Seaworthiness

Thanks Guillermo.

I am aware that scientists can differ in their opinions. However, I'm struck by the fact that there seems to be only a few studies on inversion and seaworthiness. I get the strong impression (from going through the naval architecture library at my old university) that things like predicting performance of dry-running transoms and catamaran wave interaction have been studied much more, yet there is still no definitive answer in those areas.

Compared to the enormous masses of research, with double-blind trials, replication of results, etc etc etc that goes on in other areas of science. Listening to my girlfriend talk to her university colleagues about meta-analysis of 40 or so other experiments here, 20 other studies there etc makes the state of formal knowledge in seaworthiness look fairly poor in comparison, as far as I can see. I'm not saying they are not valuable, I'm merely putting forward that because the formal studies are so few that they are merely one piece in a jigsaw puzzle, and that the experience of expert sailors in real life should be given considerable weight when considering the makeup of a seaworthy boat.

Mike, interesting quotes earlier. I'm definitely on Dix's side, but I'd rather have positive buoyancy as well.

Re Rising Farrster - do you know that it was Farr who did the keel? Did the builder only contract for the lines? I believe that builder has in the past only contracted for part of the design.

The ABS requirements for Rising Farrster's keel were also held to have been insufficient. ABS is made up of engineers and NAs, and they got it wrong; and the NAs and engineers who gave evidence had different opinions; and the same thing happened in the Skandia case.

Given that the area of seaworthiness is little studied (in comparison to other areas of engineering and science) and there is considerable disagreement between experts, should we not merely use those studies and expert opinions as just one source of information, and also seek out opinions of expert users (of ALL ranges of belief) based on their actual experience with boats (light and heavy)?


Vega, re "Don’t you believe that Farr or Finot are qualified NAs?"

Farr isn't a qualified NA or engineer, although the company employs many. Farr's partner Bowler is a well-qualified engineer.

Anyway, interesting discussion. I still remain firmly in middle ground, positive that the cost of improvements in safety of boats must be seen in relation to the effects that increased cost will have on the rest of the sailors' lives; sure that too much attention is paid to capsize compared to the much more common causes of loss of life; firmly dubious of any one bunch of people who claim that they alone hold the truth, and also convinced about medium beam, damn strong keel attachments, and positive buoyancy!

 

(the bold marks are mine)

Mike, very interesting quote, and I can not agree more. Different types of boats, different approaches on seaworthiness, the importance of strength, good seamanship and the importance of knowing the strong and week points of each boat and act accordingly...seems perfect to me.

From that same link that you have posted, I will quote the opinion of Stephen Baker “of Stephen Baker Yacht Design. Mr. Baker has designed everything from catamarans to centerboard cruisers, including Mini Transat and Globe Challenge boats”:

In order of importance, what features or characteristics would be present in a small (25-feet or under) sailboat of your own design that you would willingly take off-shore?

BAKER: In rough order of importance:

1.Unsinkable - using solid flotation if possible, such as thick foam core.
2. Fixed keel
3. Easily reefed
4. Fully watertight companionway
5. Enclosed cockpit (i.e. full lifelines)
6. Full height lifelines (27")
7. The ability to self-right from at least 125 degrees of roll (180 preferable but hard to achieve)
9. Sealed mast with external halyards (to help with self-righting ability)
10. Enough headroom to at least sit upright while on the head (an under-rated characteristic).
11. Sailable (and preferably sailed) by 3 or 4 maximum.
12. Fast enough to get out of trouble (also an under-rated characteristic)
13. Open accommodations to avoid claustrophobia
14. Large enough berths (6'4" minimum) for all crew.
15. Real head with holding tank, chemical toilets just don't hack it in a storm
16. Watermaker
17. SSB
18. All items required for a Class I Offshore race as defined by ORC, if not already included. A life raft is a really comfortable thing to have around, but difficult in 25ft. I realize I would probably have to work very hard to get all this into 25ft, but I'd love to try.

We can see that for him, capsizing risk comes only in 7th place.

I have said it before, but I fully agree with the importance of the ease of reefing and the possibility of reefing without getting out of the cockpit.
Having the boat always under control in what regards sail area, and maintaining the balance of the sails is very important to the boat seaworthiness and you can’t do that if you cannot reef the boat easily. In heavy weather, it is very dangerous to reef sails if you have to go forward, in an unstable and slippery boat.

I agree with everything except beam and I will add strong shroud attachment.

About beam I will not be able to generalize. There are very seaworthy narrow boats, seaworthy medium beam boats and seaworthy large transom boats. It all depends on the way the boat is designed, on the stability curve, positive and negative areas, AVS, max RM, RM at 90º and on the dynamic behavior of the hull in the water.
Different types of hulls have different type of dynamic behavior, with advantages and disadvantages.
(Of course I am not talking about fat beamy and badly designed boats)

I firmly refuse the idea that there is only a correct approach to Design a seaworthy sailboat and that only heavy weight boats are seaworthy. The seaworthiness of a boat results of the adequate integration of many factors and different kinds of boats approach seaworthiness from different angles. Each type of boat (if it is a successful type with practical proofs of seaworthiness) has its own strengths and weaknesses and the skipper should know exactly what they are and how to take advantage of them in sailing his boat to safety.

 

Chris (CT 249)

You say "there is considerable disagreement between experts" I would like to take you to task on this. I do not think there is.

Marchaj used the results of and worked along with many other researchers in fact you will find little contradiction in any of their research. Discrepancies are inevitable but this does not amount to considerable disagreement.

So little of this work is published outside of Engineering/NA circles that you would be unaware of it. Marchaj's book is an attempt to popularize the issue with enough mathematics to satisfy other more academic folk. He was also a prolific producer of other material along with his peers; they all draw on each others research and verify the same wherever and whenever possible.

You will find that Martin has the greatest respect for Marchaj and that his continuing research has so far only turned up a few minor discrepancies egg the coach roof volume on RM in certain sized boats. So now we accept that, but all the supporting work that showed no contradiction...what of that?

Interestingly enough Martin is an advocate for a higher LPS and even mandatory wave tank testing of hulls leading to some alteration in the rules to produce safer racing boats. He would be worth you contacting. He's in Launceston now but he'll probably tell you to enroll.

Since the bulk of this sort of conclusion is from physics experiments and fits mathematically predictive models it is more about defining the constants in those models and refining predictive behavior for predictable conditions egg a breaking following sea, a beam on breaking sea etc.

You don't use double blind trials in physics since the experimental material is incapable of self modification.
You just repeat the experiment a few times. You get your baselines from comparing different hullforms and verification from similar studies in different institutions.

"Seaworthiness" did spend some time discussing the various IOR boats but it also spends a lot of time discussing a synopsis of the researched mechanics of hull behavior (not just Marchaj's work) and that is what we are interested in. There is no body of work that I am aware of that shows any of this theory to be fundamentally incorrect. If there was I wouldn't be writing here.

Is anyone aware of any really contradictory research?

Researchers such as Gerritsma, Paulling, Kure, Cane, Spears and Renilson have (along with Marchaj) spent a lot of time on the issues of small boat characteristics.
I am amused that many people (including you Chris) have not actually read Marchaj's book and yet have a very prejudiced view of it. He wrote it to popularize the issue. Academic papers are very dry in comparison.



Cheers

 

I totally agree with Mike Johns. A lot of resarch has been done on seaworthiness matters and behaviour of all kind of vessels at sea, being several of its components thoroughly studied, stability in waves among others. Any NA knows this. Many papers, books and studies from a variety of investigators and institutions are available at any NA Investigation Institution or School library. Many of such papers and books have been thorougly cited not only in this thread but in many other in these forums.

Marchaj's book is a very interesting divulgation book on sailboats' seaworthiness with a solid scientific approach, maybe the more focused on it but not the first one on the matter, nor the last. Many authors of such divulgative and reference books, that can be found at any NA's and sailboat designer's office, have treated seaworthiness, seakeeping abilities, seakindliness and the like more or less extensively, before and after, all of them basically coinciding on the criteria. Many of the contemporary work use Marchaj's previous work, one way or another. To my mind come now books like Davis', Claughton/Shenoi/Wellicome's, Eliasson/Larsson's, Vigor's, etc., just to cite popular ones on boats and yachts design.

What is amazing is people critizising or commenting such books/works without having read them. And on top of that, some even dare to pontify about whatever Naval Architecture and Marine Engineering matters, without having the minimum formation on them, or only a very, very superficial one (which is evident from their postings)

Daringness is Daugther of Ignorance.

 

Mike, the reference to double blind trials etc arose because the Claughton tests were done with an RC model and his article said that it took some time before they were controlling it correctly, or something similar (I can't find it at the moment). I was wondering whether the possible effect on the results has been accounted for; what was "correctly"? Human control in other experiments has been queried. I'm interested in science and reading guys like Kuhn and Gell-Mann or about the old Eddington and Millikan experiments does make it obvious that even physics experiments are not totally value-free at all times. However, I have since read David Lyons' report to the coroner re the '98 Hobart; he also says that the Claughton etc studies are well respected. I therefore agree that my questions were probably unwarranted.

I too am an advocate for high LPS and I am very glad that my own yacht has a high LPS. However, I note that many boats with a high LPS have got into major trouble, sometimes with fatal consequences for their crew, and I wonder whether there is not too much concentration on the particular aspect of low LPS, compared to other factors. I note that boats with a high LPS may well be more expensive and that we have still not been told what part of the family budget the typical sailor will cut to pay for a more expensive boat, and what effect this will have on their overall health and safety. I cannot see how this factor is ignored; statistically you are probably much safer getting experience on the water in a cheap low LPS boat and driving a safe new Mercedes when you're not sailing, than driving an older car and stressing out to put all your cash into a big heavy boat for the statistically unlikely event that high LPS will make a difference.

I am rather amused that you (Mike) have made several assumptions on this forum that have been demonstrated to be incorrect,* yet you have not acknowledged this in any way. I acknowledge that I will have to read Marchaj once more, and that I am not an NA or engineer. I admit, I would have liked to have done NA but my maths isn't upo to it. Maybe you could in turn acknowledge that your own knowledge of the rating rules, lightweight boats and the % of heavy versus light boats that have got into trouble in major races is not 100%?**

In reply to Guillermo, I suppose exactly how much "a lot" of research is depends on what you're comparing it with. Is there "a lot" of study on yacht design, compared to the study on biology, physics, psychology, cosmology? Yacht design is a pretty small field compared to other fields of science, therefore isn't it reasonable to say that, compared to those other fields, on single part of yacht design does not have "a lot" of research.

I value a high LPS and love the fact that my own boat has a very high LPS. However, I still question the fact that there has been so much concern about inversion when it has been implicated in only a small minority of fatal accidents, and other factors seem to be largely ignored. I still cannot work out why, for example, the inversion of the Nicholson 30 which caused one (or two) deaths in the '79 Fastnet was the subject of so much controversy, while the two who died from one of the cruisey, slender, heavy-displacement Ohlson 35s seem to be ignored. Why are Banjers not studied after two deaths, when Farr 40s are extensively studied after two deaths? Don't those who die on heavy boats deserve the same research?

About your comment "What is amazing is people critizising or commenting such books/works without having read them. And on top of that, some even dare to pontify about whatever Naval Architecture and Marine Engineering matters, without having the minimum formation on them, or only a very, very superficial one (which is evident from their postings)".

Personally, I think that you two deserve respect because of your formal qualifications, but so do people who have qualifications through sea miles. Just to look at one of the people whose feelings about seaworthiness have been scoffed at by one of you two - it includes over 35 Hobarts; many return passages shorthanded. There's talk of the 1979 Fastnet experience - he was there and he was there at the enquiry. This is a highly intelligent man, with experience that would blow almost any offshore owner in the world out of the water, and it seems that his experience ranging from steel long-keel double-ender to IOR boat to IMS boat to IRC boat to One Designs is given almost no credit on this forum. Mike places high value on experience - "Direct offshore experience is the best qualification for any offshore designer" he says - but then utterly discarded the experience of this man merely because he doesn't have the right letters behind his name. Why is experience so valuable in informing a designer what boat to create, yet of no value in informing a vastly experienced sailor what boat to commission?

If you say that only people with formal qualifications deserve the respect you expect, can I ask whether you believe that applies only to NAs and engineers, or does it apply to people qualified in other disciplines? Don't you ever "pontificate" on architecture, medicine, car design, economics, law, biology (for or against genetic engineering etc), even football or politics? Do you believe that only those qualified in a field are able to comment? I am qualified in a field that is (frankly) a lot harder to get into than engineering or naval architecture, and my field is widely (and correctly) criticised - as are many other fields. If my field can be discussed, why not yours? Discussion of another person's professional field is surely perfectly normal. I understand that you are the expert in engineering but surely we can discuss matters? Furthermore, if only experienced people can comment on a field, then only experienced racers or sailors of light boats could comment on their performance.

Not all engineers or NAs agree that light boats are dangerous; some NAs and engineers sail light boats and do not feel that they are dangerous. See Andy Dovell (NA)'s piece on "Yacht Design Naiad at http://www.equipped.org/sydney-hobart/Volume 07.htm If we have to automatically believe NAs without reservation or criticism, why can't we believe the NAs who actually sail these boats rather than the ones who don't????

I used to coach several NA students in dinghy sailing; they needed a fair bit of help! Merely being an NA is not a passport to becoming the font of all knowledge about sailing, therefore surely it is reasonable for laymen to pose questions.

There are NOT "many papers, books and studies....available at any NA school library" near me; what is (I think) the only NA university course in my country does not have much information.

There seems to be a mindset that the people who sink in offshore races are mindless hoons. Interestingly, one of the two (I think) boats that sank in the '98 Sydney-Hobart was a heavy-displacement long-keel double-ended that had sailed to the USA and back. It was owned and skippered by a "safety engineer, or university lecturer in safety" (to quote his testimony to the coroner) who creates Masters' courses in safety for universities. As he said himself, he was an (experienced) cruising sailor, not a racer (although his earlier Roberts cruiser, from one of the designers I think I've seen held up as an example, had started two Hobarts and failed to finish both times). Yet this safety engineer's heavy-displacement cruiser sank when the hull fell apart.

When a safety engineer caps his third failed Hobart in two respected heavy-displacement cruisers by sinking the boat, there seems to be a hint that lightweight racers, race mania or ignorance of engineering and safety are not always the cause of problems. The apparent assumption that it's the small and/or lightweight racers driven by foolish racers that cause the problems, and the fact that only such boats are used as the subject for tests, gets me riled at times.

To quote a skipper from the '98 Hobart' "When you get one of these giant waves.... it doesn't matter whether you're in Mr Sid (sic) Fisher's Ragamuffin or the biggest boat in the race or the tiniest boat in the race, if it falls on you you'll get rolled....if he gets a big wave he's gone, light boat, heavy boat, whatever boat....people don't seem to understand that".

Surely if we are serious about safety we should be looking at the all boats that actually sink and the boats that actually kill people, and not at only a minority of them. Surely the deaths on boats with high LPS and the rollings and sinkings of heavy boats should be viewed as seriously as those on lightweights, and studied just as much.


* Fairly minor things, like the allegation that the good proportion of the small lightweights that finished the 2005 Hobart only finished because they sheltered from the heavy winds; that Finnisterre was fast, instead of 12%+ slower than a Beneteau 40.7; that the IRC favours lightweights (check the 2006 Hobart for rebuttal of that). Still, they do seem to perhaps demonstrate a lack of knowledge about fast boats.

I agree that these are fairly minor. However, you're obviously smart and reasonable. Don't you think that maybe they indicate that you start from a position that is not entirely unbiased, just as we all do?

** I agree that there are problems with using races as examples of the way boats handle seas. You said in the earlier thread that to do so was to rely on apocryphal evidence. This may well be true - but when people selected the Nicholson 30 as an example of a dangerous boat to be tested in inversion tests after the '79 Fastnet, they seemed to be doing exactly that. I understand that you would investigate the factors involved in deaths, but why so much concentration on only one factor??

 

CT, all the aspects you have talked about have been taken into consideration on serious seaworthiness studies.

The directive that defines European certification of boats has been based on studies. The methodologies of those studies were based on the analyses of experiences. All available and relevant information on boat seaworthiness was reunited, and that means not only information on boat accidents but also the opinion of experienced sailors.
They have analyzed all the known cases of capsizing and boat accidents. They also gathered information, among very experienced ocean sailors, on boats that were seaworthy and unseaworthy. Then they have analyzed all the information based in EXPERIENCE to determine what the characteristics of safe boats were.

That analysis was done basically under two perspectives, one the AVS (LPS) other the RM at 90º of the boats. They tried to find common characteristics of the safe and unsafe boats regarding not only the ease how they recover from an inversion but also the energy they offer to capsizing on a limit situation.

You can have a boat with a very high AVS that is much more easily capsized than a boat with a lower AVS. That is a very common situation with faster cruiser-racers or race boats. Why should a boat that can recover more easily from an inversion be considered safer than a boat that is much more difficult to capsize? When a boat recovers from an inversion it is normally a crippled boat, without mast and sometimes a flooded boat with a compromised intact stability.

Only a right balance on these main two situations makes sense (never minding the contribution and integration of many others), as it only makes sense, for determining seaworthiness principles, to rely on the experience gathered with real boats and real situations. Models can help, but as it has been often stated in this forum, the results with models are not always true with real scale boats. Recent Australian experiences with tank testing, regarding inversion recovery, are a very good example of this. They were unable to reach any real conclusions, because tank testing results contradicted theoretical predictions and they were not sure why, mainly because those theoretical predictions seemed to be in accordance with real boat testing situations.

Wanting to restrict the Seaworthiness issue to a discussion of AVS/LPS or to say that seaworthy boats are the ones that are made in accordance with principles that were laid 20 years ago, is the wrong way to look at the problem, and it is not the way researchers look at it.

The analysis of the reasons that make certain boats more or less seaworthy than others (based on real evidence), as a way to define the principles that result in seaworthy boats, is the way to go and the only way that can explain why a boat like the French centerboarder is a seaworthy boat, a boat that accordingly to Mike’s vision on seaworthiness would be a very dangerous boat.

Attesting the seaworthiness of this kind of boat are 20 years of ocean experience that have made this kind of boat the preferred passagemaker in France, a nation not only known by its oceangoing sailors, but also by its Naval Architects and also as the World’s biggest manufacturer and exporter of cruising sailboats, including oceangoing ones.

French naval community is very experienced and it is not plausible that they have been wrong for the last 20 years.

Theory should explain facts, based on experience. It is not the facts that should conform to theory.

If facts and experiences are not according with theory, then the theory is wrong or at least, partially wrong.

 

I found this old post while drafting my earlier reply. It's interesting to see what boats people recollect, years later, to be great examples of seaworthiness.

In the first ROTW race, there was only one finisher, plus one who could have finished. All others retired or died.

However, Ray's mention of City of Dunedin implies he meant the 1982 BOC race. The placings overall went;

1st - Non-rule "Open 56"
2nd - Old non-rule 49 footer (very light for its day).
3rd - 50' IOR boat (designed for the Admiral's Cup as a lift keeler)
4th - 53' IOR boat
DNF - Classic shorthanded voyager - Wrecked
DNF - Non-rule "Open 56" - Sank
DNF - Non-rule Open 56 - retired on leg 1.

Class 2

1st - Fin keel masthead sloop, not dissimilar to a '70s IOR boat.
2nd - Fast Passage 39 or Valiant 40
3rd - Fin keel kevlar/Airex foam IOR design.
4th - Unknown
5th - Fast Passage 39 or Valiant 40
6th - City of Dunedin - 40 days behind second last (I think he did stick it on the bricks and get it salvaged, though)

DNF- Non rule boat (sank)
DNF - Non rule boat (ret Leg 1)
DNF - Non rule boat (ret. Leg 1)

It could be just my conservative nature, but I'm not 100% sure that a race that sees 3 sinkings and 1 salvage out of 16 entries can be held up as an example to all. Interesting that all three of the despised IOR boats got around. One of their skippers has two solo circumnavigations, another three singlehanded round the world passages and over 120,000 singlehanded miles. I thought no one of that experience was supposed to like IOR boats?

What "extensive support network" has been put in place for modern round the world sailors? Jeantot at least was in daily radio contact with France in the first race. One or two of the Golden Globe entrants were rescued.

By the next BOC, many of the boats were like today's Open racers albiet narrower and heavier.

I'm still surprised that boats that sank 3 times out of 13 are "excellent example of the best in cruising design", while boats that had a 100% finishing record are said to be rule-distorted anomalies.

 

Well put.

IMO not all IOR boats were bad. The IOR rule could produce bad boats that did well under the rule. The rule also gave us unbalanced rigs, with huge headsails and tiny mains that are absolutely no fun to sail deep in a breeze. I'm happy to see that current production boats are showing up with bigger mains and sensible (IMO) rigs.

 

[FONT=&quot]

Touche
Or are they just assumptions different to your assumptions made from different viewpoints?

I am not sure what you refer to here. I'm sure I've made the odd mistake at times I do in my work too (which is why we use peer review). Perhaps you can give me a list so I can admit to them, or argue the point.[/FONT]

[FONT=&quot]

Chris the foremost Uni in Australia for Naval Architecture and Marine Engineering in here in Tasmania The Australian Maritime college (AMC). They also have the most sophisticated wave tank here recently enlarged at great cost. This is Martin Renilson's home.

 

Yes, you are right of course (I'm glad I put an "I think" in the earlier post . I tend to forget it just because I don't think it was around 14 years ago when I was at uni at UNSW, which I believe then had the only NA course in Oz. Mea culpa.


Since there has been an implication from the "heavy boat NA" side of this discussion that problems are caused by light boats in the hands of non-engineers, can I ask you for a reaction about the loss in the '98 Hobart of Mintanta, the heavy Swanson designed and built long-keel double-ender owned by a safety engineer? In a climate where it seems that some fingers are always pointing at lightweight racers as the cause of losses, isn't it significant that it was such a boat was one of the few losses? If safety engineers can sink their heavy boats, why blame other sinkings on lightweights and racing sailors?

If qualified NAs cannot be gainsaid or queried, what are we to make of Andy Dovell (possessor of a Masters, which would beat being a "mere" NA in qualification poker) when he says that displacement made no difference to chance of rolling (link provided earlier)???

Since inversion and capsize of small and light boats is an issue, can I ask your reaction of the quote in my earlier post, saying that if you get a bad wave, that whether you're in "the biggest boat in the race or the tiniest boat in the race, if it falls on you you'll get rolled."?


Please let me state that I'm not saying that I hold all the answers, or that I am qualified to comment on many aspect of design, or that I don't make mistakes. . I am very interested in this area but I have a strong feeling that some of the "heavy boat" brigade are coming at it from an assumption that they are correct; that's why I get a bit annoyed by the concentration on inversion, which is only a minor factor in the deaths in the races that lead to the studies.

Because of my interest in the area, in my last year of racing other people's boats I sailed on several of the extremes - from a boat similar to Finnisterre, to water ballast maxis and 30 foot lightweight IMS racers. I am not at all sure that the proponents of the heavy brigade have done the same.

 

As far as I know, quite a lot of research. Either in relative or absolute terms. This doesn't mean that everything has been studied already. Much more research is needed for sure, being one of the things I miss an accurate and scientifically approached statistical research on sailingboats seaworthiness.

Of course there are many factors other than stability involved in life losses at sea, and I'll be glad if somebody discuss those. I'm personally focusing on stability just because it is of my present interest. But what is interesting is that nobody else focuse a discussion on other related matters...I'm wondering why.
(On the Olhson-Nicholson thing, I'll answer later. I didn't bring into discussion Banjers as I do not consider them safe ocean crossers, in spite of the several ocean crossings they have done.)

Just take it literally. Please don't suppose that it has any other meaning that precisely what is written.

Absolutely.

I'm old enough to have learnt to not do so. The older I get, the deeper I realize how much knowledge I do not have, so it's better for me to remain silent or maybe humbly saying "in my opinion..." "I think that..." "maybe...." and the like. If you review my posts you may realize that generally speaking I try not to pontificate, but just give my opinion. Even on naval architecture. Maybe I'm wrong, but I think that people 'pontificating' (or 'pontifying'? Which word is correct, if any?) around at these forums, without having enough knowledge on the matter in discussion, tend to misunderstand and mistify in their own advantage the meaning of what has been written.

Of course not. But the not qualified should keep an attitude not so soberb as to think they know more than the qualified ones (Wherever their qualification comes from)

And it is...?

I have supported this thought in one of my previous posts. But I'm not talking here freak waves. Although we can ask at least what are the desirable characteristics of an oceanic cruising boat to survive one of those.
Anyhow, let me quote Warwick Hood on the '98 Sidney-Hobart:
"I don’t accept that the race’s weather or sea state should be taken as unusual. In an appendix to the book Heavy Weather Sailing, Laurence Draper of the British National Institute of Oceanography describes how very large waves may suddenly occur out of a normal ocean wave system. Even given the very rapid deterioration of the weather in the last Hobart race, well-designed, built and maintained yachts should be able to stop racing and seek shelter or stop racing and heave to or stop racing and sail slowly away from it."

I totally agree.

Cheers.

P.S. Maybe you and the rest are interested in reading the attached document.

 

A quick post to bring in some other interesting papers:

- Claughton, A. and Handley, P 1984, An Investigation into the Stability of Sailing Yachts in Large Breaking Waves, University of Southampton Ship Science. Report No. 15, January 1984.

- de Kat, Jan O, 1999, Dynamics of Vessel capsizing in Critical Wave Conditions. Workshop on Safety of Ocean Racing Yachts, Sydney, 28 March 1999.

- Mundle, R., 1999, Fatal Storm: the Inside Story of the Tragic Sydney-Hobart Race. International Marine/McGraw-HIll, 1999.

- Renilson, M., Binns, J. R., and Tuite, A., 2001, The Re-Righting of Sailing Yachts in Waves - A Comparison of Different Hull Forms, Proceedings of the 15th Chesapeake Sailing Yacht Symposium, Annapolis, MD January 26-27, 2001.

On fishing vessels' stability in following and breaking seas there are a lot of studies that may be also applicable to sailing yachts.

Cheers.

 

I believe that you have been blinded by your particular choice of perspective on seaworthiness. There were plenty of people that have suggested that it didn’t make much sense the main emphasis on a particular case of boat stability: The ability to recover from an inverted position. They have talked about a lot of other more relevant causes of loss of life at sea and have given different views on seaworthiness, puting the emphasis on other issues.

To refresh the discussion, and to point out what were the relevant seaworthiness issues posted in this thread, besides the ones related directely with the recover from an inversion, I will make a sort of resumee of the posts that have taken a different look at seaworthiness.

I hope it will help:

[/COLOR]

Regards

 

The information I have is that this boat was not retired because she was knocked down or rolled but had retired from the race through a sensible decision of the skippers along with the other 65% of the fleet and was motoring back to Eden when they discovered water below. It is suspected that the keel-garboard area suffered fatigue failure and de-lamination . The boat sank under tow and was lost . (Did you read the thread on fatigue?)

That the vessel was included in Dovell’s synopsis of vessel knockdown questions his unbiased stand and certainly alters his conclusion. As he said himself his report was not complete and was subject to alteration as more data became available.


A Safety Engineer it has the word Engineer in it but it is not one of our categories for professional engineers.

A very successful designer of contemporary racing yachts is likely to have a biased view. Did he alter his synopsis after all the details became available or did he leave some misguiding information in that report because it suited ? I presume that you are aware that there is not overwhelming agreement with his summary?

As for the qualification issue, the base qualifications ensure that you can talk the talk enough not to make a fool of yourself. They give you a grounding good enough to start work. Or pick up a treatise book or paper by a more experienced person or researcher and understand the talk. Anyone with a graduate degree will understand the game of "higher degrees" in Enginering it makes little difference whether you have a PhD or a Graduate degree unless you want to do funded research.
(Actually his relevant qual is a 3 year post grad in Engineering (by study not by research) on a BSc so I am fairly sure that his degree would be considered on equal terms to a 4 year engineering degree.)

These are what we call boundary conditions Push it to the extreme then back off a bit and do the analysis, What shape wave when and how it breaks, what orbital velocity etc.
Don't you think it can be an excuse sometimes to say my boat broke because it encountered the ultimate wave?
If it does get squished we are concerned with what happens next, will the boat be strong enough, will it lose its rig, will it experience a violent inversion and lose its rig or will it dip its rig under the water 30 degrees and return same side rig intact? We know enough about characteristics to predict a trend amongst design types.

I think that is coming from the proponents of the extreme beam brigade. I was and continue to come at this from the principles that I have learnt and observed and have what I consider sensible supporting evidence.

But it is a major factor in the destruction and damage of boats.

I have owned and cruised heavy full keeled wineglass 39 footers, a relatively light beamy fin-keeled spade rudder 60 footer (yes ok a 57 footer ) and my current Adams 45 a fin keeled performance cruiser. I've had various dinghies my favourite being a 125. I sail an extreme racing boat at times. I'd like a Pogo 40 it would be great fun.

We are also discussing cruising boats in this thread .

Other reply to follow when I get 10 minutes.

 

I've read it. I've also read the papers, or articles by the authors on their papers, in three of the four cases you mention. I wonder if the author of the other is the Jan de Kat whose trimaran fell apart in the '68 OSTAR, when he was a young man?

You mention the Renilson tests.You also quote evidence that Warwick Hood gave to the '98 Hobart inquest. Warwick's evidence also included the assertion "It is submitted that the proposed tests by Dr Renilson will have little use. The subject yacht (the Farr IOR 40 Naiad) was 1 of a number which were rolled through 360 degrees and with the exception of that yacht did not suffer the alleged stability deficiency".

If Hood is correct, the Renilson's tests you quote are of little use. If Hood is incorrect (and the results of Renilson's tests indicate that he may well be mistaken) then we have proof that Hood is not always correct. If he is not correct regarding the Renilson test, why assume he is correct regarding the '98 Hobart?