Sailing boats' Stability, STIX and Old Ratios

[Guillermo]

Thanks for the support, Perry.
There are always people around these forums just owning a big ego but little knowledge, trying to teach even the more knowledgeable people. :rolleyes:

We should follow Horacio when he says:

"Beatus ille qui procul negotiis ut prisca gens mortalium,
paterna rura bobus excercet suis solutus omni fenore,
neque excitatur classico miles truci neque horret iratum mare
forumque vitat et superba civium potentiorum limina."

But we are not Horacio.... ;)

[Pericles]

"Happy the man who, far from the troubles of commerce,
just as the venerable ancients,
works his inherited fields with his steers,
free from money-lending,
neither roused by grim battle signal, as a soldier,
nor fearing the angry sea."

Probably the only period in history to which those words would have applied is the Bronze Age. especially in Britain, so far from city states and early empires.

Blood of the Isles by Brian Sykes.

As every schoolboy used to know, the episodes of group migration into the British Isles were remarkably few between the Norman Conquest of 1066 and the beginning of modern mass immigration after 1945: the French Huguenot refugees, the modest flow of Ashkenazi Jews, and a few others. Nevertheless, in recent years the politically-correct elites on both sides of the Atlantic have begun to promote the improbable contention that Britain has always been a land of immigration.

Ironically, just as this has become an article of faith, genetic evidence has begun to pile up about how profoundly wrong it is. Not only did immigration after 1066 play a vanishingly small role in the makeup of the offshore islanders, but even the famous invasions of previous millennia—Normans, Vikings, Anglo-Saxons, and Romans—merely added a fairly minor overlay to the prehistoric gene pool.

Political control and even language varied in the British Isles over time. But the oldest occupants endured, adapted, and flourished. In the words of Oxford University geneticist Bryan Sykes in his new book Saxons, Vikings, and Celts: The Genetic Roots of Britain and Ireland [published in the United Kingdom under the title Blood of the Isles]:

"We are an ancient people …"

The family trees of the English, Scottish, Welsh, and Irish are overwhelmingly indigenous to the British Isles since far back into prehistoric times. The title of Sykes' first chapter, "Twelve Thousand Years of Solitude," summarizes this finding. The "average settlement dates" in the Isles for the ancestors of modern British and Irish people, he estimates, were around 8,000 years ago.

Historical population genetics is an extremely complicated science. It's not uncommon for well-known authorities, such as Sykes and his rival L.L. Cavalli-Sforza of Stanford, to differ. Bearing that in mind, Sykes' recreation of the genetic history of Britain and Ireland appears plausible.

Sykes' team obtained DNA samples from 10,000 individuals in the United Kingdom and Ireland and reviewed genetic records for 40,000 more. They looked at functionally trivial mutations in the Y-chromosome to group each man into clans based on patrilineal lines of descent (e.g., Abraham begat Isaac who begat Jacob who begat …). And they examined mitochondrial DNA to group individuals into matrilineal descent clans. (I reviewed in VDARE.com Sykes' 2001 book The Seven Daughters of Eve, which outlined the initial European-wide genealogical discoveries revealed by mitochondrial DNA. If you are interested in the understanding the technical aspects more, please see that article.)

From his database, Sykes concludes that the majority of the genes of the peoples of the British Isles are descended from the oldest of the modern inhabitants: Mesolithic hunter-gatherers, who began arriving 10,000 years ago from Continental Europe after the end of the last Ice Age, as soon as the islands became habitable again.

Global cooling had pushed modern humans out of northern Europe and down into refuges near the Mediterranean, remixing the early peoples of Europe. (This may be one reason that, as Cavalli-Sforza has noted, Europeans are the most physically homogenous of all the great continental races.)

From the South, big game hunters trekked north again as the ice melted, some getting all the way to Britain. Before the seas fully rose, Britain was connected to Europe by a land bridge, and the Thames was a tributary of the Rhine!

A smaller but still important genetic contribution later came from the Neolithic farmers, who had begun thousands of years before slowly spreading northwest from the Middle East's Fertile Crescent.

Both the hunter-gatherers, who had sought refuge from the ice in Mediterranean lands, and the farmers, who had emerged from the Fertile Crescent, appear to have followed the same two main routes to the British Isles. One was a western oceanic route from Iberia north, primarily settling in Ireland and western Britain. (I would speculate that the somewhat darker coloration of the Welsh reflects this sunnier origin.) The other main path was a central continental route up the great river valleys into northern Europe, and then west to eastern Britain.

In the British Isles, the hunter-gatherer-fishermen presumably stuck to the water's edge, while the farmers cleared the inland forest. This meant there were few incentives for a genocidal clash between them, allowing the genes of both to survive in large numbers. Over time, some of the hunter-gatherers must have learned to farm, permitting them to be fruitful and multiply. The two groups appear to have merged, a happier outcome than typically seen in more recent collisions between farmers and hunter-gatherers.

Sykes writes: "Overall, the genetic structure of the Isles is stubbornly Celtic." (Interestingly, this means that the Irish and the English are largely the same—and Sykes is unable to discern any difference at all between the Ulster Catholics and Protestants, or “Scotch-Irish”, as they are known to American immigration history).

Sykes points, out, however, that the term "Celtic" is something of a misnomer:

"The 'Celts' of Ireland and the Western Isles are not, as far as I can see from the genetic evidence, related to the Celts who spread south and east to Italy, Greece and Turkey from the heartlands of Hallstadt and La Tene in the shadows of the Alps during the first millennium BC."

The British “Celts” have been in the British Isles long before the emergence of Central European Celts known to anthropology and the military history of the Roman Republic. These British “Celts” adopted the Celtic language, but otherwise their relationship with the continental Celts, if any, remains unknown.

Sykes guesses that the proliferation of La Tene-style handicrafts in Britain was not the result of mass immigration from Central Europe, as anthropologists have long presumed, but simply of British Isle goldsmiths learning to copy the latest style from the Continent. (Similarly, the recent mass-production in China of knick-knacks emblazoned with the Celtic Cross for Dublin tourist traps doesn't mean that Guangdong is suddenly filling up with Irishmen.)

Sykes observes:

"It seems to me that the constant tendency to interpret past events in terms of movements is completely the wrong assumption. Surely the correct starting point is to assume that our ancestors were sufficiently resourceful and skillful to pick up virtually any skill."

The half of modern British/Irish DNA that comes from female ancestors is especially native to the Isles.

Sykes points out that after the arrival of the agriculturalists in Britain:

"The genetic bedrock on the maternal side was in place. By about 6,000 years ago, the pattern was set for the rest of the history of the Isles and very little has disturbed it since."

The one region where there was subsequent large-scale female immigration was the northern islands of Shetland and Orkney. Some 30-40 percent of today's inhabitants trace their maternal ancestry to Viking women.

There was also a limited immigration during historic times of women into eastern and northern England, accounting for 10 percent of the maternal genes in the east and 5 percent in the north.

Whether these women were Saxons, Vikings, or Normans is hard to say because they are all so similar genetically. The Angles, Saxons, and Jutes, who invaded England after the Roman evacuation in 410 A.D., were from southern Scandinavia and northern Germany. The Vikings, who sacked the monastery of Lindisfarne as early as 793, were centered merely a little farther north and west. The Normans were simply Vikings who had conquered Normandy and adopted the French language.

Sykes’ guessed, based on sketchy historical evidence: most of this newer maternal-side DNA was introduced by the Vikings.

The Vikings/Normans were incredibly dangerous—their conquests ranged from the Volga to North America, from Greenland to Sicily—for the paradoxical reason that during the Dark Ages they cooperated with each other better than their less ferocious victims did. (To defend against Viking raids, Europeans eventually evolved feudalism, the fundamental institution of the Middle Ages, to support the expensive knights in shining armor needed to rapidly mobilize and defeat a Viking raid.)

Yet, despite their taste for rapine and pillage, the supremely opportunistic Vikings were not averse to family outings either, apparently bringing their womenfolk with them to farm in Orkney and East Anglia.

The Romans appear to have imported almost no women into Britain. Sykes found only a "tiny number" of examples of exotic mitochondrial DNA that might represent female slaves imported by the Romans from Syria or black Africa.

The famous historic invasions left a larger, but still limited, mark on the male Y-chromosome.

Roman soldiers no doubt left children behind, but it's hard to pick them out because, as the Empire matured, fewer Legionnaires were recruited from increasingly decadent Italy, and more from the northern reaches of the mainland Empire, where the men were genetically closer to the British.

All together, the Saxons, Vikings, and Normans account for the ancestors of about 10 percent of Englishmen living south of the old Danelaw line between London and Chester, and 15 percent north of it, "reaching 20 per cent in East Anglia."

(Remarkably, this ancient ethnic palimpsest can be seen to this day in the United States. As David Hackett Fischer pointed out in his great history of British settlers in America, Albion's Seed, the American Puritans tended to originate in East Anglia and other once-heavily Danish regions of England. In turn, the American states founded by Puritans and their descendents feature the most famous colleges and the highest NAEP school achievement test scores.)

That the people of the British Isles, whose offspring founded and still profoundly shape the American nation, have been a homogenous racial group for 6,000 years has many implications.

For one thing, it offers an important perspective on the current obsession with the supposed educational blessings of racial diversity. Virtually every college president in America publicly denounces the mentally-stultifying effects of a non-diverse student body. (Diversity of opinion, of course, is somehow much less fashionable on campus.)

And yet, William Shakespeare, who likely never left homogenous England in his life, sketched what is perhaps the most diverse array of personalities in world literature. Nor have the British Isles—home to Samuel Johnson and John Lennon, Oscar Wilde and the Duke of Wellington—been grievously lacking in real life individuality.

This is not to say that the close observation of racial diversity doesn't add interest to our understanding of humanity … or Shakespeare wouldn't have made Othello, the Moor of Venice, the tragic hero of one of his greatest plays.

What it does show, however, is that even in the most superficially uniform racial groups, there is almost endless human richness to be found.

The book is on my Xmas present list and Elliott will buy it!:?:

[url]http://www.amazon.co.uk/Blood-Isles-Bryan-Sykes/dp/0552154652/ref=sr_1_1?ie=UTF8&s=books&qid=1194887179227&sr=1-1[/url]

Perry

[Pericles]

Vega,

Who are you? We know what you are, but we don't know why you are being so obnoxious? You persist in making basic mistakes and appear to lack attention to detail. Unforgivable in an architect.

"António, thank you for your kind words. I am just an Architect and an old salt (a capitán de yate, like you) that has taken an interest in sailing boat’s stability. I have learned a lot and there is always a lot more to learn. Anyway, I know something about it and I try to make that knowledge available to the ones that know less than me.

As you can see on post 32 of this thread, I have said that probably your boat has been certified (some years ago) as having a 119 AVS and a 48 STIX


Quote:
Originally Posted by Vega View Post
But I can tell you that the Stix of the boat is not 51 but 48 and the AVS is not 126, but 119, considering MinSC.

But on post 39 I have wrongly referred the certified numbers as 51 STIX and 119º AVS instead of the correct numbers, posted by me on post 32, that were : 48 and 119.
(red for mistaken number, blue for the intended one)


Quote:
Originally Posted by Vega View Post
...I agree that if this is the curve you are talking about (picture), probably the STIX is bigger than 51 (48)…but I am confused, because Beneteau had previously released as stability information: 51 (48) STIX and 119 AVS.

On post 54, when trying to explain to you why Guillermo had obtained a significantly higher STIX, when using the curve you provided (the one with a bump) I have persisted in the mistake and I have used 119ºAVS and a 51 STIX, referring to the certified stability numbers, instead of the correct figures, I mean 119 and 48.

I was trying to say that the curve that you have posted (with an AVS of 126º) and that Guillermo used to calculate a 51 STIX, without that bump (not considering the cockpit influence on the stability), would give 119º AVS and a smaller STIX, probably the certified 48 (and mislead by the previous mistake, I have posted 51).


Quote:
Originally Posted by Vega View Post
....
If you pick that curve and take away the bump, continuing the line, you will see that you will obtain a 119ºAVS, if you continue that curve you will also have a lot more of inverted stability.
If you consider that curve for calculating the AVS, I believe you will obtain 51 (48).
....
Your boat was certified when the no-bump curves were used, so the certified values are AVS 119º, and 51 (48) (STIX. But if it was certified now, they would use the curve given to you by Beneteau, and the AVS would be 126º and the STIX higher.

I am sorry for the confusion, that is, if you did not understand what I mean .

I will edit posts 38 and 54 to correct those mistaken numbers."


You are not helping with the discussions as you are not willing to learn. However we are most willing to learn about your credentials, your experience, your education, your career and the boats you have designed and built.

In other words, as King Juan Carlos might have said to Chavez in Santiago, "Put up or shut up! "



Pericles

[kwb1312]

Pericles,

interesting reading your post #252.

Quote:
That the people of the British Isles, whose offspring founded and still profoundly shape the American nation, have been a homogenous racial group for 6,000 years has many implications.

Could we conclude that American politics today is the result of a low genetic diversity caused by a too small gene pool from the British Isles? ...si tacuisses:rolleyes:

[Guillermo]

"Intellegis Pericles esse philosophum?" Tum kwb1312 nimium mordaciter: "Intellexeram", inquit, "si tacuisses" :p

[Vega]

Vega,

You persist in making basic mistakes and appear to lack attention to detail. Unforgivable in an architect.



I am afraid that without the blues and reds, what you have posted is not clear.

If someone wants to have a look at it, it is here:

http://www.boatdesign.net/forums/showthread.php?t=20154&page=5

But I don’t understand you. Architects can not make mistakes? Neither one as simple as switching (by mistake) a previously posted number (by me) by another number (the one that Guillermo had calculated)?

If you keep looking to that thread you are going to see that all the rest is correct, I mean the explanation on the divergence between the two AVSs and the two STIXs, and that is the important part. There is a big difference between a mistake and an error.


Do you care to explain exactly what you are talking about when referring to basic mistakes?


You are not talking of post 250 of this thread, are you?


I don’t understand also why you keep posting on this thread things that have nothing to do with it, I mean like this one:



....he has a tendency to state the obvious as if it is a nugget of gold that only he has discovered, and then he gets it wrong!

Quote:
Originally Posted by Pericles :

I would love to have a Gunboat 66, when and if the next Jacques Varbre takes place and shadow the leading ORMA, probably Groupama 2, all the way to Bahia, Brazil and about a few miles from the finishing line, let the Gunboat have its head and surge past the trimaran, to take line honours, whilst having a good meal at the table and glugging the Bolly.
….
Am I dreaming? Absolutely!

Quote:
Originally Posted by Vega:

Yes you are dreaming. There is an incredible huge difference between a fast cruising cat like Gunboat 66 and a top racing trimaran like Gruparama. It’s like to say that a Ferrari F50 can be a match for a F1. Fact is that a simple racing formula ford, with be faster on a track.

Even an Open60 would be faster than the Gunboat. The Gunboat can make 36k? An Open60 also, even more. What counts is the wind needed to go fast.

If the conditions were very bad, as had happened on other races, you would see that the difference between the trimarans and the Open60’s would be a lot smaller and that the trimarans would experience a lot more retirements from the race than the monohulls (breaking, capsizing).

I like both types of boats, but we have to be fair regarding the strong and week points of each one and to see the difference between top racing boats and fast cruising ones.

Pericles:

Gunboat speeds are posted on their site. Where is your reference for IMOCA speeds and in what wind speeds?

Vega with remarks like that, you should not be so eager to post. Better you hide your lack of knowledge, rather than confirm it to all and sundry. Learn from the man! Guillermo is a NA.

Hell's teeth, if you bad mouthed my professional competence in the field in which my own company operates and I came face to face with you, I would not be so patient as Guillermo and you would be holding your teeth on your hands. I'm English and settling such contentious disputes after due warnings, is a great tradition with us.

Pericles

I did not know that Guillermo worked with big racing High-Tec boats.

Anyway I will post your comments on the proper thread, the thread from where you have taken these posts. Perhaps some of the guys that post there or that know and are interested in racing boats can comment on your ideas.

By the way, do you really think that the performance of the Groupama racing trimaran has something to do with the performance of the Gunboat 66 cruising cat?

[kwb1312]

Quote Guillermo:
"Intellegis Pericles esse philosophum?" Tum kwb1312 nimium mordaciter: "Intellexeram", inquit, "si tacuisses"

Qualis autem homo ipse esset, talem esse eius orationem :D

[Pericles]

Guillermo,

Are philosophers understanding? It is kind that you felt that kwb1312 was biting when he quoted Boethius "If you had been silent, you would have remained a philosopher" to which I reply "Quid quid latine dictum sit, altum viditur, atque memento nulli Romanorum qui locutionem tuam corrigant".

kwb1312,

Marcus Tullius Cicero?

Qualis autem homo ipse esset, talem esse eius orationem

At the speech, do you recognise the man?

To whom do you refer?

Pericles

[Pericles]

kwb1312

I must agree that politicians, American, French, British, are bottom feeders in the gene pool. That much is true. From reading about the history of Brittany it would seem the people there have much more in common with Britain than with France.

After the withdrawal of Roman troops in the reign of the emperor Honorius,the Romano-British were forced to fight for themselves but quickly developed their own armies among hiring barbarians from across the Sea. Romano-British were divided politically as former soldiers,nobles and officials declared themselves kings fighting amongst each other allowing later peoples to take Britain. The depredations of the Picts from the north and Scotti (Scots) from Ireland forced them to seek help from pagan Germanic tribes of Angles, Saxons and Jutes, who decided to settle. However, the Germanic tribes became hostile against their hosts and began to conquer their territory. Romano-British culture, over the course of six centuries, was restricted to the western fringes of the island in Wales, Devon and Cornwall and the north in Strathclyde, Cumbria and Elmet. Some of the Romano-British may have migrated to Brittany and possibly Ireland.

http://en.wikipedia.org/wiki/Romano-British

Pericles

[kwb1312]

Pericles,

Not biting, just mild irony. I don´t think we disagree in the matter, but throwing Shakespeare, Oscar Wilde and „the American nation“ in one pot asked for some reply. - For the sake of argument.

Re. Qualis autem..... it was my direct reply to Guillermo´s „Intellegis Pericles esse philisophum“, and ref. to your sentence „....and I came face to face with you, I would not be so patient as Guillermo and you would be holding your teeth on your hands.“

As to Mr. Sykes: I do not know how correct his results are, as depending on e.g. the number of markers you might get quite different results. But even if we assume he is right without any if´s and but´s, so what Pericles? Were you afraid that the „politically-correct elites“ (Quote P.) are right? Don´t worry, they are not. And despite what our constitution says neither science nor speach is free. But here we are more than only „slightly off topic“ and we better return to Stix and MOC (especially MOC :rolleyes: )

[Pericles]

Agreed.:) It was mordacity.:confused:

An interesting diversion, nevertheless. You had me working for a while.:D :D

Pericles

[Guillermo]

Interesting to review some of Vega's interesting opinions at the “Keels and Keels again” thread:


Guillermo, I don't find surprising the lack of serious technical data about the Match II keel problem. Bavaria is obviously not interested in it, neither the other big builders, because they use similar low cost techniques to fix the keels to their boats.

Some years ago, here in Portugal the keel of an almost new Dufour (I think it was a 36) "moved" several centimeters up when the weight of the boat was all put on the keel. Another Dufour, this one, a friend’s brand new 32 broke one of the interior structural reinforcements when it was moved to the water (by a crane).

........................................
But not so simple, you still have the misinformation, provided by boat builders and magazines. Lots of people don't know they are making crazy or dangerous things simply because they are mislead.

.......................................
Two years ago, I was in my boat at Lagos Marina, when a British gentleman (about 60 years old) asked permission to come aboard.
It turns out that he had a boat just like mine, (a recent Bavaria 36) and wanted to know if, in my opinion, our boat was an oceangoing boat.

Well, I said no, that I thought it would be alright for short oceanic jumps, ( 4 or 5 days) provided that we had a good weather forecast, but that for crossing oceans, with all the uncertain weather that a long jump implies, it was risky (the boat weighs 4,7Tons, with a ballast of only 1,3T).
Then he said to me: Damn, it is just what all those guys have said to me, in Azores, in the Caribbean and in the States. It turns out that this gentleman had sailed solo to the US and back. He had just arrived some days before.
He also said to me that he hadn’t believed those guys with heavy boats because he knew that his boat was a certified Class A boat , an Oceangoing boat (he thought that they had just old fashioned slow boats).

Well, I don’t think that I had fully convinced him, guess that he had thought that I was not very brave, to say the least.

And that is not an isolated case, I know of a fellow countryman (an Azorean fisherman) who has chosen a brand new Bavaria 37 to circumnavigate the world. At least that one, when he finished, had already discovered that it was not exactly the right boat for the job

So I guess that intentional misinformation (as a way of selling more boats) is a problem and can be a dangerous problem.

....................................
I mean, as Guillermo has pointed out correctly “Some of the builders in this dangerous down-pricing boats race, claim their boats comply with ISO 12215, so they are 'not guilty'. But they forget to mention this standard is still under discussion, so not fully approved yet. And I doubt some of the reinforcements I've seen even complies with ISO 12215!”

I believe that if we pick a boat from the same builder (the ones that now only comply with ISO 12215) and compare it with another, built 15 years ago, we are going to find that the older boat is a stronger boat, a boat that will vastly exceed Iso 12215, a boat that is slower but also safer than the new boat.

I find this unacceptable.

.....................................
...Fact is that most of the builders – all the big ones (with special incidence in Europe) are selling inexpensive boats with big and attractive interiors, calling them cruiser boats. Those boats are certified as Class A boats, that means unrestricted oceangoing boats…and obviously they are not.

When you go to a boat show (that’s the place most people go when they want to buy a new boat), the boats you see are these, and consumers don’t have any reason to suspect that those are not really strong oceangoing boats. After all, the shiny catalog does not provide any real information about stability or structural integrity, nor about the way the keel is bolted, but it says that that boat is a certified oceangoing boat (from 33ft up, from all the major builders) and that should be enough.

Fact is that most people don’t understand why there are in the show some small stands with some boats that look the same and cost a lot more and even if they have the money to buy one of those, why should they do it? They look the same, apparently they are the same and after all by the same price of one of those expensive 40ft they can buy a 45ft or a 49ft with a lot more inside space…

I don’t think that sufficient information is provided to the buyer, I even believe that the provided information is misleading and I think that that is unacceptable and criminally dangerous.


I cannot less than strongly agree with him.
(But then I feel somewhat confused comparing this with some of his statements in several of his recent posts at this and other threads.....)

Cheers.

[Vega]

Interesting to review some of Vega's interesting opinions at the “Keels and Keels again” thread:

...................................................

I cannot less than strongly agree with him.
(But then I feel somewhat confused comparing this with some of his statements in several of his recent posts at this and other threads.....)

Cheers.

Putting your quote on context:



The design brief for racing craft (of any sort, air ground, water, etc.) places the primary goals on the end result, performance.
….
In cruising craft, the design brief is quite different, requiring a level of redundancy and heft that a racer or performance oriented craft, couldn't tolerate and remain competitive. I have no problem with well engineered bolted keels, but I error on the side of not breaking things, so my stuff generally is slightly heavier then necessary. A cruiser design will do well to use similar margins (and for the most part they do) it's the "cross over" type of design that run into trouble, lulling folks into thinking it's a cruiser, but in fact, it's built like a racer.


I agree with you but I don’t think that what you say is what it is really happening. I mean, as Guillermo has pointed out correctly “Some of the builders in this dangerous down-pricing boats race, claim their boats comply with ISO 12215, so they are 'not guilty'. But they forget to mention this standard is still under discussion, so not fully approved yet. And I doubt some of the reinforcements I've seen even complies with ISO 12215!”

I believe that if we pick a boat from the same builder (the ones that now only comply with ISO 12215) and compare it with another, built 15 years ago, we are going to find that the older boat is a stronger boat, a boat that will vastly exceed Iso 12215, a boat that is slower but also safer than the new boat.
I find this unacceptable. If you compare with the car industry, all cars are a lot safer now if you compare them with 15 year old models.



This is the fault of the buyer, not the designer. If you want a cruiser, you can have one, but you'll get beat around the buoys. If you want a racer, then they're available, but avoid hitting things other then the marks. If you buy a "performance cruiser" then you'll looking for issues to test. It's a bit like mentioning honesty and politicians in the same sentence. As a rule, you'll get one or the other, a rare example will provide both.




I don’t agree with you here. Fact is that most of the builders – all the big ones (with special incidence in Europe) are selling inexpensive boats with big and attractive interiors, calling them cruiser boats. Those boats are certified as Class A boats, that means unrestricted oceangoing boats…and obviously they are not.
When you go to a boat show (that’s the place most people go when they want to buy a new boat), the boats you see are these, and consumers don’t have any reason to suspect that those are not really strong oceangoing boats. After all, the shiny catalog does not provide any real information about stability or structural integrity, nor about the way the keel is bolted, but it says that that boat is a certified oceangoing boat (from 33ft up, from all the major builders) and that should be enough.

Fact is that most people don’t understand why there are in the show some small stands with some boats that look the same and cost a lot more and even if they have the money to buy one of those, why should they do it? They look the same, apparently they are the same and after all by the same price of one of those expensive 40ft they can buy a 45ft or a 49ft with a lot more inside space…

I don’t think that sufficient information is provided to the buyer, I even believe that the provided information is misleading and I think that that is unacceptable and criminally dangerous.

I have posted this almost two years ago. As you can see I thought much like you, in what concerns modern boats and cruising.

I learn fast and I change my views accordingly. All the data that I have received along these two years have changed my judgment on many things.

So, I would say, sorry PAR, you were right and I was wrong:) .

On the last two years I have looked closely to a lot of boats. I want to have a bigger one and I have contacted a lot of manufacturers that have boats that for a reason or other, interest me. Most of the time I have received all the information I wanted (about stability and about structural integrity), many times from the technical department and sometimes I have been invited to visit the factory and see by myself how things were done.

During this time I had the opportunity to compare stability curves of typical big production cruisers from 15 or 20 years ago with stability curves of big production typical modern cruisers.

The modern ones are better. The boats are stiffer, can carry more sail and have a better AVS. The boats are lighter, but modern materials make them as strong and stiffer.

About the European certification and Class A boats, well, they were right and I was wrong. I have said that Class A boats should have at least a 40 Stix. Nonsense, I believe that the knowledgeable technicians that have made ISO 12215 knew what they were doing and I believe that the last modification, introducing the need to take into account the boat stability data on Max Load Condition, was a further step on the right way.

I also believe that I was wrong in assuming that an expensive 40ft boat, like de Halberg-Rassy, was more seaworthy than a big production 49ft, like the Jeanneau. Their stability curves say otherwise and if not as luxurious, the Jeanneau is a strong boat, and certainly an offshore boat.

Yes, I have learned and I have changed. When are you going to change:D ?

I will post the picture of a boat that I was designing when I have posted that (two years ago). It was what I considered then, as the boat I wanted for cruising ( I remember you liked the boat).

I will post also a drawing of another boat, one that I began drawing when I understood that the first drawing didn’t represent the boat I wanted anymore (too heavy and too slow).

I have abandoned that too. I will modify a lot of things. Not fast enough, not stiff enough.

The differences between those two boats are in consonance with the differences between what I thought two years ago and what I thought some months ago.

Cheers

[Guillermo]

I have posted this almost two years ago. As you can see I thought much like you, in what concerns modern boats and cruising.

I learn fast and I change my views accordingly. All the data that I have received along these two years have changed my judgment on many things.

So, I would say, sorry PAR, you were right and I was wrong:) .

On the last two years I have looked closely to a lot of boats. I want to have a bigger one and I have contacted a lot of manufacturers that have boats that for a reason or other, interest me. Most of the time I have received all the information I wanted (about stability and about structural integrity), many times from the technical department and sometimes I have been invited to visit the factory and see by myself how things were done.

During this time I had the opportunity to compare stability curves of typical big production cruisers from 15 or 20 years ago with stability curves of big production typical modern cruisers.

The modern ones are better. The boats are stiffer, can carry more sail and have a better AVS. The boats are lighter, but modern materials make them as strong and stiffer.

About the European certification and Class A boats, well, they were right and I was wrong. I have said that Class A boats should have at least a 40 Stix. Nonsense, I believe that the knowledgeable technicians that have made ISO 12215 knew what they were doing and I believe that the last modification, introducing the need to take into account the boat stability data on Max Load Condition, was a further step on the right way.

I also believe that I was wrong in assuming that an expensive 40ft boat, like de Halberg-Rassy, was more seaworthy than a big production 49ft, like the Jeanneau. Their stability curves say otherwise and if not as luxurious, the Jeanneau is a strong boat, and certainly an offshore boat.

Yes, I have learned and I have changed. When are you going to change:D ?

You openly admit now you had no idea two years ago. What makes you think you have learnt something? And why on earth do you think we have to believe you now? I think the problem is you have not enough technical knowledge and you change opinions with the wind, as I've told you before. I just think you didn't know why you were saying what you were saying two years ago, and you still do not know why you are saying what you are saying now.

I know you think professionals here who do not share your point of view are stupid by not changing their ideas so easily, but I'm afraid you're just moving with fashion and marketing. That easy changing of opinions precisely reflects your lack of knowledge. And that lack of knowledge (and your extraordinary big ego!) makes you think you know something. But you still know 'nada de nada' on these matters, my friend. In my humble and stupid opinion, of course.

Yes, I believe you when you say you have review a lot of boats and info from many manufacturers, your efforts are laudable, but I'm afraid that what you have now is just a big 'diarrhea' in your head. You have not properly digested yet the received info, as it is thoroughly reflected in your posts and statements.

As far as I know you have never performed an stability test and calculation in your life, neither an structural one, but you dare to scorn professionals here, who have done that for years and who have no interest in selling you a boat, just trying to contribute to these forums with their experience.

On top of all that you distort reality and other people's words to try to support what you're saying, as you do with PAR here. And what is worst, you do award yourself things other people have said, like the STIX 40 thing, who was not said by you, but by Rolf Eliasson (one of those knowledgeable technicians you mention) and posted by me (As it was with the needing of taking also into account the data in the MLC condition to assess STIX if MLC>1.15*MOC. You had no idea of that. Just review this STIX thread.)

By the way, what has ISO 12215 has to see with STIX?
Have you finally got your own copy of relevant ISO norms?
Have you studied already some basic books? Which ones?

You're not trying to learn from the people who know more than you. You're just trying to demonstrate you're the smarter guy, in spite of your lack of formation and experience, which I find annoying and unfruitful.

Finally, let me quote here Pericles the Great :) , who did a good radiography of your posts, some of us here do share:


Vega,
...why you are being so obnoxious? You persist in making basic mistakes and appear to lack attention to detail.
...................
You are not helping with the discussions as you are not willing to learn.
....................
Vega....talks in generalities.... has a tendency to state the obvious as if it is a nugget of gold that only he has discovered, and then he gets it wrong!
....................
...with remarks like that , you should not be so eager to post. Better you hide your lack of knowledge, rather than confirm it to all and sundry.
(But I don't share his 'teeth' thing...;) )

Cheers.

[Guillermo]

I will post also a drawing of another boat, one that I began drawing when I understood that the first drawing didn’t represent the boat I wanted anymore (too heavy and too slow).
I have abandoned that too. I will modify a lot of things. Not fast enough, not stiff enough.
May we know the main dimensions, displacement, ballast, sail area, GZ curves, prismatic coefficient, wetted area, polars, intended material and structure, etc, etc, for the two boats, so we can better understand you? Also knowing your briefing agenda for the design would be of great help. Thanks in advance.

Cheers. :)

[TeddyDiver]

Okey!
What I found from Guillermo's replies here:

6.2.1.1 The requirements given below, and in 6.2.2 and 6.2.3, shall apply to all downflooding openings, except:
a) watertight recesses with a combined volume less than LhBhFm/40, or quick draining recesses.

and

Φda1 is the angle of heel at which openings which are not capable of closure to tightness degree 3 of ISO 12216 having a combined total area, expressed in square millimiters (mm2), greater than the number represented by (50Lh^2) first become inmersed."

So a for a boat of Lh=12 m, all openings greater than 7200 mm2 (0.0072 m2), which's closuring device (If any) doesn't comply with required tightness degree, shall be checked for this.

Those are small openings, not big. Let's say a vent with a diameter of 96 mm, or two of 68 mm diameter flooding at the same angle, i.e. (So the word "combined" in the rule)

Are these 6.2.2 and 6.2.3 included in which of the ISO Books? I find it frustrating to pursue requirements scattered around:mad: And further do they include requirements for bigger watertight (like companionway" hatchess



What amazes me is why there are people who think they have the right to cross an ocean without the proper equipment, but we do not see the same kind of people claiming for that same right to cross the Kalahari, climb the Everest or just go deep diving.[/I]

Believe me, they do that too:D

My problemo is the same as stated from Nauticat

"Hello Mr. Gefaell
The stability of the boat is more than enough for category A, but it is the side doors, which makes it extremely difficult to get it in category A, as those are considered as flooding openings.
I hope this explains the situation. The same thing with our Nauticat-331 and Nauticat-44.
best regards
NAUTICAT YACHTS OY
Veli Kärjä"

Allthough it's not a real problem but if there's a possibility to make a ISO approved watertight side door (non flooding) so I'd like know how

[Guillermo]

Are these 6.2.2 and 6.2.3 included in which of the ISO Books? I find it frustrating to pursue requirements scattered around :mad: And further do they include requirements for bigger watertight (like companionway" hatchess
Are you asking what is the pecific ISO rule where those were taken from? I do not have the norms here, but I think I mentioned which one it was ( It would be nice if you tell me which of my many posts is the one you now quote). Anyway, if you're seriously interested please send me a PM and I'll check the rules and tell you.


Believe me, they do that too:D [B]
Without the proper equipment? I'll be grateful if you show me just a single case.


[B]Allthough it's not a real problem but if there's a possibility to make a ISO approved watertight side door (non flooding) so I'd like know how

Ask this people:
http://www.pointeng.co.uk/marinedivision.asp
http://www.usaslidingdoors.com/
http://www.wkdoors.com/sliding-doors.htm
http://www.imsgroups.com/
http://www.grumsen.dk/Default.asp?ID=129
http://www.winel.nl/cms/index.php?option=com_content&task=view&id=26&Itemid=87


Cheers.

[TeddyDiver]

I think found even better in post 36:
"c) watertight compartments used to provide buoyancy shall be constructed to watertightness degree 1 in accordance with ISO 11812 and hatches and doors satisfy watertightness degree 2 of ISO 12216"

Believe these standards are what I'm looking for. However I'm not familiar how all the ISO standards are organized and published so I'm not sure are these relevant with the ISO 12217-2? I'll check up some details tomorrow and study the links you gave and send PM after that..


Without the proper equipment? I'll be grateful if you show me just a single case.
Discovery or NatGeo channel had a series about Mount Everest Season. They showed a couple cases where some groups of climbers were going to the Death Zone without even emergency Oxygen or meds to handle Odema (insulin?). Without like suicide attemp...
Deep Diving is something every now and then someone tries with ordinary recreational scuba setup. It means no redundancy, inadequate gas supply, using air instead of mixed gases (Trimix= He, N, O;Nitrox or O2 for Decompression) no planning etc...
So a rowboat to China is quite sound compared to some of these loonies...

[dskira]

And the factor never considered is the SCF and ICF
the first very important is: The sick crew factor
The second: The incompetent crew factor.
For the STIX we can put a thousand more factor it will kept the push papers in Bruxelles very busy and the big production boat almost alone on the market since the STIX is quite tailored for them. More paper work is exactly what we need! Architecture naval degenerate in sort of paperwork competition, machines punching number without talents to pretend the boat designed is perfect, since the STIX is perfect and the software too! But the fact production boat with perfect STIX number lost there keel don't bother nobody since they are perfect. The fact they capsize and stay upsidedown don't bother nobody since they are perfect. The STIX miracle, the Parthenon of stupidity and waste of time.

[Guillermo]

dskira,
Well, I would not say STIX is the Partenon of stupidity and a waste of time, because it is not. Problem is it is being taken as what it is not. Here some of my first words when opening this thread:

"....As we can see STIX provides not enough information about the seaworthiness of a boat (It was never intended to be a clue to this, but this idea is spreading around quickly) and may even be a tricky and dangerous number. Seaworthiness is a complex matter, involving stability, all around scantlings, quality of movements, and a long etc.

I think manufacturers/designers should at least be obliged to publicize the STIX Factors and not only the number itself (Which is not even mandatory!). And even better, publish also the 'old' ratios and parameters, for the people to have a more complete view and understanding of the boat.
.............

Again in my opinion, most probably a great pressure from modern mass (and light) boats producers (and their designers) was put into the process. Those manufacturers produce very nice boats for Club racing and coastal cruising in fair weather (what most of users do) and fun to sail, but of course they want not many of their models to be obliged to be labelled as Category C, what they should be in most cases."
..............

The problem is that as people understand almost nothing about these matters, they tend to fix to a simple rule, as it couldn't be other way. And STIX is becoming dangerously a kind of 'magic' number among boatowners. What is worst, this Design Categories scheme is tending to confuse people's judgement on a boat's ability to survive bad weather, in my opinion. I think nowadays Category A means in a growing number of people minds, that the boat is able to go anywere, which is not true even under the RCD. Categories are a clue but not a 'Safety Act'. In my opinion this misunderstanding is being consistently encouraged by manufactures; and designers as well....

Taken from the "Recreational Craft Directive and Comments to the Directive Combined":
"The directive does not include any navigation or usage rules and there is no link between the design categories and any such rules; taking into account construction safety, the user is only clearly informed of what the boat was designed and built for in relation to certain parameters of significant wave heights and wind speeds."


Your SCF and ICF factors :) are not considered in the STIX, not in any other boats evaluating system, indeed, but in the 'Old' ratios one there are some of them trying to reflect the quality of the movements of a boat, as they are the Motion Comfort Ratio (MCF) and the SI Stability Index (SI).

Cheers

[TeddyDiver]

I sended the question here just becouse it might interest someone.

Here’s some data of my motorsailer project. The first part is imperial, displacement with max load. Latter part containg values for STIX is metric, displacement with min load. Values with ? are questimates, either having some flexibility +- or just pure questimate.

Beam 10
LOA 33
LWL 31
Disp in lbs 13000
Disp in cu ft 203
Sail area 533 ?
Sa/D 15.5
MCR 29
CSF 1.7
D/L Ratio 195
SL Ratio 1.6


A gz 35 ?
A s 40 ?
h CE 7 ?
GZ90 0,6 ?
B wl 2,5
B h 3,05
L bs 9,5
F l 0,971104986
m sc 4800
F r 5,142857143
F b 1,920258142

Displacement Length Factor
FDL 0,96
Beam Displacement Factor
FDB 1,01
Knockdown Recovery Factor
FKR 1,33
Inversion Recovery Factor
FIR 1,23
Dynamic Stability Factor
FDS 0,7
FWM 1
FDF 1

STIX 34,9

Both FDF and FWM are 1 becouse of 90 deg downflooding value when the companionway door would submerge (max load). However I’m making the door watertight. The first question is if it makes a benefit for STIX calculation increasing the downflooding angle (actually there wouldn’t be any downflooding angle anymore if all ventilations are self closing).
In the ISO 11812:2001(E) are requirements for “watertight” cockpits in 5.2 “A watertight cockpit or recess shall: have its sills in accordance with clause 8, and  show a degree of watertightness in accordance with clause 9".
In clause 9 the watertightness requirements are:
"All surfaces of watertight cockpits up to hC shall have a watertightness degree 1".
For quickdrain cocpits theres a table of watertightness degrees for different opening places in the cockpit, but not for totally watertight cockpits.
In Annex E there’s tests only for openings in watertightness degrees 2 and 3 not for degree1.
So to my second question: Is it appropriate to use the same table (9.2.1 table 6) for watertight cockpits too, or should degree 1 be used fo all closing appliances, and if, how to test?

Teddy

Edit:
There's some inaccuracy (in my opinion) in the term "watertight" cockpit, or it might have a better description in some other part of the ISO standards. However there's two way's to understand it. Either it's it's a watertight "tub" open above the hight hC, or it can be understod as closed cockpit.
In the first case calling a bath tub without a drainage "watertight" is hilarious ;), and in the second case just it's just no adequatly prescribed..
Either way, it won't solve my quiz with the deg 1 watertight closing appliance. The links in Guillermos reply were about Solas watertight doors. A bit overkill in 10m motorsailer :)

[Guillermo]

Teddy,
If you provide me also with the following data:

Total Draught T
Body draught Tc
Moulded depth H
Ballast
Mast height (Over Wl)
Heeling Arm (Hce + Hclr)
Engine Power (Continuous)

I will produce my own guestimate on STIX (as well as some other numbers) and we can compare results.

About your question on watertightness of appliances in cockpit, I have to read first the rules at the office. Maybe next week.

Cheers.

[TeddyDiver]

Hola Guillermo!

Total Draught T 1.48m
Body draught Tc 0.48m
Moulded depth H 1.73m
Ballast 1 200kg cast iron Vcg -1.2m 700kg waterballast Vcg -0.7m
Mast height (Over Wl) 11m
Heeling Arm (Hce + Hclr) 6.8+0.7=7.5
Engine Power (Continuous) 18kW

The engine I currently have for the boat is rated 71hp at 3600rpm. I'm planning to optimize it for 2000 rpm/60-75% of the max power.


BR Teddy

Edit: Seems that there's allways something to add. The plan is for gaff rigg. The mast height doesn't include topsail spar. Hence the high Hce compared to the mast height.

[Guillermo]

OK, thanks.
Asuming engine's power as 40 HP, here some numbers for her.

TEDDY'S MOTORSAILER RATIOS AND PARAMETERS
Length/Beam Ratio (2Lwl + Lh)/3B = 3,16
Lwl/Bwl Ratio Lwl/Bwl = 3,78
WL beam/Body draught Bwl/Tc = 5,21
Mould. D/Hull draught H/Tc = 3,60
Breadth/Mould. D Bmax/H = 1,76
Length/Mould. D Lh/H = 5,81
L float / Lhull Lwl/Lh = 0,94
Ballast/Disp Ratio W/Disp = 0,32
Displacement/Length Ratio D/L = 195,36
Sail Area/Disp. Ratio SA/D = 15,43
SA (metric)/ Power (Imp.) SA/HP = 1,21
Power/ Disp. Ratio HP/D = 3,14 HP/ton
Hull speed HSPD = 7,46 Kn
Potential Maximum Speed PMS = 7,93 Kn
Velocity Ratio VR = 1,06
Best motoring speed (1.1) CSPD = 6,12 Kn
Capsize Safety Factor CSF = 1,70
Motion Comfort Ratio MCR = 29,37
Roll Period T = 3,43 Sec
Roll Acceleration Acc = 0,06 G's
Stability Index SI = 1,13
Angle of Vanishing Stability AVS = 120 º
Upright Heeling Moment UHM = 13624,76 Ft*pound
Righting Moment at 1º HM1º = 325,76 Ft*pound
Heeling Moment at 20º HM20 = 11581,31 Ft*pound
Righting Moment at 20º RM20 = 5846,79 Ft*pound
Dellenbaugh Angle DA = 41,82 º (14 kn wind)


I have more numbers for her I do not dare to post, as they still need serious checking and further development.

As a first impression she seems to be a tender boat, needing more beam at the WL, although this is totally speculative.

Are you sure Hce is as high as 6,8 m?

Cheers

[TeddyDiver]

Thanks Guillermo! It's really big help to get some number crunching and opinion about the project. Some of the ratios are somewhat unknown to me, so I'll make a search and study them a bit..
The beam is allready what it is, and I got to live with it. It was actually restricted to 3m becouse I'll maybe have to trailer it twice a year some 20km.
The Hce 6,8m is my "worst case scenario" in this case with the largest top sail for light air. Without a top sail Hce is 4,8m and sail area 10m2 less.
The tenderness is actually a bit less than looks obvious at first sight. Aft part being very beamy compared to Bwl. It worsens somewhat helm, but is a compromise with the actual purpose of the boat mostly as a coastal cruiser & dive and sportfishing boat (occasionally making passges).

Teddy

[Guillermo]

Asuming Hce = 4,8 m (Anyway, you wouldn't fly the top sail in a 14 kn wind) if you bring beam on the waterline to 2,75 m instead of 2,5 m, the Dellenbaugh angle comes down to around 22º, which although still being somewhat high for a boat this size, is a much more reasonable figure than 41,82º.

Cheers.

[TeddyDiver]

I haven't before paid attention to Dellenbaugh Angle. Quite interesting and shows that I must pay more attention to GM and also consider ways to lower CE. With GM it helps increasing the amount of casted ballast and shaping it to get Vcg lower. Actually I expected, and can live with, some 20-30deg (old fashioned way) heeling angle in avarege sailing conditions but some reconsidering I got to do.

[TeddyDiver]

Looked bit more closely Dellengbaugh Angle. The formula does work realisticly to maybe 25deg heel depending somewhat on the hull geometry. Perhaps with larger heels (tender boats) a preheel should be considered. Let's say 15deg preheeling and measuring then half Bwl from lee side and using this doubled as a virtual Bwl. At the end the preheel angle and calculated angle sum up a more realistic angle.
Any thoughts?

[Guillermo]

But, what's the use for that? :confused: Dellenbaugh angle only intends to give a clue on how stiff or tender a boat is, this is, simply an indication on her initial stability, that's all. It does not -and cannot- pretend to say nothing about stability at greater angles.

Cheers.

[TeddyDiver]

But, what's the use for that? :confused: Dellenbaugh angle only intends to give a clue on how stiff or tender a boat is, this is, simply an indication on her initial stability, that's all. It does not -and cannot- pretend to say nothing about stability at greater angles.

Cheers.
Got a though that it could give also some additional information about the stiffness under sails in stonger winds/seas? It's allready obvious in the GZ curves, but maybe as a secondary method.

[Antonio Alcalá]

Hi Guillermo. What do you think about the STIX of this sailboat?

A good friend has a interesting offer but sincerely i´ve never heard something about her: The Neptun 32 .

http://www.boatsandoutboards.co.uk/view/F181112

I have tried to find some information about her, but today i´m not a lucky man ;)

Thank you friend

[TeddyDiver]

The Neptun 32 .
I have tried to find some information about her, but today i´m not a lucky man
I found something:

Model Year: 1975
Length: 9,60 m / 31,49 '
Beam: 3,00 m
Draught 1,59m
Weight: 5.000,00 kg or 3,6t? (different source)
Speed 7,29
Material hull: GRP
Material superstructure: GRP
Cabins: 2
Beds: 5
Number of sails: 3
Sail Surface: 40,00 m ²
Tank volume: 160,00 l
Motor: 1 × 14,71 kW or 14hp

BR Teddy

[Antonio Alcalá]

Thanks a lot Teddy, you certainly are a lucky man!!! i suppose this will be fine for Guillermo in order to calculate an estimative stix.

Best winds

[TeddyDiver]

Thanks a lot Teddy
Thanks to Google:D
One remark conserning google searches. Somewhat different results with same search parameters when the country selection is changed. Like google.fi or google.no etc.. even when the search results are in english

[Antonio Alcalá]

Länge über alles: 9,60 m
Länge CWL: 7,50 m
Breite über alles: 3,00 m
Tiefgang: 1,40 m
Segelfläche am Wind: ca. 40 m2
Großsegel: 16 m2
Genua(Rollfock): 22,5 m2
Blister: 51,6 m2
Yardstick: 112
Gewicht: 5.000 kg
Verdrängung: 3.600 kg
Ballast: 1.500 kg
Material: Kunststoff GFK
Baujahr: 1975
Kabine(n): 2 Kabine(n), 5 Kojen, Nasszelle: mit WC und Waschbecken
Anz. Motoren: 1 Diesel mit Welle
Motor/Fabrikat: Bukh
Leistung: 14,71 kW (20 PS)
Brennstofftank: 160 l
Frischwassertank: 180 l
Kategorie: Motorsegler
Liegeplatz: Hooksiel, Nordsee, Deutschland
Ausstattung:
Ballastkiel,Balanceruder mit hydraulischer Radsteuerung und Notpinne, Steuerstand mit Motor-Bedienung und Kompass, selbst lenzender Ankerkasten
Besegelung & Rigg:
Mast, Baum, 1 Vorstag, 1 Babystag, 4 Wanten, 1 Achterstag, Fallen, Fockschot, Großschot, Niederholer, Yachtblöcke, Dirk, Hebelwinschen, Fockleitschienen, Groß-Segel mit Segelpersenning, Rollfockeinrichtung mit Segelpersenning (Anlage und Segel, Neu 1999) , Blister (Neu 1980)
Einrichtung & Aufteilung:
Salon, Polsterbezüge Stoff, Gläserbord , Vorhänge, Kartentisch, Pantryschrank mit Spüle und Pumpe, Achterkajüte, Duschraum/Sanitärraum mit aufstellbarem Vorluk, WC manuell, nach Außenbord abpumpbar, Waschbecken, Kleider- und Wäscheschränke, Schiebeluks für Salon und Achterkajüte sowie Steckschotten mit Flügeltüren,
Pantry:
Gas-Herd 2-flammig, Spüle, Schränke für Geschirr- und Besteck
Nautische Instrumente:
Echolot, Sumlog, Kompass, GPS, Windmessanlage, UKW-Seefunk, Barometer
Planen & Persenninge:
Plichtpersenning, Sprayhood
Technische Ausrüstung:
Schalttafel mit Batterie-Hauptschalter, Sicherungen Ampere-und Voltmeter, 1 Bordnetzbatterie 12 Volt, 105 Ah, Radio, Wassertank mit elektrischer Pumpe und Entlüftung, Tanoylüfter, Innen- und Außenbeleuchtung mit Decksbeleuchtung
Zubehör Badeleiter, Seereling, Bugkorb, Heckkorb Niro, Anker mit Kette und Leine, Bilgepumpe mechanisch, Flagge mit Stock und Halter, Cockpittisch, inkl. Bootsanhänger ungebremst (ohne Straßenzulassung)

[Guillermo]

Here you are, Antonio:

NEPTUN 32
data from: http://www.caputatse.de/boot/neptun_klasse/werft_prospekt_neptun.pdf

INPUT
Lh = 9,60 m
Lwl = 7,50 m
Bmax = 3,00 m
Bwl = 2,70 m (?)
Draught T = 1,60 m
Body draught Tc = 0,50 m (?)
Moulded depth H = 1,75 m (?)
Disp = 3500 kg
Ballast = 1500 kg
Sail area = 40 m2
Mast height = 11 m (?)
Heeling Arm = 5,04 m (?)
Power = 15 KW


OUTPUT
Length/Beam Ratio (2Lwl + Lh)/3B = 2,73
Lwl/Bwl Ratio Lwl/Bwl = 2,78
Ballast/Disp Ratio W/Disp = 0,43
Displacement/Length Ratio D/L = 231,40
Sail Area/Disp. Ratio SA/D = 17,63
Power/ Disp. Ratio HP/D = 2,64 HP/tonne
Hull speed HSPD = 6,65 Kn
Velocity Ratio VR = 0,98
Capsize Safety Factor CSF = 1,99
Motion Comfort Ratio MCR = 21,12
Roll Period T = 2,18 Sec
Roll Acceleration Acc = 0,15 G's
Stability Index SI = 0,81
Angle of Vanishing Stability AVS = 125 º

Estimated STIX = +/- 37 (to be taken with great care)


Cheers.

[Antonio Alcalá]

Thanks a lot !!!!!;)

[Guillermo]

Antonio:
Please note SA/D ratio is 17,63

Cheers.

[Antonio Alcalá]

NEPTUN 32

INPUT

Lh = 9,60 m
Lwl = 7,50 m
Bmax = 3,00 m
Bwl = 2,70 m (?)
Draught T = 1,60 m
Body draught Tc = 0,50 m (?)
Moulded depth H = 1,75 m (?)
Disp = 3500 kg
Ballast = 1500 kg
Sail area = 40 m2
Mast height = 11 m (?)
Heeling Arm = 5,04 m (?)
Power = 15 KW

OUTPUT

Length/Beam Ratio (2Lwl + Lh)/3B = 2,73
Lwl/Bwl Ratio Lwl/Bwl = 2,78
Ballast/Disp Ratio W/Disp = 0,43
Displacement/Length Ratio D/L = 231,40
Sail Area/Disp. Ratio SA/D = 11,46
Power/ Disp. Ratio HP/D = 2,64 HP/ton
Hull speed HSPD = 6,65 Kn
Velocity Ratio VR = 0,98
Capsize Safety Factor CSF = 1,99
Motion Comfort Ratio MCR = 21,12
Roll Period T = 2,18 Sec
Roll Acceleration Acc = 0,15 G's
Stability Index SI = 0,81
Angle of Vanishing Stability AVS = 125 º

Estimated STIX = +/- 37


PUMA 34

INPUT

Lh = 10,35 m
Lwl = 8,20 m
Bmax = 3,35 m
Bwl = 3,02 m
Draught T = 1,85 m
Body draught Tc = 0,63 m
Moulded depth H = 1,75 m
Disp = 5400 kg
Ballast = 2400 kg
Sail area = 55 m2 (WILD GUESS)
Mast height = 15.5 m (WILD GUESS)
Heeling Arm = 6.94 m (WILD GUESS)
Power = 13,5 KW

OUTPUT

Length/Beam Ratio (2Lwl + Lh)/3B = 2,66
Lwl/Bwl Ratio Lwl/Bwl = 2,72
Length/Draught Ratio Lh/T = 5,59
Beam/Draught Ratio Bmax/T = 1,81
WL beam/Body draught Bwl/Tc = 4,79
Ballast/Disp Ratio W/Disp = 0,44
Displacement/Length Ratio D/L = 273,17
Sail Area/Disp. Ratio SA/D = 18,16
Sail Area/Wetted surface SA/WS = 2,43
Power/ Disp. Ratio HP/D = 1,54 HP/ton
Hull speed HSPD = 6,95 Kn
Potential Maximum Speed PMS = 7,82 Kn
Velocity Ratio VR = 1,13
Best motoring speed (1.1) CSPD = 5,71 Kn
Capsize Safety Factor CSF = 1,93
Motion Comfort Ratio MCR = 25,85
Roll Period T = 2,96 Sec
Roll Acceleration Acc = 0,10 G's
Stability Index SI = 0,88
Angle of Vanishing Stability AVS = 126 º
Dellenbaugh Angle DA = 24,06 º (14 kn wind)
Wind pressure coefficient WPC = 0,88

Estimated STIX 37,14


FIRST 345

INPUT

Loa = 11,00 m
Lh = 10,55 m
Lwl = 9,08 m
Bmax = 3,49 m
Bwl = 3,14 m
Draught T = 1,45 m
Body draught Tc = 0,57 m
Moulded depth H = 1,75 m
Disp = 5700 kg
Ballast = 2050 kg
Sail area = 50,73 m2
Mast height = 15,01 m
Heeling Arm = 6,58 m
Power = 21 KW

OUTPUTS

Length/Beam Ratio (2Lwl + Lh)/3B = 2,74
Lwl/Bwl Ratio Lwl/Bwl = 2,89
Length/Draught Ratio Lh/T = 7,28
Beam/Draught Ratio Bmax/T = 2,41
WL beam/Body draught Bwl/Tc = 4,69
Ballast/Disp Ratio W/Disp = 0,36
Displacement/Length Ratio D/L = 212,37
Sail Area/Disp. Ratio SA/D = 16,16
Sail Area/Wetted surface SA/WS = 2,05
Power/ Disp. Ratio HP/D = 2,27 HP/ton
Hull speed HSPD = 7,31 Kn
Potential Maximum Speed PMS = 7,90 Kn
Velocity Ratio VR = 1,08
Best motoring speed (1.1) CSPD = 6,00 Kn
Capsize Safety Factor CSF = 1,97
Motion Comfort Ratio MCR = 24,00
Roll Period T = 2,78 Sec
Roll Acceleration Acc = 0,12 G's
Stability Index SI = 0,80
Angle of Vanishing Stability AVS = 120 º
Dellenbaugh Angle DA = 16,13 º (14 kn wind)
Wind pressure coefficient WPC = 1,31

Estimated STIX 38,68

My friend wants a safety boat for the Atlantic Crossing, but rather the smallest the better. Wich would be your choice Guillermo?

:)

[Guillermo]

Puma 34, if in good condition.

Cheers.

[Antonio Alcalá]

I thought the same, but it seems the Neptun has an incredible and safety superstructure, unless you have another information. Both have the same STIX....

[Guillermo]

I find Neptun's MCR and SI may indicate a harsh behaviour. But you know:
"Horses for courses...."

Cheers.

(Caution: Do not trust my estimated STIX numbers at all. Still in needing of thorough tests and development)

[White Knight]

[QUOTE=Crag Cay;115082]Hi Vega, Guillermo et al. I really do mean to write something about the nature of the information that should be provided to the buying public with all new boats. I will post it in Guillermo's new thread about this.

However, a couple of points you made here does illustrate the limitations of the current system. Vega here has prioritised displacement in a 'seaworthy vessel' where others might put more emphasis on something else. But by lumping all these criteria into one correct 'answer' (either Category or even STIX, etc), we must all either concur what these qualities should be, or be happy to allow other 'learned people' to prescribe an answer for us.

My alternative, which I will expand on in the other thread, is to keep the information about all the qualities of the boat separate. Give the buyer details on the boat's strength, resistance to knockdown, comfort factor, weatherliness, recovery from 90 degrees, behaviour if rolled, susceptibility to crash damage, etc, etc. Then the buyer can choose where to make his own trade offs.
NOW HEAR THIS! FROM THE CHIEF ---
Hi guys, I've poroused over half of this thread and have to jibe in here with a layman's view. C. Cay is trying to simplify things here for the average Joe, reading boat mags and going to an occasional boat show; who is going to write a big check one day one sail away. He wants something simple to compare a few boats that look good to his eye, not techno-speak and coded engineer jargon. His concern is for performance, sure; but mostly he wants someone to assure him that his family and friends will be safe to trust him upon the sea! He wants to give his crew and guests a nice ride. That may mean quick ride to some and secure ride to others. Guillermo's comments affixed to his response to Luso in post #85 are more telling to him than the raw numbers. Go back and read it as Luso must have. HE WAS GIVEN THE FACTS WITH EXPERT INTERPRETATION. Simple and to the point!. It was Guillermo who suggested this thread to me and I probably know more about STIX already than this Joe boat shopper ever will. Something like the old "food pyramid" that gives a clear picture as to the suitability of a vessel to specific parameters might be helpful. You brainiacs need this discourse to help set classifications and regulations, but somehow before you quit this thread find a simple way to pass the information to guys like me who just want to buy the right boat. Thanks for listening,, Mark

[White Knight]

I have felt that but didn't know why! Thanks again!

[philSweet]

Some comments from the peanut gallery.

STIX does have some interesting features. One number that classifies marketabily, can be used to compare boats of vastly different hull form with respect to safety at sea (Guillermo has convinced me that comparing very similar boats in fine detail, as in many of the examples in this thread, is probably not its strong point), and also gives the layman an indication whether a particular design has emphasized safety (does STIX exceed boat length in feet). That's a lot to ask from one number. I think it has been very cleverly constructed. Am I wrong in thinking that this is the first widely available piece of boat data whose presentation is not controlled by the owners of the intellectual property. A precedent of a sort? (then again, how widely distributed is it?)

Regarding the conveyence of this information to the public, there would appear to be some conficts of interest here. The guild nature of the profession of boat designers is a fact of life and pushing an agenda contrary to that profession's traditions and views of what constitutes its best interest is going to be hard work. Adding more independant variables to the equation would involve getting more data from designers. Adding more variables should also reduce the distribution of STIX numbers, and this in itself is an important consideration. Changing the formula for STIX in a way that improved all of its current uses would be quite an accomplishment. That said, I like the "u" suffix proposed to designate the presence of the unsinkability factor. Has anyone floated this balloon in other arenas?

White Knight- Yes, the boat buyer would love to have a simple system to compare similarly priced and sized boats, but should we expect boat designers to provide the formula? but somehow before you quit this thread find a simple way to pass the information to guys like me who just want to buy the right boat. I'd rather they keep at each other and keep building better boats. I think the formula you seek is a very personal thing, like a fingeprint.

Guillermo, would you place a note in you original post that the spreadsheet has evolved. I downloaded several versions in succession as I discovered them. Thanks in advance.

What is "heft ratio" (vertical distance from fridge to cupholder? :D ) I couldn't find this anywhere but in this thread.

Have there been any studies in the distribution of STIX numbers? Has the distribution changed since the formula was enacted?

[Guillermo]

That said, I like the "u" suffix proposed to designate the presence of the unsinkability factor. Has anyone floated this balloon in other arenas?
I don't know, but certainly not me.


Guillermo, would you place a note in you original post that the spreadsheet has evolved. I downloaded several versions in succession as I discovered them. Thanks in advance.
Unluckily I cannot do that, as those posts are old ones and editing function is only available for relatively recent ones


What is "heft ratio" (vertical distance from fridge to cupholder? :D ) I couldn't find this anywhere but in this thread.
Its a ratio similar to the MCR (Motion Comfort Ratio), developed by a member of these forums, but unlucikly I don't remember now his nick. :(

He wrote:
"Heft ratio works like this: 20*disp. vol./(Length * Beam^2). 'Beam' is taken as the (Waterline Beam + the beam 1/8th the waterline Beam up)/2. I consider a HR of 1.0 a good compromise. I like higher numbers such as 1.5 to 2.0, but thats just my personal taste. For multis, I add the Beams of the two most leeward hulls together to figure their HR."

It has the vertue of being adimensional, so you get the same figure either in metric or imperial units.

Have there been any studies in the distribution of STIX numbers? Has the distribution changed since the formula was enacted?
What do you mean by the 'distribution of STIX numbers'?

Cheers.

[philSweet]

Guillermo,

I was thinking of a simple scattergram. Boat length on the x axis, STIX number on the y axis, and a bunch of dots representing boats in production at any given time. Wondering how much STIX scores have shifted over time.

[Guillermo]

Phil,
I don't know if somebody has worked out such scattergram and then follow up its variations with time. Not easy, as STIX is relatively new and not all boat manufacturers and/or designers make it available to the public. As a matter of fact there is a clear tendency not to inform about it. Most manufacturers just inform about the design category.

Cheers.

[deepdwn8]

All of this is extremely interesting, and I really want to learn about the calculations and other things involved in the boat building/design world.

Does anybody have books or litterature that I could read and study on the matter...

or colleges that specify boat engineering and design?
-Dan

[Guillermo]

Dave Gerr: Boat Strength and The Nature of Boats

Lars Larsson and Rolf Eliasson: Principles of Yacht Design

Skene's Elements of Yacht Design



Cheers.

[richardsnowstar]

Hi, Does anyone know where I can get official Stability info for a 1985 Southerly 115. I need it to get the yacht MCA coded for charter. Any help would be appreciated. Thanks, Richard.

[Guillermo]

Perhaps it could be useful if you contact the RYA and ask them http://www.rya.org.uk/Pages/Home.aspx

Cheers.

[richardsnowstar]

Thanks for this, I have since found the information on their site at http://www.rya.org.uk/KnowledgeBase/technical/Pages/stabilitydata.aspx

Richard.

[TeddyDiver]

Think this Eric Sponbergs post should be duplicated here. Also link to the original thread http://www.boatdesign.net/forums/boat-design/center-flotation-calculation-implications-30857-14.html
ON A SCALE OF ONE TO TEN—THE “S” NUMBER (S#)

Wouldn’t it be nice to rate the performance of all sailboats on a scale of one to ten?

Here’s the problem—we have different ways to rate a sailboat’s potential performance in the form of design ratios, handicap rules and ratings, and level ratings. In fact, rating systems have been around for centuries, dating back to England and the realm of Queen Elizabeth I—over 400 years. And in all that time, sailors and designers have continuously argued over what makes a boat go fast, and what should be measured and rated in order to allow disparate designs to compete on equal terms. VPP programs and CFD codes have tried to make performance ever more definable, but these tools require sophisticated programs and specialized people to run them. An alternative solution is to race in one-design boats, but, unfortunately, not everyone wants the same boat. On top of that, not everyone wants to race. Still, we want to be able to judge performance—we always want to know about performance.

A similar problem crops up with advertising hype—this or that boat is a racer/cruiser, cruiser/racer, racing machine, or simply just a dog that can’t get out of its own way. Who defines these things, and how is anyone supposed to make sense out of it all?

A rating number from 1 to 10 might simplify things for the average sailor and designer. What can we do with the information we already have without resorting to a consultant—some way that anyone can rate any boat on a scale from 1 to 10? Has anyone done this? Yes, someone has.

Back in the mid-1980s, I designed a “Boat-in-a-Box” sailboat—that is, a boat that could ship inside a standard 40’ shipping container—for a client in Texas, Mr. A. Peter Brooks. At the time, he and I both were also consulting for Cat Ketch Yachts Inc., the builder of the Herreshoff and Sparhawk cat ketches. Brooks was a retired business consultant and author, and he did some writing and marketing for the company. I designed all the carbon fiber free-standing masts for the boats. Brooks invented the idea for what he called the “S” Number (S#)—a single number between 1 and 10 which could rate the performance of all sailboat designs. This idea was published in Telltales, a southern Texas boating magazine, in April, 1988. I have never seen anything like it, before or since.

The concept is rather simple and is based on the Displacement/Length ratio (DLR) and Sail Area/Displacement ratio (SA/D), both of which we have discussed in the last few weeks. We know that DLR relates to drag—heavier displacement for a given length results in more drag, and boats with high DLRs are slower than boats with low DLRs. We also know that SA/D relates to power—more sail area for a given displacement results in more speed, and boats with high SA/Ds are faster than boats with low SA/Ds. We have also plotted SA/D versus DLR in a chart, and have seen how the spread of data points relates to boat performance. We use these same ratios—SA/D and DLR—to calculate S#, so we don’t need any new computer program to achieve our goal—just one new equation.

The equation for S# is an exponential and logarithmic function using DLR and SA/D as the primary variables. We already know how to calculate DLR and SA/D, and I am going to remove the slash “/” from SA/D so that it is less confusing in the S# equation— we’ll use the term “SAD.” Although the S# equation looks complex, it can be easily programmed into a calculator or a spreadsheet. Here it is:

S# = 3.972 x 10^[-DLR/526 + 0.691 x (log(SAD)-1)^0.8]

Brooks developted this equation with the assistance of Dr. Fred Young, at the time Dean of the College of Engineering at Lamar University in Beaumont, Texas. I spoke with Dr. Young by telephone some years ago just to make sure I understood the equation correctly, and he was very helpful.

Brooks collected a list of boat designs and their particulars from various published sources and calculated their S#s. Then he classified the boats according to the following categories:

· Lead Sled: S# = 1 to 2
· Cruiser: S# = 2 to 3
· Racer-Cruiser: S# = 3 to 5
· Racing Machine: S# = 5 to 10

The reasons for the ever-broadening scale of category names is simply a function of the logarithmic scale embodied in S#. This appears to be an asymptotic function. You can never reach the number 10, and you can never reach the number 1, both of which are the asymptotes.

Now we have a way to definitively categorize boats, not a wishy-washy, vague notion; we got a unique number for each and every design! I attach the spreadsheet that I used to calculate the SAD and DLR numbers in that chart I posted last week (S# Chart 01). Included in that spreadsheet is the S# calculation (pink column), and next to that is the category name for each boat. I sorted the data according to descending values of S# so that you can see how the categories play out. Also included in the spreadsheet is S# Chart 01 of SAD vs DLR for these boats. There are other charts there, too, which you can study or modify at your leisure.

The magazine sources for these sailboat designs are listed at the top of the data table and in the left-most column with the date of publication in the second column. They are all published data from advertisements and design reviews that I have collected over the years. As I review the magazines, I continually add data to this table. The original Telltales data that Brooks used and published in 1988 is included. I find it discouraging that in recent years the magazines have been slacking in publishing worthwhile design data on boat designs. Sometimes, it is difficult to get even the most basic of information—some small piece is frequently missing, and you don’t necessarily find it on the manufacturers websites. But we gather what we can.

Now here is where my contribution to S# comes in. Overlaying this chart of SAD vs. DLR, I have calculated and plotted the traces of constant S# so that you can see how they subdivide the boat population. I attach this chart as well (S# Chart 02). In the data table, I highlighted in yellow a few of my designs, and then have labelled them in the chart, just to give you some context.

So what do we see? S# Chart 02 can be interpreted as follows:

A boat that is very lightweight and has lots of sail area will have a low DLR and a high SAD. It has a high power-to-weight ratio, and so it will be very fast. Its S# will be between 5.0 and 10.0. It will be a “Racing Machine.”

On the other hand, a very heavy boat that has a small sail area will have a high DLR and a low SAD. It has a low power-to-weight ratio, and it is not going to be a very good performer. Therefore, its S# will be between 1.0 and 2.0. It will be a “Lead Sled.”

For S# values between 2.0 and 3.0, the boat will have a decent amount of volume to carry people and goods but won’t necessarily be a real hot-shot sailer. We can place these boats in the “Cruiser” range.

For S# values between 3.0 to 5.0, the boat will be in the middle ground between “Cruisers” and “Racing Machines”, so we can call them “Racer-Cruisers” (or “Cruiser-Racers” if you prefer.)

Therefore, the net result of the S# is a clear delineation of sailboat performance using a convenient scale from 1.0 to 10.0, and by this we give definitive meaning to typical descriptive names. In fact, Brooks claimed that the S# is a fairly reliable predictor of PHRF or IMS rating. For two boats of the same length, the one with a higher S# will be faster, will take less time to sail around a course, and therefore will have a lower rating. However, in the same article, this footnote appears: “Both Dr. Young and the author stress that the ‘S’ number is not a handicapping or rating system, but a guide to probable boat performance vs. other boats of comparable size.” I personally agree with that opinion.

Something else that is quite interesting is shown in the next chart (S# Chart 03) also included in the spreadsheet. I had the notion to divide SAD by DLR and plot that against S# and got a surprising result. All of the data forms a unique cluster in a very well-defined curve. These are two independent functions plotted against each other. Rarely in science do we see such a profound correlation of data. I am not absolutely sure of the ramifications of this, and maybe I am reading into it more than I should, but I would have expected a broader spread of data points in this chart. The relationship of the SAD/DLR ratio to S# is extremely solid as indicated by the cluster of points along its trend line. The equation for the trend line shown at the top of the chart is another way to approximate S# in a simpler cubic equation. Throughout the lower categories, S# follows the trend line almost exactly, and it is only in the Racing Machine category where there is some scatter away from the trend line. If we plot S# versus some simple dimension or factor such as LOA or Displacment, we see no discernable relationship to S# at all. But S# vs. SAD/DLR gives us a very unique view of sailing performance.

I am not mathematician enough to explain why this works as we see it. I have, however, on occasion, presented plots like S# Charts 02 and 03 to clients to review the performance they have in their current boats or are trying to achieve in a new design. It seems to give them a clearer understanding of what their current boat does or their new boat is going to do. S# is a way to be a little more scientific in layman’s terms. This gives us a better tool to clearly showcase performance without having to go to the model tank, measure resistance factors, plot results, correlate them to full scale, and then do VPPs on top of all that. A picture says a thousand words, and this seems to do a pretty good job.

You will also see in the data table and in the charts a calculation and plot of Ted Brewer’s Motion Comfort Ratio (MCR) plotted against S#. I will explain that in next week’s topic.

In the meantime, you are all free to use this database and spreadsheet as you please. You may add to it as you do your own designs or review the designs for others. You may change it around and expand it however you want. You may do other analyses and manipulate the data at your will. Send it to your friends, fellow designers and fellow sailors. Pass it around. Discuss it. Use it. The S# is for the public domain, and I hope it adds to our better understanding of sailboat performance. Time will tell.

Eric

[Guillermo]

Thanks for bringing my attention to Eric's excellent post, Teddy. Not enough time now to participate in the forums these days (work traveling), I'll study this interesting S number carefully when back home.

All the best.

[Alfredoc]

Hi all,
someone can help me?
I've tried to calculate the STIX of the Jeanneau SELECTION 37 but whit infruttuosely results!!! :confused: :confused:
Could you help me:?: :?: :?: :?:

Cheers

Alfredo

[TeddyDiver]

Pretty sure they don't announce all the necessary data you to do that. Have you the spreadsheet for the STIX formula? If not here's a copy. Just throw the numbers in, but be aware, crap in.. ;)

[Alfredoc]

Thank's Teddy,
i've tried but i haven't all the numbars, in few week i have read all this iteresting post, I'm not a technician but a simple corintian sailor who wont make a sail race who the committee want boats whis a stix >32 like a A class:(

ciao

Alfred

[Guillermo]

Alfredoc.
I have found something useful here: http://cruisingresources.com/Jeanneau_Selection_37

But to be able to work out an approximate STIX (roughly) I need a profile plan showing the sail plan and the underbody. If you provide me with such a plan I can do the numbers for you.

Cheers.

[Alfredoc]

Dear Guillermo,
first of all thank you for this trade is really interesting for learnig about boat and her stability.
the only numbers who i have are the one-desing roule: http://selection37.com/francais/aps/JaugeDec05.pdf

personally i need changing mast (more short ) but if my boat have a low stix and avs is unnecessary

here i join a irc certificate of a selection modified (with the short mast)

ciao

Alfredo

[Guillermo]

Those are more accurate numbers, excellent. Now we need a profile drawing.
Cheers.

[Alfredoc]

This are the only two design who i have :(

a lot of thank's

ciao

Alfred

[Guillermo]

OK.
I'll work on them this weekend.
All the best.
Guillermo.

[Guillermo]

Sorry I have not been able to work on it this week end (busy boating and spearfishing with kids). I'll try to do it some day this week.
Cheers.

[Alfredoc]

Guillermo don't warry !!!!!!!

I've no hurry

When you can, you are giving me a great gift

Thanks a lot

ciao

Alfred

[Trif]

Can somebody estimate the STIX for the 30 ft. cutter (http://www.whisstock.com/page_02.php?page=02&page_id=2.14&design=67&PHPSESSID=6fe67d84b798e1e7b2253dcdd1d3bd26) designed by George Whisstock?

I think this boat might be much seaworthy than many modern day sailing boats, and I'm intrigued by its designated B category, not A. Maybe somebody has a clue for this.

Best regards!

[TeddyDiver]

Seems to be the centerboard version so it's obviously bit "worse" considering STIX values..

[Trif]

Seems to be the centerboard version so it's obviously bit "worse" considering STIX values..

I am not interested in centerboard version, but the deep fin keel.

[TeddyDiver]

Sorry but the data on the page you linked was for the centerboard.. click "Design Data" below the plan prizes to see GZ curves for both versions, and to me it seems that the deepkeel version might be in A category. To know for sure ask from the designer..
BR Teddy

[Trif]

Sorry but the data on the page you linked was for the centerboard.. click "Design Data" below the plan prizes to see GZ curves for both versions, and to me it seems that the deepkeel version might be in A category. To know for sure ask from the designer..
BR Teddy

Well, the designer says it's the size involved in the category given. Anyway, the boat seems sound for me.

[Crag Cay]

There is a size and displacement quotient in the STIX calculation, with lengths less than about 32ft and displacements less than 3.5 tons both being deemed 'undesirable' for an CAT A vessel and therefore heavily penalised. There are some boats that do manage CAT A despite being under 30ft LOA, such as the Fisher 25 and Vancouver 28, but they have extremely high displacements.

The heightened significance of this 'size quotient' in categorising boats under 32 feet, make the use of the RCD a poor indicated of 'seaworthiness' on sailing boats of this size. Therefore you need to look at all it's qualities and make up your own mind.

[Trif]

I have noticed that Hallberg Rassy 31 has pretty similar dimensions and GZ curve, and it is an A category. At more than 4.25 t, 067 design is quite heavy.

It is said that Multichine 28 (Roberto Barros) could fit A cat, and is much lighter, has more beam and little lest.

Maybe adding a bulb, about 200 kg, to its keel could improve a bit. I think will definitely improve its stability. Anyway, the ballast is 39 % of its displacement, not something you could find on modern boat.

Best regards!

[TeddyDiver]

Anyway, the ballast is 39 % of its displacement, not something you could find on modern boat.
That's more or less where it is.. there's a lot more difference in the D/L ratio..

[cduck]

Alfredoc ---

I've got a lot of info on this boat (IMS certificates, have done both keel and rig changes). Please feel free to contact me for details.

[Alfredoc]

Cduck

I've send you an e-Mail

Ciao

Alfredo

[Guillermo]

Friend Konstantin, from Russia, brings my attention to a bug in the FKR formula at the spreadsheet to calculate the STIX I had uploaded to this thread.

It was written:
FKR = 0,875+0,0883*Fr (If Fr >=1,5)
But it should be:
FKR = 0,875+0,0833*Fr (If Fr >=1,5)

I attach here the corrected spreadsheet,

Thanks a lot Konstantin! :)

[Alfredoc]

Ciao Gullielmo, when you can you remember my Stix and my Avs?

Thanks too much

Alfredo

[Guillermo]

Ciao Alfredoc,
you are right and I must apologize. I have been losing my time, efforts and patience at other thread of these forums. Let's come back to work where it worths while. I'll do the numbers for you within this next weekend. (Promised! :) )
Cheers.

[Alfredoc]

Here are some info: http://sailboatdata.com/viewrecord_metric.asp?class_id=1254
Others information are at page 21 of this thread
In this time i've tried to contact Joubert-Nivelt but i've no repay :(:(

Thanks for all

ciao

Alfredo

[Guillermo]

Alfredoc,
I have been working your numbers, for a height of mast over DWL of 16,11 m aprox (as per the drawings) and I get an approximate STIX well under 23, so the boat cannot reach more than the C category. For sure I'm wrong....:confused:

I'll revise everything tomorrow. Now going for dinner with wife and friends :)

Cheers.

[Alfredoc]

the total height of the mast is 16.320 mt but to the deck the height of the mast is 14.930 mt

C category :confused: no fear next time who i have 20 knots :D:D

good dinner

ciao

Alfredo

[Guillermo]

Alfredoc,
Still revising my numbers, I have a doubt with the Wind Moment Factor. I'll be back to you later as I'm now leaving for some sailing (gorgeous sunny day!) :)
Cheers.

[Alfredoc]

enjoy :):):)

....here in Milano are raining :(:(:(

ciao

A.

[Guillermo]

Hi Alfredoc!
Finally I've found some time to revise things.
I get an estimated AVS of 116º and with this an STIX of around 32 (there was a bug in the FWM), for an Afl around 100º. This figure is right into the A category, but AVS is not enough to comply.

As the formula to estimate AVS does not properly take into account volumes over deck, its value is probably higher (differences with the real thing can be as much as 15º). If we asume AVS as being around 120º (which complies) and Afl as 110º, which are probably more approximate figures, then STIX would be around 34-35.

The precise STIX can only be calculated with the correct data and GZ curve.

Cheers.

[Alfredoc]

Thanks a lot Guillermo that's a very good news!!!!

Now i must take contact with JOUBERT NIVELT for a real A class certificate, i hope to find them because the e-mail adress who is in internet is old :(
Otherwise i must go in la Rochelle :D:D:D:D

Thanks too much again

Ciao

Alfredo

[Guillermo]

Don't trust very much my STIX numbers, as they are a rough approximation only, with a lot of assumptions for the unknown data.

Cheers.

[Guillermo]

I'm wondering about this boat's STIX.....:D

http://www.gizmodo.es/wp-content/uploads/2010/11/500x_lovelove1_01.jpg

http://www.gizmodo.es/wp-content/uploads/2010/11/500x_jpg_installation-allsopp-0344f.jpg

http://www.gizmodo.es/2010/11/02/el-barco-en-hundimiento-perpetuo.html

http://www.gizmodo.es/wp-content/uploads/2010/11/500x_jpg_au_port-24c3c.jpg

[Guillermo]

I heve been discussing STIX matters lately at an spanish forum, so I have somewhat neglected this thread, the original one on the subject, because of my sparse time available.

I originally opened this thread stating: "I post this thread to discuss Sailing boats' Stability, their STIX and the correlation with 'old' ratios and parameters."

Well, through this thread and the spanish forum one I have had the opportunity of analyze quite a bit of boats' numbers, as well as getting some feedback from owners, designers and boatyards about their seaworthiness and behaviour. It has been, and it is yet, an interesting exercise and a learning opportunity.

In this process I have found some nice examples of how STIX is a tricky number which may lead to incorrect assumptions about a boat's ability to cope with bad weather from the point of view of safety, if it is taken as the only information to make up our mind (which is what we do when we do not have not enough formation/information about a particular subject and a "magic" number is offered to us). We have discussed about this before in this thread, even passionately, as well as about some of such boats, usually light and fast ones.

Today I want to bring here another example of how STIX alone can mislead our judgement, this time in a contrary case: A classic heavy and well proven seaworthy boat with a surprisingly low STIX, the Hans Christian 48T (http://www.hanschristianyachts.com/t48/48home.htm)

http://user.online.be/~cd00902/48T_DH_reefed.jpg

Well, this pretty lady (to my taste at least), with a proven record of safe blue water sailing around the world, has an STIX of 32.5 (!!) which is barely over the limit to consider her in A Category under the RCD. Amazing! :eek:

The reason for this is the FDS (Dynamic Stability Factor) in the STIX formula is very low (0.53 thus spoiling the rest of factors which show good figures), because the considered downflooding angle is not specially high (86º) due to her traditional low sheerline, and the GZ curve is relatively "flat" (but her RMs are pretty good because of her heavy displacement). AVS is 114º (All this in the MOC, minimum operating condition, as defined in ISO 12217. Ruled AVS for this boat is 100º)

Here some of her excellent traditional ratios, which give us a clue of her nice behaviour at sea:

Motion Comfort Ratio = 45,42
Capsize Safety Factor = 1,61
Roll acceleration = 0,05
Stability Index = 1,17

I want to heartly thank Jack Hall of Pantawee Marine (http://www.pantaweemarine.com/) & Hans Christian Yachts (http://www.hanschristianyachts.com/) and Rick van Mourik of Rimo Yachting, their representative in Europe, for their kindness and honesty providing to me the detailed STIX calculation and stability curve. Not all boatyards are available to happily release such information, as I have checked myself.

Cheers.

[TeddyDiver]

I want to heartly thank Jack Hall of Pantawee Marine (http://www.pantaweemarine.com/) & Hans Christian Yachts (http://www.hanschristianyachts.com/) and Rick van Mourik of Rimo Yachting, their representative in Europe, for their kindness and honesty providing to me the detailed STIX calculation and stability curve.
That's really great of them :D

[Tad]

Guillermo.....

I'm just curious.....is the stability curve provided for the Hans Christian based on a calculated VCG or on the results of an inclining experiment?

I ask because I have a theory that almost all published stability curves of stock production boats are done with VCG as calculated from a base boat. Every cruising boat on earth is equipped with additional heavy items on the deck, above the deck, or in the rig. My interest is in the real VCG of "ready for sea" cruising boats.......any info is welcome.......

Thanks

[Guillermo]

Guillermo.....

I'm just curious.....is the stability curve provided for the Hans Christian based on a calculated VCG or on the results of an inclining experiment?

I ask because I have a theory that almost all published stability curves of stock production boats are done with VCG as calculated from a base boat. Every cruising boat on earth is equipped with additional heavy items on the deck, above the deck, or in the rig. My interest is in the real VCG of "ready for sea" cruising boats.......any info is welcome.......

Thanks
A good question Tad. As per ISO 12217 stability for that boat has to be derived from an stability test (Class A & 12m+ length => Option 1 & Notified Body => stab test), and I asumed that. Anyway I will ask them.

Cheers.

[fcfc]

A good question Tad. As per ISO 12217 stability for that boat has to be derived from an stability test (Class A & 12m+ length => Option 1 & Notified Body => stab test), and I asumed that. Anyway I will ask them.

Cheers.

Are you sure ?

annex C 2.2 case c) from ISO12217-2:2002 explicitely allow for calculated VCG under some conditions.

[Guillermo]

annex C 2.2 case c) from ISO12217-2:2002 explicitely allow for calculated VCG under some conditions.
Yes, you're right. But in my opinion that's not the better practice and I always do the inclining experiment. That's why I asumed, perhaps naïvely, everybody does. As said, I'll ask HC Yachts.

Best regards.

[Tad]

I don't think any naval architect will argue that an inclining is not the best way to establish actual "as built" VCG.......but the buying public do not know this.....and they do not understand the significance of load condition when the calculation or inclining is done.

For instance on a steel cruising sailboat I recently ran stability calculations for the AVS at full load is 95 degrees and at arrival condition (10% tanks) only 83 degrees (VCG from inclining).......This is with the big rubber boat and outboard up in the davits, genoa on the furler, full batten mainsail on the boom (not hoisted), two anchors on the bow, big liferaft on the cabintop, dodger up, radar and solar panels and windmill and barbecue all in place........

[Guillermo]

After telling the people of HC Yachts about this thread, they do not answer my e-mails any more....:(

[Tad]

Sorry to hear that Guillermo......

[lausl]

I have had a spreadsheet for solving the VCG from incling experiment data, its gone in the nirvana somehow, and I thought it was from the spreadsheet page here, but a cannot find it,,

Does anybody know of a source or wants to share?
Regards,
Klaus

[Guillermo]

You may ask Brian Trenhaille:
http://www.hawaii-marine.com/templates/
Have a look at the bottom of the page.

Cheers.

[Nick.Rollings]

Hello List

Just reading this thread on stability and old boats.

Suzi and I are looking at a Valiant 40 for liveaboard cruising on the East Coast of Australia and would value your oinion on this design. We plan to undertkae coastal cruising for the first year, and then venture to fiji or similar.

thank you

Nick and Suzi


Olá António,

Your post is not big but to answer to all your questions it would be necessary a huge one:rolleyes: .



That’s a myth. Some of the old boats are still good boats but most of them are just old and outdated designs. Most of them are slow, heavy, undercanvased boats, with old rigs (that in many cases need a complete substitution) and they have reefing systems that need the presence of a crew man at the foot of the mast, a situation that can be dangerous in troubled seas. It is true that they are normally more comfortable (because they are heavier) in a seaway.



The difference in speed between one of those old and heavy boats and a fast cruiser can be very considerable and in that case there is some truth in that. But comparing with your boat that difference will be no more than 2 knots, and I don’t think that it will be important, regarding the ability to escape low pressure systems.

Regarding the roll periods of those boats, they would be a little higher than in your boat, but not much, and that has to do with comfort and not with seaworthiness (unless you get seasick at sea). If the difference in roll period can be considerable between your boat and an old and heavy one (making the older one more comfortable), I don’t believe that you would feel a significant difference in comfort, comparing your boat with a sport cruiser, like the First 47.7, in what concerns rolling.
In this kind of (modern boats) the amount of difference in forefoot is more important regarding comfort.

As I have shown in this thread (see the comparison between the Jeanneau 44), regarding seaworthiness, normally for big production boats, and for the same range, the sports boat is not less seaworthy than the cruiser boat and sometimes it is even more. On the other hand, the superior sailing area will make it a boat more difficult to handle and a boat that will need a lot of reefing work (not that it will be more difficult to reef, just that you will need to do that a lot more times).



I would say 40, with a minimum weight of 5T and a minimum AVS of 120º.

Stix number, with a minimum AVS and a minimum weight is the best general rule they could provide to make an evaluation of sailing boats stability and seaworthiness.
Personally I find that displacement has not the importance it deserves in the STIX calculation.

The Dehler 29 is a very good boat, but with a weight of around 3T do you really think that the boat will be safe sailing in force 10 winds and 7m waves? I would like to put all the guys responsible for the actual criteria that define Class A boats, inside a Dehler 29 in those weather conditions:D .

Probably not, because you are a sailor, but if you where a kid buying his first cruiser boat, coming from dinghy sailing and knowing very little about the ocean or boats, why should he not believe in that official certification? And armed with that false assurance expose himself (and others) to dangerous situations that could end in tragedy?



Yes, certification of anything regarding safety should be a serious matter (and in my opinion this one is not credible).

But one thing is the certification which advises you about what is officially considered safe, another thing is the freedom of setting sail in a boat of your choice.

I am for the responsible advice, but also a defender of the individual liberty. The advice should be one that you follow or not, and should have nothing to do with the freedom and possibility of sailing in the boat of your choice to where you want;) .

Saludos

[Guillermo]

Have you read this?
http://bluewaterboats.org/valiant-40/
http://en.wikipedia.org/wiki/Valiant_40_sailboat
http://www.boatus.com/jackhornor/sail/Valiant40.asp
http://www.cruisingworld.com/sailboats/boat-reviews/valiant-40

[Nick.Rollings]

Greetings from Aus,

Thanks for your reply and links, yes I have seen thess sites and used them (and the Valiant owners group) as the basis for my decision for a Valiant (or similar). I have also been over 2 Valiants in the last year and like them very much.

However, this site is a little different to others I read in that you guys are into boat design and the various methods of assessing a yachts suitability for a particular purpose. I guess I was after a professional opinion in terms of the yachts design to back up the positve stories we read in these other sites, particularly in light of V40's being old boats. I use Carl's sail calculator for basic stuff.

I think if I read between the lines however, you are saying the Valiant 40 is fine for what we want to do?

thanks


Nick

[Guillermo]

Hi Nick,
As I'm traveling I have not had time do an in-deep look to the Valiant ratios. Could you please post the ones you got using Carl's calculator?

I have only got this:

Sail Area/Displacement....15.2
Displacement/Length.........255
Ballast/Displacement..........34

Those are nice numbers for a short-handed globetrotter, to my taste. Ballast/displacement could have been somewhat higher, but it's good enough.

I also like her long keel and protected rudder, as well as her handsom canoe stern.

Her relatively low freeboard will probably make her downflooding angle (to the companionway) somewhat low by today's standards, which can negatively affect her STIX, as it happened in the commented case of the Hans Christian 48T

Having said that, I have to say I love the boat and I find it pretty adequate tou your intended plans. :)

Cheers.

[Nick.Rollings]

Thanks again for your advice on this, particularly since you are busy travelling.

Its just great to hear a professional dicussion on a yacht I (think) I know to be a good balance for our requirements. And, yes, she does have a nice rear end!

Carls Sailing Calc gives

Valiant 40
LOA 39.34
LWL 33.88
Beam 12.32
Disp 22306
SA 768

Disp to LWL 256
LWL to Beam 2.75
Hull Speed 7.8
Motion Comfort 33.96
SA to Disp 15.51
Capsize Ratio 1.75
Pounds / Inch 1491
Sailing Category - Cruiser

I'll do a bit of swatting up on STIX as well, its always fun to learn new things.

thanks

Nick

Hi Nick,
As I'm traveling I have not had time do an in-deep look to the Valiant ratios. Could you please post the ones you got using Carl's calculator?

I have only got this:

Sail Area/Displacement....15.2
Displacement/Length.........255
Ballast/Displacement..........34

Those are nice numbers for a short-handed globetrotter, to my taste. Ballast/displacement could have been somewhat higher, but it's good enough.

I also like her long keel and protected rudder, as well as her handsom canoe stern.

Her relatively low freeboard will probably make her downflooding angle (to the companionway) somewhat low by today's standards, which can negatively affect her STIX, as it happened in the commented case of the Hans Christian 48T

Having said that, I have to say I love the boat and I find it pretty adequate tou your intended plans. :)

Cheers.

[Guillermo]

Here the numbers I've worked out for the Valiant 40. All to be taken with perhaps something else than a grain of salt, as I have taken rough measurements on the avilable plans in internet.
(Mix of metric and imperial data, sorry)


INPUT

Hull length (m) = 12,16
Waterline length (m) = 10,36
Maximum beam (m) = 3,76
Floatation beam (m) = 3,38
Total draught (m) = 1,83
Body draught (m) = 0,76
Moulded depth (m) = 1,72
Freeboard (m) = 0,96
Displacement (kg) = 10.206
Ballast (kg) = 3.500
IJPE area (m2) = 71,7
Air draft (m) = 15,66
Heeling arm (m) = 13,30
Engine power (HP) = 54,4
I (m) = 14,30
J (m) = 5,6
P (m) = 13,5
E (m) = 4,7
Height keel (approx.) = 1,07
Length keel (approx.) = 3,78


OUTPUT (with some assumptions)

Block coeffcient = 0,37
Prismatic coefficient = 0,56
Waterplane coefficient = 0,7
Main section coefficient = 0,67

(2Lwl+Lh)/3Bmax Ratio = 2,91
Lwl/Bwl Ratio = 3,06
Length/Draught Ratio = 6,64
Beam/Draught Ratio = 2,05
Beam waterline/Body draught = 4,45
Ballast/Displacement Ratio = 0,34
Displacement/Length Ratio = 256
Sail Area/Disp. Ratio = 15,49
SA (metric)/ Power (Imp.) = 1,32
Power/ Disp. Ratio (HP/Ton) = 2,42
Hull speed (kn) = 7,81
Potential Maximum Speed (kn) = 8,19
Velocity Ratio = 1,05
Efficient motoring speed (kn) = 6,41
Capsize Safety Factor = 1,75
Motion Comfort Ratio = 34,0
Heft Ratio = 1,16
Moment of Inertia (kg*m2) = 46232,43
Roll Period (sec) = 3,86
Roll Acceleration (G's) = 0,07
Stability Index = 1,03
Calculated Angle of Vanishing Stability (º) = 121

Upright Heeling Moment (kg*m) = 4831,20
Righting Moment at 1º (kg*m) = 217,16
Heeling Moment at 20º (kg*m) = 4106,61
Righting Moment at 20º(kg*m) = 2021,94
Dellenbaugh Angle (º) 14kn wind = 22,25


Initial Metacentric height (m) = 1,2
Asumed AVS (º) = 121
Asumed downflooding angle (º) = 90
GZ at downflooding angle (m) = 0,44
GZ at 90 degrees (m) = 0,44
Area to downflooding (m*deg) = 39,03
Area to AVS (m*deg) = 45,85

STIX (to input displacement) = 29 (B category)


Most probably the STIX is higher, but anyway it seems to be not very high, as it was the case of the HC 38T. If real downflooding happens around 100º then STIX goes up to 31. If it is 110º, then STIX rises to 33, just within the A category. But we have to consider these boats were designed without STIX in mind. Are they less safe because of that? No, in my opinion.

Again: Please be VERY cautious about all this STIX thing. It's based in very, very rough (and may be wrong) approximations.

[Crag Cay]

With all due respect Guillermo, I think you should consider removing those figures for a number of reasons.

Firstly, the designer is still active and if anyone wants the full calculations for the Valiant 40, Bob Perry does a consultation service where he would be more than happy to answer any question.

Secondly, although you cage your calculations with plenty of caveats, the STIX figures fly in the face of all established experience with this particular boat. I have never heard of any 'seaworthiness' problems with the Valiant 40, so to even suggest it is CAT B would appear to be number crunched nonsense. Either there are gross errors in your assumptions, or the credibility of the ISO standard takes yet another blow to its credibility.

The big issue with buying a Valiant 40 is paying the right price for them. The combination of their wide age range, their quite small accommodation for their size (without the cute / silly stern they are only a ~37 foot boat) and the wide variation in the quality of repairs to the ones with Uniflite fire retardent resins, has to all be set against their reputation and cult status.

[Guillermo]

Crag,
I respect your opinion, but after considering it I think I'm going to keep the post as it is. This is a boats design forum and any of us has the right to analyze whatever boat if done with the proper respect to its designer. Specially if the designer is of the size of Bob Perry.

I am not disrespecting him at all as I'm clearly expliciting my numbers may be wrong and also I'm explicitly saying I do not care if the STIX is low or not to like the boat and find it a lovely and excellent one. One of those I would like to own myself.

In my opinion this case is, as in the case of the HC48 T (STIX of only 32.5 as per the info provided by the builder himself) one more example of why STIX has to be taken with a grain of salt when used to judge a boat and do not take it as the "word of God" as some do.

Read again my first post in the thread, please. From there:

"....STIX provides not enough information about the seaworthiness of a boat..... and may even be a tricky and dangerous number. Seaworthiness is a complex matter, involving stability, all around scantlings, quality of movements, and a long etc."


I will write Bob Perry and make him aware of these posts just in case he wants to make any kind of comment or contribution and even any kind of criticism to my numbers and opinions. I think that's fair enough.

All the best. :)

P.S.: Done. I have sent a message to Perry Design to make them aware of these posts.

[Nick.Rollings]

Thank for taking the time to run these figures. I fully take on board the uncertainty in the figures and their subsequent interpretation.

They further suggest that the Valiant 40 is a fine yacht and would suit us perfectly for our intended use.

Unfortunatel;y the one I was goig to look at has sold!

Happy sailing.

Nick






Here the numbers I've worked out for the Valiant 40. All to be taken with perhaps something else than a grain of salt, as I have taken rough measurements on the avilable plans in internet.
(Mix of metric and imperial data, sorry)


INPUT

Hull length (m) = 12,16
Waterline length (m) = 10,36
Maximum beam (m) = 3,76
Floatation beam (m) = 3,38
Total draught (m) = 1,83
Body draught (m) = 0,76
Moulded depth (m) = 1,72
Freeboard (m) = 0,96
Displacement (kg) = 10.206
Ballast (kg) = 3.500
IJPE area (m2) = 71,7
Air draft (m) = 15,66
Heeling arm (m) = 13,30
Engine power (HP) = 54,4
I (m) = 14,30
J (m) = 5,6
P (m) = 13,5
E (m) = 4,7
Height keel (approx.) = 1,07
Length keel (approx.) = 3,78


OUTPUT (with some assumptions)

Block coeffcient = 0,37
Prismatic coefficient = 0,56
Waterplane coefficient = 0,7
Main section coefficient = 0,67

(2Lwl+Lh)/3Bmax Ratio = 2,91
Lwl/Bwl Ratio = 3,06
Length/Draught Ratio = 6,64
Beam/Draught Ratio = 2,05
Beam waterline/Body draught = 4,45
Ballast/Displacement Ratio = 0,34
Displacement/Length Ratio = 256
Sail Area/Disp. Ratio = 15,49
SA (metric)/ Power (Imp.) = 1,32
Power/ Disp. Ratio (HP/Ton) = 2,42
Hull speed (kn) = 7,81
Potential Maximum Speed (kn) = 8,19
Velocity Ratio = 1,05
Efficient motoring speed (kn) = 6,41
Capsize Safety Factor = 1,75
Motion Comfort Ratio = 34,0
Heft Ratio = 1,16
Moment of Inertia (kg*m2) = 46232,43
Roll Period (sec) = 3,86
Roll Acceleration (G's) = 0,07
Stability Index = 1,03
Calculated Angle of Vanishing Stability (º) = 121

Upright Heeling Moment (kg*m) = 4831,20
Righting Moment at 1º (kg*m) = 217,16
Heeling Moment at 20º (kg*m) = 4106,61
Righting Moment at 20º(kg*m) = 2021,94
Dellenbaugh Angle (º) 14kn wind = 22,25


Initial Metacentric height (m) = 1,2
Asumed AVS (º) = 121
Asumed downflooding angle (º) = 90
GZ at downflooding angle (m) = 0,44
GZ at 90 degrees (m) = 0,44
Area to downflooding (m*deg) = 39,03
Area to AVS (m*deg) = 45,85

STIX (to input displacement) = 29 (B category)


Most probably the STIX is higher, but anyway it seems to be not very high, as it was the case of the HC 38T. If real downflooding happens around 100º then STIX goes up to 31. If it is 110º, then STIX rises to 33, just within the A category. But we have to consider these boats were designed without STIX in mind. Are they less safe because of that? No, in my opinion.

Again: Please be VERY cautious about all this STIX thing. It's based in very, very rough (and may be wrong) approximations.

[George Keune]

A last correction (And I hope the very last one!) of the STIX spreadsheet.

Caro Mr. Guillermo,

Can you help? I believe I understand the calculation as per you xls. My question how to calculate "area to flooding Agz" and "area to AVS"

[Guillermo]

Caro Mr. Guillermo,

Can you help? I believe I understand the calculation as per you xls. My question how to calculate "area to flooding Agz" and "area to AVS"
You need the GZ curves of stability in the MOC and MLC conditions (this last if applicable).

[nikmik]

Mr. Guillermo,

I started with the construction of the following characteristics yacht:
-Desing length 8.975 m
-Lengthover all 8.975 m
- MAx beam 2.500 m
- Desing Draught 0.530 m
- Displacment 5.25 t
- Block coeff 0.40307
- Prismatic coeff 0.5469
- Vert. prismatic coeff 0.5290
- Lenght on watherline 8.287 m
- Beam on waterline 2.118 m
- Entrance angle 18.868 deg
- waterplane coeff 0.6228
- midsship coeff 0.7876
Conditions must be beam max 2.5m.
Is it possible with this trough will be STIX class A

[Guillermo]

Hi, nikmik
Those data are not enough to know it. Have a look at the attached STIX spreadsheet to find out what the necessary data are.
Regards.

[neelie]

Maybe this is thread drift - if so, I apologize but, I guess the subject being Angle of Vanishing Stability it is semi relevant.

The crux of my question, is just how relevant is this number?

Retirement beckons and I am now looking at a couple of cruising boats, HR46 and an Alubat Ovni 455. Two extremes and yet both equally competent cruisers.

One has an AVS of say 140-ish plus and the other may be lucky to have one of 110.

It is fair to say that capsize past 90 degrees will in all likelihood be wave induced.

The center board fraternity say that with their boards up, there is markedly less propensity for the wave to "trip" the boat up. Assuming this is true (and I don't know for sure that it is), then an AVS of 110 would seem quite proper would it not?

So in the real world of compromises, should this difference in AVS influence ones choice of boat?

Years ago, I would have said yes, but now I have become cynical of ratios and "magic" numbers, All the ratios can be manipulated by manufacturers putting out data that is not exactly correct.

I am now of the opinion that real world experience is the only measure. Am I wrong?

[nikmik]

Neelie
My idea is that I make a boat this feature before retirement. I am now in the design phase. then all the screams of finance unfortunately

[MikeJohns]

............
So in the real world of compromises, should this difference in AVS influence ones choice of boat?..............

I am now of the opinion that real world experience is the only measure. Am I wrong?

There are many factors that affect the safety of a crafts crew. AVS is one of them.
It is however well proven that the risk of the boat inverting in waves is closely related to the area of the RM curve from 90 degrees to AVS. Also the deck edge is the real 'tripping device' not the keel.

Also another very important issue is what happens after the craft inverts, or the time to re-right. Studies verified with comparison to real world events show a good general relationship between time to recover and AVS.
At 110 degrees the boat will generally be close to killing crew trapped on deck before a wave large enough to re-right it comes along. Once the AVS gets over around 140 degrees it takes seconds and not minutes and you'll even be conscious if you were trapped on deck under the boat.

There are plenty of other design features too that affect safety.

Also there are factors like the accuracy of forecasting of wind and waves, the experience of the crew and the condition of the gear. If you can avoid survival situations and keep a craft within it's sensible limits of safety then you can sail anything safely.

STIX is not the greatest measure of craft safety, it's too easy to fudge the measure IMO.

[Guillermo]

If you can avoid survival situations and keep a craft within it's sensible limits of safety then you can sail anything safely.

STIX is not the greatest measure of craft safety, it's too easy to fudge the measure IMO.
Agree. :cool:

[Tad]

STIX is not the greatest measure of craft safety, it's too easy to fudge the measure IMO.

IE is the 110 degree AVS of the Ovni with the keel up or down?

[neelie]

The center board of the Ovnis are not ballasted and would have only a small effect on the righting moment.

As far as the AVS of 110 for the Ovni, I stress that I do NOT know this to be fact. One of the best kept secrets in the yachting world is the AVS of the Ovni series.

I agree AVS is but one of many variables, I am just trying to get a subjective feel for how much weight it merits in the grand scheme of things.

I saw a table of Length vs desired AVS for Cat 1 boats. For 15 meters, the recommended minimum AVS was 121.8. Can anyone calculate the AVS to such precision?

[souljour2000]

I just got a hold of a Morgan-designed CB '66 Columbia 40...and I'm looking for input I suppose because this model had only 55 made and doesn't come up much as a bluewater boat and she deserves some consideration since her 15 minutes of fame back in the 60's...as a derivative of "paper tiger" and "sabre"...
Not withstanding the issues with her deck which needs replacement/re-cored in most of the foredeck and the fact that the valiant 40 was probably built a bit more robustly in terms of bulkhead tabbings and hull/deck flange,etc.....I other wise think the Columbia 40's numbers stand with the Valiant 40 or many other boats...add to her 8400 lbs lead the diesel hung low below the salon sole and she is stiff and has a low cabin profile...any thoughts..?.I feel I got a good blue-water platform(at the right price)given that she needs alot of work...Don't wanna be a thread -killer though my rep precedes itself I suppose...:p

In any event...I think I got my girl finally... thanks be to the sea-gods...and though a bit slower than some she's easy on the eyes...and could be even more with some work...
this is from Sailcalcpro .....I think the sail area might be off though for one thing..it' seems high..and I've seen lower numbers elsewhere...

Performance Comparison
LOA Columbia 40
39.16
Valiant 40
39.34
LWL Columbia 40
27.75
Valiant 40
33.88
Beam Columbia 40
10.66
Valiant 40
12.32
Displacement Columbia 40
18200
Valiant 40
22306
Sail Area Columbia 40
747
Valiant 40
768
Capsize Ratio Columbia 40
1.62
Valiant 40
1.75
Hull Speed Columbia 40
7.06
Valiant 40
7.8
Sail Area to Displacement Columbia 40
17.27
Valiant 40
15.51
Displacement to LWL Columbia 40
380
Valiant 40
256
LWL to Beam Columbia 40
2.6
Valiant 40
2.75
Motion Comfort Columbia 40
38.29
Valiant 40
33.96
Pounds/Inch Columbia 40
1057
Valiant 40
1491

[neelie]

Sounds ok to me, if you're happy with your boat, then you're golden. And in the end that's all that matters. Life is full of compromises and the best anyone can hope for is a bit of happiness.

Otherwise get a 20ft diameter steel ball welded up in 1/2inch plate, attach a 20 ft keel with 10 tones of lead at the end. You'll have an AVS of 180 and be totally bulletproof. But in the end, will you be happy?

You have a nice boat, be happy with it.

[Guillermo]

The Columbia 40 is a very nice boat, and her numbers are pretty fine for a blue water cruiser. Enjoy it.

[souljour2000]

Thanks guys...I think she's gonna take me somewhere someday...I hope to get her rails wet this summer but I got a ton of projects...right now am waiting on PO to send me the fuel injectors in his possession...and then we'll pop those in and see what happens...so at least I know whether I can maneuver her under her own power...

[Michail]

I have been following this discussion for a while, and I found it very interesting. However, the boats which were covered are relatively large. I just wonder whether it is possible to design a small boat (19 - 20 feet LOA) with a STIX of say 35, which would put it into A Cat.

I have played with the formulae, and it seems that it is possible, provided that one accepts a few limitation of the boat (like being underpowered having SAD something like 15, heavy, relatively narrow, designed as submarine to comply with the downflood angle, having a superstructure for reduced inverted stability, etc.).

The standard microtoners of that size seem to fit the C Cat, and at best can approach B.

I wounder whether such a design would be feasable (in practical terms).

[TeddyDiver]

I wounder whether such a design would be feasable (in practical terms).

Your have to design one so we can see the practicality thou can't see the point becouse such a small boat has other more limiting restrictions than the STIX number to be real ocean going vessel. Look at some smaller SAR boats, quite seaworthy designs but not meant for oceans either..

[Michail]

The idea is not to have a boat for long ocean passages, but for sailing in South Pacific near Chile, i.e. relatively short passages, but for any weather even beyond the minimum A class conditions.

The design requirements were the following:
- carry legally required safety and standard equipment (estimated at 130 kg., a long list of about 50 items, including life raft, tools, water, radios, anchor, etc)
- carry stores for two persons for a maximum of 30 days.
- carry crew of two.
I estimate that the net useful load capacity of the boat should be around 700kg. to satisfy the above. Assuming a sturdy fiberglass hull with keel, the empty boat could weight 1000 kg., and fully loaded, a maximum total of 1700 kg. Minimum sailing weight around 1350 kg. Using Elisson as a rough guide, an estimate of 5.8 meters LOA and 2.0 BOA would seem to be the lower limit to accomodate that weight without making the boat a simple square barge.

I like the idea of SAR boats, but I am talking about sailboat (mainly because I do not trust engines, and prefer sails).

[Guillermo]

Flicka 20 (http://www.flicka20.com/) is a proved oceancrossing little boat, but its mass under 3.000 kg doesn't allow it to enter Cat A.

There are several old threads in these forums about pocket and micro cruisers.

Cheers.

[Michail]

I have stumbled upon the Flicka boats before, and I loved them. However, there are several problems with them (at least for me):

1. I have not seen them on sale in Chile. Here, the most common boat type of this size is the microtoner.
2. They are too heavy. They seem to be trailarable, but it is not something to be taken lightly. And they need a crane for downloading, since they have a draft of 1 m.
3. I could not find any plans available.

What I am looking for is a practically trailarable boat (max. empty weight 1100 - 1200 kg.) which can be launched from slip, i.e. with a launching draft of something like 60-70 cm. The only way to achieve this would be with a hoistable dagger/bulb keel. (Now such a design is obviously counterproductive for blue water sailing. However, the marina space in Chile is extremely expensive, and may cost much more than the boat itself, so that the trailarability and ease of launching is an aboslute requirement for me.).


I did not realize that there was a weight limitation for cat A. I have downloaded the ISO 12217-2, and there indeed appears the standard clause which specifies 3000 kg, however, there is also an alternative set of conditions (6.3.2) which apparently do not specify a mass requirement for a A Cat, so in theory one could built A Cat boat of less then 3000 kg. Correct me if I am wrong, because I have just started to look through this document.

My point is not to try to comply blindly with ISO just for the sake of it (there is no legal requirement in Chile), but only because I think that compliance with it would result in a safer boat.

[TeddyDiver]

My point is not to try to comply blindly with ISO just for the sake of it (there is no legal requirement in Chile), but only because I think that compliance with it would result in a safer boat.
You think wrong. You would end up with a pig, a STIX A class pig. Better to make water tight self rightening lift keel boat, be happy with it, and not to worry too much with compliances. That is IMHO
BR Teddy

[Guillermo]

Michail,
Forget about the A Class thing for such a boat. There are plenty of safe and seaworthy enough small boat designs around there. Choose the one that better suits your requirements, as Teddy says, buy it or build it and enjoy it.

Cheers.