. It's time to move along. No?

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I don't think it should be that way. There should be more material built/layed up as one complete unit, or go back to keel bolts going through solid floors.

 

Perhaps, one can always guess and speculate.

 

I am laminator. How much more material. I know one layer, two, ... ten layers (or even more) . But I do not know how many is "enough that it does not break".

 

And who told you that some more material would NOT result in the same ending, only some monthes or years or simply some groundings later ?????

fcfc, I'm simply comparing this generation of "white boats" that are gluing stiffeners and a layer of glass into hulls, to past practices that the entire hull, all load bearing structures where layed up as one solid unit. I don't know, maybe I've had the privilege of sailing on well built solid boats. The guy doing the layup, you, does not make the decision on how many layers. A naval architect and engineers decide the final scantlings, you are but a cog in the mighty world of boat construction.

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The design met all requirements of the ABS, the only source of scantlings at the time the design was put into production. With a relatively minor increase in the area and thickness of a few washers, it also me the requirements of the ISO standards published later.

 

My long time contention has been that, absent proper conservative real engineering calculations, and given that production (and custom) boatbuilders alike are going to point to these standards as exonerating, that they need to be revised to be much more robust. The ABS certainly did not contemplate thin bulb keels, the ISO does not apparently contemplate normal construction methods and operational hazards.

 

Either make these standards fool proof so fools can use them, or eliminate them so that they cannot be used foolishly and then pointed to, post facto, as exoneration.

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fcfc, I'm simply comparing this generation of "white boats" that are gluing stiffeners and a layer of glass into hulls, to past practices that the entire hull, all load bearing structures where layed up as one solid unit. I don't know, maybe I've had the privilege of sailing on well built solid boats. The guy doing the layup, you, does not make the decision on how many layers. A naval architect and engineers decide the final scantlings, you are but a cog in the mighty world of boat construction.

 

 

But again, how an engineer or naval architect can guess the final scantling when they do NOT know how hard one particular boat will be used ?????

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My long time contention has been that, absent proper conservative real engineering calculations, and given that production (and custom) boatbuilders alike are going to point to these standards as exonerating, that they need to be revised to be much more robust. The ABS certainly did not contemplate thin bulb keels, the ISO does not apparently contemplate normal construction methods and operational hazards.

 

Either make these standards fool proof so fools can use them, or eliminate them so that they cannot be used foolishly and then pointed to, post facto, as exoneration.

 

 

 

How much cost to build an FOOL PROOF sailboat ? and WHO will buy it and make the yard building it get a living . That's all.

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My long time contention has been that, absent proper conservative real engineering calculations, and given that production (and custom) boatbuilders alike are going to point to these standards as exonerating, that they need to be revised to be much more robust. The ABS certainly did not contemplate thin bulb keels, the ISO does not apparently contemplate normal construction methods and operational hazards.

 

Either make these standards fool proof so fools can use them, or eliminate them so that they cannot be used foolishly and then pointed to, post facto, as exoneration.

 

 

 

How much cost to build an FOOL PROOF sailboat ? and WHO will buy it and make the yard building it get a living . That's all.

 

 

The boat doesn't need to be foolproof. The standard for keels should be, if those standards are being used by fools. But going further, the keel probably should be too. And it isn't expensive: probably an extra $100 - 200 would have kept that keel on. If you are going to cut corners, do it in the rig, the accommodation, the fancy portlights - not in the keel.

 

Suppose Boeing built jetliners like that. Maybe one in 100 or one in 1000 crash. Not a very big percentage. Acceptable? It isn't just the probability of failure for a system that must be taken into account, it is also the consequences of that particular failure. If a deck cleat leaks 'cause it was underrated, that is an annoyance. If the keel falls off, it's more critical. Kind of like the wings falling off an airplane - are you saying that's OK as long as the builder can make a living doing it?

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Well several previous generations were pretty much "fool proof". Anyone ever run an Alberg 30 aground and then have the keel fall off :rolleyes:

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Note to new naval architects.

Sailboats sail in wind and waves. Sometimes the wind is quite high and the waves quite large.

Sailboats also run aground. Sometimes a lot, depending on the area.

Previous generations of boats could do these things and not fall apart.

Glad I could help ;)

 

 

fcfc, I'm simply comparing this generation of "white boats" that are gluing stiffeners and a layer of glass into hulls, to past practices that the entire hull, all load bearing structures where layed up as one solid unit. I don't know, maybe I've had the privilege of sailing on well built solid boats. The guy doing the layup, you, does not make the decision on how many layers. A naval architect and engineers decide the final scantlings, you are but a cog in the mighty world of boat construction.

 

 

But again, how an engineer or naval architect can guess the final scantling when they do NOT know how hard one particular boat will be used ?????

 

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^^ But, were slower by 2/10 of a knot. Surely your life isn't worth that much?

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Well several previous generations were pretty much "fool proof". Anyone ever run an Alberg 30 aground and then have the keel fall off :rolleyes:

 

And were is Alberg today ? How much sales last year ?

 

Customer simply NO LONGER want to buy an Alberg 30.

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My keel is still on too and I am way faster B)

The C&C keel stub from the late 60s to early 70s was very strong. No way the keel is coming off without ripping the boat to pieces.

 

 

Well several previous generations were pretty much "fool proof". Anyone ever run an Alberg 30 aground and then have the keel fall off :rolleyes:

 

And were is Alberg today ? How much sales last year ?

 

Customer simply NO LONGER want to buy an Alberg 30.

 

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The boat doesn't need to be foolproof. The standard for keels should be, if those standards are being used by fools. But going further, the keel probably should be too. And it isn't expensive: probably an extra $100 - 200 would have kept that keel on. If you are going to cut corners, do it in the rig, the accommodation, the fancy portlights - not in the keel.

 

Suppose Boeing built jetliners like that. Maybe one in 100 or one in 1000 crash. Not a very big percentage. Acceptable? It isn't just the probability of failure for a system that must be taken into account, it is also the consequences of that particular failure. If a deck cleat leaks 'cause it was underrated, that is an annoyance. If the keel falls off, it's more critical. Kind of like the wings falling off an airplane - are you saying that's OK as long as the builder can make a living doing it?

 

 

100$ for fiberglass. OK, but how much for the engineering needed to know you need 100$ more fiberglass ?

 

Have you ever checked a jetliner / weight price, and compared it to aluminium / weight price ???

 

 

are you saying that's OK as long as the builder can make a living doing it?

 

Yes, somewhat. If the boat is viewed as too dangerous, the builder will have a hard time to make a living of it. But if the boat is unnecessarily costly, he will also have hard time selling it. There is a narrow gap to find.

 

 

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As regards X Yachts, we had a 412 which, after a grounding, suffered significant detachment of the metal frame from the hull skin, so the whole aft end started to wiggle. Made it home safe, but a major repair!

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If the keel falls off, it's more critical. Kind of like the wings falling off an airplane - ?

 

 

BTW, HOW it has been found that airplane wings NEED to sustain 4G for 30 seconds ?

 

Cannot the boating industry do the same for keels ?

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Loads on boats are vastly harder to model than loads on airplanes.

 

 

If the keel falls off, it's more critical. Kind of like the wings falling off an airplane - ?

 

 

BTW, HOW it has been found that airplane wings NEED to sustain 4G for 30 seconds ?

 

Cannot the boating industry do the same for keels ?

 

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3. Any grounding has the potential to cause significantly more damage than may be subjectively assessed or visually apparent, including matrix detachment. It is therefore important that all groundings, including those perceived to be ‘light’, result in an inspection for possible damage by a suitably competent person.

 

That will do wonders for insurance rates. Some years I would be running an inspection a month :o

3.1. Quit building fragile boats :rolleyes:

Gee, I guess thats two inspections Ill need this month!

 

Doesnt say much for modern construction does it?

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Not a fan of hull liners full stop. Makes construction cheaper but proper built in structure is surely a better answer? If you had a collision with something and water was leaking in from behind the liner, how the hell would you get at it to diagnose and try to limit flow? Maybe I'm missing something.

Liners do make for less, and less skilled labor for construction, enables modular interior components by eliminating variances between hulls, etc. they can be quite strong and a properly chosen and applied adhesive should be stronger than the laminate. In other words, the bond should not fail before the hull or liner material does. Yes, liners make it harder to modify or repair a boat through its life and you can't get access behind furniture foundations to inspect, but how many series production boats are modified substantially as far as layout goes? I know that a number of liners have come loose and those are either failures in engineering or process and are unacceptable.

 

I have no problem with glued boats as compared to laid up "stick built" boats with hundreds of secondary bonds. Tabbing can tear away. The difference or really in repairability after damage occurs.

 

I like how deep draft, fin keel boasts sail as compared to full keels and I don't think anyone wants to go back to CCA days in design. I don't like very thin keel attachments that through bolt through skin, even if the skin has a second layer of a liner pan. We talked about the stresses when C-R was lost and a narrow chord on a deep fin places enormous strains on the attach points in relatively benign conditions. Establishing a load case for accelerated loading such as bashing into or falling off 4 M waves and the numbers get into the question of "how bad is bad?" Take the quality of market threaded rod these days and add in some wear and tear over time and sprinkle in a "light grounding" or two and I want the keel attachment to be a part of the boat that never fails.

 

I'm with DDW. The standard for keels need to be idiot proof because some idiot will design to it.

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Loads on boats are vastly harder to model than loads on airplanes.

 

 

 

If the keel falls off, it's more critical. Kind of like the wings falling off an airplane - ?

 

BTW, HOW it has been found that airplane wings NEED to sustain 4G for 30 seconds ?

 

Cannot the boating industry do the same for keels ?

This. I can tell you how many g's an airplane will pull befor you stall the wing and can write an operational procedure that says you don't enter known turbulence at a speed that will allow you to overstress the wing. I can the design the wing strucuture to operate without damage at 1.5 times the limit load and for an ultimate strength of 2 times that. The. I'll make that limit load a "fail operational" condition that will get you home with damage with a catastrophic load in the 2.5 X condition.

 

I'll do static testing to prove the strength before the airplane gets certified.

 

Then I'll conduct accelerated life testing of the structure to at least 2 lifetimes of use and stay at least twice the simulated flying ahead of the most heavily used airplane in service. I'll evaluate every failure in that testing and put out airworthiness directives requiring incorporation by a certain number of flight hurts as a condition of further use.

 

The industry is very good at this. I think it was the B-777 that failed in test within .1% of the design criteria. Repairs have to be done by licensed mechanics and inspection records retained.

 

Assessing the "flight envelope" of a boat is extraordinarily hard. Ask the canters how many actuators and actuator mounts just came apart when they were designed to be bullet proof. At the same time, when you look at many failures, such as Coyote, the Cape Fear boats, this boat and many others, the designs, as executed, were not sufficient.

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As regards X Yachts, we had a 412 which, after a grounding, suffered significant detachment of the metal frame from the hull skin, so the whole aft end started to wiggle. Made it home safe, but a major repair!

 

well, something is going to give...

 

Arcona yachts are available with a rubber bumper built in to the front of the keel - i guess because it's pretty common to hit rocks in scandanavia.

 

 

keelpro_500.jpg

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Loads on boats are vastly harder to model than loads on airplanes.

 

 

If the keel falls off, it's more critical. Kind of like the wings falling off an airplane - ?

 

 

BTW, HOW it has been found that airplane wings NEED to sustain 4G for 30 seconds ?

 

Cannot the boating industry do the same for keels ?

 

 

 

But actually probably easier to measure. So easy that it has been done a number of times, each time the paper subsequently published expressed surprise that the loads (primarily dynamic) where larger than the then current standard contemplated.

 

Also much easier to address than in the airplane industry: in an airplane, weight is your enemy, in your keel, weight is your friend. It makes very little sense to make the keel lightweight.

 

If I am sailing further away from the dock than I am willing to swim, please make the keel and hull shell foolproof. Everything else can be slap dash if you must.

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Beneteau's error was making The Liner Part of The essential structure. I Called The guy who designed my boat ( also a Liner boat ) and asked him about my liner and Keel failure. he said The Keel attachment on my boat Is engineered as if The Liner adds ZERO structure. He also mentioned a 8x factor of Safety

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That sounds more comforting than the 1.04 factor mentioned in the MAIB report. ABS allowed just a factor of 2x on a very simple minded and charitable calculation. ISO 12215 has a more realistic calculation, but also seems to require only 2x safety over the static case (actually as I read it only about 1.5x to material yield, 2x to material failure. To me yield in the keel is a failure, but what do I know?).

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I don't see a whole lot of strength in that design and using splooge to hold the pan to the liner is a punters game. Worst of all there is no way to check the condition of the splooge holding the bits together after a grounding.

The report suggests that Beneteau inspect plugs from any holes cut through pan to check thickness and integrity of layup.

 

 

It is a bit worrying that Beneteu had a service bulletin detailing how to repair a detached matrix in this boat, and that the MAIB had no trouble finding multiple instances to look at, and multiple repair examples to study.

 

 

Regarding grounding, this was a charter boat with a hired captain. No charterer ever describes any grounding as other than "light", nor I suspect, does any hired captain.

In their defence… 8000 boats built this way; but I still agree with you.

 

From the repair invoice it appears it was pretty major work undertaken after what was a 'light grounding' in Cowes :

 

‘Remove floor boards and pipe work in way of damaged areas. Cut flanges off six bays, grind back hull, laminate and sides of structural floors. Bond structural floor to hull with GRP, lightly rub down and apply wax gel. Drill off limber holes, refit pipes and floors. Clean vessel. Lift plate washers and re bed’.

 

I don't quite understand the repair methodology described. "Cut flanges off six bays" Does this describe cutting the `lids' off the tops of the box sections or does it describe grounding out and removing the pans? I think it is the former since the plates for the keelboats were lifted and rebedded only after the remedial work was done, therefore the pans weren't touched. If this is the case it would appear that the transverse grid boxes were reinforced but the pans in the liner where the keelboat went through were left alone.

 

I still have a problem with the photograph taken in the Carribean of the crew member in the looking into the bilge having also taken the trouble to remove the table. Who does this by way of routine inspection? I think there is something to be explained here. i.e. They had concerns.

 

Another thing that doesn't sit quite right is that they couldn't find the source of water ingress. Any experienced sailor would surely include keelboats in his search? Could it be possible that the initial ingress of water was through a stress crack running alongside one of the raised grid/beams? Since the keel is bolted through the pan it allows some deflection up to the edge of the grid which is in effect an inflexible hard point.

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That description on the repair invoice sounds wrong. It sounds like just the interior pan was "fixed", worked on. They made sure the pan was nicely fixed and reattached to the bottom of the boat. I don't see anything that states the actual boat bottom was even worked on. When the boat grounded, the upper aft corner of the keel could have moved violently upwards causing de-lam to the actuall bottom of the boat. If that was not addressed, it was only a matter of time.

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Re: the photo, you might remove the table for racing and also check the bilges are dry, as wet is heavy and thus slow.

 

Looking at that arcona - surely a lifting keel with a fuse, that allows it swung up in overload is a better solution if where you sail is shallow and rocky?

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Re: the photo, you might remove the table for racing and also check the bilges are dry, as wet is heavy and thus slow.

 

Looking at that arcona - surely a lifting keel with a fuse, that allows it swung up in overload is a better solution if where you sail is shallow and rocky?

You can easily see the bilges on a 40.7 without removing the table. It doesn't look like a job where they were removing weight but it could be.

 

It would appear from report that the pans that the keelboats go through didn't have any repairs done to them.

 

It's curious that after the investigation they can't be sure what the actual work was. i.e. "probable" and "possible" areas attended to. The shipwright must have a very poor memory.

post-14496-0-51452800-1430371865_thumb.png

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So given that the attachment is brittle (stainless loses nearly all strength when distorted) is there a possibility of a secondary attachment?

 

eg: stainless braid from the keel to the hull / liner. Sure it won't stop water ingress if the bolts let go, nor would it be sailable but it could stop the boat going completely turtle in <2 seconds.

 

Even 5 minutes would have given these guys some chance to get into a life raft with an EPIRB. Depending on water ingress and availability of a crash pump perhaps hours or days?

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Further thought and the secondary attachment would tear large holes in the hull very fast once the bolts let go.

 

Still perhaps possible that a cheap add-on (during build) could give you minutes in such a situation.

 

EDIT: Just kicking an idea around since clearly the economics aren't going to suggest building it differently but it seems this failure could well be fatal coastal cruising.

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Further thought and the secondary attachment would tear large holes in the hull very fast once the bolts let go.

 

Still perhaps possible that a cheap add-on (during build) could give you minutes in such a situation.

 

EDIT: Just kicking an idea around since clearly the economics aren't going to suggest building it differently but it seems this failure could well be fatal coastal cruising.

I think it's simpler than designing a `backup structure'.

 

Build the boat in a way that's both tough enough and if it has a problem is obvious enough.

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I don't see a whole lot of strength in that design and using splooge to hold the pan to the liner is a punters game. Worst of all there is no way to check the condition of the splooge holding the bits together after a grounding.

The report suggests that Beneteau inspect plugs from any holes cut through pan to check thickness and integrity of layup.

 

 

 

Of the individual layup, yes, but not the integrity of the 'splooge' bond between the grid layup and the hull layup

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Further thought and the secondary attachment would tear large holes in the hull very fast once the bolts let go.

 

Still perhaps possible that a cheap add-on (during build) could give you minutes in such a situation.

 

EDIT: Just kicking an idea around since clearly the economics aren't going to suggest building it differently but it seems this failure could well be fatal coastal cruising.

I think it's simpler than designing a `backup structure'.

 

Build the boat in a way that's both tough enough and if it has a problem is obvious enough.

 

 

Maybe, but isn't that akin to saying make the primary parachute perfect?

 

When the failure mode leads to possible death perhaps there should be a backup solution, even if it isn't perfect.

 

EDIT: I am trying to speak in terms of cost and what could be done cheaply. Perhaps you are right and bolted on keels could be engineered without more cost to behave as you say.

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It's a for shit design and construction methodology. If the keel bolts went up through a floor that spread the load across the boat it would still be sailing today. The moment could be greatly increased with minimal cost. But what do your expect from a company that uses brass skin fittings.

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Further thought and the secondary attachment would tear large holes in the hull very fast once the bolts let go.

 

Still perhaps possible that a cheap add-on (during build) could give you minutes in such a situation.

 

EDIT: Just kicking an idea around since clearly the economics aren't going to suggest building it differently but it seems this failure could well be fatal coastal cruising.

I think it's simpler than designing a `backup structure'.

 

Build the boat in a way that's both tough enough and if it has a problem is obvious enough.

 

 

Maybe, but isn't that akin to saying make the primary parachute perfect?

 

When the failure mode leads to possible death perhaps there should be a backup solution, even if it isn't perfect.

 

EDIT: I am trying to speak in terms of cost and what could be done cheaply. Perhaps you are right and bolted on keels could be engineered without more cost to behave as you say.

 

I've never thought of a keel as having backup systems… Not that your suggestion doesn't have merit.

 

Nobody seems to know how to survey for possible delamination of the grid/liner. The only method being to lower the boat onto the keel and examine the deflection; however Beneteau have no factory specification for this.

 

It actually seems an ok form of examination but there is no spec. so very subjective.

 

The framing in the keel area may need to be more traditionally attended to for the sake of strength and diagnosis after grounding.

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I've never thought of a keel as having backup systems…

 

 

Neither had I until I saw that you could remove a keel with so little damage to the hull.

 

I am aghast that it appeared to take a few bolts shearing and a some tearing across a couple of laminates of glass, personally I would have wanted the whole ass of my boat to disintegrate before that.

 

But in reality I will be buying where money dictates I can get fun for $$...

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In aircraft something as critical as the keel has to either have redundant attachment systems or one system that is so strong it just is NOT going to come apart absent a catastrophic overload.

We know how to make extremely strong keel attachment systems. We have pressure now to not do this because either the manufacturer wants to save money or get the last 0.1 knots out of a design.

In fairness to brand B, the boat either was weaker than we think or it hit something pretty hard in the past from the repairs detailed.

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this report makes me feel better, but also worse regarding my boats grid. Mine is a bunch of aluminum beams, with the keel bolts coming through them.

 

So I don't think the grid will fail unless a sub surfaces under us.

 

However, now I have dissimilar metals in a salt water bath, so how to check the bolts without dropping the keel?

 

That other thread with the nice bolt head/nut that was pulled out using a shop vac has me worried.

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Did anybody else have the feeling that the report gave Beneteau pretty much a pass? Lots of discussion about how they engineer and test and document (which surely came straight from the horse's mouth) and not very much about being able easily to locate 12 boats with similar damage after light groundings. Not much comment about them publishing a service note about how to repair such damage (indicating it was not uncommon). No comment about how in other series production boats with similar runs and usage this is not common, and even unheard of.

 

The report tread very lightly on Beneteau.

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I just wanted to say to the group here, that we assisted in the MAIB investigation, but were unable to review a draft of the document before it was published. I think there a few inconsistencies in the report, but on the whole it is a well written document.

 

The report does indicate that prior groundings were repaired in an unknown way. Just to be 100% clear, at FYD we have no knowledge of the Beneteau dealer recommended repair procedure. That by itself is a pretty worrying. Even if that was followed, we don't necessarily know that it would be sufficient.

 

We take safety very seriously and will issue an announcement/addendum to the MAIB report with some other considerations. The biggest thing I want to emphasize is, please contact your yacht designer if you have any questions. If you have an incident that potentially caused structural damage, contact your yacht designer. If you have an impending repair contact your yacht designer.

 

In this particular instance the hull liner laminate (do not call it a matrix), is not a trivial simple laminate. Replacing it with some unknown laminate to similar thickness would not necessarily be adequate. Please ask first. It almost incomprehensible that a repair could be made in a critical area like this without guidance. Please let us help you.

 

We will be back with more, after we've had a chance to fully digest the report. Stand by.

 

Patrick

Patrick

thanks for the guidance - comments.

I have reciently purchased a First 40.7 I would like to know how to check the hull liner laminate and then repair if needed. I am keenly awaiting your response to report.

 

 

 

Tom

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My take is that we have normalized the idea that groundings cause major damage. Any thread about keels coming off usually contains something like "maybe the boat ran aground and repairs were not done at all or correctly". Old style boats that did not so suffer are dismissed as grandpa's 2KTSB.

Did anybody else have the feeling that the report gave Beneteau pretty much a pass? Lots of discussion about how they engineer and test and document (which surely came straight from the horse's mouth) and not very much about being able easily to locate 12 boats with similar damage after light groundings. Not much comment about them publishing a service note about how to repair such damage (indicating it was not uncommon). No comment about how in other series production boats with similar runs and usage this is not common, and even unheard of.

 

The report tread very lightly on Beneteau.

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Did anybody else have the feeling that the report gave Beneteau pretty much a pass? Lots of discussion about how they engineer and test and document (which surely came straight from the horse's mouth) and not very much about being able easily to locate 12 boats with similar damage after light groundings. Not much comment about them publishing a service note about how to repair such damage (indicating it was not uncommon). No comment about how in other series production boats with similar runs and usage this is not common, and even unheard of.

 

The report tread very lightly on Beneteau.

 

i think that anytime a modern narrow-chord keel hits the bottom, there is a good chance that substantial work will be required - i think the authors just accept this, and seem to think that once a few groundings occur.., the responsibility for making the boat seaworthy rests with the owner

 

I've never even been on a beneteau, so i have no particular love for them...

 

but they are not the only production builder with keel issues - at least theirs seem mostly to be the result of groundings!

 

many jboats have needed substantial keel strengthening, without ever running aground - and that was with keels that don't even have very narrow chords!

 

Bavaria have had a bunch of boats with keel problems - if i recall, there were fatalities on one boat, and someone can correct me, but i don't think a prior grounding was an issue.

 

i am sure there are others

 

i am not sure who the other boats with similar production runs are.., but i am not sure any boats with narrow keels are immune to damage after a grounding

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Did anybody else have the feeling that the report gave Beneteau pretty much a pass? Lots of discussion about how they engineer and test and document (which surely came straight from the horse's mouth) and not very much about being able easily to locate 12 boats with similar damage after light groundings. Not much comment about them publishing a service note about how to repair such damage (indicating it was not uncommon). No comment about how in other series production boats with similar runs and usage this is not common, and even unheard of.

 

The report tread very lightly on Beneteau.

Very lightly on design and construction.

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I would want NO iron based bolts/nuts even if zinc coated as they are a time bomb

or any iron or steel grid or mast base/foot as even zinc coated iron will RUST over time

 

and about 3 or 4 times the number of bolts used spaced not in a single row

but semi random in a wider spacing to spread the load and reduce the point loads and crack growth

with not all bolts going directly down but at a varying angle

 

on a greatly thicker local hull laminate directly over the keel NOT an add on BS pan SPLODGED IN

BUT BUILT AS A INTEGRAL TO THE HULL LAYUP

 

if a fine keel root is an design feature set the keel root in socket recessed into the built up hull

to allow ample area for connection flange

 

this is an area that MUST be over done NOT a place to save material costs

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Maib report doesnt assign blame, the subsequent MCA process could lead to that. Sounds like the operators at least and maybe b will be awaiting that anxiously...

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Did anybody else have the feeling that the report gave Beneteau pretty much a pass? Lots of discussion about how they engineer and test and document (which surely came straight from the horse's mouth) and not very much about being able easily to locate 12 boats with similar damage after light groundings. Not much comment about them publishing a service note about how to repair such damage (indicating it was not uncommon). No comment about how in other series production boats with similar runs and usage this is not common, and even unheard of.

 

The report tread very lightly on Beneteau.

 

i think that anytime a modern narrow-chord keel hits the bottom, there is a good chance that substantial work will be required - i think the authors just accept this, and seem to think that once a few groundings occur.., the responsibility for making the boat seaworthy rests with the owner

 

I've never even been on a beneteau, so i have no particular love for them...

 

but they are not the only production builder with keel issues - at least theirs seem mostly to be the result of groundings!

 

many jboats have needed substantial keel strengthening, without ever running aground - and that was with keels that don't even have very narrow chords!

 

Bavaria have had a bunch of boats with keel problems - if i recall, there were fatalities on one boat, and someone can correct me, but i don't think a prior grounding was an issue.

 

i am sure there are others

 

i am not sure who the other boats with similar production runs are.., but i am not sure any boats with narrow keels are immune to damage after a grounding

 

 

Narrow keel boats require engineering to deal with the loads. If you design and build them the same way you did with a fat short keel (which is exactly what they are doing) then there will be (and has been) trouble. Feeding the loads into a thin fiberglass shell over an area 3 ft long by 6 inches wide isn't going to take the same solution as feeding the same loads into an area 10 feet long and a foot and a half wide. A boat with a narrow keel can be as immune from damage as they used to be, but it cannot be done without thought, perhaps a little effort, and modest cost.

 

The used to build airplane wings big and fat and with a bunch of wires and struts to hold them on. Now they are narrow and thin but they still stay on - but no one tries to just stitch them to the thin skin with a few bolts. Unchanged traditional construction applied to radically different design is a recipe for failure.

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The age-old engineering tradeoff:

Fast

Strong

Cheap

 

Pick two ;)

 

Old fashioned wing design: Still used when hitting a brick shithouse needs to demolish the shithouse instead of the airplane:

g164a_luisrosa.jpg

 

 

Did anybody else have the feeling that the report gave Beneteau pretty much a pass? Lots of discussion about how they engineer and test and document (which surely came straight from the horse's mouth) and not very much about being able easily to locate 12 boats with similar damage after light groundings. Not much comment about them publishing a service note about how to repair such damage (indicating it was not uncommon). No comment about how in other series production boats with similar runs and usage this is not common, and even unheard of.

 

The report tread very lightly on Beneteau.

 

i think that anytime a modern narrow-chord keel hits the bottom, there is a good chance that substantial work will be required - i think the authors just accept this, and seem to think that once a few groundings occur.., the responsibility for making the boat seaworthy rests with the owner

 

I've never even been on a beneteau, so i have no particular love for them...

 

but they are not the only production builder with keel issues - at least theirs seem mostly to be the result of groundings!

 

many jboats have needed substantial keel strengthening, without ever running aground - and that was with keels that don't even have very narrow chords!

 

Bavaria have had a bunch of boats with keel problems - if i recall, there were fatalities on one boat, and someone can correct me, but i don't think a prior grounding was an issue.

 

i am sure there are others

 

i am not sure who the other boats with similar production runs are.., but i am not sure any boats with narrow keels are immune to damage after a grounding

 

 

Narrow keel boats require engineering to deal with the loads. If you design and build them the same way you did with a fat short keel (which is exactly what they are doing) then there will be (and has been) trouble. Feeding the loads into a thin fiberglass shell over an area 3 ft long by 6 inches wide isn't going to take the same solution as feeding the same loads into an area 10 feet long and a foot and a half wide. A boat with a narrow keel can be as immune from damage as they used to be, but it cannot be done without thought, perhaps a little effort, and modest cost.

 

The used to build airplane wings big and fat and with a bunch of wires and struts to hold them on. Now they are narrow and thin but they still stay on - but no one tries to just stitch them to the thin skin with a few bolts. Unchanged traditional construction applied to radically different design is a recipe for failure.

 

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I wonder what the objectives and purposes of the investigation reported were. If I owned one of these boats (the exact same model or a boat that had some relevant similarlites which I was able to recognise) I would have read the report in the hope of getting some idea of how likely it was that the keel would drop off my boat on the next trip I had planned. Having read it I don't think I would have felt I was any the wiser.

I wonder who had input to the report. It might have been more interesting if someone with an 'engineering approach' had provided some input.

It would be interesting to know how much this investigation and its report cost. Anyone got any thoughts on what it is worth?

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From Dashew's Cruising Encyclopedia, 1998:

 

Most modern yachts are engineered using the American Bureau of Shipping (ABS) rule as a
guideline. The problem with this is that the rule only considers sailing loads, and if that is all
you’re shooting for, it does a reasonable job with cruising keels (but not with highly stressed racing
fins).

With modern yachts, however, the rule severely underestimates the load in a grounding situation,
as modern yachts typically have lighter keels than older designs and travel at much higher
rates of speed. The lighter keel allows you to reduce structure. But the higher speed demands
more of the boat when you collide with the bottom.

Over the years, we’ve found that by using the rule loads as a base, and then multiplying by a
factor of four, we’ve gotten keel structures that stand up pretty well.

 

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Ref us7070's point on Bavaria. The keel failures on Match 42's were nothing to do with groundings, despite Bavaria's attempts to suggest so. REALLY bad engineering and quality control were to blame.

 

Note - this was specific to one model, with some overflow into the Match 38 and 35, but they were not as bad, and most Bavaria cruising models have not shown any similar defect.

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moutsbay, I am sure the MAIB used every available source. We know that Farr contributed, and I am sure Bénéteau did too. They dug for as much background on this boat's history as possible.

 

No judge and jury involved. These people had the job of investigating this incident and reporting what they could find. They had no remit to recommend changes to design or construction procedures. However, their findings may lead to changes?

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I wonder what the objectives and purposes of the investigation reported were.

 

https://www.gov.uk/government/organisations/marine-accident-investigation-branch/about

 

About us

What we do

The Marine Accident Investigation Branch investigates marine accidents involving UK vessels worldwide and all vessels in UK territorial waters.

Our job is to help prevent further avoidable accidents from occurring, not to establish blame or liability.

 

In 2013 the Marine Accident Investigation Branch received 1336 reports of accidents of all types and severity which led to 33 separate investigations being launched.

 

Who we are

We are an independent unit within the Department for Transport. Our 4 experienced accident investigation teams are supported by an administrative team. Were based in Southampton and have 34 members of staff.

 

Our responsibilities

Were responsible for:

 

carrying out investigations to determine the causes of accidents at sea

publishing reports that include our recommendations on improving safety at sea and the actions weve taken

increasing awareness of how marine accidents happen

improving national and international co-operation in marine accident investigations

 

Our priorities

maintain our position as one of the worlds leading safety investigation organisations

help set standards in marine accident investigation by following best practice and asking those we work with to do the same

provide our staff with regular specialised training to keep expertise up to date

And the even have a nice little corporate video.

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I suspect any surveyor or repairer involved in the repairs after the Cowes grounding maybe under the spotlight.

 

How could you affect repairs to the 6 pans shown and not have suspicions about the area where the keel was attached?

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so, it seems like the GRP hull in the area of the keel is solid laminate

 

the liner (matrix) is apparently made in a similar fashion as the hull, so i am assuming it is also a solid GRP laminate - although Patrick Shaughnessy from FYD might be implying in his post above that there is something special about the construction of the liner...

 

the two pieces are glued together, but if the glue fails - which is known to happen after some groundings - the liner can move wrt the hull, and this movement can weaken the structure somehow allowing the keel to fall off.

 

clearly relative movement could lead to the keel bolt holes enlarging, and maybe some other holes forming, allowing water ingress

 

there is not much detail about exactly why the keel falls of - i could imagine a few scenarios..., but i am surprised they didn't speculate a bit more about this

 

so, one thing i have always wondered about this type of build.., is why the keel bolts only go through a "bay" of the liner, and not through the beams which are also part of the liner, and cross the keel...

 

this seems to me like it would be much stronger, as it would do a better job of distributing the keel loads over a large area than simply having backing plates on the liner bay.

 

Patrick - can you comment on this?

Bolt loads will crush the beam structure in the first beat upwind in 15 knots!!!

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so, one thing i have always wondered about this type of build.., is why the keel bolts only go through a "bay" of the liner, and not through the beams which are also part of the liner, and cross the keel...

 

this seems to me like it would be much stronger, as it would do a better job of distributing the keel loads over a large area than simply having backing plates on the liner bay.

 

Patrick - can you comment on this?

 

Because the beams are hollow.

 

You cannot bolt thru without crushing them.

so make them capable of taking the load....

 

they probably wouldn't have to be completely solid.

Amaze us all with your composite engineering skills.

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so, it seems like the GRP hull in the area of the keel is solid laminate

 

the liner (matrix) is apparently made in a similar fashion as the hull, so i am assuming it is also a solid GRP laminate - although Patrick Shaughnessy from FYD might be implying in his post above that there is something special about the construction of the liner...

 

the two pieces are glued together, but if the glue fails - which is known to happen after some groundings - the liner can move wrt the hull, and this movement can weaken the structure somehow allowing the keel to fall off.

 

clearly relative movement could lead to the keel bolt holes enlarging, and maybe some other holes forming, allowing water ingress

 

there is not much detail about exactly why the keel falls of - i could imagine a few scenarios..., but i am surprised they didn't speculate a bit more about this

 

so, one thing i have always wondered about this type of build.., is why the keel bolts only go through a "bay" of the liner, and not through the beams which are also part of the liner, and cross the keel...

 

this seems to me like it would be much stronger, as it would do a better job of distributing the keel loads over a large area than simply having backing plates on the liner bay.

 

Patrick - can you comment on this?

Bolt loads will crush the beam structure in the first beat upwind in 15 knots!!!

 

 

not if it was solid g10

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so, it seems like the GRP hull in the area of the keel is solid laminate

 

the liner (matrix) is apparently made in a similar fashion as the hull, so i am assuming it is also a solid GRP laminate - although Patrick Shaughnessy from FYD might be implying in his post above that there is something special about the construction of the liner...

 

the two pieces are glued together, but if the glue fails - which is known to happen after some groundings - the liner can move wrt the hull, and this movement can weaken the structure somehow allowing the keel to fall off.

 

clearly relative movement could lead to the keel bolt holes enlarging, and maybe some other holes forming, allowing water ingress

 

there is not much detail about exactly why the keel falls of - i could imagine a few scenarios..., but i am surprised they didn't speculate a bit more about this

 

so, one thing i have always wondered about this type of build.., is why the keel bolts only go through a "bay" of the liner, and not through the beams which are also part of the liner, and cross the keel...

 

this seems to me like it would be much stronger, as it would do a better job of distributing the keel loads over a large area than simply having backing plates on the liner bay.

 

Patrick - can you comment on this?

 

Bolt loads will crush the beam structure in the first beat upwind in 15 knots!!!

not if it was solid g10

Don't forget to reinforce the surrounding hull laminate around this, it'll just tear out an even bigger hole in a hard grounding.

 

It's purely an economically driven process.

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Did anybody else have the feeling that the report gave Beneteau pretty much a pass? Lots of discussion about how they engineer and test and document (which surely came straight from the horse's mouth) and not very much about being able easily to locate 12 boats with similar damage after light groundings. Not much comment about them publishing a service note about how to repair such damage (indicating it was not uncommon). No comment about how in other series production boats with similar runs and usage this is not common, and even unheard of.

 

The report tread very lightly on Beneteau.

 

i think that anytime a modern narrow-chord keel hits the bottom, there is a good chance that substantial work will be required - i think the authors just accept this, and seem to think that once a few groundings occur.., the responsibility for making the boat seaworthy rests with the owner

 

I've never even been on a beneteau, so i have no particular love for them...

 

but they are not the only production builder with keel issues - at least theirs seem mostly to be the result of groundings!

 

many jboats have needed substantial keel strengthening, without ever running aground - and that was with keels that don't even have very narrow chords!

 

Bavaria have had a bunch of boats with keel problems - if i recall, there were fatalities on one boat, and someone can correct me, but i don't think a prior grounding was an issue.

 

i am sure there are others

 

i am not sure who the other boats with similar production runs are.., but i am not sure any boats with narrow keels are immune to damage after a grounding

 

 

Narrow keel boats require engineering to deal with the loads. If you design and build them the same way you did with a fat short keel (which is exactly what they are doing) then there will be (and has been) trouble. Feeding the loads into a thin fiberglass shell over an area 3 ft long by 6 inches wide isn't going to take the same solution as feeding the same loads into an area 10 feet long and a foot and a half wide. A boat with a narrow keel can be as immune from damage as they used to be, but it cannot be done without thought, perhaps a little effort, and modest cost.

 

The used to build airplane wings big and fat and with a bunch of wires and struts to hold them on. Now they are narrow and thin but they still stay on - but no one tries to just stitch them to the thin skin with a few bolts. Unchanged traditional construction applied to radically different design is a recipe for failure.

 

 

I said above that I didn't like the design.., nevertheless...,

 

FYD have a few engineers on their staff, and they have designed a lot of good boats. I assume, but don't know, that they did the engineering for this boat.

 

it's clear that the design does not rely on a 3ft by 6 inch piece of fiberglass to take the keel load - the whole liner/matrix is supposed to take the keel load and spread it over a much larger area - so they are not idiots.., they do understand the issues involved with these keels.

 

and apparently, the structure works pretty well.., under normal sailing loads

 

the problem is that damage from a grounding can diminish the ability of the structure to spread the load -

 

worse, it is apparently very difficult know for sure that the full extent of any damage has been discovered. Also, it appears from PS's comments above that there might be subtleties to the design and construction of the liner, as well as its bonding to the hull, that might not be fully appreciated by the person doing the repair.

 

another serious concern is that we don't really know what the threshold is for taking the keel of and examining the whole structure - clearly if you hit a rock at 8kts, you probably have trouble.., but what about a "soft grounding"? do a few soft groundings add up to a hard grounding?.., and so on...

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Just look at the structure designed by bene and compare it to the structure on Frankie that Bob designed. Sorry, I give bene no free pass for designing a substandard, it's your boat, take care of it structure.

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Did anybody else have the feeling that the report gave Beneteau pretty much a pass? Lots of discussion about how they engineer and test and document (which surely came straight from the horse's mouth) and not very much about being able easily to locate 12 boats with similar damage after light groundings. Not much comment about them publishing a service note about how to repair such damage (indicating it was not uncommon). No comment about how in other series production boats with similar runs and usage this is not common, and even unheard of.

 

The report tread very lightly on Beneteau.

 

i think that anytime a modern narrow-chord keel hits the bottom, there is a good chance that substantial work will be required - i think the authors just accept this, and seem to think that once a few groundings occur.., the responsibility for making the boat seaworthy rests with the owner

 

I've never even been on a beneteau, so i have no particular love for them...

 

but they are not the only production builder with keel issues - at least theirs seem mostly to be the result of groundings!

 

many jboats have needed substantial keel strengthening, without ever running aground - and that was with keels that don't even have very narrow chords!

 

Bavaria have had a bunch of boats with keel problems - if i recall, there were fatalities on one boat, and someone can correct me, but i don't think a prior grounding was an issue.

 

i am sure there are others

 

i am not sure who the other boats with similar production runs are.., but i am not sure any boats with narrow keels are immune to damage after a grounding

 

 

Narrow keel boats require engineering to deal with the loads. If you design and build them the same way you did with a fat short keel (which is exactly what they are doing) then there will be (and has been) trouble. Feeding the loads into a thin fiberglass shell over an area 3 ft long by 6 inches wide isn't going to take the same solution as feeding the same loads into an area 10 feet long and a foot and a half wide. A boat with a narrow keel can be as immune from damage as they used to be, but it cannot be done without thought, perhaps a little effort, and modest cost.

 

The used to build airplane wings big and fat and with a bunch of wires and struts to hold them on. Now they are narrow and thin but they still stay on - but no one tries to just stitch them to the thin skin with a few bolts. Unchanged traditional construction applied to radically different design is a recipe for failure.

 

 

I said above that I didn't like the design.., nevertheless...,

 

FYD have a few engineers on their staff, and they have designed a lot of good boats. I assume, but don't know, that they did the engineering for this boat.

 

it's clear that the design does not rely on a 3ft by 6 inch piece of fiberglass to take the keel load - the whole liner/matrix is supposed to take the keel load and spread it over a much larger area - so they are not idiots.., they do understand the issues involved with these keels.

 

and apparently, the structure works pretty well.., under normal sailing loads

 

the problem is that damage from a grounding can diminish the ability of the structure to spread the load -

 

worse, it is apparently very difficult know for sure that the full extent of any damage has been discovered. Also, it appears from PS's comments above that there might be subtleties to the design and construction of the liner, as well as its bonding to the hull, that might not be fully appreciated by the person doing the repair.

 

another serious concern is that we don't really know what the threshold is for taking the keel of and examining the whole structure - clearly if you hit a rock at 8kts, you probably have trouble.., but what about a "soft grounding"? do a few soft groundings add up to a hard grounding?.., and so on...

 

 

I think you'll find the Farr office does the line drawings and calculations then Beneteau does the engineering.

 

The problem with the 40.7 is that when Cheeky Rafiki required repairs, the type of construction made it very difficult to affect a `best practice' repair.

 

The keelboats are cast in with no chance of removal (i.e. aft keelboat may have been weakened but not replaced because it was almost impossible to do so).

 

The adhesion of the pan to the hull is impossible to examine except indirectly by deflection and hammer taps.

 

The one piece hollow liner that is also the support for the floorboards is not removable or easily replaceable like a seperate `cracked' frame would be.

 

I'm almost certain there would have been a conversation around the grounding and repairs needed that acknowledged these problems. i.e. To affect a stronger repair would have been very expensive; so a `cost constrained' repair was done.

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Lot's of focus here on maintenance and engineering, which is fair enough. I don't know enough about either to comment. I took away another thought in reading the report.

Wednesday 14 May 2014
1014 – email, from Cheeki Rafiki
‘position update at 1000ut 37 00N 052 05W 24hour run 176miles…just hit a big
wave hard and it fixed the stereo.’ [sic]
Thursday 15 May 2014
2022 – email, from Cheeki Rafiki
‘we have been taking on a lot of water yesterday and today. today seems worse
i think stbd water tank has split so that is drained checked hull and sea cocks for
damage but cant see any. i will go for a swim when weather improves in about
24 hours we are currently monitoring the situation horta is 900 miles away. our
position is 38 38N 048 59W any thoughts from your end i will check emails in 2
hours’ [sic]
Friday 16 May 2014
At 0410 on 16 May 2014, following an initial personal locator beacon (PLB) alert at
0405, RCC Boston received a PLB alert with positional data that was confirmed by
MRCC Falmouth to be from the skipper’s PLB. At 0415, RCC Boston sent an email
to Cheeki Rafiki and MRCC Falmouth, stating:
‘…We received 406 alert from your vessel. Please provide updates…’
At 0432, having accessed Cheeki Rafiki’s email account, Stormforce Coaching’s
principal/director sent an email to RCC Boston, copied to MRCC Falmouth, stating:
‘I am shore side contact for this vessel, and have picked up your email. The
yacht as yet has not.
The skipper…, called my mobile at 0329 UTC, we did not have a very good line,
he said “this is getting worse.” I asked if he had read an email from the night
before, he said “No, i have not seen email for some time, i will download email
and call you back” As of now 0428 UTC they have not downloaded your or my
email to them. I will keep you informed if I hear from them again,
At about 1400 on 17 May 2014, the container ship Maersk Kure located the upturned
hull of a small boat, which was believed to be Cheeki Rafiki.


So sometime on Weds after 1014 CR started taking on "a lot of water" and the keel broke off sometime between 0329 and 0432 on Friday. There was some of Weds, all of Thurs and a few hours on Friday to issue a "Pan Pan" yet the skipper did not. 36 hours after the keel broke, Maersk Kure spotted the yacht, by the sound of it randomly rather than as part of a search, so it wasn't a completely empty ocean out there. I wonder what the outcome would have been if the young skipper had issued a "Pan Pan" or if Stormforce Coaching had recommended that he did so.

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I suspect any surveyor or repairer involved in the repairs after the Cowes grounding maybe under the spotlight.

 

What "spotlight"? AFAIK the investigatory process ends here.

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I wonder what the objectives and purposes of the investigation reported were.

 

You could read the second page.

 

Extract from

The United Kingdom Merchant Shipping

(Accident Reporting and Investigation)

Regulations 2012 – Regulation 5:

“The sole objective of the investigation of an accident under the Merchant Shipping (Accident

Reporting and Investigation) Regulations 2012 shall be the prevention of future accidents through the ascertainment of its causes and circumstances. It shall not be the purpose of an

investigation to determine liability nor, except so far as is necessary to achieve its objective, to apportion blame.”

NOTE

This report is not written with litigation in mind and, pursuant to Regulation 14(14) of the

Merchant Shipping (Accident Reporting and Investigation) Regulations 2012, shall be

inadmissible in any judicial proceedings whose purpose, or one of whose purposes is to

attribute or apportion liability or blame.

 

 

 

It would be interesting to know how much this investigation and its report cost

 

Would it? Why is that then?

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I suspect any surveyor or repairer involved in the repairs after the Cowes grounding maybe under the spotlight.

 

What "spotlight"? AFAIK the investigatory process ends here.

 

 

Yes yes, but lawyers never stop there.

 

The boat was repaired in the area of the keel attachment after a grounding then the keel falls off some years later

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They quite often get invited to do work for overseas governments as well

They do do a great job, its tax payer money well spent.

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anyone talking about how to manage old laminate yet, that has been pounded and is very difficult to determine the strength of let alone has crash damage?

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I suspect any surveyor or repairer involved in the repairs after the Cowes grounding maybe under the spotlight.

What "spotlight"? AFAIK the investigatory process ends here.

 

Yes yes, but lawyers never stop there.

 

The boat was repaired in the area of the keel attachment after a grounding then the keel falls off some years later

 

And the evidence is somewhere at the bottom of the ocean. Nobody is now about to sue those involved in repairs.

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I suspect any surveyor or repairer involved in the repairs after the Cowes grounding maybe under the spotlight.

What "spotlight"? AFAIK the investigatory process ends here.

 

Yes yes, but lawyers never stop there.

 

The boat was repaired in the area of the keel attachment after a grounding then the keel falls off some years later

 

And the evidence is somewhere at the bottom of the ocean. Nobody is now about to sue those involved in repairs.

 

 

Probably...

 

But, you know lawyers.

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