Bayesian Interim Report

KevinV said:
Thinking about the whole keel up thing - I wonder if the motion of the boat might have been uncomfortable at anchor (and motoring) with the keel down - like a yacht without it's mast having too fast a motion? That that's the reason they had it up, even though they had plenty of depth? Also, having it down would cause more wear on the mechanism, so might only be done when needed (sailing)(I know from a Tartan 37 I spent time on that the centreboard would clonk to and fro horribly if not sailing)? Or could keel-down have caused hunting at anchor - hence avoiding putting it down? Lastly, might something have got lost in translation from the Italian - rather than "motoring condition", saying "when not sailing"(which would include at anchor)? Just ideas, but so far I have heard no actual explaination why it was up.

Whatever the case may be, I have to commend a crew who can go from asleep to a flurry of pertinent activity in 6 minutes at the very worst part of the circadian cycle. They didn't win, but not from lack of effort.
Click to expand...
I read somewhere that the keel was up as when it is down it rattles around when at anchor as the boat swings.
 
Reading the report, it is clear to me that this is a freak weather event. The Met office are cited as saying that the formation of a supercell on the night of the incident as probable. Hence localised extreme wind speeds and direction in all three dimensions might have been experienced by the Bayesian and not the Sir Bayden Powell. In other words chance played a part in which if either vessel was affected.

The vessel was approved by a certifying authority so was legal. I would imagine that if the interim reports finding stands, there will be a recommendation for CAs to review contents of stability booklets. But I can’t see them recommending designing a vessel to withstand a micro burst or other such extreme feature of weather.

I don’t see the relevance of anchor dragging, AWA, keel up or down, down flooding or whatever. These boats are designed by qualified naval architects, working to established (but also dynamic) codes who understand big vessels. If you get struck by extremely strong winds, with dramatic and rapid changes in direction (as down drafts cause when hitting the surface or the spiralling nature of up drafts mentioned in the report) there will always be a risk of a sailing vessel (and perhaps vessel of other types) foundering.
 
Last edited:
Mark-1 said:
It was widely reported that the keel was always left up at anchor due to the noise of it clanking around.
Click to expand...
certainly it was widely rumored...

i never saw an informed statement saying that this was the case.

i would be surprised if the centerboard could clunk back and forth on this yacht.
 
DownWest said:
Yes, I had a look, but along with the blatherers, there are some NAs and other pros with good info. It is a long thread, so be warned. IIRR 6K posts..
Click to expand...

Assuming we're talking about the SA thread yeah. If there's a better source maybe someone can link to it. The level of detail from NAs and people working in the industry was really good. You can easily skip the useless/non factual posts.
 
Laser310 said:
certainly it was widely rumored...

i never saw an informed statement saying that this was the case.

i would be surprised if the centerboard could clunk back and forth on this yacht.
Click to expand...

Pretty sure it came from a past crew member or Captain of the yacht.

Either way this will be a documented operating procedure, so we will find out for sure at some point.
 
boomerangben said:
These boats are designed by qualified naval architects, working to established (but also dynamic) codes who understand big vessels.
Click to expand...

Yes, and those NAs are limited by constraints. There is no way by choice any NA would add an opening that wasn't on the on the centre line. But in these vessels they had to because of other requirements. (IIRC space and asthetics.)

I don't doubt any NA could develop an unsinkable boat if they had freedom to make any decision they deemed useful. In fact, I could!
 
Last edited:
Mister E said:
I wonder how many vessels are designed with a direct hit from a tornado?
Would any pleasure craft ever be built if this was one of the design parameters?
Click to expand...

Maybe I'm naive, but I'd assume most/all monohull sailing vessels absolutely would survive a knockdown and would handle ~40° of heel without any drama at all.

I'm sure that many sailing vessels get damaged or destroyed in tornados but I'd imagine that is typically other modes of failure than knockdown on open water.
 
boomerangben said:
Reading the report, it is clear to me that this is a freak weather event.
Click to expand...
60kt winds are hardly "freak weather events"! Get them every year in the UK.

I get that the situation developed quickly in this instance, but this was clearly a vessel that needed a lot of nursing in heavy weather.
 
DreadShips said:
60kt winds are hardly "freak weather events"! Get them every year in the UK.

I get that the situation developed quickly in this instance, but this was clearly a vessel that needed a lot of nursing in heavy weather.
Click to expand...
I fully get that a steady, sustained 60kts is not freak. But in a usual gale, it builds over time and changes in intensity and direction relatively slowly, giving a vessel time to weather vane if at anchor.

A supercell would provide very dramatic changes of speed and direction, including a vertical component at a time scale that is less than the time taken for a vessel to weather vane.
 
Mark-1 said:
Yes, and those NAs are limited by constraints. There is no way by choice any NA would add an opening that wasn't on the on the centre line. But in these vessels they had to because of other requirements. (IIRC space and asthetics.)

I don't doubt any NA could develop an unsinkable boat if they had freedom to make any decision they deemed useful. In fact, I could!
Click to expand...
I think you are misunderstanding the role of a naval architect. Any vessel (apart from unmanned) has to function with a human - vessel interface and the role of the naval architect (amongst others) is to provide a compliant vessel that meets customer requirements.

But as I said before, I think this was an instance where no amount of design would have saved the day. No boat is unsinkable if you want humans to use it.
 
boomerangben said:
I think you are misunderstanding the role of a naval architect. Any vessel (apart from unmanned) has to function with a human - vessel interface and the role of the naval architect (amongst others) is to provide a compliant vessel that meets customer requirements.

But as I said before, I think this was an instance where no amount of design would have saved the day. No boat is unsinkable if you want humans to use it.
Click to expand...

Self evidently the process of meeting customer requirements is *exactly* what I meant by "other requirements".

It would be simple to make this vessel heel safely way beyond 40° by blocking the vents but then everyone would suffocate and the engines wouldn't run.

Equally I said I could easily make an unsinkable vessel - I could- it would be a 2l coke bottle - try taking the family to Studland in that!

Far from misunderstanding the role of a NA I was explicity spelling it out.

As I say, if the NA had total freedom of design choices it would have been a very different boat. There was a very detailed youtube vid by an NA spelling out the compromise of the vent location. It certainly wasn't the case the the NA simply didn't understand the balance of the decision.
 
boomerangben said:
I fully get that a steady, sustained 60kts is not freak. But in a usual gale, it builds over time and changes in intensity and direction relatively slowly, giving a vessel time to weather vane if at anchor.
Click to expand...

Not in that area. Short sharp thermal storms are typical, not the gradient winds we're used to.
 
boomerangben said:
… The vessel was approved by a certifying authority … I would imagine that if the interim reports finding stands, there will be a recommendation for CAs to review contents of stability booklets. …
Click to expand...

The CAs do assess the stability requirements and stability data of large vessels and small vessels, and are required to note the availability of the stability data on the vessel. That can be in the marine operations manual, or the stability book, where that format is allowed. What the CAs don’t do, is verify if the stability data is being used by the crew, or understood. However, stability is a key element of CA work at assessment time, initial or periodic, and will also validate the stability design data calculations and measurements, pre approval. If they don’t, they won’t class the vessel. Periodic assessments will be less robust, verifying presence of stability data for the management of the vessel, and validating no material changes have been made which could impact stability.

My experience comes from recent coding and recoding, yachts in the UK and assessing aspects of large vessels in conjunction with other colleagues who perform the marine assessment. I would think that the “stability book” and marine operations manual would be in place and verified on the Bayesian, which I do not think anyone is disputing.

On ships, at anchor, water tight, and weather doors have to remain closed, on leisure yachts, I am not aware of the requirements. They already have issues with lifeboat, abandon ship drills, which they are obliged to do, but may not because their guests are perceived to be too far up their own egos to do pleb stuff.

The Bayesian incident reminds me of the Marques incident where there was lots of speculation around stability, however, she was hit by a sudden squall and significant wave that rolled her under.

Roman poet and philosopher, Titus Luceretius Cams
Never trust her at any time, when the calm sea shows her alluring smile.​

—De Rerum Natura Titus Lucretius Cams 99-55 B.C.
Click to expand...
 
RunAgroundHard said:
The CAs do assess the stability requirements and stability data of large vessels and small vessels, and are required to note the availability of the stability data on the vessel. That can be in the marine operations manual, or the stability book, where that format is allowed. What the CAs don’t do, is verify if the stability data is being used by the crew, or understood. However, stability is a key element of CA work at assessment time, initial or periodic, and will also validate the stability design data calculations and measurements, pre approval. If they don’t, they won’t class the vessel. Periodic assessments will be less robust, verifying presence of stability data for the management of the vessel, and validating no material changes have been made which could impact stability.

My experience comes from recent coding and recoding, yachts in the UK and assessing aspects of large vessels in conjunction with other colleagues who perform the marine assessment. I would think that the “stability book” and marine operations manual would be in place and verified on the Bayesian, which I do not think anyone is disputing.

On ships, at anchor, water tight, and weather doors have to remain closed, on leisure yachts, I am not aware of the requirements. They already have issues with lifeboat, abandon ship drills, which they are obliged to do, but may not because their guests are perceived to be too far up their own egos to do pleb stuff.

The Bayesian incident reminds me of the Marques incident where there was lots of speculation around stability, however, she was hit by a sudden squall and significant wave that rolled her under.

Roman poet and philosopher, Titus Luceretius Cams
Click to expand...

I think it's entirely likely that nobody was to blame: It was a private vessel, the design did what it was supposed to do, the build quality isn't in question and the crew seem to have followed their normal procedures.

That doesn't mean that this style of vessel are a terrific idea, and a comparison with the loss of a replica of a vessel from an era when life was cheaper and death at sea was part of the job isn't very encouraging at all.
 
I’m not qualified to comment on this thread so I won’t! I’d like to ask though, when there’s a mention of a boat at anchor “weather vaning” to the wind - would that expression be the same as “weather cocking” which is the expression I’ve grown up with. I curious and not intentionally being pedantic!
 
You must log in or register to reply here.

Share this page

Top