Another Big Canting Keel Boat has Blown-up its Mast

In what seems to be the most current expression in how much strain is being placed on the rigs of these big canters, Wild Oats has lost its monster carbon stick at the Maxi Worlds off Porto Cervo, Sardinia.

Read the story here: http://bymnews.com/news/newsDetails.php?id=14836

Doesn't look like pure stick failure on this one from the report. Going all the way back to the intro of this keel type (canting system) on race boats, there has been a consistent and regular dropping of very expensive masts on this type of boat.

Interestingly enough, the dropped rig frequency for non-canting keel equipped boats is nowhere even close to the rate that these big dudes lose theirs. The principle difference in the design of the boats... the canting keel.

Now, I'm not an engineer, nor am I a pro rigger or composite mast designer, but something is going on here and nobody is talking from those who know.

Fascinating.

 

Rigging

According to the crew, they heard one small bang and shortly thereafter the mast exploded probably indicating a rigging part failure.
They were sailing in 10 knots and choppy seas and had just previously been sailing in 14 knots and much heavier seas.
Oately intends to have the boat ready for the Sydney -Hobart which it has won two years in a row.

 

Yes, probably so. With the limited info available and the huge potential number of things that can break... along with the rig having been cut away, it'll probably be some time before they let this out, if ever.

The question still remains as to why so many of the rigs/masts on these boats are dropping when fixed keel boats have no consistent history of similar maladies on a such a regular basis.

Remember I asked this question way back in late December after the S/H concluded and you went off on me?

Quote: Chris Ostlind from post #103 S/H Battle of the Canters http://www.boatdesign.net/forums/sho...t=14833&page=7

"Furthermore, what was most startling was that fully 38% of the boats with canting keels that were supposed to start the race had to fall out or not start at all due to demolished masts. Since when is that a statistic to crow about? If it had been a bunch of different maladies that had mysteriously befallen the canting fleet, then you could say it was an unfortunate run of bad luck. When it's all due to mast failure, you can't simply ignore the fact and start tossing kudos for a job well done. How many boats of the non-canting variety had their masts taken down in the very same conditions? Was it equally as problematic when looking at a percentage of the traditional keel fleet?

Nearly 40% failure, out of the event, all from the same problem...? That has seriously problematic written all over it. I'm willing to be corrected on this position, but I still haven't seen any info that would tell the story differently. Perhaps Randy could shed some light on the stress issues for canting keel equipped boats and how that loading is pushed through the rig under the stress of racing?"

Your response:
Quote: Doug Lord from post #111 S/H Battle of the Canters page 8

“The rig doesn't give a hoot what’s under it: a canting keel, two or three hulls, or a belly full of lead-just so long as it is designed and built properly for the RM developed by whatever means. There is absolutely no association whatsoever between canting keels and rig failures-or at least there shouldn't be. The science of rig design and construction for a given RM has been around generations longer than have canting keels. The only area I can see any possible guilt by association is in the fact that the masts have come down on racing sailboats....”

Yes, Doug, the caveats are understood, but it doesn't explain, at all, why this happens so frequently to canting keel equipped vessels and no where near as often for non-canters. Apparently, the rig does care upon which type of keel it is mounted.

New and obsessively inspected fittings and rigging parts do not suddenly break on a regular basis. Sure, it could be a rather small part which has brought down this rig. The question looms, though, as to what sorts of unexpected and enormous loads beyond "The science of rig design and construction for a given RM has been around generations longer than have canting keels"

I would suggest, as I have for 8 months now, that there's more going on here than can be easily explained with simple, time worn expressions.

There are some reference papers here dealing with the issues, but it's still precious little real data in this world of closely held secrets for big dollar efforts:
http://www.boatdesign.net/forums/showthread.php?t=18306&highlight=canting keel mast failures

 

Righting moment and more

I will nail my colours to the mast right now and make it plain that I am not a fan of canters. The spectacle of the Sydney to Hobart racers with their motors on to go sailing doesn't sit right with me. I think though that there are some interesting engineering problems with canters.

I understand that the RM will be much higher on a canter but the canter's RM is constantly changing. Canters have a bloke who sits with his hand on the control and can wiggle the keel to windward and back. This will tend to decrease the shock absorbing characteristics of the rig if he anticipates gusts (as a good sailor should). On top of this the dynamic RM will change as well.

As boats go up and down waves their weight changes. As you go up the wave you are more stable and as you fall off the back the boat gets less stable. Sail a dinghy in big waves and the effect becomes obvious. As a canter has a huge bulb out to windward it will be subject not only to the shock loads from falling off a wave but it will also experience an acceleration to windward. All monos have this happen but it will have greater effect on a canter.

On top of this you have the ability to make the boats narrower and then decrease the staying base increasing loads. This increase is exponential rather than linear.

Smart designers know these things but I think we would be silly to suggest that there is not a lot of Rule of thumb in rig design. Someone has to put the fudge factors and safety factors into the computer program. I think that experience on one boat does not always translate directly to another.

 

----------------
Mr. Ostlind, do you have any facts to back this up? I mean statistics of all mast failures from ,say 2004-2007. I don't believe the statement you made here but so far I haven't been able to find any statistical sources to back up that belief and your assistance in finding the facts would be helpful.
I don't believe for one instant that these failures are CAUSED by the canting keel. I think they are more likely to be issues with design, construction and/or maintenance of small rigging parts.
I think racing sailboats, regardless of their keel type or lack thereof, are very much more likely to have rigging failures than non-racing boats.
Wild Oats was designed by one of the best design offices around- Reichel-Pugh- and has been raced hard for years in tough conditions.To think
that their engineering was faulty this far down the line is absurd-its much more likely to be an issue with a part that was supplied for rigging that was either not maintained properly or whose actual characterstics did not meet the designers specifications.
This boat is one of the foremost examples of the fastest monohulls on the planet-so far- and Wild Oats and other canting keel boats such as the Volvo 70's, Open 60's etc. have revolutionized the speed of large monohull sailboats bringing their speed damn close to that of multihulls-within 5% by some estimates.
The canting keel -regardless of how it is moved- will be at the forefront of the fastest monohulls
under sail from now on and when combined with hydrofoils and on-deck moving ballast will again make a huge leap in self-righting monohull performance.( At least I hope it goes this way!)

 

More Data???

I have read that many of these state-of-the-art boats have strain gauges and data collection systems that display and log forces while underway and for later analysis. Is any of that data published for recent failures?

Might it be true that dynamic use of the canting keel can produce dynamic rig loads that are higher than on a boat with a fixed keel where the force will quickly increase the heel??

Not my area of expertise at all, but I'd bet the data will tell something that, in 2 or 3 years, will become 'conventional wisdom'.

 

Well, canting keels allow to carry more sail up for a given condition, more sail up means more strain, and these boats use to be designed in the limits, so....

 

Doug, I suspect that nobody has anything like absolute statistics on a global basis for mast failures, whatever the cause.

Last year's Sydney/Hobart event saw just under 40% (specifically 38%) of the canting keel equipped fleet knocked out of the race due to mast failures of one kind or another. Some were straight-up mast failures, some were attributed to failed rigging leading to mast failures, but all of them had to retire due to collapsed masts, regardless. At the same time, it appears that none of the trad keel boats suffered dismastings in the very same conditions. Weird serendipity? No, I think not.

All this leads me to believe that the regular mast failures of the canters is much more about the unknown forces being brought to bear, especially on the very sensitive rig components. Early canters suffered regularly from broken rams, broken ram mounting points and problematic swinging hinges in the hulls. When the engineers got those issues figured out, the forces got transferred to the next most vulnerable elements on the boat... the rig, the mast and all the associated elements connected to same.

 

So Chris, I just don’t get where the joy is in luring Doug out into a donnybrook when you know you are going to pummel him in the first round?
I can tell you know full well why and how these rigs are broken and what the significance of their loss is to the racing teams involved.
Your use of auto racing analogies is classic misdirection intended to confuse and confound.
Your tirade about maintenance is a disclosure of the obvious and your pretense that you don’t understand the mindset that would perceive the loss of a 400k mast as an acceptable risk (among a certain crowd) is pure poseur and pompous noise.
Are you so bored?
Holy **** man….there are some real hurdles out there…Doug doesn’t qualify.
Think about how you are spending your time!!



d

 

Good comedy Mr. Ostlind

 

I'll weigh in with Mr. Doug on this.
I think the mast failures on canters has to do with the design motivation of the canting keel boat, not with the canting mechanism itself. The primary reason for having a canting type boat is extreme speed- the whole boat is designed around this premise. How many moderate displacement canting keel cruiser-racers are there?
zero.

Also, because of the extreme righting moment and offset CG of the canter, the usual design methods are probably a bit off. I'd suggest there is a bit more uncertainty in the design loads for a canter than a typical boat, epsecially in a seaway. How much? Who knows?

The failures mean:
1) loads/design aren't right
2) construction is flawed
3) some combination of the 2.

Structural uncertainty in composites is a big issue, but not unique to canters, so we can rule that out. So, we are left with choice 1. If we assume the engineering can be done given the loads (not always though) then we are left with the loads are not right. So perhaps for canters, either a different methodology or higher set of safety margins are required.

 

Well, not actually zero, but before I get into what boats are roaming the water with canting keels in the moderate size range, perhaps you could let me know what you determine moderate to be? With the big boys up in the 90's region, that leaves lots of room down below for the other size boats to be considered moderate. I'm guessing that it would be something like 30-60' ?

We'll get back to that, but suffice to say, there are many of them out there not of the maxi boat variety.

What is a fact, though, is that there would be no loading issues of this enormity without the canting keel being present, so it seems fairly prudent to not exclude the originating source of the problems present. Like I indicated, we are not seeing large numbers of boats, whatever the size, losing their masts and/or rigging when they are equipped with fixed keel structures. With the major element of difference being the complete, canting keel structure and its resultant movement from port to starboard, we see a huge departure from the norm of typically non-failing, fixed keel boats. That is what couples the structures of the hull and the canting keel.

And that is the main point of my observation... That these boats are introducing huge new dynamic loads into the structure of the craft and that load is finding its way directly into the rigging and focussing in the weakest part of the rigging chain. Unfortunately, this has lead to several rigs falling down, some additional situations of simply collapsing the mast in compression and/or, out of column failures.

Doug Lord likes to say that the designers already know the loads present and that it's a simple matter of plugging in the needed heft in the rig and the stick and Voila... the mast stays intact. I say it's not that simple and that these guys are pretty much winging it from race to race, trying to get a handle on what is really going on out there.

Witness the regular self-destruction of the keel pivots and rams during the last Volvo Ocean Race when millions of dollars had been poured into the boats that were set to race, all-out around the world in some really nasty conditions. Similar situations developed in the Velux 7 Oceans event with some really top teams retiring with very big problems from the keels and masts. The designers of these boats were not entry level design guys just getting started in the trade, such as myself. They virtually all came from high profile design shops with huge brain power on staff and many years of design experience at the cutting edge.

In the recent failure of the Wild Oats rig, one of the crew remarked that they were mystified that the rig fell down when the boat was in a kind of easy cruise mode... further, that he would have understood the rigging failure better if it had happened when they were really leaning on it in a rough sea state.

The probable facts of that mystery scenario of breakage are that the substantive damage had already been done, most likely when they were really humping it and the next, even slightly more than casual, load just took everything one notch too far and bang!. There are lots of failure modes and the "after the fact" thing is one that happens with some frequency.

Well, I wish we could rule that out, but when anything fails, it would seem prudent to take a look at the related systems to see what sources of loading they may be contributing, even slightly, to the failure of what looks to be an unrelated structure.

Have you ever seen a situation with a car in which the tires continually wear out and cause flats. This condition could be faulty tires, but more likely, it's something like the wheel bearings, alignment, crappy shocks, a funky ball joint, etc., causing the problem. To quickly exclude on source of potential load contribution to a failed rig is to overlook what may be the primary cause.
Solid trouble-shooting would take you back to the square one position so that all systems can be observed for what they do, or do not contribute.

I say all this, even though I essentially agree with you... that the problem is much more likely in the #1 entry on your list; that the load/design is not right. But that is not Doug’s position at all. In fact, his point is that it is purely accidental and has no bearing on the dynamic potentials being transmitted through the boat. Almost all the extra loadings are due to the different, canting keel system and the way that the keel allows the boat to be sailed when compared to a fixed keel yacht.

With this issue going down with some frequency, it makes complete sense that the crews and engineers for these boats would be going over the rigging parts with scopes and any other tools at their disposal for any signs of possible failure before putting up the rig at the next racing venue. There is just way too much money riding on the business of getting the boat to the next event, moving the crew and getting the boat put back together and ready to race, to let the outcome fall to a poorly inspected fitting.

Some fittings do fail without warning and well before their working life has come and gone. That will always happen and it's one of the costs of going racing. But to have so many happen in a regular and almost predictable fashion is well beyond that possible failure rate.

To sum-up, WA… it looks like you are much more in agreement with my position, than you are with that of Mr. Lord.

 

Speed Kills

One of the most telling things is the history of high powered, highly loaded, fast sailboats. Failures are just plain more likely on fast boats with high dynamic loading like canting keel racing boats and racing multihulls; ORMA multies can have way more RM than Wild Oats in a 60 footer-300,000 ft lbs! These boats-both multies and canting keel boats have been around for years and years and there have been rigging failures. There always will be on highly loaded race boats.
Look at the recent failures:
Abn Amro WON the toughest ocean race in the world-the Volvo- then later entered the Sydney -Hobart and lost the rig. Wild Oats won the Sydney-Hobart TWICE and sailed in many other ocean races just now losing its rig in 10 knots. Maximus lost her rig in the Sydney-Hobart after well over a year of hard racing including a transatlantic record.
But there are dozens and dozens of canting keel race boats that have had no rig trouble whatsover! I just heard from Jim Pugh of Reichel-Pugh Yacht design today in response to an e-mail I had sent him. He said the he thinks the Wild Oats failure is the FIRST of their numerous canting keel designs!
The facts suggest that fast, highly loaded race boats with speed-induced dynamic loading of the rig may fail in ways that aren't completely understood. This, of course, includes ALL boats that are potentially subject to this kind of loading such a ORMA Tris,G Class Multies, Open 60's etc,NOT just canting keel boats.
There is absolutely NOTHING intrinsic to canting keelboats that directly links rig failure to the canting keel. Rigging faiures on these kinds of fast boats- be they canting keel boats or big multies- have one thing in common: speed.
If there was a design fault or if the canting keel was the evil weapon some have suggested then there would be failures on all canting keel boats not the miniscule percentage of all canting keel race boats that have had failures. Speed and the dynamic loading that it induces on fast boats is the cause-perhaps thru poor rigging part fatigue design or? There is no greater rigging failure rate in canting keel raceboats than there is in big fast multihull race boats.
The fact that Reichel-Pugh have had only one rig failure on a canting keel boat speaks volumes...
----------
As best as I can determine there were 7 canting keel boats in the last Sydney-Hobart*; only two lost there rig(28.5%). In total, nine boats retired from that race-only two of the nine with canting keels.....
*canting keel boats actually starting the race
ISAF - Rolex Sydney Hobart Yacht Race 2006
Address:http://www.sailing.org/default.asp?ID=j6vFh?A1l

 

Well, Doug, sorry to inform you, but as I originally quoted way back in late December... There were eight canting keel boats entered in the S/H this last year and three of them, for certain, dumped their rigs. You, of course, would probably be referring to the ABN Amro and Maximus inciddents as obvious sources of pain for the canter-o-philes, but just before the race started, Diabetes (ex-Nicorette) had its mast fall all around them, preventing their arrival at the start line.

A quote from that experience: “The line-up for the 2006 Rolex Sydney Hobart dropped to 79 today after Ludde Ingvall's 90ft maxi Diabetes was dismasted during a training sail.

While sailing under reefed main and jib in 16-17 knot easterly winds off Sydney Heads, the mast appeared to compress causing it to buckle and fall overboard, said a disappointed Ingvall, a two time line honours winner of the Sydney Hobart race.”

And, looking back at your own comments with regards to canting keel drop-outs, we find this note: "NEWS Flash-- Apparently, one of the new Cookson 50 canters "Living Doll" also was among those that retired-can't find out what the problem was so far."

So, Doug... when you add-up all the numbers of broken boats with canting keels out of a fleet of 8 total, you get four failures with three of them, for certain, out due to dropped masts and an unknown cause for the last one.

That's where the 40% mast failure rate comes from and it speaks for itself. And it could be higher if the last boat also dropped its rig.

Can you point to a single cause of mechanical DNF in the fixed keel fleet that hovers in the 40-50% DNF region? Oooo, oooo, I'll answer that one...! The answer is absolutely no. First of all, there was not 40% of the fixed keel fleet suffering from any kind of single malady, much less due to dropped masts.

Really, Doug, that argument has been put to bed.

The rest of your post is just lots of words that amount to nothing of consequence when addressing the primary argument. You're simply trying to BS your way around the issues and everyone knows that when they read the post. Just get to the point, support it with something like facts, don't schmooze and be graceful about not getting it right.

We'd all like to see you address your misgivings with some style and then simply get on with things. There's no harm in not having all the answers. We're all just learning things here.

If you want to know what is going on with the rig failures and how the big spar makers and boat designers feel about it, write them a letter (the designers and engineers of the boats with the repeat failures of rig and rigging) and ask them to come clean with the reasons for the failures. If they answer you, you'll know that there's no big deal and they want to share the info. If they blow you off, you'll also know that you are walking on very serious territory for them and there really is something to keep quiet until they can get it figured out.

How much do you wish to wager that it's the latter that you will experience? Did you ask Jim Pugh if the mast came down due to loading stress? Did he offer any reasons or did he simply give you the professional shuffle? Why don't you show us the questions asked by yourself and the answers given by Pugh? From your indication, it looks like even he is unsure about how many of their canters have actually broken, for whatever reason. I'm not up on this at all, but who were the designers of the repeat broken canters in the last VOR? Did R/P have a hand in any of that carnage, or was it somebody else?

Get in touch with the actual data, Doug and not some dose of material that makes you feel good. Figuring out problems like this is uncomfortable for anyone who is a proponent of the technology. What you wish to defend, actually needs to be sorted and understood so it can be corrected. There's no correction in the mix if you keep pretending that nothing is wrong.

Let's see... a contemporary example outside of the boating environment. Hmmm, OK, the foam flying off the Space Shuttle thing that has caused many people to die as well as wrecked a mega million dollar spacecraft. What would have happened at NASA if they refused to acknowledge that a silly hunk of foam could do enough damage to a space ship wing that it could melt it on re-entry?

Nope, Doug, they all had to dig deep and address that reality so they could understand how to do it better the next time. You really need to do the same thing if you're going to approach broken boats with anything like a scientific method for understanding what is going wrong. There' no room for emotions in the process of discovering solutions. Just get into the flow of that and you'll be all right.

This thing you're doing now.... it doesn't work.

 

I'll state my stance more succinctly-
I don't see that canters are "bad" boats. I think the engineering needs to be worked on a bit (loads, safety margins)
I don't think I'd want to do a heavy weather extended passage on one, but if others do, let 'em go be the test bed if they choose to.

It might be interesting to see how a 35 foot canter would do. As boats get larger, the loads just get scaled up by size in most design methods. I would suggest the less obvious loads that are present in smaller boats fall within safety margins, so less failures happen. But in bigger boats, my guess is that these loads, dynamic, misalignments, fatigue, etc. are not strictly scaling to fall within the safety factors. I think there is some response function on many of the loads that is tough to quantify, because there is little to zero experience base. Small boats and large boats sail in the same sea, and perhaps the response per input is increasing disproportionately with boat size.

The design climate for these large canters is "go fast!!" So they are being pushed to the limits as far as engineering from the get go. You don't see a 42 foot cruising Swan with a canting keel, displacement of 25000 lbs and a heavy aluminum spar, it would be comical and have no purpose.

I like Juan K's analogy of canters vs. catamarans. Canter is a negative catamaran, it's using negative buoyancy to windward, a cat uses positive buoyancy to leeward.