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“Cheeki Rafiki” Tragedy, Time For Changes

Overturned hull of the Cheeki Rafiki

I think most everyone in the offshore sailing community is aware of the tragic loss of the Beneteau First 40.7 Cheeki Rafiki.

What We Know

Much internet ink has been expended speculating about what may, or may not, have happened to the boat and her crew. But two things we know for sure at this point are:

  • The keel is missing from the wreck.
  • The liferaft is in its original stowage position.

That would seem to indicate that disaster struck very quickly and in a way that prevented this experienced crew from taking steps to save themselves.

Beyond that, we can all speculate for months, as I’m sure will happen in the media and on the forums, but none of that will do much, or maybe anything, to prevent a recurrence. This post is my attempt to look at what we can do.

Cheeki Rafiki is Different

I always take a keen interest when a yacht is lost, and often write about it, because I believe that studying casualties at sea is one of the most important things we can do in our quest to sail offshore safely. But the Cheeki Rafiki loss is different. Not just because four sailors are missing but because, unlike with most losses at sea, I think that there is little anyone, including the crew, could have done to avoid this tragedy, given the current state of offshore sailing.

Don’t get me wrong, I’m not saying that a keel failure is acceptable, and I expect that the appropriate authorities will investigate and try to determine what happened, but what I am saying is this accident may have been inevitable, just as I believe that the tragic loss of sailors’ lives in the 1979 Fastnet race was inevitable, given the state of offshore sailing at that time.

I firmly believe that Cheeki Rafiki should be a wake up call for the offshore sailing community, just as the ’79 Fastnet was. And, once again, we should honour the memory of those who lost their lives by making some fundamental changes.

Keels Are Different

What fundamental changes you ask? Before we get into that, let me quote the late Don Jordan, designer of the Jordan Series Drogue and an aircraft engineer:

In the design of aircraft, certain machinery and equipment is in a separate category, “safety of flight”. These items must be absolutely reliable and must be capable of enduring the worst environment that the aircraft may encounter.

I would argue that the ballasted keel of a sailboat is the marine equivalent of a “safety of flight” item—an item that simply must not fall off for the expected service life of the boat. A sudden keel failure, particularly in heavy weather far from land, well, that’s the marine equivalent of the wings falling off an aircraft in flight—there is pretty much nothing that airmanship or seamanship can do to avert a tragedy.

Yes, I know. I have heard the suggestions that the crew of Cheeki Rafiki would have survived if:

  • The liferaft was stowed in a more accessible place.
  • The liferaft had had an automatic release.
  • Ditto the EPIRB.

And on it goes. To me all of that is like saying “don’t worry about the wing structure, let’s just make sure all the crew have parachutes and the escape hatches work”. No, a sudden inversion due to keel loss is such a catastrophic event, particularly in heavy weather far from help, that even with the best gear in the world survival is doubtful.

And yes, I know that several Open 60 sailors have survived sudden keel loss, but at least two have not; besides which, the crew of Cheeki Rafiki didn’t sign up for that kind of risk.

By the way, it is tempting to say that many more parts of a sailboat should be in the “simply must not fail” category but, if we did that, boats would become even more ridiculously expensive than they already are. And anyway, we can deal with potential failure in, say, rigs with frequent inspection and parts that fatigue with use (stays, for example) with regular replacement—not so keels.

And, after all, if the mast falls down the boat still floats. And even if the hull is ruptured, and the water pours in, there is a reasonable chance of getting into the liferaft. Neither are trivial but they are, in most cases, survivable.

What Changed?

First 36.7 keel 1Before we look at what needs to be done, we need to understand why we have a keel problem. After all, up until a couple of decades ago, sudden keel loss on offshore sailing yachts was extremely rare.

What changed? I’m sure there are a lot of factors here, but I think a big cause is the move to keels that concentrate most of their weight at the bottom and couple that with a very small attachment area at the hull.

Don’t get me wrong, I’m not saying that every boat with a keel like this is dangerous, but there is no question that keels like this are much more difficult to design and build strong enough.

The even more worrying aspect of this is that many boats with these intrinsically difficult to engineer keels are now aging. And while their keel attachments may have been adequately strong when the boats were new, I worry that the ravages of fatigue and/or multiple groundings may have made a large number of boats out there at risk for sudden keel loss.

What We Need To Do

In this kind of situation it is always tempting to say “they need to do something”. The faceless “they” comprising boat builders, designers and regulators. But the bottom line is that it’s simply impractical to expect mass production boat builders to increase the price of their products, or cut their profit margins, to fix a problem like this without changing the market conditions that caused the problem in the first place.

Or to put it another way, we won’t get strong keels until we-the-market start insisting on strong keels. Just as we-the-market started insisting on more stable boats after the ‘79 Fastnet. And yes, I know that regulators and race organizers have a part to play here, but it is still up to us to support them.

New Boats

So what do we need to demand of the industry that supplies the boats we go to sea in, as it relates to keels?

Grounding Proofing

We must insist that the keels are engineered to withstand a grounding at hull speed without structural damage.

Fatigue Proofing

Materials fatigue, in which a structure that was plenty strong enough when it was built weakens over time due to cycle loading and then fails, has, over the years, caused many disasters, most notably in the aviation industry. But it does not have to be that way.

You see, engineers know, to a high degree of accuracy, how much strength common construction materials lose over millions of load cycles. And so it is perfectly possible to design keel to hull joints so that, even after decades of hard sailing, there is more than enough strength remaining to do the job. We must insist that we will only buy boats that are engineered this way.

By the way, fatigue explains a lot about why we have the failures we do on sailboats, so I strongly suggest you read Matt’s excellent article on the subject, and my follow up on how you can use that knowledge to make your boat more reliable and safer.


If enough of us question enough boat sales people about these criteria and insist on a well-reasoned answer, instead of fixating on the latest whiz-bang electronic or electric gadget, these improvements can and will happen, just as more stable boats (both static and dynamic) have resulted from the market’s insistence on them.

So what about the cost of all this? I’m no engineer, but I understand, from those that are, that incorporating the two criteria above would not be expensive in relation to the cost of the typical offshore boat, probably less than 1%—surely it’s worth it. And if every builder is pressured to improve keels, there are no competitive pressures to prevent any builder from doing so.

I also think that regulatory bodies should add the above requirements the offshore classification.


But what about the existing fleet? Well that’s a hard one, probably harder than solving the problem in new boats. But if we do indeed, as I believe, have a ticking time bomb in the form of thousands of boats with keels that, while probably adequate when new, are not adequate after a couple of groundings and a few million load cycles, we must grasp the nettle.

We must demand that those we hire to survey second hand boats being sold and boats that have suffered a grounding, carefully look for evidence of grounding in the former case and render an opinion in writing on the damage in both cases.

No, they won’t get it right every time, and nor should we expect them to, but they must be duly diligent in searching. Yes, this is not easy, but it’s not impossible either. There are tell-tale signs of keel problems to come—dings on the keel filled with putty and carefully painted over, evidence of patching around the hull to deck joint, furnishing and fittings that no longer fit properly—and surveyors should be looking for them, particularly on deep keel boats with small keel attachment areas.

My thinking is that every survey should include a section on examination of keel attachment with special attention to possible grounding damage and any evidence of flexing. In cases where there is any doubt, I would suggest this process should include suspending the boat off the ground and subjecting the keel to a known sideways force and then measuring deflection. And if there is still doubt the surveyor should withhold his or her report until the keel has been removed for full inspection.

Yes, these are big and expensive changes, but no more than the introduction and use of moisture meters and insistence that hulls be peeled and recoated was when customers realized that there was a major problem with water invading fibreglass laminates.

An Halls Spars engineer inspects a carbon fibre mast using an ultrasound machine.Further, just as most of us started to insist that we would only patronize surveyors with moisture meters, we should be rewarding surveyors with more business who look for and adopt new and innovative ways to detect keel to hull joint problems.

The carbon fibre mast industry already uses relatively inexpensive hand held ultrasound machines to look for laminate damage in carbon masts that have been hit by lightning and I’m informed that it is likely that the same machines, in skilled hands, could detect laminate damage in keel to hull joints. We must insist on the adoption of this technology, or something like it.


This is my best attempt at learning something from the Cheeki Rafiki tragedy. I’m sure it’s not perfect, but one thing I do know, we in the offshore sailing community must not just return to business as usual or just shrug and say “they should do something”.  It is up to us to make something happen by changing the market forces that drive boat design and construction, and start looking at existing boats with a much more critical eye.

One other point, nothing in the above should be taken as an implied assertion of cause, fault or blame as it relates to the loss of Cheeki Rafiki. That tragedy simply inspired me to write a post about keel strength that had been slowly forming in my mind for some time.

I would like to close by offering our sincere condolences to the family, friends and loved ones of the crew of Cheeki Rafiki.


I would be the first to admit that I’m not an expert in yacht construction and may have things wrong in this post. If so, I would be grateful to the engineers and naval architects in the audience for corrections, and particularly for alternative solutions. Please leave a comment.

If you are a lay person with suggestions relating to this post, I’m all ears, but please keep it positive. Just saying my ideas won’t work, without suggesting something better, does not help.

One other point on the comments. I will delete comments that contain wild accusations about blame or cause.

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Meet the Author


John was born and brought up in Bermuda and started sailing as a child, racing locally and offshore before turning to cruising. He has sailed over 100,000 miles, most of it on his McCurdy & Rhodes 56, Morgan's Cloud, including eight ocean races to Bermuda, culminating in winning his class twice in the Newport Bermuda Race. He has skippered a series of voyages in the North Atlantic, the majority of which have been to the high latitudes. John has been helping others go voyaging by sharing his experience for twenty years, first in yachting magazines and, for the last 12 years, as co-editor/publisher of AAC.

122 comments … add one
  • Dick Stevenson Jun 9, 2014, 4:44 pm

    John and all,
    There has been a good deal of discussion/worry about hull damage, but the kind of grounding being discussed would also (I believe) leave the rigging/mast compromised. Again this is an area where damage can occur, be vital, and not necessarily reveal itself easily.
    Dick Stevenson, s/v Alchemy

    • John Jun 10, 2014, 8:23 am

      Hi Dick,

      I would certainly agree that a grounding can damage many other mission critical parts of a boat as well as the keel. However, as I postulate in the post, I think we in the sailing community should stay focused on fixing the sudden keel failure problem and not diffuse our efforts into making the whole boat grounding proof, laudable though that goal might be.

  • Laurent Jun 9, 2014, 5:42 pm

    I understand the whole thread has discussed different topics this far, among them :
    – 1) the technical issues about Cheeki Rafiki, why did the keel break, what is the risk of such accidents in today’s yachts and is it technically feasible, at what cost, to reduce this kind of risk to near zero.?
    – 2) the commercial issues about yachts with possible much stronger keel attachments: can we find any in current production, could it be a good commercial argument considering the possible added cost and/or weight (“A40” project…) ?
    – 3) the possible question about Cheeki Rafiki’s builder, was this boat reasonably built considering the regulation and the builder’s commercial discourse, and/or, was is reasonably advertised considering the way it was built ?
    – 4) the US Coast-Guards research efforts for Cheeki Rafiki crew, where they adequate, insufficient, excessive etc.?…
    – ….

    I have no clear cut opinion about each and every of those points, but I understand that Cheeki Rafiki crew hired a sailing yacht in the UK to participate in Bermuda race, which meant that they also had to sail it from UK to Bermuda and back, I understand that they did it according to current guidelines for this sport as practiced by good level amateurs (which they were…), with a seemingly appropriate sailing yacht they hired from a reputed yacht-renting company. They were not breakneck-type kind of guys, and I didn’t understand they took much more risks than they were supposed to in those circumstances.

    So, must this accident be considered like some very rare strike of very bad luck, which should not alter the current practice of anybody (boat builders, amateurs sportsmen etc…), or should we conclude otherwise ?

    Personally, I think qualified good-level amateurs sportsmen should be allowed to take a few limited risks provided the “institutions” (boat builders, race organizers, boat renting companies etc…) are very clear in describing the kind and the amount of those risks. I understand that, in the case of Cheeki Rafiki, it was most likely not correctly done.

    Considering the US Coast-Guards, I understand that Cheeki Rafiki crew was well within the limit of what could be described as “reasonable risks” considering the information they could obtain, and the current practice in sail-yachts races. For that reason, I understand that the sea-rescue public resources that were spent trying to salvage them was part of the insurance we can reasonably expect as taxpayers.

    • Eric Klem Jun 9, 2014, 6:40 pm

      Hi Laurent,

      You bring up a very important point which is whether this is a one time problem which does not warrant changes to design, manufacturing, etc or whether it really should be a call to action. It is my opinion that changes are often made based on emotions rather than on good hard data and this often applies as people respond to a tragedy. As we know, things like materials have a distribution of values for each property and it is likely unreasonable to design something so that you can never have a failure but you can make the probability of one be extremely close to zero.

      I thought about this a little when John first put his post up and I decided that keel failures are indeed much too common so this is not a one time event. I am unaware of a database of worldwide rescues/losses but if one existed, it could be analyzed to really figure out what we should be focusing our attentions on. I read the BoatUS publications as they have likely one of the best databases out there and I know that they try to be proactive about examining it. Unfortunately, I find their articles to be incomplete and I don’t know whether it is because they dumb them down or if they don’t look deep enough (for example, saying that X% of boats sink due to hose failure doesn’t tell you if it is a random sampling that sink or if it can really be solved by replacing the hoses regularly, in other words, they should try to correlate the hose failures to a cause and a remedy).


    • John Jun 10, 2014, 8:18 am

      Hi Laurent,

      I agree entirely that the crew of Cheeki Rafiki took what should have been a reasonable risk and therefore had every right to expect that a credible effort would be made to rescue them. And, I believe that effort was made.

      The cancelation and restart of the search is a much more difficult question, and since I have no expertise in the area of accessing survival probabilities with time, I have no opinion on that.

  • RDE Jun 9, 2014, 6:43 pm

    A few quotes from an sailor who has owned and raced a number of First series Beneteaus including the 40.7 model. He seconds the comments I have been making about the inherent problems caused by attaching keel bolts through a (so called) structural liner.

    “In my opinion, anyone who has a production boat with a solid polyester GRP hull with a structural hull liner must (at some time and commensurate with boat use) give very serious consideration to addressing laminate and grid connection fatigue”

    “In my latest First I found the hull laminate thickness was the thinnest either side of the sump, presumably done to assist bilge water flow to this sump!!!”

    “I have a number structural concerns attached to “white boats” after a period of use and particularly those produced over the last 15 or so years, some of which relative to initial outlay and outcome are easy to correct. For appendages, these concerns include:

    1. The absence or minimal use of “integral” stringers in areas of high load and therefore the reliance on a structural hull liner and its method of connection to the hull; and

    2. Keel connections and the long term shear load capacity of adjoining hull laminates accommodating normal day to day flex fatigue and as well as sudden impact fatigue through groundings, knock-downs etc. ”

    From Sailing Anarchy June 7,2014

  • Enno Jun 10, 2014, 5:14 am

    When comparing to the aviation industry I find it striking how different the handling of the wreckage is. After an aircraft accident everything is done to find the wreckage with the purpose to learn from it. In this case one did not salvage the wreckage as a policy even though it would have been comparably easy. I find this quiet sad. Bulletproof evidence of the cause might have changed the way boats are build, just as it is usual in the aviation industry.
    I hope the A40 get a lead keel with a heavily overengineered attachment.

  • Jeremy Gurney Jun 11, 2014, 8:57 am

    A very interesting discussion on a very important subject. I have not read all the comments, and apologise if I am repeating anything that others have said.

    Thoughts on four separate aspects come to mind:
    – Reason for Cheeki Rafiki’s loss
    – Check of existing boats
    – Prevention of fatigue
    – Launching of liferafts

    1. Establishment of the cause of Cheeki Rafiki’s keel loss.

    Based on information at present available, the cause of the failure that led to the keel loss can only be guesswork. To make further progress the hull would need to be recovered to enable it to be examined. The upper part of any bolts that have broken, if not still in place, will be within the hull, and examination of the fracture surfaces would show whether failure was due to fatigue or other causes.

    2. Checking the condition of the keel attachment of existing boats.

    On many boats it is very difficult to remove keel bolts to check their condition. It occurs to me that it should be possible to check for incipient fatigue cracks by ultrasound. I think other contributors have also mentioned this possibility.
    If the upper end of the bolt is accessible, as it usually is, an ultrasonic check would involve sending a signal down from the top and checking for echoes. The basic technology exists, but possibly the kit for this particular application needs to be developed.
    It would not be unduly expensive, and would, ideally, be available at boatyards with an operator trained in its use.
    All boats could then be subject to a routine check.
    The potential problem with this is that fatigue cracks, once they have started, grow very quickly. As soon as a crack is detected in one bolt, all of them would need replacing.

    3. Prevention of fatigue failure of keel bolts.

    When you think of all the different loads, arising in different conditions, it is very difficult to determine accurately the loading spectrum to which the keel attachments will be subjected. This would require a widespread programme of instrumentation of boats being sailed in all conditions.
    Although this could be done, it would require a lot of organisation and a lot of time; so lets leave that aside for the time being.

    In the absence of detailed information about the loading pattern, which would allow the design to proceed in accordance with established codes of practice, we need a different approach.
    This would be that the design and construction should be such as to prevent the keel bolts feeling any changes in loading.
    This can be done by pre-tensioning the bolts to more than the maximum anticipated load. It is important that the contact surfaces (the top of the keel and the underside of the hull) are a perfect fit, probably flat, so that there is no possibility of relative movement.
    Any loading applied by the keel to the hull is then accommodated by variation in the bearing pressure between the two, and the bolts feel nothing because their length does not change (no change in strain, no change in stress).
    This is exactly the principle used in ‘big end’ bearings in engines, where the two bolts are tensioned to more than the maximum force experienced. If this were not done, the bolts would fail in fatigue.

    Does anyone know what the existing design specification says? Maybe it needs updating.

    4. Ease of life raft launching.

    I am not convinced that liferafts stored in lockers are as easy to launch as they might be.
    Many years ago, when we were setting up our boat for long distance cruising, I saw in a marina a yacht with a life raft mounted on the pushpit. I was duly impressed, and copied the principle for our boat, having a purpose designed frame made out of stainless steel tubing.
    It has a simple release mechanism, which is easy to operate and requires little strength, with the boat either the right way up or inverted (although this has not been tried!)

    It is worth consideration, and, perhaps, further development.

    • Ed Jun 11, 2014, 5:17 pm

      Re your
      #1. When SS steel meets fibreglass…
      Suspect the fibreglass.
      #3. design for worst case

  • Dominic Jun 23, 2014, 2:41 am

    Do you not think that modern boats are being designed and built too lightly for commercial reasons?

    • John Jun 23, 2014, 7:56 am

      Hi Dominic,

      Partly for commercial reasons, yes. But more important, I think, is that generally an industry will give a market what it asks for. As I say in the post, the key to change is educating the market to ask for something better.

  • Homero Jun 29, 2014, 12:23 am

    This was a huge wakeup call for me. I am in the process of choosing an used boat for a long passage ( Florida to Brazil) and the first thing that came to my mind was: If it is going to be an used boat, then better to have a long integral keel boat like Island Packet… where the keel cannot drop. Is my assumption correct?
    Thank you.

    • John Jun 29, 2014, 7:34 am

      Hi Homero,

      A full keel boat with encapsulated ballast like the IP is certainly one approach to the problem. Having said that, there is no intrinsic reason that a bolt on fin keel can’t be engineered properly and safely, and I think that many are.

      The other issue is that encapsulated keels are not without their potential problems either, most notably difficult to repair water ingress between the ballast and the skin as a result of even a minor grounding.

      The bottom line here is that the real issue is good engineering and construction, not a particular boat type.

      • Homero Jun 29, 2014, 3:35 pm

        Dear john and Bill
        Thank you for your reply and comments. It is scary for someone without the proper knowledge and experience, to trust a surveyor without the proper instruments to analyze corrosion and weakness in keels of a 10-15 years boat. Congratulations on the excellent site.

  • Cornelius Jun 29, 2014, 9:59 am

    I remember, that the crew oft he Cheeki Rafiki reported in one of their last contacts via sat phone, that the ship was leaking. And they said, they didn’t know, from where the water entered. Today it seems clear, that this was the beginning keel problem. For me personally, as I am sailing a similar ship, I arrived at the conclusion, that in case of undefined leaking, I would immediately tack the ship and have someone to observe, if the keel bolts in the bilge are moving. If yes, I would directly prepare everything for leaving the boat – and leave the boat as soon as possible.. This is my learning from this tragedy.

  • Bill Attwood Jun 29, 2014, 10:03 am

    Hi John and Homero.
    As the owner of a long-keeled Rustler 36 I feel obliged to respond. John´s comment that a properly engineered attached keel should give no problems may be (I use may advisedly) true, but how on earth is a boat buyer to know if his keel/hull joint meets the necessary requirements? Comments like “buy an A40” not permitted!
    There have also been many comments above on the effects of grounding with an attached keel, and the resulting invisible damage/deterioration.
    I have run aground in my boat a few times, but with never more damage than a chunk out of the laminate at the front of the keel, repaired easily at the next haul-out.
    My advice to anyone, particularly if buying a second-hand boat, would be go for the encapsulated, with the keel an integral part of the hull moulding. It is interesting that long- (any number of british and US classics) and short-keeled (eg HRassy, Najad) yachts seem to be confined to a niche market, and that all of the big builders have attached keels. Even the Swedish builders seem to have moved to the attached keel system for their new boats. I just wonder whether this might be a cost-saving development. Speed may be an issue, but surely the difference on a long voyage will be insignificant when one looks at all the other factors affecting daily runs?
    I have a question for you, John, on a separate topic, high-output alternators. I have bought and installed an Aquamaax, which has not been without problems. I have discussed my wish to make a comment on the AAC relevant post with Aquamaax Europe, and they have no problem with criticism providing it is fair, constructive and objective. I would let them see my comments before I post. My experiences – how the problems were resolved – may also help anyone else who decides to go for this alternator. Is the AAC website a suitable forum for this? I should also be happy if you wished to moderate the post before it goes up.
    Yours aye,

    • John Jun 30, 2014, 6:14 pm

      Hi Bill,

      I think that we are closer on the keel issue than might first appear. As I said to Homero, selecting a full keeled encapsulated keel is one way to pretty much solve the sudden keel loss problem, however, to then say that only full encapsulated keels are appropriate for offshore voyaging is, in my opinion, a stretch too far. There are plenty of good bolt on fin keel boats out there that were properly constructed and are perfectly safe from sudden keel failure. After all this whole keel loss thing did not start until comparatively recently and bolt on keels have been around for a very long time.

      There is even a logical argument that properly checking a bolt on keel boat is easier, in that you can drop the keel and really check things out, not something you can do with an encapsulated keel.

      Also, let’s not forget that there have been plenty of bad boats built with encapsulated ballast complete with horrors like steel punchings in cement as ballast.

      And there is no denying that a well built bolt on lead keeled boat will, in almost every case, need less repair after a grounding on something hard (file off the ding) than any encapsulated keel where the fibreglass almost always gets ruptured at the leading edge leading to all kinds of potential fun and games, including getting the cavity dry enough to allow the repair.

      The bottom line is that you can’t be safe just by saying buy a boat of a certain type without doing the due diligence to make sure that the boat was built right and that nothing has happened since launch to compromise that.

      Don’t get me wrong. I own an encapsulated keel boat, so I’m not prejudiced against them, I’m just pointing out that there are benefits and drawbacks to both methods of keel attachment.

      As to your comment on alternators, sure, bring it on. It should be added to this post.

  • Paul J. Nolan Jul 6, 2014, 2:29 am

    The headline “What’s Changed?” next to the picture of that ridiculous keel had me laughing as the answer is all too self evident. After seven decades of observing the changing nautical scene a couple things stand out: a big decline in seaworthiness of many yachts and a cooresponding decline in the general level of seamanship. When I was a kid the sport was a lot, lot smaller. The way people generally entered it was to crew on a one a design for a couple seasons, then buy one and skipper it oneself, eventually moving up to a cruising boat. The maintenance demands of wooden boats limited interest in the sport to but a few. Thus fewer people were absorbed into sailing over a much longer period. Now it is not unusual for a person with zero knowledge or experience to buy a 40′ Hunter and cast off (I’ve seen it with my own eyes). And why not? It steers with a wheel just like a car and it has an engine too, also like his car. And if he encounters difficulty, why, there’s a radio to call the Coast Guard for help, just like calling 911 on his home phone. I have often looked over the several thousand (?) boats in my harbor and thought not one person in twenty here has any idea what this sport is about.

    And boats too have in many cases declined and that decline has been largely accepted. Skip Novak, after racing around the world several times, left the sport saying incredulously, “They’re planning to race full-tilt IOR boats in the Southern Ocean.”. That was thirty years ago. Now, IOR boats look seaworthy compared to some of the junk I’ve seen in the past ten years. Canting keels, anyone? While I agree that fin keels can be engineered and constructed to be perfectly strong, there are limits. A Peterson keel can be made that is safe, even in a hard grounding; a fin with a depth of ten feet, a four thousand pound bulb and a chord length of 21 inches cannot. And it is inevitable that whatever is found in the racing fleet will eventually find its way into the cruising fleet. The keel shown in the above photo is not seaworthy. It has no place on an offshore boat. And a walk through a boatyard will turn up many other examples from the amusing, like wheel steering on a Catalina 27 to the hiking wings on the 5500 lb. 40 race boat that was lost in last year’s Mackinaw race along with two lives.

    Many things drove these changes, but three stand out: materials revolution, competive pressure and radio communication. With the development of fiberglass, it was no longer necessary to spend dozens of long man-days every spring working on the boat. Glass hulls and decks, aluminum spars, Dacron sails and running rigging and stainless steel standing rigging…anyone could own a boat. And with the new materials boats could be lighter and faster. Finisterre was about 22,500 lbs., a Cal 40, about 15,000. And today a Cal 40 is regarded as a heavy boat. And compare Sayula II and Flyer (great name), the winners of the first two Round the World races to the pro ocean race boats of today. At the same time there has been a revolution in radio communications. UHF, epirbs, satnav, Iridium, computers, the internet…all this breeds a false sense of security and complacence even in experienced sailors. I am convinced that if all forms of electronic communication—sending and receiving—was banned from all racing sailboats, you’d see a big increase in seaworthiness. That change in equipment and attitude would eventually migrate to the cruising fleet.

    I’m not saying the crew that perished when their keel fell off were not good seamen. I’m sure they were. My point is that over the years equipment, practices, and attitudes that are the antithesis of seaworthiness and seamanship have been permitted to infiltrate our sport until they have become the accepted status quo.

    Paul J. Nolan

    • Frans Jul 6, 2014, 6:35 pm

      Mr. Nolan: very well said! Thank you.

    • John Jul 6, 2014, 6:42 pm

      Hi Paul,

      I agree with most of your analysis of the problems in offshore voyaging today. This site and this boat are our attempt to make the situation better, even if it’s only by just a little bit.

      My point being that what we try to do here at AAC is come up with solutions, no matter how flawed and inadequate they may initially be, rather than just identify a problem and leave it at that. Often, as has happened with the Adventure 40, that initial flawed solution becomes something quite worthwhile over time, usually with the help of the readers on this site.

  • Bob McDowell Nov 11, 2014, 6:49 am

    I own a 2003 Bavaria 49 that I use in the Adriatic for coachin and sail training. I will, in a few years, sail the boat to the US to sell. Before I go though I will pull the keel off the boat, replace the keel boats and re-install. I have been quoted 5000€ for the whole procedure including having the hull checked with ultrasound and any suspect areas ground out and replaced. This is NOT a lot of money to spend on a what will be a 15 year old boat (5% of the value which I will recover in resale value). This will bring the hull-keel joint back to original specs and as the boats have not had a problem I feel good about doing this. (the boat is not a Match version!)
    I am wondering if on these older boats a multilayer CF laminate on the outside made wider than the keel footprint through bolted to a molded CF pan that was laminated to the “Grid” would make a good long term fix. The cost would be “insignificant” regarding the value of the boat especially if you could spread the tooling costs to several boats. The boat I have is a Step-up investment for my final “retirement” boat (will continue to work-sail till I can’t) that will be an “ocean going boat” maybe the Adventure 75?

    • John Nov 11, 2014, 9:51 am

      Hi Bob,

      What a great comment, and a great attitude to the problem.

      As to your question on the CF laminate, I’m not qualified to answer it (although it sounds like a good idea) but we have some engineers around here who are. Hopefully they will weigh in.

    • Laurent Nov 11, 2014, 11:00 am

      Considering custom composite reinforcement of keel-hull joint:
      – I am afraid that many potential buyers might be very uncomfortable with thick extra laminates (more than a couple of millimeters…) added between hull & keel root, general idea is that this kind of reinforcement is generally not done unless there was a start of failure detected on boat, or a serious weakness known on boat model, so, I guess that many would-be buyers will consider the half-empty bottle (possible problem with boat or boat model) rather than the half-full one and pass their way.
      – Between hull and keel-bolt nuts, I understand that adding a stainless sheet at least 8 mm thick with the shape of keel upper section, perhaps segmented to make way for grid if necessary, plus some local composite reinforcement-and-bedding under that sheet to obtain an even pressure from keel bolts to internal hull surface, is a good idea that should not worry potential buyers if it looks professionally done. I understand that this kind of reinforcement might have prevented the sinking of Cheeki Rafiki. I am a bit wary of larger internal composite reinforcements unless there is a start of failure detected on boat or a known weakness on boat model….

      • John Nov 11, 2014, 11:23 am

        Hi Laurent,

        Thanks for fielding that one, it was definitely beyond my technical pay grade.

    • Eric Klem Nov 11, 2014, 11:50 am

      Hi Bob,

      It is quite unfortunate that people need to even contemplate the type of reenforcement you are describing as it is much more difficult to do after the fact instead of up front when the boat is built. It does seem that many boats were underbuilt in this area or were built with construction methods which do not hold up over time.

      It is always very tricky to mix different materials together. The main reasons for this are that they have different stiffness, different thermal expansion properties and they can be difficult to attach. Carbon fibre is great stuff but it is significantly stiffer than fiberglass. If CF is put around the keel attachment, it will carry almost the entire load until it fails at which point the load will transfer to the fiberglass (the load on a material is proportional to the deflection so at small deflections, the load in CF will be high and fiberglass will be low). You will also end up with a big stress concentration at the edge of the CF as you will go from very stiff to not stiff. There are things you can do in the design to mitigate some of this but you can’t fully mitigate these issues. If you plan to reenforce a fiberglass boat, I would use fiberglass to do it and you should have someone who can model the structure look at it to make sure that you don’t create a stress concentration somewhere. Believe it or not, added material can increase the likelihood of failure if it is done incorrectly.


      • Bob Nov 12, 2014, 5:12 am

        Mixing of laminates of different stiffnesses can be and is done all the time. The wings and fuselage of my sailplane are made of GRP/CF/foam cored laminates. The engineering design on the wings is simple and elegant. The wings bending in flight is beautiful to see.
        On reinforcing the keel area, maybe thinking that the area is a CF skin with a solid FG core would make it easier to visualize. Yes the CF would have to taper to the ends on the outside including going to a cf cloth with less thread count in the outer layers. The inner laminates could be glued to the grid so the stresses can be mitigated.
        I was taught by my father to laminate with FG and polyester in 1968 when we built our first boat. That boat is still going strong. He was not an engineer (nor am I) but he built stuff engineers designed. He always added to scantlings from the “engineered” data using his store of knowledge. He built boats and airplanes, cars and racing motorcycles, iceboats and landyachts, and many other cool things (my dad’s garage was the place to hang out for the neighborhood kids). Man, do I miss that guy!
        So, the take is, CF and FG can properly be used together. We don’t have to have the thinnest, most elegant solution as it is going on a boat with 1960’s engineering in the hull. The process, the hull would be ground down to clean laminate (not core, if it exists in the keel area, some question on that). A multilayer CF patch, properly tapered to all the edges, vacuum formed to the underside. Internally, grinding the area in between the grid where the keel bolts are located including up the sides of the grid and vacuum forming a CF pan making sure to mitigate the stress areas in corners. Before laminating the CF (in and out) drilling oversize holes where the keel bolts were and filling with a high density filler for load bearing. Re-drill the keel bolt holes (from the template you made, right?) re-installing the keel as per standard practices with stainless backing plate and you are good to go!
        What thinks you?

        • John Nov 12, 2014, 8:31 am

          Hi Bob,

          When you asked your initial question, I had forgotten that Matt, AAC Engineering Correspondent had written a piece over at his site on the challenges and dangers of mixing carbon and fiberglass. Well worth a read.

          The key quote in Matt’s piece is: “Don’t mix materials with radically different mechanical properties in parallel in the same load path.”

          When deciding what to do, keep in mind that both Matt and Eric are very smart professional engineers and I have yet to run across a technical situation where either of them were wrong.

        • Laurent Nov 12, 2014, 8:59 am

          In my opinion Cheeki Rafiki went down because of a badly engineered keel-hull joint not mastering the engineering subtleties of stiffness differences between molten-iron and polyester/glass-fiber composite…

          If the question is “what can we do to avoid this kind of fate”, I would answer that, for safety-related boat parts, you should either: never mix materials with very different young modulus, or, make complete professional engineering studies of the cases before adding high-modulus materials (FEA…) .

          In present case, unless there is a start of failure or known weakness on boat or boat-model, I do believe that keeping things as they are, and doing nothing on composite is probably safer than tempering with carbon fiber on a thick glass-fiber/polyester hull. However, I understand that a limited amount of added glass-fiber + polyester or glass-fiber + epoxy should not do any harm and that a stainless backing plate looks like a good or very good idea, but carbon fibers looks at most like an overkill, and at worst, like a possible source of serious problems.

        • Eric Klem Nov 12, 2014, 11:48 am

          Hi Bob,

          In rereading my comment, I realized that it can be read more generally than I had intended so let me try to clear that up although my conclusion remains the same for the application we are discussing. As John quotes Matt on, mixing materials gets tricky when you are trying to put them in parallel so that they share a load. If they are used to carry different loads or put in series, this is not an issue. Take an example where you are trying to hold 2 steel plates together with a 10mm^2 piece of carbon fiber and a 130mm^2 piece of fiberglass each of which are 100mm long. Each piece has a strength of 17,300 N (I am just pulling these numbers from engineering toolbox and they are very generic so they may or may not apply to specific layups) so it would be easy to assume that the two pieces could together hold 34,600 N. However, once you increase the distance between the two plates by 1.2mm, the carbon fiber has a tension of 17,300 N and the fiberglass only has a tension of 1900 N. If you increase the displacement at all, the carbon fiber will break and hold no load meaning that you can only effectively hold 19,200 N with this connection which is only 55% of what you would get by adding the tensile strengths. If you had two carbon fiber or two fiberglass rods, you could actually get to the full 34,600 N (load balancing is actually quite tricky so you usually end up slightly lower but not much). Things get even worse if you make the cross sectional areas more different. In engineering terms, this shows the importance of the Young’s Modulus which is a measure of stiffness.

          Things get a bit trickier when you get away from a straight tensile force case. As you point out, we mix materials all the time but the key in doing this is that you can’t assume they share a load equally. In most cases, the different materials are being used to handle different loads so it is not a big deal (sometimes within the same part such as a composite with kevlar fibers in one direction and carbon ones in another). Engineers actually spend a large part of their time designing the connections between these materials as they are what need the most reenforcing and careful design. In some really advanced applications, you can actually vary the material properties in the same material depending on your location and local loading but this is the stuff of high end racing only at this point for boats.

          Back to the original question of combining carbon fiber and fiberglass at the root of the keel, I think that I would much rather use fiberglass only. If you add carbon fiber which is nicely tapered, you will end up with deflections in the thin area of the taper that are large enough to cause small failures to occur. Once these occur, they will migrate into the thicker layers until you end up at a point in the carbon fiber that it is strong enough to carry the load entirely and you will simply have a large stress concentration. If you accurately mimicked the properties of the existing fiberglass, you could do exactly what you are discussing with careful tapering and you would not see these failures while meeting your original goal of strengthening the structure. The key here is that you are trying to lower the stress in an area by adding more material for the force to be distributed over so this is a “parallel” application.


          • Erik de Jong Nov 12, 2014, 1:50 pm

            In addition to Eric’s very good comment, I’d like to add an example which I use a lot to explain differences in materials to people without an engineering back ground.

            Imagine a piece of rope and a piece of bungee cord that are both the same length. Tie them to something and start pulling them both with one hand. As you can well imagine, you will only pull the rope because the bungee cord will stretch a long distance before it can take any load. All load will therefore be taken by the rope, until it breaks, than the bungee cord will take over. In this case, the hybrid is only as strong as the individuals on their own rather than their combined strength.

            An identical situation occurs when Carbon Fiber and fiber glass are combined. The Fiberglass acts as the bungee cord in this case, and the Carbon fiber as the rope.

            The combination of the two different materials can be used in some cases if you want to make a structure stiffer, rather than stronger, but one needs to carefully analyze a structure. Usually it is not a good idea to combine materials in one laminate that have different moduli of elasticity.

            Given the complex number and direction of loads around a keel, I agree for 100% with Eric and would not use Carbon Fiber at all, unless you replace the entire structure by carbon fiber, but in that case you run into a whole lot of other very complex problems.

    • John Nov 13, 2014, 9:18 am

      Hi Eric, Erik, and Laurent,

      A huge thank you for responding on this one with your usual clear explanations of complex issues. I hope everyone around here realizes, as I do, how fortunate we are to have you guys around.

  • Bob Nov 12, 2014, 4:10 pm

    Ok, the experts have spoken! Thanks for the education, I did read Matt’s article o mixing composites. Now I have to go and make some samples just to see. I told you I am not an engineer! I will make some samples and test them to distruction, something I do well! Then I will believe the engineers as I know they are correct but I am hard headed.

    PS besides it will be fun!

  • Ed finn Nov 12, 2014, 10:11 pm

    Re your last post
    Your not ‘hardheaded’
    Just careful!

    “Samples and test them”…testing and measurement is the root of all Science.


    • Marc Dacey Nov 13, 2014, 10:25 am

      This discussion of differing materials and the engineering of same is very lucid for the non-engineer. Thanks to all involved…and now I have to look into “Young’s Modulus”!

  • Erik de Jong Apr 29, 2015, 11:06 am

    The official MAIB investigation report on the loss of ‘Cheeki Rafiki’ has been published:

    • Marc Dacey Apr 29, 2015, 4:44 pm

      A sobering read. Thanks.

    • John Apr 30, 2015, 10:28 am

      Thanks, Erik, I have put it on my reading list.

  • Nick Kats Apr 30, 2015, 5:29 am

    At the Horta, Faial, Azores marina someone painted a mural in memoriam to Cheeky Rafiki. I’m sorry I did not take a picture of it. It is on the ground near the head of the marina basin, on the far side.

  • pat synge May 6, 2015, 7:56 pm

    Highly experienced boatbuilder George Stead’s thoughts about keel attachment.—A-UK-production-yacht-builder-speaks-out/134063

  • Dick Stevenson Dec 17, 2015, 6:12 pm

    Hi all,
    More info on the keel falling off of the big Oyster can be found at
    My best, Dick Stevenson, s/v Alchemy

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