Bayesian Interim Report

[ylop]

as much as we all might want to hate superyacht guests.., and feel the need to disparage them.., there is nothing to suggest that these guests were stupid.

I don't think for a minute the guests were stupid. Actually it might be better to assume your guests are all stupid - so like a cruise ship need everything spelled out for them on arrival (perhaps they do this).

on the contrary, they were pretty successful people working in a range of highly competitive fields.., where they are probably all accustomed to delegating important work to others and then making good, and profitable, use of this work.

exactly - so are they assuming that if there is a problem the crew will inform them? Perhaps the crew did everything that would be expected of them - I have no information to contradict that. However even if they followed all the current wisdom, this case MAY have lessons to learn about whether that wisdom was right. Notice who survived - the crew who were up and about, and the guests who had moved around too. The only crew member who died was the chef who had gone to the galley to secure stuff from flying around.

There is no reason to believe they would not listen to advice or instructions from experienced seamen concerning their safety

I don't think I suggested this was the case. Clearly a question for the inquiry is what advice were they given. eg. it might make sense to say "stay in your cabin" if it keeps guests out the way of the crew (or flying pianos) but does that make them more likely to get trapped.

There has been a lot of online discussion about "escape hatches", but as far as I know, nobody has definitively shown there were any.

In any case, as the MAIB report makes clear, this event happened really quickly, it was dark, and many of the victims were likely sleeping when it began.

I think that, sadly, for most of the victims it was not survivable.

Well that's a topic for the investigation. The actual roll was quick, but the whole sequence was not as sudden as that.

0300 the weather was clearly worsening.
0330 it had woken some guests
0355 the deck hand could see it was unusual enough to film.
0357 they were dragging
0400 bad enough for deckhand to wake captain
0406 disaster struck
0422 eprib deployed but hull still afloat

So there were windows of opportunity where interventions MIGHT have saved lives IF the captain and crew had understood the risk. 1. If the time between 0300-0355 had been used to ready the engines and lower the centre board they might never have rolled. If the time from 0355-0406 had been used to get everyone mustered they might all have been saved.

 

[Mark-1]

True - however boats with AVS less than 90 will not pop back up once the wave / downdraft has gone away.

In this case the vessel takes on over one ton of water per second at a bit over 40° through a one metre square vent. So AVS is probably not the critical issue. Ironically at that point it would probably be safer if it was inverted quickly becaise it wouldn't sink and maybe divers could get them out. I assume the fact that the mast touched the bottom held it at an angle where air could escape and water get it. (All total conjecture.)

 

[westhinder]

So there were windows of opportunity where interventions MIGHT have saved lives IF the captain and crew had understood the risk. 1. If the time between 0300-0355 had been used to ready the engines and lower the centre board they might never have rolled. If the time from 0355-0406 had been used to get everyone mustered they might all have been saved.

That of course is what the Italian judicial authorities will be focusing on

 

[flaming]

In this case the vessel takes on over one ton of water per second at a bit over 40° through a one metre square vent. So AVS is probably not the critical issue. Ironically at that point it would probably be safer if it was inverted quickly becaise it wouldn't sink and maybe divers could get them out. I assume the fact that the mast touched the bottom held it at an angle where air could escape and water get it. (All total conjecture.)

But it went over, so it wasn't coming back.

I think the downflooding is actually a bit of a red herring here. 1 ton per second sounds a lot, but the boat weighs over 400 tons.

 

[Mark-1]

.0300 the weather was clearly worsening.
0330 it had woken some guests
0355 the deck hand could see it was unusual enough to film.
0357 they were dragging
0400 bad enough for deckhand to wake captain
0406 disaster struck
0422 eprib deployed but hull still afloat

So there were windows of opportunity where interventions MIGHT have saved lives IF the captain and crew had understood the risk.

True, but I don't think there was any way to understand the risk, the squall was an unknown quantity and the fragility of the boat was too. AFAIK the boat nearby didn't get their passengers up in case of capsize. I'd guess the crew thought the chances of heeling past ~40 degrees that night were close on zero, and that was a reasonable assumption.

I would be amazed if there has ever been a boat in the Med, private or commercial, where they routinely summon everyone up in these circumstances for fear of entrapment in a sinking.

(All conjecture, obvs.)

 

[Mark-1]

But it went over, so it wasn't coming back.

I think the downflooding is actually a bit of a red herring here. 1 ton per second sounds a lot, but the boat weighs over 400 tons.

Yes, in this specific case. (Although are we sure? Did the mast hit the water immediately or was it pinned at a point well below it's AWS until water altered the AWS and took it past that point?)

However, assuming downflooding is irrelevant in this case, which I agree it likely is, in general use as a sailing boat I'd say 15% of it's total weight per minute going straight into the engines and then down to the lowest point of the hull is a far bigger concern than flipping over in general useage. ...and that assumes the inlet is only 0.5m under which is conservative.

 

[flaming]

Yes, in this specific case. But I'd say 15% of it's total weight per minute going straight into the engines and then down to the lowest point of the hull is a far bigger concern than flipping over in general useage.

In general usage yes.

it didn't capsize and sink in general usage though... It capsized and sunk at anchor when hit by a squall.

 

[Poignard]

[...]

0300 the weather was clearly worsening.
0330 it had woken some guests
0355 the deck hand could see it was unusual enough to film.
0357 they were dragging
0400 bad enough for deckhand to wake captain
0406 disaster struck
0422 eprib deployed but hull still afloat

So there were windows of opportunity where interventions MIGHT have saved lives IF the captain and crew had understood the risk. 1. If the time between 0300-0355 had been used to ready the engines and lower the centre board they might never have rolled. If the time from 0355-0406 had been used to get everyone mustered they might all have been saved.

I asked my wife; "If we were keeping anchor watches, and you were on watch, and you saw thunderclouds and lightning that seemed to be getting closer, what would you do?"

She replied: "Wake you up."

 

[ylop]

That of course is what the Italian judicial authorities will be focusing on

It may be that there is no evidence of criminality, that doesn’t mean there are no lessons to learn.

 

[dunedin]

AVS and other common measures of stability are for the _static_case.

It's pretty unlikely for a boat just sailing along to be gradually heeled past it's AVS, and so it's not that clear that the AVS of a sailboat is really that great an indicator of safety.

The far more likely case is that a boat gets rolled by a breaking wave, and the AVS does not really give much of an indication of how likely a boat is to resist rolling, where dynamical effects come in to play.

even a high AVS boat will get rolled by a big breaking wave.

The Ovni sliding idea is more applicable as a way to handle the dynamic effects of a breaking wave, rather than as an aid to a boat with low static stability.

Given that these, and similar low static stability boats, successfully sail all around the world, it's worth asking whether high static stability is really an important safety factor.

There is the issue of a rolled boat staying upside down.., but I also think this issue is exaggerated.

Static stability clearly helps performance - stability is the most important determinant of sail carrying power, it reduces heel and thus reduces leeway, and has other benefits. A potential downside is that it increases rigging loads, and may make rig care and inspection more important.

Clearly the Bayesian is a different and very exceptional case, but yes for cruising yachts it does seem the “breaking wave” scenario is perhaps a bigger risk when crossing oceans. And it is not clear that a high AVS is the key factor.
Thousands of crusing catamarns seem to sail the oceans with very few capsizing in storms - much fewer than i would have expected. It does seem that sliding sideways may be a safety factor (and daggerboards down therefore a danger factor in such extremis).
Also it does seem that the GGR style boats with long keels seem to be quite prone to capsizing - perhaps due to their high resistance to sliding - whilst the shallow boats like Ovnis (and Open 60s) with narrower keels perhaps less so.
One could definitely create a hypothesis (if not a proof, yet) that the beam plus side slip is a safety feature.
Clearly until the limits are exceeded where the high AVS comes in once upside down (assuming the figure is not artificially created by a high coachroof which has been inundated/ smashed).

 

[Mark-1]

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I asked my wife; "If we were keeping anchor watches, and you were on watch, and you saw thunderclouds and lightning that seemed to be getting closer, what would you do?"

She replied: "Wake you up."

But you're not a passenger, you're part of the crew. In this case the entire crew were up.

 

[ylop]

But you're not a passenger, you're part of the crew. In this case the entire crew were up.

I think his point was “his crew” (wife) would have woken him (“the skipper”) at 0300 when it was obvious the thunderstorm was going to hit them/come close.

The Baden Powell may have escaped because of luck (not getting his by the same supercell), because its design was less vulnerable or because its crew were summonsed on deck earlier and had manoeuvring ability to keep into the worst of it.

 

[Mark-1]

I think his point was “his crew” (wife) would have woken him (“the skipper”) at 0300 when it was obvious the thunderstorm was going to hit them/come close.

The Baden Powell may have escaped because of luck (not getting his by the same supercell), because its design was less vulnerable or because its crew were summonsed on deck earlier and had manoeuvring ability to keep into the worst of it.

I hadn't really missed the point, I *had* missed the fact that there wasn't enough time to wake the Captain and use the engines to 'help' get the bows headed into the direction of the wind. (Or at least their best guess of it.)

Personally I think it's irrelevant but, in hindsight, it certainly couldn't have hurt. (Of course, waking the Captain for every thunderstorm carries its own risk - you end up with a sleep deprived Captain.)

 

[Poignard]

But you're not a passenger, you're part of the crew. In this case the entire crew were up.

But they weren't woken until nearly an hour after the deckhand (the only person on watch) first observed the thunder and lightning appearing to be getting closer. By which time it was too late.

Why didn't he report it sooner?

Was it because he didn't consider it any more worthy of note than something to be videoed and posted on social media?

 

[Poignard]

But you're not a passenger, you're part of the crew. In this case the entire crew were up.

See posts 272, 274.

 

[Mark-1]

But they weren't woken until nearly an hour after the deckhand (the only person on watch) first observed the thunder and lightning appearing to be getting closer. By whic

Why didn't he report it sooner?

Was it because he didn't consider it any more worthy of note than something to be videoed and posted on social media?

I wish I hadn't replied to that post. I hadn't appreciated how close the squall was when the Captain was woken and that makes the point a fair one.

However since I am involved, the crewmember was told to wake the Captain when the wind reached 20kts, which he did. So that was why he didn't wake the Captain earlier.

....and yes, I'm 100% certain he didn't regard it as noteworthy, it was just another nasty squall that was going to get the cushions wet, I'm sure they see dozens.

In hindsight it was something less common, but nobody knew that at the time.

....but yes this isn't an argument I wanted to have, clearly in hindsight, waking the Captain could not have hurt, and might have helped, so the point was a totally fair one.

 

[ylop]

I hadn't really missed the point, I *had* missed the fact that there wasn't enough time to wake the Captain and use the engines to 'help' get the bows headed into the direction of the wind. (Or at least their best guess of it.)

Even if there was nothing special about the storm at 0300, by 0355 the deckhand thought it was significant enough to tell his followers on social media, but not his captain. That is probably difficult to explain. Although I expect it is not an uncommon response in 20 somethings. Could they have saved her (or more guests) with 5 mins more warning? Nobody knows.

I don’t know how common thunderstorms are but I’d have thought the captain would want to be aware in case the boat was struck?

 

[westernman]

I wish I hadn't replied to that post. I hadn't appreciated how close the squall was when the Captain was woken and that makes the point a fair one.

However since I am involved, the crewmember was told to wake the Captain when the wind reached 20kts, which he did. So that was why he didn't wake the Captain earlier.

....and yes, I'm 100% certain he didn't regard it as noteworthy, it was just another nasty squall that was going to get the cushions wet, I'm sure they see dozens.

In hindsight it was something less common, but nobody knew that at the time.

....but yes this isn't an argument I wanted to have, clearly in hindsight, waking the Captain could not have hurt, and might have helped, so the point was a totally fair one.

Yes. A F8 for a yacht this size is nothing alarming.
For my yacht, I start to get worried about dragging my piddling little 75lb CQR anchor - not about the wind itself.

 

[westhinder]

It may be that there is no evidence of criminality, that doesn’t mean there are no lessons to learn.

Most probably not, in that there will not have been any intention to do wrong. But I take it the investigation will be far broader than that, and may well focus on the crew’s duty of care and whether they have acted in time to save as many lives as possible. It is notable that the interim report does not mention in its timeline that an order was given to muster all the guests.

 

[flaming]

Most probably not, in that there will not have been any intention to do wrong. But I take it the investigation will be far broader than that, and may well focus on the crew’s duty of care and whether they have acted in time to save as many lives as possible. It is notable that the interim report does not mention in its timeline that an order was given to muster all the guests.

I would hope that it would also look at the design of the vessel, and the information that was available to the crew about its limitations.