Seaworthiness

Chris

Sorry I didn't realise that was a footnote I thought it was to Guillermo.

You called me intellignet and reasonable.........Chris thanks.

You need to edit that post to take your comments out of the quote frame.

I will have to re-read those threads. I have also been thinking more about the corollaries we can draw. Maybe it would be good to re-visit that topic in a new thread?

We all have a position from which we argue I think my perception of fast is that it is not a "slow and steady " vessel but capable of good and satisfying performance. That I might be 12% wrong based on your racing statistics is a fairly legal argument !

The comment on SYD-Hobart withdrawls was valid 65% of the fleet withdrew maybe 25% ? (I need to look this up) sheltered in Eden and carried on after the bad weather passed , From that I think my argument was that you cannot draw conclusions from the finishing boat statistics as though they were all in the same conditions. But I will need to re-read the thread.

Heavy boats can be very able performers, they’ll never beat the skimming dishes for maximum velocity, but when we come back to sensible cruising hull-forms the paradigm changes.

 

I am talking of Blue water cruising boats

Let me quote what I have posted so far about heavier boats that seems to be getting a little distorted at times and attracts some rather dubious comments:


Narrow light boats are certainly more seaworthy than beamy light boats but a heavier boat if it has the right characteristics will (all things being equal) be more comfortable.
Vertical acceleration is governed by mass to water-plane area and is the most debilitating motion. The heavier the boat for a given water-plane area the lower the acceleration, in addition the heavier boat has a far greater roll and pitch inertia

We want a hullform that returns us to port in one piece and will do so repeatedly in all weathers for years of reliable service. Strength and durability don't equate well with light scantlings.

The heavier boats are far less likely to be knocked down in the first place particularly if they have a heavier rig .

The easiest way to get sea-kindliness is with displacement and displacement allows many other benefits to the cruiser. Strength and weight are on opposite sides of the coin, this is a hard engineering fact. Narrow deep and long is arguably one of the more seaworthy hullforms (Marchaj).

Lets consider two 40 foot boats, one 7 tons and one 15 tons; [… or 5.3 tonnes for the POGO 40 ] To both vessels add a genset, 2 tons of fuel and water, provisions for a crew of 4 a radome, lifreaft a dinghy or two and their motors , 2 sets of ground tackle and a some spare sails. (say 3 tons all up) The lighter boat is now floating a foot down on her lines, her loaded DL has become heavy and her hullform is not beneficial to perform well with this load at sea ie Cp is now detrimental, in addition she now has a very compromised stability since her shallow hullform denies sensible stowage and mounting of much of the gear. GM is now so low that the boat cannot stand up to the canvas she so desperately needs. The heavy 40 footer displaces those 15m^3 of water, her volume is able to absorb engineering tankage and emergency ground tackle at a vertical position that often has a neutral or even positive effect on her stability, in addition she is designed to operate close to this displacement, her GM remains the same and she will be faster and far more seaworthy than her cousin above.


We can design boats built for sea-kindliness and seaworthiness better than the "old" types all round, that we can improve markedly on the safety aspects of modern vessels with relatively small compromises.
I am not advocating that we should all be sailing antiquated Le Havre pilot cutters either, these sorts of vessel have other issues that we can improve upon significantly but it illustrates one extreme against another and are useful for that purpose; to aid understanding of the principles .


The argument is not that we should all be sailing bomb proof vessels capable running a pirate radio station in a Winter North sea. It is that extremes are speed driven spin-offs from the racing, that the advocates of the extremes are good at waiving the research which shows that they can be detrimental.

Calls to freedom of choice are at least honest. Denial that there are problems is not helpful to the discussion. I also think the appeal to statistics without proper gathering of data is misleading. There may be good statistical data harvesting in the waters of European countries but what happens outside of these? How many Benetau 390 inversions from Australia ever got a mention in the European data…..Nil. Ditto for all the other countries (as an illustration).


I would like to re-introduce a few statements that have been challenged particularly by Vega:

Naval Architects often write books and papers and are involved in research.
A lot of yacht design is by unqualified designers (giving the public what they desire).
There is a very strong current social trend towards more extreme hull-forms.
Tank testing for safety in a wave tank is seldom if ever performed.
Science particularly engineering science is often definitive and historic (together) and the science of Naval Architecture has not changed significantly over 20 years.
Marchaj ( for one ) is a prominent scientist who’s research in the main is just as applicable today as it was 20 years ago.


Vega you for example say;

In your opinion it is not acceptable to trade speed for seaworthiness. You also said that you cannot agree that beam is detrimental to seaworthiness.

I really think that this view is the current marketing trend that people have accepted, that speed is more important than safety and that we should ignore any evidence that suggests that this may lead to a drop in seaworthiness. I think yachting magazines drive the trend to a large extent is a social trend driven by a racing perspective.

The body of scientific evidence has shown that as a vessels beam becomes more extreme it has several detrimental characteristics. Such as: increased risk of violent knockdown (over a more moderate hull-form), a poor ratio of inverted to virtual stability, long inversion times if knocked down, poor survival characteristics in extreme weather when compared to more moderate hull-forms, and a lowering of sea-kindliness .

The argument that boats in an open class will converge on the most seaworthy hullform is not correct. They converge on a compromise between seaworthiness and speed. Past experience suggests that in order to be competitive you accept a high level of risk. The Southern ocean has pointed this out often enough. The Mini’s also show the trend of speed vs seaworthiness tradeoff.

Even the creators of the Pogo say that the 40 is a compromise between cruising and racing, but in reality it is a racing hull. My view is that it has a very poor suitability for blue water cruising for many reasons and I doubt that anyone seriously contemplating a cruise would buy such a vessel. It is an extreme boat, a fun boat for limited coastal cruising and a good racer (read my comments above regarding loading of these boats for cruising).

It is apparent that some people have never been in severe weather let alone a storm at sea, have never found themselves relying on their hull designer for their very lives. Have never been at sea out of sight of land for even a few days let alone an ocean passage.

I have said before I think the lack of real experience amongst many yacht designers and marketers is a concern, too many people draw on the experiences and values of racing skippers.

Fantasies of idylic coastal sailing under full control in the black hell of unexpected weather at night with the family sick with terror and the boat surging out of control slipping down waves trying to run under bare poles because you are too scared to go fwd to hank on a storm jib. These are often the realities of light cruisers caught in bad weather, motoring until the engine dies , calling for an airlift because they just want to get off ( like the cyclone that hit the NZ cruising fleet ). Sea-kindliness is very important in heavy weather, it makes the difference between total incapacity and depressed misery. Look at all the European boats for sale in the Caribbean because the world cruise ended there after bad experience crossing the Atlantic in its more benign latitudes.

 

"The advocates of the extremes are good at waiving the research which shows that they can be detrimental."

The advocates of the heavy boats are also good at waiving the incidents in which their boats get into trouble and sometimes kill people. My main point is not the research itself - it is the fact that the research concentrates on certain causes of accidents and largely ignores others.


"I also think the appeal to statistics without proper gathering of data is misleading."

Perhaps; I would love to see the proper gathering of data. Remember, I am not an advocate of extremes. I really want to see safer offshore boats. I had offers to sail some of the worst-affected boats in '98, so it chills me to the bone to see the film of them and read the reports; but for a decision to say "nope, I'm doing the Laser nationals and worlds" it could have been me who was the subject of a coroner's report.


Re Mintanta and "that the vessel was included in Dovell’s synopsis of vessel knockdown questions his unbiased stand and certainly alters his conclusion."

The skipper's evidence says that "increased water would come in as we were knocked down....then we'd right again." So the skipper said, to the police for a coroner's enquiry, that the boat was "knocked down". It seems that we should perhaps agree with the man who was there that his boat was "knocked down" and therefore Andy was correct to include it in a list of boats that was "severely knocked down".

You say Andy is biased, because he is a designer of successful lightweights. Surely the designers of heavyweights or of unsuccessful lightweights can also be biased. The more Andy can promote lightweights, the more money he makes. The more heavyweight designers can promote heavyweights, the more money they make.

Why ascribe the opinion of the designers of lightweights - who have similar formal qualifications and actually race these boats in major races - to bias, and not admit that the designers of heavyweights have a similar reason to be biased?

If Andy is biased towards modern lightweights, why did he go to considerable effort to make the structural problem with decks well known? I think he wrote the summary and then an article for Australian Sailing. In both he referred to problems on B52, an MBD design. To say that someone who publicises problems in his own design is so biased that he hides other problems seems to be stretching the point.

The list of boats that were knocked down IS incomplete; it doesn't include the steel Adams 40, or the S&S 34 that went 180 or close to it and lost the stick......If we take out Mintanta we have to include those two heavyweights. And even if Mintanta was only "knocked down" rather than "severely knocked down", I cannot see how a discussion of safety offshore can ignore the fact that Miintanta, a classic heavyweight, SANK.

Re the qualifications of Miintanta's qualifications; he's got a doctorate, he is an engineer of some sort, he's spent years as an academic and accident investigator. My point was that he's not a a racing hoon who is ignorant of safety, as competitors in races are often said to be. When such a man has his boat sunk, the conception that sinkings in races are due to idiot ignorant racing hoons is seen to be suspect. When the crewman from a boat owned by an professor of engineering who has worked in MIT's naval architecture department is only saved by a miracle, the idea that problems in races are due to ignorant racing hoons is again seen to be very suspect.

There's a great deal of discounting engineers from your side; you discount Dr Brian Emerson, you discount Andy Dovell, you probably discount MBD employee Bruce McRae (honours graduate of AMC and former manager of commercial testing tank there) who I think also races and certainly designs MBD lightweights; Guillermo seems to discount Prof Peter Joubert's opinion that any boat in the Hobart could have been knocked down; and then we laymen get knocked for questioning other NAs!


Re "Don't you think it can be an excuse sometimes to say my boat broke because it encountered the ultimate wave?"

Certainly. However, this reasoning should be applied to lightweights as well as heavyweights. Sometimes there seems to be an assumption that the heavyweights fail when they encounter ultimate waves that no boat could survive, while the lightweights fail because they are flimsy dangerous flyweights.

"These are often the realities of light cruisers caught in bad weather, motoring until the engine dies , calling for an airlift because they just want to get off ( like the cyclone that hit the NZ cruising fleet )."

Can we get some more information on the weight of the light cruisers that were involved in that cyclone??? As far as I can find out, the monos that sent Maydays are;

Silver Shadow - Craddock design cruiser-racer; I think it was a conventional masthead rigger. Survived storm.

Quartermaster - Sank. No details known to me.

Mary T - Offshore 40 yawl. 1963 Rhodes design. 22,000lb displacement on 28.7ft waterline. Cancelled Mayday. HEAVY DISPLACEMENT

Destiny, a U.S.-based Norseman 447 (45 feet) - Ran under drog, pitchpoled then rolled 360, abandoned. 28,000lb displacement, 12,000lb ballast on a 37.5ft waterline. NOT A LIGHTWEIGHT

Pilot - Westsail 32 from Maine (not a calm-weather area). Abandoned. 19,500lb displacement, 7,000lb ballast on a 27'6" waterline. NOT A LIGHTWEIGHT

Sofia, a New Zealand-based Atkin 32-ft double-ended cutter. Went to drogue, rolled twice, stayed inverted "what seemed like an eternity", dismasted, abandoned. Atkins are NOT lightweights.

"Waikiwi II, a 44-foot sloop from New Zealand with a very experienced crew of five: She was pitchpoled, dismasted during a knockdown, and lost her rudder. Farr 1220 (masthead rigged fast cruiser). Was hit by a ship during rescue.

So only one, possibly two, of those boats was even medium displacement.

Do you stand by the statement that the problems in this event were caused by light displacement?

 

I don't think so. But I am interested . Just how did the heavy boats get into trouble and kill people.
Look at hullform, then separate out structural failure becuase of light scantlingsand separate out material deficiencies.
For Example you have often cited the "Winston Churchill" as an example.

We could really do with a researcher here, too many people think that a search engine onthe internet produces all available information (not you).

Really? "every time we were knocked down" turns into severely knocked down?
This is the kind of artisitc license that distorts reports. Did you see the synopsis by Taylor stating that after interview it was clear that she was not knocked down in the sense used by Dovell?

That doesn't stop him being prone to bias which was my point.

Why not? What was it doing to his reputation had this gone on?
When a problem is as clear cut as tht he has a professional obligation under the law (code of conduct).

Can you give me the names of those two please.

Why did it sink? this is a materials argument not a hullform argument.

Youv'e lost me there ( but it sounds like more spin).

Question away, I am not so sure about "discounting" as saying that the racing fraternity is often keen to protect their reputaion .
Also if we take each case carefully in turn rather than as a gross generalisation a different picture imerges, eg a graph used as the basis of a sysnopsis that has dubious data in it doesn't discount a very brilliant Engineer it questions the basis of his report whether wilfull or ignorant. Notice that he covers himself from this at the end of hiss own synopsis.

No I perceive that there may be times when the lightweight will escape a big breaker by giving to the sea, but there will be times that she will not.

 

Three of the "lightweight" designs that sent Maydays in the NZ cruising rally.

 

Take '79 Fastnet. Flashlight, Ohlson 35, '79 Fastnet, lost 2 crew. Ariadne (Carter 34) lost 4, yet the studies concentrated on Grimalkin (2 dead).
The losses from Flashlight were caused by poor harnesses or harness use, and a knockdown. The characteristics of the boat may have been of little relevance once the knockdown had happened, but few people made that distinction in the case of Grimalkin (the Nicholson half tonner) where the skipper died after being knocked out by a can of food while he was down below (I think; my copy of the report is in the attic). A Buchanan OFfshore 40 also lost a coiuple of people, from memory, and was abandoned but I will have to check the report.

I say again, I don't like the fact that Grimalkin stayed upside down; I prefer boats that recover; but lightweights were involved in only a minority of deaths yet copped most of the blame. In the same way that it is unfair to criticise all heavyweights for the loss of Winston Churchill due to a structural problem, it is unfair to criticise all lightweights for someone getting hit by a poorly-secured can in a knockdown, when a heavyweight cruiser lost 2 crew due to poorly-secured harnesses in a knockdown.


Re "Really? "every time we were knocked down" turns into severely knocked down?
This is the kind of artisitc license that distorts reports. Did you see the synopsis by Taylor stating that after interview it was clear that she was not knocked down in the sense used by Dovell?

No, it would be interesting to see the Taylor interview. I'm not sure that Dovell ever defined "severely knocked down".

This is a hullform argument, but part of the argument for the heavy hullform is that it is stronger. That seems to make the fact that the boat fell apart significant. Incidentally I did my first ocean race, a stormy Sydney-Noumea, on a Swano 42. We were racing Mintanta, then called "Anna Drie". Again, this is close to the bone for me.


Re "When the crewman from a boat owned by an professor of engineering who has worked in MIT's naval architecture department is only saved by a miracle, the idea that problems in races are due to ignorant racing hoons is again seen to be very suspect.".....Youv'e lost me there ( but it sounds like more spin).


Sorry, it was a very well-known incident. The boat was Joubert's Kingurra. A man went over in a knockdown (boat had an LPS of 125.4) and was badly injured. Boat could not (IIRC) get back to him but a chopper happened to be overhead and got him. It's all in the coroner's report, it is NOT spin.

"Can you give me the names of those two please."

The Adams 40 was Gundy Grey, the S&S 34 Solandra. Also Polaris/Solo Globe Challenger rolled 360. Statements are in the enquiry.

When we talk about "gross generalisations" can you please inform us how an Atkins 32, Westsail 32, Norseman 447, Farr 1220, Craddock 42, and Rhodes Offshore 40 consist of a fleet of lightweights???????

I think that much of the "problem" in discussing seaworthiness comes from the way each side tends to view the other. I've actually sat there, coming home from a race, and talked with one of the people and a very prominent owner about the risk of offshore racing now that we all have kids. The assessment was that the risks are small compared to the rewards. About 40,000 people have done the Hobart; about 10 have died. The equal major cause of death has been heart attacks, I think, and then on S&S boats as more than anything else. I have seen a massive increase in safety-mindedness in the fleet. When I started as a 16 year old in 1979, I was a freak because I always carried a personal strobe. These days it's common.

I think if the lightweights were not blamed for things like the Maydays sent out by Atkins double-enders and Westsails out of NZ, if the designers of lightweights were recognised as experienced and competent by their professional peers, communication would be improved and things may improve still further.

 

Unfortuantely a lot of your posts do spin off into some uncharted territory and In chasing the ball we get off the real issue at times.

Here I think you are mistaken. Hullform and Hull material are quite a different concern.

When something fails we would like to know why; what do we do to prevent this type of failure in the future. Is it an inate characterisitc of the hullform or is it poor workmanship or design.

This boat failed due to a combination of factors related to the hull material, age (stress cycles) and probably exacerbated by hydrolysis. We cannot be certain without examination but from my own experience with these boats quality of production has been a problem at times in the layup.

Perhaps the two most prominent advantages of heavier boats are the considerable reserve strength (which reduces fatigue issues too) and the increased sea-kindliness in severe conditions.

As for calling for an airlift because they just want to get off ( like the cyclone that hit the NZ cruising fleet ) is that the people wanted to get off because they were scared miserable and sick not that it was a light fleet. Poorly written sorry. I was going to carry on with another paragraph on seakindliness and getting off boats but I ran out of time. Rel to fastnet too.

Lets look that one up. It was significant and tragic but most of the boats as with the fastnet were afloat after the event with little damage as I recall .

Queens Birthday storm of 1994 off New Zealand if anyone wants to reasearch it?


Back to work

 

Happy New Year!

Nice side step. I think you have equated weight with strength on at least one occasion. You have implied that light boats cannot be strong enough. Now you point out that just because a boat is heavy that it is no guarantee of strength. I would put forth that just because a boat is light it is no guarantee that it is not strong enough.

In one paragraph you say this heavy boat failed, in the next you say that heavier boats have considerable reserve strength ..? How much heavier did this boat have to be?

I don't remember anyone answering this question: What is the definition of heavy? Is it a certain weight? Is it a certain ratio? Can the D/L ratio be used to define what is considered heavy or light?

The information that I have been able to find indicates that boats with D/L ratios that keep them in displacement mode have not gotten much faster in the last 100 years. They tend to make passages in the 1-1.4 S/L range. If we would like to make faster passages we must sail boats that can sustain S/L ratio speeds over 1.5. that means Multi's or ULDB mono's.

Interesting also is the fact that an ULDB 50-60 ft LWL boat can have better comfort ratio numbers than a 300 D/L 30 footer.

Is it the opinion of the heavy is better NA's that no ULDB can be both seaworthy and seakindly?

After looking at some of the passage speeds recorded over the years, I'll concede that unless the design can plane (or semi-plane at S/L 1.5-2.5), we might as well just scale Dorade up or down to suit the size of our crew. She managed a 24 hour run at S/L = 1.44 in 1931.

There is no reason for a boat with D/L 200+ to adopt the hulform of the modern racer, it cannot take advantage of it.

I also have to question again the focus on stability and inversion as a major part of what makes a boat seaworthy.

You talk of protecting innocents. There is a chance of your child getting hit by a truck every time they get near a public road. Do you force your child to wear a helmet and full body armour every time they cross a street? or do you teach them to look both ways before stepping into the road?

I think the level of focus should be equal to the level of risk. No one has provided evidence that capsize or inversion is a large problem for modern boats compared to all the possible causes of lost boats or lost lives. When asked how a boat can be condemned after one instance of inversion, we get a comment that all the inversions in Australia were not included in the research ... no numbers that show that there were ANY ... but the insinuation that there were. That's spin and cheap innuendo if I've ever seen it.

Every time the question of probability of capsize is asked, it gets side stepped with replies like, "but if it did capsize, wouldn't you want it to right promptly?" Sure if my grandson walked out in front of a truck, I would want his mother to have encased him in full body armour. Although the chances of loosing him in a traffic accident are many times higher than loosing him because a hull didn't self right quick enough, I don't consider the risk high enough to buy body armour for him.

Since no one has provided any data that would make me think that there is a high risk of capsize, I will assume such data does not exist. Since it does not exist, why then are some people so fixated on capisize and inversion time as huge design issues? Is it their hobby? Their source of income? I don't get it. (probably because I'm not a degreeed engineer?)

Scare tactics don't work either:

You should write novels ... your responses are rarely supported with data.

The parents of those poor folk "too scared to go fwd to hank on a storm jib" never taught them to look both ways before crossing the street ...

Carry on

Randy

 

quote RHough

I put you in green ok?

Nice side step.

You should see my left hook! Happy new year to you too


I think you have equated weight with strength on at least one occasion. You have implied that light boats cannot be strong enough. Now you point out that just because a boat is heavy that it is no guarantee of strength. I would put forth that just because a boat is light it is no guarantee that it is not strong enough.

In one paragraph you say this heavy boat failed, in the next you say that heavier boats have considerable reserve strength ..? How much heavier did this boat have to be?

Randy

Any builder could make a very heavy boat from a good design out of rotten wood and rusty nails. Please get some logic in these arguments. Please

I have not implied that light boats cannot be strong enough, I have stated that it is hard to get a high level of reserve strength and a light boat without going to expensive materials.

A boat can be strong enough for moderate conditions and yet be broken up or have its coach roof smashed off or its rudder or keel broken by heavy seas, or collision at sea or grounding. Fatigue is the enemy of all highly stressed materials ( and I do fatigue and stress analysis of boat structures for some racing yacht designs too ), it should not be hard to accept that a heavier boat can have scantlings that provide a higher factor of safety (that is yield/design stress) .

Surely you would agree a high level of reserve strength is a very good safety feature?

I don't remember anyone answering this question: What is the definition of heavy? Is it a certain weight? Is it a certain ratio? Can the D/L ratio be used to define what is considered heavy or light?

Now I suppose we are back into trends and this is why I wanted to talk of "heavier boats" and "lighter boats" so things don't get too polarised or xenophobic.

The information that I have been able to find indicates that boats with D/L ratios that keep them in displacement mode have not gotten much faster in the last 100 years. They tend to make passages in the 1-1.4 S/L range. If we would like to make faster passages we must sail boats that can sustain S/L ratio speeds over 1.5. that means Multi's or ULDB mono's.

I agree and as I posted twice now in this thread what happens to the ULDB when it is used as an out and out cruising boat? FOR EXAMPLE The Pogo 40 cruising with 4 people aboard and cruising long term. A reasonable cruising load for 4 people crossing the atlantic and cruising the Carribbean would see D rise from 5.5 to say 8 Tons. No more ULD , poor sail area to displacment, poor or even dangerous stability figures because all the stowage is high. wetted surface becomes a hinderance in the loaded configuraton. Now the vessel is in a dangerous condition if it encounters heavy weather.

Interesting also is the fact that an ULDB 50-60 ft LWL boat can have better comfort ratio numbers than a 300 D/L 30 footer.

Like the Dashews boats the light boats can be big enough to work at around 60 feet with some comfort although comfort factor does not give you the "jerkiness" that higher speed introduces but speed gives dynamic stability too. I also feel that ocean cruising boats should as a minimum be over the mid 30 feet on deck, but you would be better for performance with a longer narrower boat of the same internal volume say a narrower 40 footer ( there is a lot more to this as well .... I know).

Is it the opinion of the heavy is better NA's that no ULDB can be both seaworthy and seakindly?

I said before a narrower light boat will be more seaworthy than a beamy light boat. But this comes back to " seaworthy" if we want a seaworthy cruiser and we define a life span then most of the grp lightweights should be scrapped after a certain length of time at sea.


After looking at some of the passage speeds recorded over the years, I'll concede that unless the design can plane (or semi-plane at S/L 1.5-2.5), we might as well just scale Dorade up or down to suit the size of our crew. She managed a 24 hour run at S/L = 1.44 in 1931.

There is no reason for a boat with D/L 200+ to adopt the hulform of the modern racer, it cannot take advantage of it.

I also have to question again the focus on stability and inversion as a major part of what makes a boat seaworthy.

You talk of protecting innocents.

Yes I have a vision of Vega and his large family (my imagination) crossing the atlantic on a poorly suited 40 footer loaded to the gunnels secure in the knowlege that his boat is the most seaworthy platform money can buy. Life gets more important as you get old.
..................
When asked how a boat can be condemned after one instance of inversion, we get a comment that all the inversions in Australia were not included in the research ... no numbers that show that there were ANY ... but the insinuation that there were. That's spin and cheap innuendo if I've ever seen it.

Not correct and offensive, there have been some here and from this knowledge I would be very surprised if there have not been many more even in Europe that went unreported, I don't make this up and I try to stick to verifyable facts or state that it is my opinion. Chris (CT249) can bear me out here or you can wait while I get you the details.


Every time the question of probability of capsize is asked, it gets side stepped with replies like, "but if it did capsize, wouldn't you want it to right promptly?"

I thought it was the opposite, every time I ask how long is a reasonable inversion time I get statistics to suggest it wont happen to most boats.


Since no one has provided any data that would make me think that there is a high risk of capsize, I will assume such data does not exist. Since it does not exist, why then are some people so fixated on capisize and inversion time as huge design issues? Is it their hobby? Their source of income? I don't get it. (probably because I'm not a degreeed engineer?)

If we have a design brief to produce a seaworthy boat and we list the desired attributes do you really think that stability should be left out?
The argument with stability is that deaths will occurr in crusiing fleets if it is neglected and for some small trade offs in the scheme of things we can produce much safer boats.


Scare tactics don't work either:

Print it out show it to you wife (or your mother) and we'll see I was hoping that it would put some of this in perspective, I could write a lot more about heavy weather, I 've been in enough myself to know that a lot of fantasy gets aired on this topic.

Seriously though Randy have you ever been in sea conditions over 50 Knots in any sized boat ? A blue water cruising boat should be able to weather 50 knots and the sea it kicks up over a day or so. Then put yourself in that at night and try helming the boat when you can't see a dam thing except the phosphorescent crest of the breaking waves and nothing of the non-breaking ones. ..

You should write novels ... your responses are rarely supported with data.

Don't get patronizing , you were just starting to sound reasonable.

which post did you have in mind and what data would you like ? The problem talking to non-engineers is to try and keep things at a level you can discuss too. Guillermo has suggested moving this to Fishing boats so we can keep the discussion a little more scientific......... We can throw in lots of equations figures and proofs since a lot of time and money has gone into the researching of these craft after a large loss of life over the years, and much of the data is also applicable to yachts. What do you think of this idea? Stability is one of the prime design considerations, so you'll like that.

Cheers

 

"Lets look that one up. It was significant and tragic but most of the boats as with the fastnet were afloat after the event with little damage as I recall ."

Most of the boats in the Fastnet were afloat after the event. Several people (ie Ariadne's crew, Trophy I think) were lost after bailing out of boats that stayed afloat. Despite the fact that something like 305 of 310 boats survived, this was the race that (IIRC) inspired books about how IOR boats were horribly dangerous. Surely the fact that boats survived, without being cared for and often after being left with hatches open, is an indication that these boats are not, as so often said, entirely dependent on being cared for by their crews.

It is often said that fat racing boats cannot survive lying ahull and need crews to take care of them - but what were all the abandoned IOR boats doing; steering by themselves? I often think boats are alive, but not to the point where they can save themselves by driving themselves around the ocean in a storm.

However, since most of the Mayday calls in the NZ cruising rally you pointed out came from heavy to very heavy conservative cruisers, we have a good indication that it is not necessarily lightweights that get people "calling for an airlift because they just want to get off."

By the way, I looked at the Rhodes Offshore 40 site while I was checking info about the NZ storm. It reminded me that one of the Offshore 40 production boats (a Pearson 40) won the 2000 Bermuda Race overall on IMS, from another Rhodes design. I actually spent some time chatting with the owner shortly before the race, and looking at his lovely boat.

The point is that it has been said that rating rules treat heavy boats harshly. The fact that Restless won one of the world's major events is yet more proof that this is not the case. Frankly I think it suits the slower sailors to blame the rule rather than look at their own ability. Older boats are not competitive in all conditions; they have the races that favour them and the ones that don't, just as other sorts do. So saying that people are forced to lighter boats by the rating rules is not correct.

 

I would love to see some numbers. I hate feeling that I'm being talked down to. When questions are asked that can be best answered with data and formulas, answer them that way. I may struggle a bit to keep up, but you will have my respect for not assuming I won't understand the answer.

On the other hand, your patronizing attitude ("The problem talking to non-engineers") has forced me to look a bit harder at boats and design features, for that I sincerely thank you.

Randy

 

Mike, you are not quoting me properly. You give the impression that I am willing to give away seaworthiness for speed. That was not what I have said and that is not my opinion.

I have said:

You think that almost everybody is wrong in what concerns seaworthiness and modern boat evolution: from the most prominent designers to the sailing magazines boat testers (that are very experienced sailors), racing ocean sailors and most of the experienced ocean sailors.. You think everybody, or almost everybody is wrong and you are right.

Sorry, but I don’t believe it and practical evidence on boat accidents does not confirm your views.

What I have said was:

And that means that not all “beamy“ boats are unseaworthy. Do you consider that a boat with the below specifications and capable of doing without outside help, as it is shown in the movie, is an unseaworthy boat?

http://www.youtube.com/watch?v=LZcwoQoNVak


From the Open60 rule:

“SELF-RIGHTING
During the measurement process, the skipper must physically demonstrate that the boat, once casized, is capable of self righting without outside help.
This test is mandatory for the issue of the first Measurement certificate.”

STABILITY CURVE AREA RATIO
The positive area under the stability curve shall be at least 5 times greater than the negative area.

UNSINKABILITY
B.7.1: Essential rule: In the event of all compartments being completely flooded, the boat shall remain unsinkable.
B.7.2: Unsinkable volume:
The boat shall possess a total volume for unsinkability, expressed in m3 not less than 130% of the boat displacement in m3:
.....
b) Crash box:
A watertight box, filled with closed cell foam, capable of being destroyed in a frontal collision without endangering the integrity of the boat shall be fitted at the bow."

 

Some thoughts on "Seaworthy"

I think that I probably agree with Mike more than it seams from my posts. Since I've been asking for data, it is only fair that I list some of my thought on what makes a boat seaworthy.

1. That it doesn't sink (pretty basic)
2. That it can sail at least 45 degrees off the true wind in most conditions and can be worked to windward in gale conditions. Windward ability in Storm conditions would be better.
3. That it has no "bad angles" in it's polar curve.
4. That it can sail upwind at at least 70% of true wind speed up to its S/L = 1.0 (bigger boats will be faster but light air dogs are not allowed).
5. That can post 24 hour runs of 200 miles or more (not in all winds at any angle, just on the beam to broad reaches that make pleasant passages)
6. That it have a secure sea berth on both tacks.
7. That it can carry enough cargo to see it's crew through a 30 day passage without substantially effecting its performance.
8. That it has a viable extreme conditions survival tactic.
9. That it can be sailed by a crew of two in all weather.
10. That it relies on no powered systems for it's basic performance.
11. That it displaces 20,000 pounds or less (I'd prefer 10-15,000 pounds for a double handed cruiser, but I'll take 20,000)

Now if Mike and Guillermo can make it hard to capsize, quick to recover from inversion and ride like a Bentley with limo tyres without sacrificing any of the performance I consider minimum I have no argument.

If not. I'll give up the cushy ride for better capsize and inversion recovery performance.

If still no, I'll trade inversion recovery for capsize resistance.

If still no, I'll take my chances anyway. I've done over 1500 miles in 36 hours on a vehicle with zero static stability. I don't mind having to stay awake and take an active role.

 

This thread goes too fast for me these days, as I'm pretty busy. A pity not being able to anwer posts with more detail. Just some quick thoughts for the time being:
- This thread is within the 'Stability' Forum, I began it, I'm interested in stability and that's why I'm focusing seaworthiness on it.
- Discussions on other matters regarding seaworthiness are welcome here, but if someone wants to focuse and discuss them in deep (what nobody has done, in spite of Paulo's effort to prove the contrary) it should better be done opening a new thread at other forum.
- I'm missing a more scientifically approach to discussion. I think it's actually too based in personal feelings, understandings and misunderstandings. We are throwing into discussion a lot of not enough analized info. And this at a pace it makes almost impossible (at least for me) to follow up if a minimum serious analysis is pretended.
- This has become (as almost always in these forums) a discussion among a few people, with very small participation of NAs and other technically formed people. This amazes me.
- I have found that bringing numbers into discussions, trying to give them a more technical approach, seems to bring them to a very quick stop. It seems everybody is delighted discussing personal feelings but almost nobody seems to want to discuss numbers with numbers.
- I would like to find a way of reconducting the thing, but it seems it's absolutely out of my control. Probably I'm not doing things the right way (or is it an inevitable malady of these forums?).
- Could we, as Randy and Mike suggest, go at an slower pace, focusing in some boat or type of boat and discuss it with numbers?

Cheers

P.S.
Chris, in my country to become an 'Ingeniero Naval' takes an average of 8 years, pretty more than what is needed to become a lawyer.

 

Why not, but in the numbers, do include cost. Seaworthiness is like any other feature on a boat. It has a cost.
And if you compare boats, do compare seaworthiness figures for boats of around the same price in same condition. (ie both new, both used 30 years, if one new and the other used 30 year, please include in the price of the used one the cost for refitting rig, sails, engine, plumbing, electricity, electronics, paints etc ... to nearly new condition).

It is about ******** to compare the seaworthiness of a pogo mini 6.5 and a swan 100 RS.