Rudder of Beneteau First 47.7, 2001

G

galloper

New Member
Joined
25 Sep 2005
Messages
9
Visit site
Reading the specs of Beneteau I understood that the spade rudder stock is made of carbon fibre composite. I am used to strong stainless steel shafts and I wonder if I can rely upon a carbon fibre composite rudder stock to the same extend as upon SS. Since I consider buying such a boat is there any any body to give me an opinion?
Many thanks Petros
 
Some years ago at the American Sabre factory I had the opportunity to compare stainless steel and carbon fibre rudderstocks for their 42 foot yacht. The s/s one took two people to lift it safely, the carbon one was easy for one person. Wewere told the carbon was stronger as well as lighter, the only negative being the expense.
 
Traditional fibreglass rudders with stainless steel stocks have an inherent problem in sealing the join between the stainless and the fibreglass, so water ingress is very common (although serious problems are surprisingly rare).

A one-piece all-carbon rudder won't develop this problem, so you can expect it to be more reliable in the long-term.
 
If you over stress then a stainless shaft will bend, probably jamming the rudder. A carbon shaft will break, possibly leaving a large hole. See Sydney Hobart news. There have,in the past, been a number of sinkings attributed to broken carbon shafts.
 
Yacht Georgia sank 2 days ago. see ybw report. Farr design brokerage listing describes this boat as having been lightened by substantial use of carbon/epoxy. Since the hull, rig, steering wheels are are listed as carbon I am guessing that the rudder stock also was. If it eventually turns out that it was stainless then I will eat my words. Unsurprisingly manufacturers of boats with carbon shafts do not go around producing documents that highlight their failings but at leaqst one major (american) builder has had issues with broken shafts. If you search you will find a number of reports.
 
As you say - just a "guess" - hardly documentary evidence! We shall have to wait for the full report (assuming that the yacht is recovered) to find out what really happened.

It is true that Hunter Yachts in the US had problems with "composite" rudder shafts, most notably a yacht in the ARC a couple of years ago.

However, to extrapolate a one off sinking of a racing boat with "maybe" a carbon fibre stock to suggest that a production boat from the world's largest builder has a rudder that might break is rather stretching things - don't you think?

If you are interested in rudder failures that lead to sinking I suggest you read the Irish MCIB report on the sinking of a Hanse 371. This is the only fully documented incident of this kind in British and Irish waters more than 15 years. Lets us hope that the Georgia incident is subjected to a similar rigorous investigation.

Are you suggesting some kind of conspiracy theory - hiding the truth? If a yacht sinks there is an investigation (in most cases). The reports from the investigating bodies are in the public domain. This is not to say that components don't fail in use, but catastrophic failure leading to the yacht foundering is very rare - only 3 cases in the UK or Ireland in the last 15 years, two of which were keels falling off racing yachts and the third the Hanse referred to above.

It is also worth pointing out that production yachts have to meet the requirements of the RCD and demonstrate that components are designed to recognised standards. Unlikely that Beneteau would compromise in this area.
 
If the 'First' series is the same as the 'Oceanis' series, then they (at least mine does anyway) have a large cone internally that houses the shaft, so that should it fail, then the 'through hull' is well above the waterline anyway..... so only a catastrophic failure that also damages the hull would be a problem.... and in my mind this kind of catastrphic failure could only realistically happen through impact damage, which would probably be serious regardless of shaft material.
 
Firstly I did not impune Beneteau, my original post concerned the relative merits of the two materials. I pointed out that the nature of failure of the different materials is different. One bends, one breaks. To suggest that volume builders always get it right is niave. Every volume builder has got it wrong on occasions. Marchai (spelling?) published an article (PBO?) showing that the industry standard calculations for forces acting on a rudder shaft could easily be exceeded in a broach. Rudder damage from impacts is hardly rare. Production boatbuilding now seems to work on the same basis as car building - if you hit things you should expect structural damage. It is because of this that the nature of the damage becomes more relevent. Bent and jammed rudder versus broken off. Spade rudder bearings should in my view always be protected from water ingress in the event of catastrophic failure either by positioning or by a boot arrangement. This is not always the case.
 
You are right that carbon fibre fails in a different way from stainless steel. Just looking for independent documentary evidence that there have been failures of the type you describe.

The Marchaj work is well known, but is very out of date in respect of rudder design. The ABS scantlings are widely used - and Andrew Simpson wrote a long article on the subject in PBO a while ago.

As I noted, it is perhaps a mistake to extrapolate from racing applications to production boats. There are thousands of boats with spade rudders with Stainless Steel, Aluminium and Carbon stocks in use all round the world without experiencing any problems. Why not try to find out why that is instead of concentrating on the rare extreme failure?

I have not said that production builders always get it right, but I think they get it more right than in the past because of a greater understanding of the design and material issues involved.

If you really think that "Rudder damage from impacts is hardly rare", you need to have evidence. In reality failures are very rare. We have 6 magazines desperate for any news to fill their pages, forums where people can share their experiences, consumer legislation and statutory bodies to investigate accidents at sea. They have not found failures on any scale. Are they all in a conspiracy?
 
Extrapolating from race design to production building is exactly what the volume buiders do. I sail a modern design (Bavaria) in the full knowledge that it sails far better than older designs but is also less robust than solid laminate long keel boats weighing far more. My concern is that cost is a prime factor in production building where as it is not in a race boat. If you adapt features of race design for production building the necessary cost reductions can also lead to a diminuition of strength.

As to evidence of damage I use my eyes. I have seen a fair number of boats in the last two years that have impacted with rocks and beaches. Fin keels and spade rudders get damaged very regularly. One North Brittany charter operator seemed to be undertaking strucural laminating work to reattach keels so frequently that I could not see how his business was viable. He told me that he would not inform his insurers because they would stop his cover.

Modern hull shapes, sandwich construction, fin keels, spade rudders, carbon stocks, carbon spars and rigs have all been developed by racing. It is arguable how well the volume builders have adapted them.

As to your argument that RCD guarrantees fitness for purpose I am amazed. My boat is category A Ocean but would hardly be my choice for the southern oceans.
 
[ QUOTE ]

However, to extrapolate a one off sinking of a racing boat with "maybe" a carbon fibre stock to suggest that a production boat from the world's largest builder has a rudder that might break is rather stretching things - don't you think?

It is also worth pointing out that production yachts have to meet the requirements of the RCD and demonstrate that components are designed to recognised standards. Unlikely that Beneteau would compromise in this area.

[/ QUOTE ]

If you think that any carbon production rudder is incapable of failing whoever made it, then you are wrong. And he makes a valid point - carbon fibre laminates will break rather than bend though whether you would be any better off with a bent rudder stock is a different matter

And as for your last para, you have just quoted a case of poor construction and thats from Germany not France! There's also Bavaria keels. There have been Bennies that werent suitable for ocean crossings (according to the authorities) and Bennies with faulty lay ups and Westerlies with keel problems too. Not only can mass manufacturers get things wrong but its probably fair to say they all do at some time or other.

As for the rarity of rudder damage from impact, in our club of maybe 100 lightly used boats we have had 3 cases of impact damage to rudders in the last 10 years that I can recall. One boat also had a keel ripped off and sank at its moorings. None of them will be subject to any reporting as you would expect if a/ no one was injured anbd b/ the boats were long out of gttee so no one to sue. My guess is that most gear failure doesnt get reported for exactly this reason. Not like failures on cars where the consequences are more likely to be fatal, quality standards are infinitely higher (French and Italian makers excepted) and there is a legal requirement for recalls and reporting.
 
Sorry, really muddled thinking here. There has always been development from racing to cruising. Nothing new - ideas are tried out lessons learned and some of the things that work become commonplace in production boats - if owners/buyers value them.

As to using your eyes - If I wanted to see damaged boats I would go to boatyards that mend them. No doubt I would see a lot. But on the way I would see (if I was bothering to look) thousands that never hit rocks, never break and never have any structural damage. If I wanted a boat to bounce off rocks regularly, I would buy a long keel steel yacht - not a Bavaria! I suggest you tell your charter operator he is using the wrong boat for the job!

You also seem to misunderstand what the RCD is about. The category A "Ocean" is not intended to indicate that the boat is suitable for "Southern Oceans". It is simply a label to indicate that it meets minimum design and construction criteria. There is plenty on the RYA website on matters RCD that will explain how it works, including critcism of many parts of it. However, there seems to be agreement that it has improved standards of design.

Finally, you mention insurance. Do you get a "loading" on your Bavaria because it is more vulnerable to damage, or expensive to repair? I don't with mine.
 
I think I know exactly what the RCD is about. Maintaining the competitive advantage of high volume producers. It demonstrably does not prevent these large production builders from selling under specified boats at times. In any other business ocean would mean ocean. The low spec needed to gain ocean certification is a direct result of lobbying during the instigation of the RCD by large manufacturers who did not want their expensive products to only be classed offshore.

Proof of fitness for purpose? Hardly.
 
Never said carbon stocks might not fail in the way described - was merely asking for evidence to support such a definitive statement.

The Beneteau that was criticised after foundering in the Bay of Biscay was built over 20 years ago, and the failure was part of the catalyst for improving both stability and construction requirements that became part of the RCD.

You have clearly not read the report of the sinking of the Hanse. For a start the failed component was made in Denmark by arguably the worlds largest manufacturer of rudder systems with a client list that includes all the major European manufacturers - mass producers and "quality" builders alike. An extensive investigation by an independent consultant metallurgist failed to identify any specific cause of the failure, although there were crticisms of some aspect of the design, manufacturing process and the chosen material. There were also no other reports of any similar failures on other boats.

The Bavaria "keels" was ONE boat and there has never been an independent report (as far as I know) that clearly identified the cause. (My anecdotal evidence from somebody who did work on the charter fleet involved suggests that rock banging was common!). I do know that there were subsequent modifications to the keel area of sister boats - one was featured on here earlier this year. However, as Bavaria have made over 20000 fin keel boats in the last 10 years or so, I fail to see how the unexplained failure of one should be used to generalise - about anything.

As to reporting failures, you are right - there is limited reporting because people just get their boats fixed. However, failures are not on the scale that some people suggest, nor are they restricted to any particular make or style of boat. This is inevitable given the level of usage and hazards that yachts face. But it is too easy to just look at the failures and ignore the non failures.

As you have only had 3 cases of rudder damage in 100 boats in 10 years, you should be able to explain every one of them. It is unlikely however, that there is any pattern, unlike two failures in our club of two examples of a popular class from a respected UK builder. Even then the failures were different. In one the rudder blade snapped off and in the other the bottom of the transom pulled away - not a pretty sight!.

So, please keep a sense of proportion as myths can take over from the real and obscure the huge improvements that have been made in design and construction of yachts.
 
I started to pen a reply pointing out your inconsistencies ( " to suggest that a production boat from the world's largest builder has a rudder that might break is rather stretching things - don't you think? " then we get "Never said carbon stocks might not fail in the way described") but whats the point?

The poor lad who was the OP simply wanted to know whether he should worry about a carbon rudder shaft and maybe whether anyone had heard anything bad about the particular ones in the Benny. As far as I know the answer to both questions is is no, and personally after some experience of carbon masts, I wouldnt worry if my boat had a carbon rudder shaft. Sure it can fail as anything made by man can fail, but I'm not convinced that fracture of carbon fibre is any worse than a bent and jammed stainless shaft.

I hope this is some help. /forums/images/graemlins/grin.gif
 
Don't see any inconsistency. The line of thinking was started by a post that said there had been a number of sinkings attributable to failures of carbon rudder stocks. No evidence was forthcoming except a reference to a racing boat that sank as a result of the "rudder breaking" - might or might not have been carbon fibre - so suggest irrelevant at this point in time.

However, it is true that the two materials fail in different ways - but that does not mean that either have a record of failure in this particular application. The "way described" referred to shattering rather than bending, not to actual failure.

Another example of things that "might" happen, but probably don't, unless there is evidence to the contrary.

So, your conclusion is correct. On the evidence there is nothing to worry about except perhaps whether the benefits are worth the expense.
 
[ QUOTE ]
The "way described" referred to shattering rather than bending, not to actual failure.

[/ QUOTE ]

The OP needs to remember that as he sits in the cockpit with the remains of his rudder at his feet. "Dont worry Carruthers - its only shattered. Its not failed"

/forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif
 
Yes, sorry too late at night. I meant the difference the properties of the material, not whether they fail in this application - for example a carbon rudder blade could shatter on impact, but the shaft stay intact.

Presumably the designers of such rudders (which include the Danish firm mentioned previously) have done their sums and decided that the difference in properties is not relevant in this application.
 
You must log in or register to reply here.

Share this page

Top