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Old 04-08-2010, 13:04   #76
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Originally Posted by tsmwebb View Post
Well, of course, boats and ships of all sizes can be lost. This one made the news recently: CBC News - Nova Scotia - Students safe after capsizing of N.S.-based ship.

I sail a 42' cat. I've made the passage between NZ and the tropics a half dozen times on it. No doubt it is a very, very small boat at times. It is hard for me to suggest an exact dividing point between small and large vessels because there are such variations in design. However, my feeling is that all else being equal the general area is around 100 tons. To me virtually all yachts are small boats. Offshore casualty samples are small and there is no central record keeping that I am aware of. So, quantifying risk and correlating it to size or type is hard. But it is obvious that the size of the sea is fixed. Boats of all sizes need to deal with the same conditions. This fact makes it harder to design, build and operate small boats as safely as large ones. Again, I can't put a number on the risk but I can say that every year I hear of losses of small boats at sea. People die. People I knew have died. In my very non-random and incomplete survey voyaging even in season and with care is more dangerous than driving. I suspect it is far more dangerous. Again, voyaging in small boats entails risk. Hard though it is to quantify it is there and it is significant.

Tom

I agree, and you point out displacement not feet, to state your case with regard to size. Having spent time aboard all manner of vessels from 2 tons to over 100 tons at Sea, I can assure you if the Sea wants to get bigger than your vessel it will The displacement helps in lessening the motion of bigger seas, hence giving one a bit more confidence in the 'ground under one's feet' IME/O. The destructive bashing of a storm sea has to be experienced to be understood. It is from this perspective that many long term cruisers choose older heavily built sailboats regardless of how 'slow' they may be.
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Old 04-08-2010, 13:12   #77
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Originally Posted by tsmwebb View Post
Ocean voyaging in small boats is not safe. Anyone who tells you anything else is trying to sell you something. If you're not okay with putting your crew and your boat in peril stay close to home.

That said long distance cruising can be made safer by learning from the experience of others. I'm very much looking forward to hearing the details of this case.

Tom
Boating is made safer with each year's experience at the helm. The size of vessel one chooses to go to Sea in is of personal choice, generally dictated by the individual's financial situation, not out of 'base knowledge' of what power the Sea can bring upon your vessel out there IMO/E. If one is cautious to a fault about getting correct weather forecasting and sticks to their plan, then it may be safe to transit in what would otherwise be a foolhardy craft. No one told the Polynesians or other South Pacific Islanders how large a voyaging canoe was too small. They experimented until they felt confident in their crafts and went voyaging. Today's modern mariners have untold resources for weather and past performances of vessels to head out informed.

I too would like to know what happened and my original post was 'tongue in cheek, not foot in mouth'
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Old 04-08-2010, 13:29   #78
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Sinking

On 17 February 2010, SV Concordia encountered what the vessel's Captain called a microburst[4] some 550 kilometres (300 nmi) southeast of Rio de Janeiro, Brazil in rough seas and high winds.[5] Satellite imagery later confirmed microburst pre-conditions.[6] The vessel was knocked onto its side within 15 seconds[7] and eventually sank 20 minutes afterward.[8] All on board successfully abandoned ship. As the capsizing was so fast, no radio distress call was made but a distress radiobeacon (EPIRB) was hydrostatically released and automatically activated[9] when the vessel sank.


http://en.wikipedia.org/wiki/Concordia_(ship)
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Old 04-08-2010, 13:37   #79
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In previous discussions about cats and squalls (and when to reef), forum members like maxingout have pointed out the tactic of adding a reef or dropping the sails completely.

From the description of what happened to Anna, I have to wonder why a crew member wasn't outside, clipped in and wearing FW gear in the forward cockpit ready to at least blow the sheets.

While the squall that caused the flip looked "the same" as previous squalls, it sadly wasn't.

Fair Winds,
Mike
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Old 04-08-2010, 13:41   #80
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Maybe someone can help.. If the wind can go up from 17-18 knts to 62 "almost immediately", then none of us should be sailing.. My guess; 90 % of ANY cat would be flipped down the rest losing the rig for sure + possibly some MOB and seriously wounded crew. Useless to discuss, in case of mono, it would be close to that, if not worst (sinking boat..)

It seems that they were prudent people sailing at 16-18 knts with one reef on the main. The next to that is not sailing at all !!!

My question to those who sails in these areas are:

1-how often one can experience this kind of change of wind in open sea WİTHOUT any sign at all ? (radar views, meteorogical alert of any kind, diving barometer, strange and unusual clouds, growing seas, etc)
2-I've heard that in this kind of situation, the rigging of a multihull catamaran should go down before the flip over. I know this is not nice. But isn't it better to be derigged rather than being upside down ??

Cheers

Yeloya
I don't know what happened in the specific case. AFIK there is little question that there are isolated acute and intense wind events that can be virtually impossible to anticipate without very sophisticated instruments. They will not show up on synoptic charts, large area meto forecasts or the barometer and my not be associated with thundery conditions or even easily identifiable clouds formations. If one is unlucky enough to be sailing when one hits the result is likely to be bad. As I mentioned before a 188' monohull sailing ship is thought to have been capsized and sunk by such an event recently. The good news is that encounters with these events at sea are very rare. There are wind events that do give some warning. For instance thundery conditions may produce water spouts, micro bursts and lightning and should be treated with great respect. If looking at GRIBS you might consider the lifted index and if it is very elevated be aware that micro bursts are more likely (though again not common at sea). I rather suspect that getting hit by lighting is far more likely than being done in by a mirco burst... It is good to attempt to prepare for each as best one can but ultimately there is no way to completely eliminate the risk. For me the bottom line is yes micro bursts happen but they are rare enough that it doesn't make a lot of sense to organize my life around them... YMMV.

As for break away rigs IMO that seems likely to cause more problems than it will cure. At the very least you'd need a system that could reliably distinguish normal but high shock loads from pounding in a seaway from overturning loads... You would not want to drop your rig every time you crashed into a square wave.

Tom
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Old 04-08-2010, 14:08   #81
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TOM

As I mentioned before a 188' monohull sailing ship is thought to have been capsized and sunk by such an event recently. The good news is that encounters with these events at sea are very rare.


http://en.wikipedia.org/wiki/Concordia_(ship)

OFF THE COAST OF BRAZIL
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Old 04-08-2010, 14:31   #82
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TOM

As I mentioned before a 188' monohull sailing ship is thought to have been capsized and sunk by such an event recently. The good news is that encounters with these events at sea are very rare.


http://en.wikipedia.org/wiki/Concordia_(ship)

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Thanks for that. That's a better link than the one I posted before. I think you linked the wiki while I was composing the above. Oddly your link looks right but doesn't work for me -- I think the editor ate your ellipses. Maybe it will be better this way: Concordia (ship) - Wikipedia, the free encyclopedia

Tom
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Old 04-08-2010, 14:44   #83
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muchas gracias senor

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Old 04-08-2010, 14:46   #84
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I think bayview was referencing the formula originated by ted brewer:

Capsize Screening Formula (commonly known as "capsize ratio") = Beam (in feet)/(Displacement (in lbs) /64)superscript 1/3

Sorry sneuman, let me explain.

The designers capsize ratio or sometimes referred to as the capsize rate is the ratio between the number of capsizes to the number of boats constructed for that particular designer, for a given year.

ie Ian farrier has a figure of around o.2%. 4 capsizes per 2000 boats sailing, . See his web site for details.

In settled conditions multis can be very easy on the crew to sail. In unsettled conditions the multihull sailor must be on guard at all time which is extremely tiring and with reduced sail for safety can be very slow compared to a mono. The alternative (capsize) is pretty much unacceptable to most.

High velocity gusts are very common in the north of Australia during the summer months when the thunderstorms build.
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Old 04-08-2010, 15:36   #85
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Some Days You Just Wish



You stayed at home


But that would be as much fun as


So you accept the risks of going outside, plan as best you can, and your reward is




while the rest of us chat about what you should have done while we



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Old 04-08-2010, 15:42   #86
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The designers capsize ratio or sometimes referred to as the capsize rate is the ratio between the number of capsizes to the number of boats constructed for that particular designer, for a given year.
Statistical significance - Wikipedia, the free encyclopedia

Tom
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Old 04-08-2010, 16:14   #87
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A Cat capsizing really is this for real because I have been assured by cat owners/sellers that this does not happen. That and not sinking and here I was just about to buy one based on those assurances. That and the fact that we could save money on not needing a life raft cause even if it did flip we could just relax on the upturned hulls until a lift arrived. I am shattered first the Titanic now this
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Old 04-08-2010, 16:26   #88
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Yes after the cat and the titanic issue i can see how you would want to give up sailing. such a dangerous sport,,, might want to take up bicycle riding on the streets of miami,,, it is most likely safer

pass the popcorn
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Old 04-08-2010, 17:08   #89
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Headline reads. "Large Cat Flipped off Niue" My first thought was somebody had an overweight cat and there was a guy named Niue...

LOL

I did read about this boat in scuttlebutt, or sailing anarchy on facebook. It sucks about cats flipping since they are not easy to right after that.
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Old 04-08-2010, 18:27   #90
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Not to distract from the always informative mono/muti debate, but here's an interesting article on microbursts.

Microburst Handbook

It's more geared towards aviation but the basics are interesting.
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