Cheeki Rafiki loss report

[Seymore]

A report of the circumstances of the loss of Cheeki Rafiki has issued.

Cheeki Rafiki crew tried to stop flooding amid 5m waves and force seven winds | World news | The Guardian

This incident is very bothersome.

[SVArgo]

Check your keels after groundings folks

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[cwyckham]

Here is a Yachting world article that goes into a lot of good detail on this.

[neilpride]

I bite my tongue on this isue... clearly the attached annex in the report enlight some
questions regarding the keel structure in the first 40.7..just my 2 cents.

[sailorboy1]

Originally Posted by SVArgo

Check your keels after groundings folks

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at least after every 3 groundings

[Polux]

The real important document is this one:

https://assets.digital.cabinet-offic...ort_8_2015.pdf

Some conclusions:

1. It is difficult to readily identify areas where a matrix detachment has occurred in GRP yachts manufactured with a matrix bonded to the hull. This is especially the case where the keel is not removed prior to inspection and where floors have been layed up between frames.

2. It is possible that some of Cheeki Rafiki’s reported ‘light’ groundings could have significantly affected the integrity of the matrix attachment in way of the keel.

3. A skipper’s perception that the force of a particular grounding is insufficient to raise concern does not necessarily mean that significant damage has not occurred to the keel and/or the vessel’s structure.

4. False indications may be obtained when hammer testing to identify matrix detachment, particularly in the area around the keel washer plates, owing to the clamping effect of the keel bolts and where the rig has been tensioned to cause compression of the matrix/hull attachment.

5. There is currently no industry-wide guidance on appropriate methods for identifying matrix detachment and conducting repairs, or on the circumstances that would necessitate keel removal.

6. Matrix detachment had previously occurred in Cheeki Rafiki, probably in bays immediately either side of the bays where the keel was bolted to the hull. It is therefore possible that detachment had also occurred in way of the keel but had not been detected because of the clamping effect of the keel bolts.

7. Had Cheeki Rafiki’s structure where the keel was attached to the hull been weakened as a consequence of previous groundings, this might have allowed movement of the keel due to transverse loading in the prevailing sea state, resulting in its becoming detached from the hull. It is also possible that the keel bolts had deteriorated.
...

1. 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.....

1. The practice of allowing a vessel to ground during training and examinations has the potential for candidates to underestimate the likely consequences of grounding. ...

1. The Beneteau First 40.7 keel washer plates would have needed to be 3mm thicker and 3mm wider for the design, incorporating only one 14mm bolt, to fully meet ISO 12215-9, today’s harmonised ISO standard for keel design and attachment.

The highlighted parts are the ones that seem more relevant to me.

Neil had talked a lot (on other threads) about the difficulty in assessing damage in a yacht with a matrix bonded to the hull. That's the case with Beneteaus and Jeanneaus. .

The system works as it is proven by the 50 or 60 000 Jeanneaus and Beneteaus out there without problems but a building defect can remain hidden and it is very dificult to acess if there are damage or not after a grounding.

[boatman61]

The overwhelming fact of life is '**** Happens'..
Rear end a car and your straight into a garage for a check on the steering etc.. ground a boat and its.. no worries.. fell over when we hit but no water in the bilge so alls good..
Darwin Rools...

[transmitterdan]

Polux,

Thank you for the summary. I think some other of your points are pretty important too. If I understand the report there was previous damage to the hull laminate adjacent to the keel found and repaired but the keel was not dropped. That seems like a big error to me.

[neilpride]

I laugh my ass with those Smart respones trying to justify 60000000 benes build and not a defect in the construction by design, yeah sure...


Wait,,, the first 40.7 is in my opinión a piece of **** in terms of strenght and quality for offshore sailing work, thats it, and the numbers crossing oceans dont matter to much to me, is the number of dirty yard guys doing the dirty Liner repairs Jobs who matter after all, let me remind you just a small example performed by MAIB.


MAIB inspectors visited five GRP repairers who had undertaken repairs to Beneteau First 40.7 yachts following matrix detachment.
Of these five repairers:

1. Three were of the view that the matrix flanges should be removed and surfaces prepared in way of the detachment before the matrix was then re-glassed to the hull with a combination of appropriate matting.
2. One was of the opinion that any remaining bonding paste between the matrix flange and hull should be ground out, with the flange left intact, and fresh bonding paste re-applied before the matrix was then glassed to the hull with a combination of appropriate matting.
3. One considered that either of the two methods was valid.

Beneteau had provided advice on its recommended repair method in documentation issued to its after sales and dealer network. This advice recommended that a flange of at least 5cm be retained and that the bonding paste should be ground out and replaced before the matrix was then glassed to the hull, in order to retain the ‘I’ beam effect and matrix stiffness.


All of the repairers agreed that the keel should be removed when necessary to effect keel repairs, a point confirmed within Beneteau’s advice. However, none of them was clear on the circumstances that would necessitate keel removal


So , they suffer Grid liner by slamming and by groundings......


During the course of the investigation, the MAIB received much anecdotal evidence regarding matrix detachments on Beneteau First 40.7 yachts. Areas notable for detachment were in the forward sections of the matrix, commonly attributed to the vessel slamming, and the area around and aft of where the keel is attached to the hull, commonly attributed to the vessel grounding.
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.
One further Beneteau First 40.7 yacht was visited, which showed signs of matrix detachment in the forward and aft sections.

The size and thicknes of backing plates dont comply with the rule, the keel cant survive without a keel bolt ,etc..

Is a fact , the 40,7 is not designed to withstand soft or hard groundings without damage the liner, even sailing to weather and slamming can damage the bond between liner and hull , and to me is a defect in construction , the CAT A decal in this boat is to me a bad ass joke without further modifications in the boat, clearly a performer in the edge of the minimun standars .... Cheers..

[cpa]

Originally Posted by neilpride

Is a fact , the 40,7 is not designed to withstand soft or hard groundings without damage the liner, even sailing to weather and slamming can damage the bond between liner and hull , and to me is a defect in construction , the CAT A decal in this boat is to me a bad ass joke without further modifications in the boat, clearly a performer in the edge of the minimun standars .... Cheers..

Spot on and thanks for the analysis. I have never been a fan of liner construction. I worry that as these boats age and experience more soft groundings we could see more tragedies like this.

[Polux]

Originally Posted by neilpride

I laugh my ass with those Smart respones trying to justify 60000000 benes build and not a defect in the construction by design, yeah sure...


Wait,,, the first 40.7 is in my opinión a piece of **** in terms of strenght and quality for offshore sailing work, thats it, and the numbers crossing oceans dont matter to much to me, is the number of dirty yard guys doing the dirty Liner repairs Jobs who matter after all, let me remind you just a small example performed by MAIB.


MAIB inspectors visited five GRP repairers who had undertaken repairs to Beneteau First 40.7 yachts following matrix detachment.
Of these five repairers:

1. Three were of the view that the matrix flanges should be removed and surfaces prepared in way of the detachment before the matrix was then re-glassed to the hull with a combination of appropriate matting.
2. One was of the opinion that any remaining bonding paste between the matrix flange and hull should be ground out, with the flange left intact, and fresh bonding paste re-applied before the matrix was then glassed to the hull with a combination of appropriate matting.
3. One considered that either of the two methods was valid.

Beneteau had provided advice on its recommended repair method in documentation issued to its after sales and dealer network. This advice recommended that a flange of at least 5cm be retained and that the bonding paste should be ground out and replaced before the matrix was then glassed to the hull, in order to retain the ‘I’ beam effect and matrix stiffness.


All of the repairers agreed that the keel should be removed when necessary to effect keel repairs, a point confirmed within Beneteau’s advice. However, none of them was clear on the circumstances that would necessitate keel removal


So , they suffer Grid liner by slamming and by groundings......


During the course of the investigation, the MAIB received much anecdotal evidence regarding matrix detachments on Beneteau First 40.7 yachts. Areas notable for detachment were in the forward sections of the matrix, commonly attributed to the vessel slamming, and the area around and aft of where the keel is attached to the hull, commonly attributed to the vessel grounding.
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.
One further Beneteau First 40.7 yacht was visited, which showed signs of matrix detachment in the forward and aft sections.

The size and thicknes of backing plates dont comply with the rule, the keel cant survive without a keel bolt ,etc..

Is a fact , the 40,7 is not designed to withstand soft or hard groundings without damage the liner, even sailing to weather and slamming can damage the bond between liner and hull , and to me is a defect in construction , the CAT A decal in this boat is to me a bad ass joke without further modifications in the boat, clearly a performer in the edge of the minimun standars .... Cheers..

Your post is a bit confusing since it is not clear what are your opinion and what are opinions of shipyards that have actually repaired the boat and Beneteau statements.

Regarding the first 40.7 to be a "bad joke" I don't think so. Several have made several full racing offshore seasons in very though conditions (including several Hobarts) without the boat experiencing keel or other problems. One has been sailed on a full several year circumnavigation with high latitude sailing (Antarctic) facing severe storms without any significant problem.

The size and the thickness of the baking plate did comply with the rule when the boat was designed however (much against what you have been saying) the RCD has been improving all the time the safety standards and today the boat would have to be built stronger on that area.

I believe the fact that most accidents relating with groundings and matrix detachment have been more frequent on this boat because it is simply the one of that type that has been built in bigger numbers. The First 40.7 was a very popular boat and 550 were built.

The boats are not all the same and a lighter performance cruiser in what regards groundings cannot be built to have the same resistance has an heavy cruiser. If a grounding occurs the boat should be properly surveyed and given the way it is built a proper inspection is not easy.

What seems more worrisome in all those that inspected the boat and in what Beneteau says is that a clear protocol is not established in what regards procedures in case of grounding and posterior inspection. They refer also that on the the PDF document that analyses the Cheeki Rafiti case.

Beneteau should make more recommendations regarding that, establishing a maximum safety protocol regarding inspections and also provide information and the needed pieces to upgrade the boat to the new safety standards.

Neil, most of the time I don't disagree with you (except in what regards new technologies and the improvements they bring), just with the exaggerated and inflammatory way you tend to deal with the subjects and that is in my opinion the case when you say about the First 40.7 : "the CAT A decal in this boat is to me a bad ass joke without further modifications".

[europaflyer]

The elephant in the room seems to me to be that the hull liner ('Matrix') is just glued in to the hull. A vast amount of evidence shows that there is no reliable way of gluing units in to a hull which have to take structural loading. It is done purely because it is quick and cheap. Combined with a single line of keel bolts, the entire bending moment of the keel translates in to a pure shear on the bonding paste.

There is a reason that more respected manufacturers leave cut-outs in the structural grid between the beams, which then allow the grid to be glassed to the hull. It's better. Beneteau don't, people die, but it's their fault for grounding it of course...

Minaret is the expert here I think, and I would be very interested to hear his opinion.

Edit: I may have been mistaken in the single line of keel bolts. The annexes to the report (https://assets.digital.cabinet-offic...eekiRafiki.pdf) show that the centre three bolts are doubled. I stand by the rest.

[transmitterdan]

This was not discussed by the MAIB report but if we are allowed to speculate as they did then I think there is another possible issue. It is well known that compressing FRP laminates with bolts and plain flat washers is a poor idea. The pressure will be too high under the washers and quickly drops to nothing very close to the washer. This pressure gradient does bad things. Also, if you tighten the bolts enough to compress the FRP without crushing it then the temperature caused expansion/contraction of the FRP will eventually either crush the FRP (rising temp) or the joint will loosen (lowering temp). FRP is not a spring so either way the keel bolts inevitably loosen.

The only way I know to bolt a high compression load to a FRP laminate is to spread that load over a relatively large area with the bolts fitted with Belleville type washers (Stacking Disc Springs) to absorb the expansion/contraction. Then the bolts can be tightened to the required preload so as to not crush the FRP. The spring washers will keep the pressure more or less constant as the joint contracts and expands. If CR had a proper backing plate inside the hull it would still be afloat IMO. Just look at the pictures and you can see the hull damage is relatively minor.

How we can get thousands of boats in the water using stupid fender washers against comparatively thin FRP laminates borders on criminal IMO. The steel (or AL) backing plate should be measured in square meters not square mm. If there was a proper backing system then the liner/hull adhesive would most likely never be over stressed and this whole inspection/repair debate would be moot.

[leftbrainstuff]

Another sobering report.

One of the oft ignored parameters in formal engineering risk analyses is the detectability of a risk. FMECA analyses also consider the criticality of failure modes. I use bolt on keels as a case study in my teaching on risk.

As an engineer a bolt on keel concentrates stress in ways that it is very difficult to design in graceful failure modes. I can certainly see the benefits for performance vessels.

Bolt on keel was an early constraint in our blue water yacht search.

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[scottmills]

I'm so sorry to all involved and the loss the families must be feeling.
I must say now, as before - myself and many of my professional captain peers will simply not deliver a 'Bendytoy' anywhere offshore.
This is not the first, nor will it be the last time a keel detaches from a hull on this kind of boat. Not seaworthy sums it up.
If you want to cross oceans, buy an older pre 80's boat. If you have a bendytoy, stay within reach of shore, or use the ICW whenever possible.
Or sell it. I personally have had nothing but bad experiences on these lightweight, mass produced boats.
Please take extreme care, and beware.