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Old 06-06-2012, 08:17   #91
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Re: Capsize Ratio's

We can't go by "common sense" here, we need to follow what has happened, and what does happen when a boat is hit by a breaking wave.

Traditionally a full keel boat capsizes less often than a long thin fin keeler. The laws of physics don't change, just the design of boats.

I think that "racing boats" are going the wrong way. As we have seen it doesn't matter how fast it can sail under light air if the first squal rolls it.

What doesn't seem to be happening, racing organisers aren't penalizing enough for boats that can't finish the race.

A million dollar design with the lastest synthetic materials and impossibly thin support members isn't going to translate to mainstream if it has to be shipped in a cargo hold to each of it's races. You end up with a super specialised craft like an indy car, that is only usefull for one specific race.

While that may be good for a specific group, what the mainstream sailing comunity needs are races like the "stock car" races where road worthy designs are tested and proven.

I'm not interested in buying for example a pulley that saves 1 oz in weight, but needs replaced every use.

Endurance races that require several sails with no repairs, or downtime, and that penalise breakages, and capsizes, and are in extreme weather, may bring some sanity back into the sport.
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Old 06-06-2012, 09:01   #92
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Re: Capsize Ratio's

Beam was important when taking "breaking" waves side on i.e. ahull, I watched the video from an english university doing tanks tests on Youtube, the results showed that ballast ratios, keels etc made very little difference when taking a breaking wave side on (the most likely way to capsize a regular boat).. More beam= bigger wave required to capsize, in general narrow hulled boats will self right quicker but in general science has proven they are more likely to need to self right!

In lay mans terms, a beamier boat in general will require a larger wave to capsize, but is more stable upside down (think cat for the ultimate in beamy boats), a narrower boat requires a smaller wave to capsize but in general will right itself quicker.

The above is only concerned with side on breaking waves.

Ballast ratios, keel types etc, made a small difference , fin keels were more likely to slide slightly down the wave, full length more likely to trip, giving the fin keel a very slight edge

If i remember correctly the breaking wave part needed only be slightly greater than half the beam of the boat. nb this is the breaking part not the overall wave size.

Please do not take my word or anyone elses on here, do your own homework
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Old 06-06-2012, 09:15   #93
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Re: Capsize Ratio's

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Originally Posted by capn_billl View Post
While that may be good for a specific group, what the mainstream sailing comunity needs are races like the "stock car" races where road worthy designs are tested and proven.
Now yer talkin, gimmee one of them there sailin boats that only tacks to the LEFT..........
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Old 06-06-2012, 09:27   #94
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Re: Capsize Ratio's

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Originally Posted by capn_billl View Post
While that may be good for a specific group, what the mainstream sailing comunity needs are races like the "stock car" races where road worthy designs are tested and proven.
Stock car racing is a poor analogy, the 'stock' cars aren't really stock anymore except for things like amateur rallying and amateur sports car racing.

The problem is not that there are purpose built racing boats with limited life expectancies, but owners of such boats that want to recoup some investment when the boat ceases to be competitive and is happy to market the boat as something you could cruise and boat brokers who are willing to do the same and boat buyers who talk themselves into believing that 'YES you can have it ALL, hurricane safe and blindingly fast and stupendously comfortable to boot'.
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Old 06-06-2012, 09:38   #95
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Re: Capsize Ratio's

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Originally Posted by Polux View Post
The ones that established that beam was important regarding capsizing and established that relation were specialists (I believe wolfson unit). That is the reason cats are so difficult to capsize. Why do you thing that modern mass production cruisers are beamy boats? Because the best NA don't no what they are doing?
How much of the increase is due to NA's believing that wider is just as safe and how much is due to buyer demand for roomier boats?

Increased beam is not a safety issue for the vast majority of boats that don't go cruising and statistically will never be caught in an offshore storm. Consequently there is little or no downside for the NA's to increase beam
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Old 06-06-2012, 09:48   #96
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Re: Capsize Ratio's

Quote:
Originally Posted by stevensuf View Post
Beam was important when taking "breaking" waves side on i.e. ahull, I watched the video from an english university doing tanks tests on Youtube, the results showed that ballast ratios, keels etc made very little difference when taking a breaking wave side on (the most likely way to capsize a regular boat).. More beam= bigger wave required to capsize, in general narrow hulled boats will self right quicker but in general science has proven they are more likely to need to self right!

In lay mans terms, a beamier boat in general will require a larger wave to capsize, but is more stable upside down (think cat for the ultimate in beamy boats), a narrower boat requires a smaller wave to capsize but in general will right itself quicker.

The above is only concerned with side on breaking waves.

Ballast ratios, keel types etc, made a small difference , fin keels were more likely to slide slightly down the wave, full length more likely to trip, giving the fin keel a very slight edge

If i remember correctly the breaking wave part needed only be slightly greater than half the beam of the boat. nb this is the breaking part not the overall wave size.

Please do not take my word or anyone elses on here, do your own homework
Regarding more stability upside down or not that has all to with the ballast torpedo on the end of a long foil keel and the effect it provides. Those torpedos don't look very big but you have to remember these are very light boats and they are deep in the water...or in sky

I had already posted Pogo stability curves showing that their AVS (LPS) is better than most boats including old and narrow ones.

They have upgraded recently the rules on safety on the 40class boats rule(Pogo). Now they have to be able to re-right themselves in flat water by their own means and they don't have, like the Open 60 a canting keel to help. They have to do it all with water ballast and off course with a big help from that torpedo on a the end of a long keel. They have already a big AVS even with empty water ballasts.

http://youtu.be/WhxmWmmAxYY

Between a beamy boat and a narrow one there is only one way to know what is the boat with a better reserve stability and bigger AVS and that's through a
stability curve. Each case is a case but modern designers are good and don't make unseaworthy boats. Off course, I would check that stability curve anyway
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Old 06-06-2012, 09:54   #97
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Re: Capsize Ratio's

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Originally Posted by capn_billl View Post
We can't go by "common sense" here, we need to follow what has happened, and what does happen when a boat is hit by a breaking wave.

Traditionally a full keel boat capsizes less often than a long thin fin keeler. The laws of physics don't change, just the design of boats.

I think that "racing boats" are going the wrong way. As we have seen it doesn't matter how fast it can sail under light air if the first squal rolls it...
John Rousemamiere,

John Rousmaniere - Wikipedia, the free encyclopedia

said recently regarding the accident on the Farallones race that modern racing boats are safer then older boats.

He was on the 79 Fastnet race and he knows what he is talking about. Rousmaniere is very conservative in what regards sailboats and gives a big importance to safety.

Only someone that does not know or don't understand the evolution of boat design and the increasingly harder mandatory criteria on safety and stability for race boats (ORC) can say otherwise.

Open boats like Class40 (Pogo), VOR 70, Open 60 or even Mini racers have even considerably more demanding mandatory safety and stability requirements then the ones needed to have a boat certified for ORC racing.
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Old 06-06-2012, 10:24   #98
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Re: Capsize Ratio's

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Originally Posted by Polux View Post
John Rousemamiere, said recently regarding the accident on the Farallones race that modern racing boats are safer then older boats.
In what context did he say newer boats were safer than older boats?
In some ways or in all ways safer?
All new boats, most new boats or some new boats?

Do you have a citation we could read?

There are plenty of people with just as much experience as he that would disagree, certainly as regards specific boats and specific design trends.
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Old 06-06-2012, 10:52   #99
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Re: Capsize Ratio's

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(...) Pogo (...) Do you guys seriously still think that this is the kind of craft that is suitable for offshore cruising? Or anything?
Pogo are not cruising boats. They are racing boats.

They are good cruising boats when sailed by sailors. Maybe less so when sailed by cruisers.

PLS post a link, I would love to read what happened, what conditions they got, etc..

Cheers,
b.
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Old 06-06-2012, 10:57   #100
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Re: Capsize Ratio's

Polux:

Read the latest Cruising World, Sail, or anything and you will find that the three boats (out of 6) finishing the latest leg on the decks of steamers are BROKEN. They are not avoiding pirates -- that was one or two legs ago.

Your comment: "Regarding the VOR 70 you are showing a lot of ignorance: They were put in cargoships not on account of seaworthiness but PIRATE attacks. " is demeaning and insulting.
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Old 06-06-2012, 11:04   #101
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Re: Capsize Ratio's

I think it's a pendulum and that the pendulum had swung dangerously against offshore safety by the time of the Fastnet '79 race.

As we know, the IOR rules of that era heavily influenced the "in vogue" family boat designs du jour and that made many of them equally suspect. Post Fastnet, the designs began to change for the better.

No doubt, the racers today are safer in many regards than they were then, but they are still extreme by any stretch. That's only natural. I think their influence on family boats is less than it was in the 70s, however, and that space and creature comforts have a disproportionately bigger influence. That's why we are getting fat boats with no handholds, multiple heads, big cockpits and lots of windage above deck.

Those are not necessarily the best influences for safe designs, either.
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Old 06-06-2012, 11:22   #102
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Re: Capsize Ratio's

brilliant thread...one of the most interesting I have read.
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Old 06-06-2012, 11:32   #103
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Re: Capsize Ratio's

If you google "pogo sailboat" you get this web-site:

www.minitransat650.com/html/pogo_sailboat.html

It contains these quotes from the builders literature:

"The Pogo is a racing and cruising sailboat created and built for the open sea. It is meant for owners wanting a performance cruiser, which is very seaworthy, ..."

"In the 99 Mini Transat a Pogo has been rolled 4 times as he was laying a hull (bad seas were building, many sailors withdraw with damage, out of 70 only 16 did not stop) and still the mast was standing.Then the sailor set a storm jib and he just saw the speed climbing into the 20 knots and then the boat pitchpoled. This was finally enough to break the mast, ..."


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Old 06-06-2012, 11:34   #104
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Re: Capsize Ratio's

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Pogo are not cruising boats. They are racing boats.
Pogo has a line of racing boats and a line of cruising boats sharing some similarities and some differences. The cruising boats are not suitable for racing and the ones that buy them are cruisers that like to have fun while sailing.

Now Pogo is selling much more cruising boats than racing boats and they have a long waiting list.

One of the cruisers that owns a cruising Pogo is the designer of the Pogos, Finot. You don't expect him to go racing with almost 80 years of age do you
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Old 06-06-2012, 11:38   #105
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Re: Capsize Ratio's

Quote:
Originally Posted by stevensuf View Post
Beam was important when taking "breaking" waves side on i.e. ahull, I watched the video from an english university doing tanks tests on Youtube, the results showed that ballast ratios, keels etc made very little difference when taking a breaking wave side on (the most likely way to capsize a regular boat).. More beam= bigger wave required to capsize, in general narrow hulled boats will self right quicker but in general science has proven they are more likely to need to self right!

In lay mans terms, a beamier boat in general will require a larger wave to capsize, but is more stable upside down (think cat for the ultimate in beamy boats), a narrower boat requires a smaller wave to capsize but in general will right itself quicker.

The above is only concerned with side on breaking waves.

Ballast ratios, keel types etc, made a small difference , fin keels were more likely to slide slightly down the wave, full length more likely to trip, giving the fin keel a very slight edge

If i remember correctly the breaking wave part needed only be slightly greater than half the beam of the boat. nb this is the breaking part not the overall wave size.

Please do not take my word or anyone elses on here, do your own homework
Something to keep in mind a full keel boat, (with no overhangs), that is being activly steered, is unlikely to sideslip down a wave leaving the beam to the breaking seas.

While a fin keel with a small spade rudder can be spun with wave force, and water weight in the cockpit leaving it beam on to the wave, and subject to capsize.
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