Cheeki Rafiki loss report

[Saltyhog]

Originally Posted by DeepFrz

That's not what people are saying. The MAIB report talked about structural damage after sailing in heavy seas. This is all about crap construction and in this whole discussion I don't think anyone has mentioned Hunter...until now.

Oh how I wish SmackDaddy was still around. He added his own brand of sauce to these threads. Just mention the "H" word, and his own personal brand brand of Spit Storm would follow. Always entertaining. I think most follow or participate in these threads for the sheer enjoyment of argument. If I were keeping score, I think Muckle Flugga has the lead on eloquence, with Polux just behind for sheer tenacity. Clearly the terrier in the fight. Then the supporting cast of Neil and minaret for stating only facts. Facts are so boring. That is they are boring until you are out there, in the middle, in a $h!t storm. Then facts become frighteningly interesting.

[Exile]

Originally Posted by Saltyhog

Oh how I wish SmackDaddy was still around. He added his own brand of sauce to these threads. Just mention the "H" word, and his own personal brand brand of Spit Storm would follow. Always entertaining. I think most follow or participate in these threads for the sheer enjoyment of argument. If I were keeping score, I think Muckle Flugga has the lead on eloquence, with Polux just behind for sheer tenacity. Clearly the terrier in the fight. Then the supporting cast of Neil and minaret for stating only facts. Facts are so boring. That is they are boring until you are out there, in the middle, in a $h!t storm. Then facts become frighteningly interesting.

Compared to the SmackDaddy threads, this one is occassioned by a much higher percentage of intelligent & cogent points being made on both sides, imho. When it comes to boats we all probably have some degree of bias, but I for one don't miss the repeatedly mindless & deliberately contentious postings from SD & some others that were so transparently personal & obviously biased. I have learned a lot and will continue to learn from the positions being rather well presented by many here, most notably Polux & Muckle Flugga. The discussion also gets contentious, of course, but I think it's more over heartfelt disagreement on the merits rather than some personal agenda.

Btw, what kind of handle/alias is Muckle Flugga anyway??!

[TeddyDiver]

IMHO a boat needing an inspection with hightec phazers x ultra klingon gadgets after a bit of roughness is piece of junk. Ok if you have the dough but 99% of the places you can sail don't have such services. So bottom line: Weekend cruiser close to big modern cities

[Polux]

Originally Posted by neilpride

But Paulo forget to mention that MAIB found a bunch of others 40,7 under repairs or with similar liner problems, is a 40,7 disease...

Yes, I would not call it a disease but a problem. Several First 40.7 showed signs of matrix detachment (lose bonding) after having suffered groundings. All the four boats that they visited that had suffered groundings:

"MAIB inspectors visited four Beneteau First 40.7 yachts that had all suffered detachments of their matrix in bays around the aft end of the keel as a result of grounding. Additionally, two of these vessels had suffered, or were showing signs of, matrix detachment in the forward section."

They say that the matrix detachment on the forward section are "commonly attributed to the vessel slamming" but inexplicably failed to have visited any boat that had suffered matrix detachment on the forward section and that had not been grounded for sure.

I am not saying that it cannot be the case just saying that they should have done that and without that it is impossible for them to state that the Matrix of the First 40.7 can weaken its bond with the boat sailing on heavy seas. They have made that regarding to grounding and made evident that the matrix can detach with grounding they have not done so regarding pounding.

Even so it seems to me that there are evidence that is the case, I mean not a sudden and catastrophic fail of the bond, as it was suggested by some, but evidence that a gradual lose of the bond can happen with age and hard use of the boat. They state that on the conclusions:

"It is possible for matrix detachment to occur in GRP yachts manufactured with a matrix bonded to the hull, resulting in loss of structural strength. The probability of this occurring will increase with more frequent and harder yacht usage. "

Of course this is equally true to yachts that have the structural matrix (not an integral one like the First) laminated to the hull. The difference is that on most cases the inspection is far easier. A bonded one, if the job is well done, can even create a stronger bond than what a laminated can provide and off course, both methods can be used together.

The basic point here is that all boats need to be regularly inspected, lighter performance boats and cruiser racers more often then heavier boats, and repaired if needed.

The First 40.7 is a 1997 boat and most of the boats were sold on the first 5 years of production and that means that most of the boats have between 18 and 13 years.

What I have been saying is that it should exist a protocol for keel inspections on this type of boats one that warrants an effective verification if the keel structure is still properly bonded/laminated to the hull and on the specific case of the Fist 40.7 and all modern Beneteaus and Jeanneaus (that are harder to inspect) a protocol from the shipyards stating how it should be done, what the tools needed, and what should be the frequency (obviously also every time the boat is grounded). Beneteau have said already how it should be repaired.

This is the basic procedure in the airplane industry simply because you don't want to be in the air when something fails and materials don't last forever. I would say that you would not want to be on the middle of an Ocean when something fails on a boat so there is some similitude here.

This accident with the 40.7 should provide the drive to take care of that problem, meaning proper and regular inspections to the boats by qualified surveyors according to a shipyard or designer time table on the specified items, including keel, rudder and rig and appropriated repairs or changes when needed. Sadly I don't believe it will be the case and we are going to see some more accidents happen before some changes are made.

I has been seen as defending the First 40.7, that is not the case, I simply try to address the problem. I don't like particularly that boat but I like it more then the Oceanis line that has a similar build and probably the only reason this problem is more common on the First than on the Oceanis is because the First is much more pushed while racing, including a lot more slamming on heavy seas and more violent groundings.

Personally I would clearly prefer a performance cruiser more easy to inspect and repair in what regards the bond or lamination between the structure and the hull. Most would not even prefer a performance cruiser but an heavier boat. There are for all tastes with their relative advantages and disadvantages.

Never said that liked Beneteaus, namely in what regards the way they are built, just that they were being treated in an unfair way and that their lack of seaworthiness and lack of build quality was vastly exaggerated on this and other threads.

[a64pilot]

One of the issues is I believe, define "hard" grounding?

See aircraft have specific inspections after a hard landing, and usually the pilot flying looks over and says, that wasn't that hard, when in fact you think, we were lucky to survive, he's in denial of course because he doesn't want to be the one that caused damage. More often than not, when damage is found, of course you hear, "It wasn't me, that must have been there from someone else"

So if we are going to inspect a boat after a hard grounding, define "hard"?

Plus I think a very good point was made that if your really a World traveler, you will often be a long ways from lifts, and boatyards.

I'm thinking this will eventually end up with recommended keel removal and inspection intervals, sort of like standing rigging. You know it had to be numerous failed rigs before a generally accepted life limit was established?

[Robin3]

The RYA have said this below in their recent bulletin justrcd by email, after the MAIB report:-

Cheeki Rafiki: safety lessons

Safety lessons from the loss of the yacht Cheeki Rafiki and her four crew


The RYA welcomes the conclusion of the Marine Accident Investigation Branch (MAIB) investigation into the loss of the yacht Cheeki Rafiki and her four crew whilst on passage from Antigua to the UK in May 2014.
Over the course of the past year, the RYA has provided information and assistance, working closely with those involved and other organisations, and speaking to the Maritime and Coastguard Agency (MCA) and Government, to actively contribute to the MAIB investigation following the tragic incident.
In the absence of survivors and material evidence, the causes of the accident remain a matter of some speculation. The Marine Accident Investigation Branch believes that the yacht capsized and inverted after the keel became detached.
It is thought that past groundings and ensuing repairs to the keel and matrix may have weakened the yacht’s structure where the keel joined the hull. The deterioration of one or more keel bolts is also possible. A loss of structural integrity may have enabled movement of the keel which was made worse by the deteriorating sea conditions.
There are opportunities to highlight important safety messages following the tragic loss of Cheeki Rafiki and the MAIB has highlighted a number of key points:

• After all groundings there should be an inspection for possible damage by a suitably competent person
• Be aware of the danger of keel detachment and have procedures in place to reduce the risk - particularly with vessels of bonded matrix construction
• Ocean passages require comprehensive risk assessment and contingency planning
• Due to the SAR limitations presented by ocean passages consideration needs to be given as to how the alarm will be raised
• When on a long passage consideration needs to be given to the location of the liferaft to ensure it is available for use in the event of a catastrophic event

The loss of the four yachtsmen was deeply felt by all those who go to sea and our thoughts continue to be with the family and friends of the missing yachtsmen.
The full MAIB safety flyer is available on the MAIB website.
Read more safety information.



Contact Us Article Published: April 29, 2015 17:02
Article Updated: April 30, 2015 16:37

[neilpride]

Originally Posted by Polux

Yes, I would not call it a disease but a problem. Several First 40.7 showed signs of matrix detachment (lose bonding) after having suffered groundings. All the four boats that they visited that had suffered groundings:

"MAIB inspectors visited four Beneteau First 40.7 yachts that had all suffered detachments of their matrix in bays around the aft end of the keel as a result of grounding. Additionally, two of these vessels had suffered, or were showing signs of, matrix detachment in the forward section."

They say that the matrix detachment on the forward section are "commonly attributed to the vessel slamming" but inexplicably failed to have visited any boat that had suffered matrix detachment on the forward section and that had not been grounded for sure.

I am not saying that it cannot be the case just saying that they should have done that and without that it is impossible for them to state that the Matrix of the First 40.7 can weaken its bond with the boat sailing on heavy seas. They have made that regarding to grounding and made evident that the matrix can detach with grounding they have not done so regarding pounding.

Even so it seems to me that there are evidence that is the case, I mean not a sudden and catastrophic fail of the bond, as it was suggested by some, but evidence that a gradual lose of the bond can happen with age and hard use of the boat. They state that on the conclusions:

"It is possible for matrix detachment to occur in GRP yachts manufactured with a matrix bonded to the hull, resulting in loss of structural strength. The probability of this occurring will increase with more frequent and harder yacht usage. "

Of course this is equally true to yachts that have the structural matrix (not an integral one like the First) laminated to the hull. The difference is that on most cases the inspection is far easier. A bonded one, if the job is well done, can even create a stronger bond than what a laminated can provide and off course, both methods can be used together.

The basic point here is that all boats need to be regularly inspected, lighter performance boats and cruiser racers more often then heavier boats, and repaired if needed.

The First 40.7 is a 1997 boat and most of the boats were sold on the first 5 years of production and that means that most of the boats have between 18 and 13 years.

What I have been saying is that it should exist a protocol for keel inspections on this type of boats one that warrants an effective verification if the keel structure is still properly bonded/laminated to the hull and on the specific case of the Fist 40.7 and all modern Beneteaus and Jeanneaus (that are harder to inspect) a protocol from the shipyards stating how it should be done, what the tools needed, and what should be the frequency (obviously also every time the boat is grounded). Beneteau have said already how it should be repaired.

This is the basic procedure in the airplane industry simply because you don't want to be in the air when something fails and materials don't last forever. I would say that you would not want to be on the middle of an Ocean when something fails on a boat so there is some similitude here.

This accident with the 40.7 should provide the drive to take care of that problem, meaning proper and regular inspections to the boats by qualified surveyors according to a shipyard or designer time table on the specified items, including keel, rudder and rig and appropriated repairs or changes when needed. Sadly I don't believe it will be the case and we are going to see some more accidents happen before some changes are made.

I has been seen as defending the First 40.7, that is not the case, I simply try to address the problem. I don't like particularly that boat but I like it more then the Oceanis line that has a similar build and probably the only reason this problem is more common on the First than on the Oceanis is because the First is much more pushed while racing, including a lot more slamming on heavy seas and more violent groundings.

Personally I would clearly prefer a performance cruiser more easy to inspect and repair in what regards the bond or lamination between the structure and the hull. Most would not even prefer a performance cruiser but an heavier boat. There are for all tastes with their relative advantages and disadvantages.

Never said that liked Beneteaus, namely in what regards the way they are built, just that they were being treated in an unfair way and that their lack of seaworthiness and lack of build quality was vastly exaggerated on this and other threads.

Paulo you should define cristal clear in your post, because the im saying v im not saying that is getting boring....just to point that early 40,7 dont even use methacrylate glue , like plexus or other hig tech stuff, they are bonded with a polyester putty, whatever you can imagine or dream about this isue is not going to change the fact,,, like a previous poster point it, coastal racing with the shore in sight,,,, or modifications here and there to strenght the keel área for offshore use ....is well know that even cranking the hydraulic backstay adjuster bend the boat like a banana,,,, can you imagine that aft 14 mm keel bolt???

[gjorgensen]

Originally Posted by neilpride

is well know that even cranking the hydraulic backstay adjuster bend the boat like a banana,,,, can you imagine that aft 14 mm keel bolt???

Absolute rubbish. Playing around one day I cranked the backstay adjuster to max (beyond even where I've ever sailed it) and went around to inspect doors, cabinets, and the keel attachment with and without it on. This was based on what we noticed on a CM1200 while racing. Result: On my 40.7 we could see no difference anywhere in the boat between no backstay and max.

You keep making wildly exaggerated claims about how terrible a boat you think the 40.7 is. The many out doing ocean crossings regularly disagree with you.

[neilpride]

Originally Posted by gjorgensen

Absolute rubbish. Playing around one day I cranked the backstay adjuster to max (beyond even where I've ever sailed it) and went around to inspect doors, cabinets, and the keel attachment with and without it on. This was based on what we noticed on a CM1200 while racing. Result: On my 40.7 we could see no difference anywhere in the boat between no backstay and max.

You keep making wildly exaggerated claims about how terrible a boat you think the 40.7 is. The many out doing ocean crossings regularly disagree with you.

Not so far , im a rigger by trade and is not the first time we got a 40,7 in our dock with problems, cranking the backstay adjuster in a couple of this 40,7 make no diference until we reach a limit, dont believe me ? i dont care....

[Exile]

Originally Posted by Robin3

The RYA have said this below in their recent bulletin justrcd by email, after the MAIB report:-

Cheeki Rafiki: safety lessons

Safety lessons from the loss of the yacht Cheeki Rafiki and her four crew


The RYA welcomes the conclusion of the Marine Accident Investigation Branch (MAIB) investigation into the loss of the yacht Cheeki Rafiki and her four crew whilst on passage from Antigua to the UK in May 2014.
Over the course of the past year, the RYA has provided information and assistance, working closely with those involved and other organisations, and speaking to the Maritime and Coastguard Agency (MCA) and Government, to actively contribute to the MAIB investigation following the tragic incident.
In the absence of survivors and material evidence, the causes of the accident remain a matter of some speculation. The Marine Accident Investigation Branch believes that the yacht capsized and inverted after the keel became detached.
It is thought that past groundings and ensuing repairs to the keel and matrix may have weakened the yacht’s structure where the keel joined the hull. The deterioration of one or more keel bolts is also possible. A loss of structural integrity may have enabled movement of the keel which was made worse by the deteriorating sea conditions.
There are opportunities to highlight important safety messages following the tragic loss of Cheeki Rafiki and the MAIB has highlighted a number of key points:

• After all groundings there should be an inspection for possible damage by a suitably competent person
• Be aware of the danger of keel detachment and have procedures in place to reduce the risk - particularly with vessels of bonded matrix construction
• Ocean passages require comprehensive risk assessment and contingency planning
• Due to the SAR limitations presented by ocean passages consideration needs to be given as to how the alarm will be raised
• When on a long passage consideration needs to be given to the location of the liferaft to ensure it is available for use in the event of a catastrophic event

The loss of the four yachtsmen was deeply felt by all those who go to sea and our thoughts continue to be with the family and friends of the missing yachtsmen.
The full MAIB safety flyer is available on the MAIB website.
Read more safety information.



Contact Us Article Published: April 29, 2015 17:02
Article Updated: April 30, 2015 16:37

No distinction made b'twn types of groundings -- hard, soft, or in-btwn.

I'm not sure what "procedures" one could put in place to "reduce the risk." Checking keel bolts while underway? I do recall Beneteau publishing a maintenance interval for dropping the keel not long after the CR tragedy. But I'm still not clear if they have adopted a protocol for what to do after the keel is dropped (Polux or others can correct if I've misstated this). It sounds like loose and/or corroded bolts are merely the symptom of bigger issues involving the laminate and/or liner rather than the culprit. There seems to be a consensus that the liner makes this area difficult to inspect, some agreement that hi-tech/expensive tools would be necessary to accomplish this, but disagreement on which tools to use.

Finally, I don't find persuasive Polux casting some doubt on the MAIB report's conclusion that mere hard sailing vs. an actual grounding could also lead to weakening of the keel attachment. If soft groundings are suspect and cause to drop the keel for inspection, then it makes some sense that hard, upwind ocean sailing could produce similar stresses, albeit over a longer period of time. This is presumably why the experts who investigated the incident and produced the reports reached this conclusion even though, as Polux points out, none of the boats they looked at apparently had a history from mere hard sailing alone.

[Muckle Flugga]

Originally Posted by Polux

Gratuitous insults and name calling says a lot more about the one that uses them than regarding the one that is bullied with them.

Regarding that place were the boat is grounded it is remarkably flat:

and if it is a stone shelf it can only be a kind of very soft stone that allows erosion to work on it like that. In fact on the other picture (on the left) you see it coming apart on small pieces pebbles :

Grounding on such a flat ground, on soft rock, would not be very different to grounding on hard sand.

No, talking about really being thrown (and not gently deposed) on hard rock and contrary to what you so emphatically say, there are know cases of boats with a similar built of the First 40.7 to have stayed on one piece.

…

But you were talking about safety and the fact that a boat stays on one piece does not mean that the sailors would survive all those violent impacts or not to be thrown on the water. In fact several members of the crew of the above boat died.

Regarding the crew surviving violent impacts against rocks a steel boat can be way worst than a fiberglass boat due to the nil absorption of impacts. It is known that car and motorcycle helmets are designed to purposely break under very hard impact, dissipating that way part of the energy of the impact and allowing a better chance of survival.

Of course the fiberglass boat will suffer more damage and will be a more difficult one to repair (I said that already) but your point was safety regarding grounding against rocks. Anyway it is a very infrequent situation one that the vast majority of sailors would never experience in his entire life.

As I said previously, a modern boat with a bolted keel has advantages and disadvantages. I can see clearly both, it seems you cannot see any advantage on modern designed boats. Don't you find odd that is the way almost all boats are designed today? Your personal preferences and the blindness that it seems to induce, does not allow you to suspect that there is a good reason why NAs have opted for most design programs, almost unanimously, for that configuration (bolted fin keel) regarding those advantages and disadvantages, even in very expensive sailboats?

Paolo, I am sorry you feel offended. Perhaps I was overstrong in my critique on a personal level and I perhaps should not have been. But I do feel frustrated by your apparent inability even to admit there may be a problem here! Pangloss isn't too rough, however, and I do stand by that one, given your apparent refusal to admit even a question mark over the status of these particular craft as being rated fit for unrestricted service.

With regards to your analysis of the rock as "soft": there is zero warrant to suggest that, and indeed its smoothness and fracturing in neat layered blocks speaks to exactly the opposite conclusion: both hard and brittle. But this idea of "soft rocks" is really, really clutching at straws. And as to the flat surface being clement? Not to the keel it ain't! And you do notice the vertical jagged edge of the rock shelf right on the breaking reefline, no? Really, I don't think geology is a strong point for you and I would lay off the suggestion that a sand beach and solid rock shelf are closely comparable, or that this particular grounding was "soft" in any way at all!

With regard to the rest, your post is mostly a strawman. If you read the second reply to your reply, as well as the subsequent post, you would see clearly that I do not claim that only steel yachts could survive several hours of pounding intact, and include a whole range of boats, which, properly constructed, so could survive at least the initial event, though there may be more questions in some cases concerning whether they could sail away again. This is stated to include lightly built modern boats with bolt on keels. So I really don't know where you get the idea that I consider that it "seems [I] cannot see any advantage on [sic] modern designed boats". I never said any such thing, and have zero idea where you get this from, particularly as I had just finished saying the opposite in a detailed reply both to yourself and one other poster! So, as to my "blindness"? Right back at ya matey!

[Muckle Flugga]

Originally Posted by Exile

Compared to the SmackDaddy threads, this one is occassioned by a much higher percentage of intelligent & cogent points being made on both sides, imho. When it comes to boats we all probably have some degree of bias, but I for one don't miss the repeatedly mindless & deliberately contentious postings from SD & some others that were so transparently personal & obviously biased. I have learned a lot and will continue to learn from the positions being rather well presented by many here, most notably Polux & Muckle Flugga. The discussion also gets contentious, of course, but I think it's more over heartfelt disagreement on the merits rather than some personal agenda.

Btw, what kind of handle/alias is Muckle Flugga anyway??!

As to heartfelt disagreement, absolutely. I have no desire to be contentious for the sake of it. As it happens I am in contact with some of the family and friends of the crew of the CR, and had frequently seen that boat at close quarters in the Solent, and so this has a quite immediate element for me. That said and in any case I am simply very concerned that unless some action is taken, further lives will be lost in dreadful and avoidable circumstances. A keel which is NOT OBVIOUSLY DAMAGED TO THE CREW OF THE SAILING VESSEL should not simply FALL OFF under ANY circumstances, much less simply sailing back home! As a commercial skip I frequently have to board unfamiliar vessels and take people I don't know to tough places. Adventure skippering and deliveries are part of what I do, as well as long term voyaging, ocean race navigation and others. I usually do due diligence on any vessel I step aboard, but perforce this is limited. CERTAINLY it includes carefully checking keel bolts and structural features of the vessel as far as I can, and for longer or tougher passages I insist on at least two days full personal survey time before slipping. However, it seriously concerns me to find that vessels such as CR may have major structural defects that neither I nor anyone else in such circumstances can detect! How can I or any reasonable person consider such a vessel seaworthy for ocean service in these circumstances, without a full technical survey of the entire keel structure before each and every such passage? This is a serious problem, which some here are taking insufficiently seriously.

As to Muckle Flugga? It is the name of a dark and foreboding but beautiful rock with a lighthouse on it which marks the true northernmost extent of the British Isles, off the Island of Unst in the Shetlands. Many years ago I rounded it in a gale in an Albin Vega, taking many hours to beat back into Balta Sound. For me it was the "coming of age" moment as skipper, rather than crew.

[Exile]

Originally Posted by Muckle Flugga

As to heartfelt disagreement, absolutely. I have no desire to be contentious for the sake of it. As it happens I am in contact with some of the family and friends of the crew of the CR, and had frequently seen that boat at close quarters in the Solent, and so this has a quite immediate element for me. That said and in any case I am simply very concerned that unless some action is taken, further lives will be lost in dreadful and avoidable circumstances. A keel which is NOT OBVIOUSLY DAMAGED TO THE CREW OF THE SAILING VESSEL should not simply FALL OFF under ANY circumstances, much less simply sailing back home! As a commercial skip I frequently have to board unfamiliar vessels and take people I don't know to tough places. Adventure skippering and deliveries are part of what I do, as well as long term voyaging, ocean race navigation and others. I usually do due diligence on any vessel I step aboard, but perforce this is limited. CERTAINLY it includes carefully checking keel bolts and structural features of the vessel as far as I can, and for longer or tougher passages I insist on at least two days full personal survey time before slipping. However, it seriously concerns me to find that vessels such as CR may have major structural defects that neither I nor anyone else in such circumstances can detect! How can I or any reasonable person consider such a vessel seaworthy for ocean service in these circumstances, without a full technical survey of the entire keel structure before each and every such passage? This is a serious problem, which some here are taking insufficiently seriously.

As to Muckle Flugga? It is the name of a dark and foreboding but beautiful rock with a lighthouse on it which marks the true northernmost extent of the British Isles, off the Island of Unst in the Shetlands. Many years ago I rounded it in a gale in an Albin Vega, taking many hours to beat back into Balta Sound. For me it was the "coming of age" moment as skipper, rather than crew.

From Wikipedia: The name comes from Old Norse, Mikla Flugey, meaning "large steep-sided island". It has frequently been noted on lists of unusual place names.

No kidding, right? Nice story, MF. Had to go check it out on Google Earth, of course. Quite a place to cut your teeth as a young sailor!

[mstrebe]

From an engineering standpoint, it is trivially easy to design and install a permanent stress indicator into FRP, although I've never seen it done.

All that is needed is the inclusion of a single continuos optical fiber thread laid into the FRP during manufacture in such a way that it winds around over the entire area of concern. This would be done as part of the layup process. Optical fiber is cheap and can be included in FRP anywhere as easily as glass mat woven roving.

When stressed, the optical fiber is deformed along with the FRP. The FRP will return to shape once the flexural stress is released, but the optical fiber will suffer permanent cracking of is sheath and core layers from being stressed. This permanent deformation can be trivially read later with a simple, inexpensive device called an optical time-domain reflectometer which would be plugged into a terminal connector on one end of the fiber, which would be located inside the boat wherever is convenient. The other end of the fiber can simply be left in the FRP wherever it happens to end.

For inspection purposes, you simply plug an OTDR into the fiber will bounce light pulses into the fiber and read the attenuation of them. This results in a simple graph that shows light losses over the length of the fiber. A lack of smoothness or abrupt change in signal will indicate precisely the amount of flexural stress that the fiber has been subjected to cumulatively over its lifetime because the stress cracking of the fiber results in light loss at that point. It also indicates how far down the fiber the stress is, but that's unimportant to this problem.

By correlating stress graphs from the OTDR readings to the results of full scale inspections, it will be possible to indicate when a hull has been subjected to enough stress to warrant full inspection.

It's simple, it's cheap, it's permanent, and it can't be faked. Anyone with an inexpensive OTDR can read it, and the signal is easy to understand: smooth continuos loss=nothing to worry about; abruptions in the signal = must inspect.

OTDRs are cheap enough for owners to carry them aboard, certainly any maritime professional and yard could have them.

Fiber is currently laid into cement on bridges and building foundations where there is seismic concern and used in exactly this manner, so the engineering practice is well known and understood.

[Muckle Flugga]

I truly hope this does not turn out to be another keel loss. Capsize and sinking is suspicious though, and the death of the little girl truly awful:

French girl dies from cold off Azores after boat sinks | GlobalPost