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Old 13-06-2008, 05:27   #46
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to put this in simple terms

a cat is less likely to invert.

a mono is less likely to stay inverted


Fair enough ??
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Old 13-06-2008, 05:56   #47
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Originally Posted by catty View Post
Lets make a list

1.Rob James fell off a multi and drowned
2. Eric Tabarly fell off a mono and drowned.
Lets make another - how many people have died on multis in Australia in the last say 18 Years, how many on monos -

Not a gee up - real question, I would really love to keep assembling data. BTW got any further info on the capsize at airlie of the 40 foot cat you mentioned, I would be keen to add it to my data base. (again - not a smart comment - a genuine request)
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Old 13-06-2008, 05:58   #48
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Originally Posted by MidLandOne View Post
And if anyone can do so I would be interested in any difference between the two for blue water insurance compared to coastal only, and also how that varies for different sailing environments around the world.
Club marine quoted about 10% less when I insured a previous cat for about $100,000 than a previous mono of similar value - in fact about $88,000.

Of course thats only one example, but its the only one I have.

(oh and the mono was a production glass boat of about 8 years of age and the multi was a custom composite - strip cedar- boat, if that is of any interest)
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Old 13-06-2008, 07:05   #49
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Midland One - the truth in the statement that cats are less likely to capsize is monohulls has nothing to do with the number of them sailing (if you re-read it, you will see I referred to likelihood of capsize, not the total number). The truth in that is because of form stability. If one looks at stability curves, conditions that will cause a capsize in a monohull will leave a cat upright. Further, there are now many cats designed with standing rigging that breaks before the boat reaches a level of pressure that would cause a wind-induced capsize.

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Old 13-06-2008, 09:11   #50
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Originally Posted by Factor View Post
Lets make another - how many people have died on multis in Australia in the last say 18 Years, how many on monos -

Not a gee up - real question, I would really love to keep assembling data. ...
I don't see the merit in just knowing how many people have died on either type. Surely it doesn't tell us anything about the safety aspects of either vessel or about the respective stability of the types.

Surely you also need to know how they died - washed overboard, heart attack, food poisoning, murdered, suicide, etc. to see how a vessel type could be factored in to the equation. Then to make a meaningful comparision, you would also need to know (at least) how many person/hours/miles were completed on on each type.

Once again, we are getting into the realm of comparing apples with .....

I THINK Catty was maling a point that both types can be "the same"
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Old 13-06-2008, 09:21   #51
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Just a thought:
Monos have many knockdowns; multis have none.
Not sure which has more capsizes.
Monos usually self-right, multis never do.
What was the original post about again?
Sorry, it was the devil who made me say it .
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Old 13-06-2008, 10:27   #52
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the number of fatalities is meaningless, as we've had a few thousand years of monohulls as the dominant design -- so by definition, more fatalities on monohulls.

In other words, there are a LOT more data points for monos than multis, which is one of the reasons that using the infamous 1994 Queen's Birthday storm to compare monos and multis is silly. There were a lot more monos than multis that went through that storm - most of them without serious incident.
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Old 13-06-2008, 10:51   #53
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Brad, you miss the point altogether. A knockdown is not a capsize. Modern self righting monohulls don't capsize unless they a) loose the keel. b) are rolled by a substantial wave.

Modern catamarans have a very high RM but once exceeded they are going over. See the story by Capt Andy or see this: April 20, 2007

Last weekend a front rolled through Lake Erie, winds went from 15 to 50 instantly, it was dark, no one saw it coming. None (of the 145) mono's capsized but many suffered knockdowns. One F27 (multi) flipped (20% of the multi fleet) another F28 almost joined them and as I understand they were very lucky.

My opinion, as the ranks of multis increase, we'll see more capsizes.


Quote:
Originally Posted by Southern Star View Post
Midland One - the truth in the statement that cats are less likely to capsize is monohulls has nothing to do with the number of them sailing (if you re-read it, you will see I referred to likelihood of capsize, not the total number). The truth in that is because of form stability. If one looks at stability curves, conditions that will cause a capsize in a monohull will leave a cat upright. Further, there are now many cats designed with standing rigging that breaks before the boat reaches a level of pressure that would cause a wind-induced capsize.

Brad
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Old 13-06-2008, 12:13   #54
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Joli, I understand that a knockdown is not a capsize. Most modern cruising cats do not capsize from wind alone either as many have rigs designed to fail when wind forces reach the point of no return (I referred to that in the passage quoted above). Further, it would be an extremely rare occurence indeed where wind speeds caused forces sufficient to capsize any cruising boat and there were not also waves to effect its stability.

In theory, some cruising cats will capsize if carrying grossly inappropriate canvass and equipped with a rig, like my own, that is not designed to fail in such circumstances. It is somewhat akin to causing engine failure in a car that is not equipped with a rev limiter by, lets say putting it in first gear and flooring the throttle until the engine over-revs and then keeping it there; or perhaps by putting it in neutral and keeping it floored. The point is that either course of action would be grossly negligent.

Anyone sailing a cat should know that you do not reef for the wind speeds, but rather the highest anticipated gusts. If they do not have a 'failsafe' rig, they should also have a quick release capability for the sheets and be ready to use them - especially if they like sailing close to the edge. Otherwise, reef down both early and often so that there is a significant margin of safety. But lets put this in perspective: once the main is triple reefed and the you are flying a storm jib, I don't of any cat that will capsize from force of wind alone in anything other than hurricane force winds. Monohulls, however, will still suffer knockdowns in conditions that would leave the cat standing upright.

And it is you who missed the point of (or misread) Captain Andy's story - his capsize was not caused by wind alone (as much as you would like it to have been in order to advance you argument), but rather by getting hit by a microburst of wind at precisely the instant the boat was hit by a rogue wave.

And please, F 27's and F28's are great boats, but they are not catamarans (what I was referring to in the quote above). I have seen an F 27 raise not only the windward ama (sp?), but most of the center hull out of the water when overpowered in conditions that didn't cause me to bat an eye. Yes, they are terrific fun and extremely fast, but they really aren't cruising boats in any normal sense of the word.
And of course, I suspect that their stability curves are much lower than any cruising cat in part because they can be fairly readily righted again, albeit with assistance (due to the folding amas).

Finally, of course as the ranks of multi's increase, we will see more capsizes. Surely, the issue is whether we will see more on a per capita basis. And as I have read here and elsewhere before, a cat is no more likely to capsize than a monohull is to sink.

Brad
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Old 13-06-2008, 12:53   #55
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Brad the problem is this: April 20, 2007
That is a capsize not a knockdown and I agree it is a rare event, though not for that boat.

Bad things can happen to any boat at any time, you and I have been around long enough to know Mr Murphy is waiting in the wings. But the thread topic is do monos capsize, the short answer is no.

You have advised in previous posts that a mono will capsize when a cat won't. Maybe that is simply semantics but a knockdown is not a capsize and a modern self righting mono will not capsize unless extreme conditions exist. Lets be acurate.



http://www.rya.org.uk/NR/rdonlyres/4...ilityIntro.pdf

Quote:
Originally Posted by Southern Star View Post
Joli, I understand that a knockdown is not a capsize. Most modern cruising cats do not capsize from wind alone either as many have rigs designed to fail when wind forces reach the point of no return (I referred to that in the passage quoted above). Further, it would be an extremely rare occurence indeed where wind speeds caused forces sufficient to capsize any cruising boat and there were not also waves to effect its stability.
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Old 13-06-2008, 13:52   #56
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Joli, the 'righting lever' or positive stability curves vary boat by boat and you have, of course, chosen one at the high end of the spectrum. As Engineer pointed out in an earlier thread, the same figure for a Hinckley Bermuda 40 (generally considered a pretty good sea boat) was only 116.5 degrees, while the Swan 40 with its extremely deep fin does not quite reach the 132 degrees shown in your diagram.

Nevertheless, I agree that most monohulls and multihulls will not capsize unless extreme conditions exist. However, lets be accurate indeed. You have said: "the thread topic is do monos capsize, the short answer is no." That may be a short answer, but it is also incorrect.

Boats typically capsize from the combined effect of both wind and waves, but lets deal with the effect of just waves alone (as we have already agreed that a monohull will typically suffer at least a knockdown at lower windspeeds than a cat). The size of the wave required to capsize any boat is directly proportional to the boats beam. I don't have the literature in front of me (and won't until at least Sunday), but as I recall there is a commonly used ratio. Since cats are beamier than monos, they require more energy (and larger waves) beam on in order to capsize. Of course there are other factors at play, but I believe that even C J Marchaj makes reference to this proposition.

In any event, while I am sorry to burst your bubble, monohulls do capsize! Some, like the Smeeton's offshore boat Tzu Hang (going from memory here on the name), can actually capsize twice in successive voyages (albeit after installing a new rig and new house before the second one, due to the damage inflicted by the first).

And as to the cat featured in your story line, it seems to me that they were grossly negligent by not reefing down when they saw the squall line approaching. Since the winds preceding its onset were approximately 11 knots, I suspect that they were carrying full sail. Most squalls in the Caribbean will bring gusts higher than 30 knots (many higher than 40) and yet they didn't reef! In any event, we cannot move to the general from the specific due to this case any more then the Smeetons, who were as you may know, incredibly experienced sailors in a much larger boat.

Brad
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Old 13-06-2008, 14:21   #57
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Lets make another - how many people have died on multis in Australia in the last say 18 Years, how many on monos -
Factor, Quite a pointless question. That is like saying, how many people have died in car accidents, between cars that are white and cars that have purple pokadots on them. There maybe a larger number of multi guy's on this multiforum, but it does not mirror the number of monos vs multis. Multis are still very much a minority out there and especially if you go back 18yrs.
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Old 13-06-2008, 14:39   #58
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Factor, Quite a pointless question. That is like saying, how many people have died in car accidents, between cars that are white and cars that have purple pokadots on them. There maybe a larger number of multi guy's on this multiforum, but it does not mirror the number of monos vs multis. Multis are still very much a minority out there and especially if you go back 18yrs.
Heigh-Ho, Silver...Cars
Silver cars are less likely to be involved in a crash than automobiles of other colors,

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Old 13-06-2008, 14:40   #59
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LPS of 135 degrees

Quote:
Originally Posted by Southern Star View Post
Joli, the 'righting lever' or positive stability curves vary boat by boat and you have, of course, chosen one at the high end of the spectrum. As Engineer pointed out in an earlier thread, the same figure for a Hinckley Bermuda 40 (generally considered a pretty good sea boat) was only 116.5 degrees, while the Swan 40 with its extremely deep fin does not quite reach the 132 degrees shown in your diagram...

Brad
Brad,

The stability curve that Joli posted may be at the high end if you include racers and coastal cruisers, but it is one that accurately describes the characteristics of a well-designed offshore cruiser. It doesn't represent an extreme nor unattainable performance by any stretch of the imagination.

In the diagram below, "A" represents the stability curve for the Island Packet designs. Note that the Limit of Positive Stability is 135 degrees. An article on the topic by IP designer, Bob Johnson, can be found at Island Packet Owners Association UK Site Blog Archive Design Notes
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Old 13-06-2008, 15:30   #60
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Heigh-Ho, Silver...Cars
Silver cars are less likely to be involved in a crash than automobiles of other colors,

Just messin with everybody.

""That is like saying, how many people have died in car accidents.....[car color]""


Sorry about the font.

But, it is directly related because some times people say things like you did and lo and behold there is a correlation after all.

Maybe there are correlations yet undiscovered?

And the end of the little article had a statement from someone in the US that said "rubbish" or some such word that someone could take offense with.

4 pages and 59 posts so far.
I don't think I was the only one messin' with folks.

But then..........I don't care.........leave it edited.
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