"Bayesian" s/y sinks in Palermo

[XDC]

Of course, the C32 will sink at 78 degrees unless you’re sailing with the washboards in and the hatch closed, I’ve been on board one at less heel than that, and watched in horror as the green stuff rushed down the hatch. The Bavaria, perhaps not.

 

[Mark-1]

It’s lowered at all times at sea to give the yacht its required righting moment. The keel is only generally raised entering harbour.

It was anchored overnight within swimming distance of shore. To all intents and purposes it was in a Harbour and not "at Sea".

The fact it was knocked flat under bare poles is pretty good evidence the keel was up and was actually designed to contribute to the ballast. (...but not conclusive.)

 

[Chiara’s slave]

Scary stuff. A Contessa is a bit less likely to succumb to that, I think, but it is the usual way yachts are put on their sides. Wind alone, it's extremely rare. That boat plainly sat high in the water on it’s side, the hatch was not at the new waterline.

 

[MikeBz]

Sounds like the most likely scenario was that the keel was retracted, massively reducing the righting force when heeled over

Not if the lifting part of the keel is unballasted - in that case the ballast is in the hull or non-retractable part of the keel. AIUI most, if not all, of these mega-deep mega-yachts are really centreboarders, presumably so that they can safely transition to shallower draft to allow them to get to interesting places. In that case speculation about whether the 'keel' was up or down is pretty much irrelevant.

 

[ylop]

Perhaps you haven't read any of their reports. Their investigators are reportedly at the scene now.

I’ve read lots of their reports. Their root cause analysis is usually very detailed, although sadly often doesn’t quite get to true cause, “XYZ Ltd prioritised profit over safety” or “Mr X is clearly a cowboy” but I think you can infer that from what is written. But sometimes they go off down weird rabbit holes that undermine their actual credibility at being driven by improving safety; some specific examples that come to mind
- RIB accident in Wales. The coding/qualification didn’t all match up and they made a big deal about it - but ignored that the boat was being used in an area where different coding and those qualifications would have been fine.
- Accident in solent (I think a rib?) ended up with person wearing a buoyancy aid as a survivor and LJ dying. Seemed to criticise the use of a buoyancy aid in the particular waters.
- Army Cadet capsize - made an issue about paperwork for the LJ maintenance, but in fact all the LJs were in working order (had they not the fatality may not have happened), many did not remember to pull the toggle but no question about how easy that is to do on surprise immersion or how well training focussing on ensuring the toggle is accessible etc.
- Loch Lomond RIB accident - seemed to recommend bylaw improvements with no consideration for whether someone who “forgot” their LJ as in this case would be any less likely to go afloat; meanwhile glossed over the fact that there is/was lack of VHF reception on the water (IIRC it remarked the boat didn’t have one - a contributing factor to that will have been that nobody listens/monitors).
- Loch Awe, as I recall the MAIB didn’t review the rescue arrangements; the subsequent FAI did and found significant opportunities for improvement - it’s very unlikely that the MAIBs conclusions on not drinking alcohol, overloading small boats or wearing LJs will prevent future accidents but it’s not the first incident on loch awe and making sure that the police/fire/cg know who should be responsible for responding is probably useful.

These examples all smack of looking for faults rather than looking at how to make boating safer. Of course they may be indicative of wider issues or safety culture but they detract from the true root cause / lessons to learn. IMHO whilst they put “we don’t assign blame” on their reports - that IS the mindset they are written with.

The Marine Enforcement Unit will look at any incident involving Brits or Brit flagged vessels. I'm not guessing, one of their staff told me this when I was interviewed by them gathering evidence about a friend of mine. Telling them they were talking gonads did not endear me to them.

 

[capnsensible]

So chapter one has been released. Personally, I'm gonna wait for the whole book and not try to out guess the ending.....

 

[capnsensible]

I’ve read lots of their reports. Their root cause analysis is usually very detailed, although sadly often doesn’t quite get to true cause, “XYZ Ltd prioritised profit over safety” or “Mr X is clearly a cowboy” but I think you can infer that from what is written. But sometimes they go off down weird rabbit holes that undermine their actual credibility at being driven by improving safety; some specific examples that come to mind
- RIB accident in Wales. The coding/qualification didn’t all match up and they made a big deal about it - but ignored that the boat was being used in an area where different coding and those qualifications would have been fine.
- Accident in solent (I think a rib?) ended up with person wearing a buoyancy aid as a survivor and LJ dying. Seemed to criticise the use of a buoyancy aid in the particular waters.
- Army Cadet capsize - made an issue about paperwork for the LJ maintenance, but in fact all the LJs were in working order (had they not the fatality may not have happened), many did not remember to pull the toggle but no question about how easy that is to do on surprise immersion or how well training focussing on ensuring the toggle is accessible etc.
- Loch Lomond RIB accident - seemed to recommend bylaw improvements with no consideration for whether someone who “forgot” their LJ as in this case would be any less likely to go afloat; meanwhile glossed over the fact that there is/was lack of VHF reception on the water (IIRC it remarked the boat didn’t have one - a contributing factor to that will have been that nobody listens/monitors).
- Loch Awe, as I recall the MAIB didn’t review the rescue arrangements; the subsequent FAI did and found significant opportunities for improvement - it’s very unlikely that the MAIBs conclusions on not drinking alcohol, overloading small boats or wearing LJs will prevent future accidents but it’s not the first incident on loch awe and making sure that the police/fire/cg know who should be responsible for responding is probably useful.

These examples all smack of looking for faults rather than looking at how to make boating safer. Of course they may be indicative of wider issues or safety culture but they detract from the true root cause / lessons to learn. IMHO whilst they put “we don’t assign blame” on their reports - that IS the mindset they are written with.

Well, we are gonna disagree. That's the way the mop flops.

 

[Mark-1]

Not if the lifting part of the keel is unballasted - in that case the ballast is in the hull or non-retractable part of the keel. AIUI most, if not all, of these mega-deep mega-yachts are really centreboarders, presumably so that they can safely transition to shallower draft to allow them to get to interesting places. In that case speculation about whether the 'keel' was up or down is pretty much irrelevant.

If so, it was knocked flat under bare poles with the full ballast it's designed to sail with. Which seems less likely, but who knows. 200mph winds focused on the mast is probably outside the design parameters so maybe...

 

[Sandy]

Your confidence in the MAIB is a little greater than mine. They will likely identify significant contributing factors - that will help interested parties know what went wrong and how it might be mitigated. However their ability to translate those into realistic recommendations/actions that actually stop future deaths is questionable. Eg, if she flooded due to open doors/hatches/windows the easy solution is obvious… but is it realistic at anchor in conditions where nobody is expecting to get knocked down? If the keel was retracted the advice is obvious, but is it realistic to restrict the range of anchorages or even safer to do so?

I don't think you fully understand what the role of an accident investigation board is.

Its role, and part of my final job was an accident investigator, as you correctly state above was to investigate what went wrong and 'identify significant contributing factors' ideally the root cause of an incident. It is NOT to give chapter and verse on what needs to be done to stop future deaths, we would publish our conclusions and issue guidelines, but what manufacturers/users/regulators did to mitigate what happened next was up to them. Over time there would be a body of knowledge and 'best practice'; if something happened in future can be looked at and compared against best practice.

Thankfully, in my experience, most safety critical industries work in calibration with accident investigations as it is only human to stop further suffering.

 

[Baggywrinkle]

The superyacht laid flat in the Westhaven, Auckland, under bare poles in the video I posted earlier was the 44m "Encore" .... mast was 60m and it seems she relied on form stability as well as carrying 60 tons of ballast.

Encore’s overall length is just a shade less than 44 metres, she sports a low silhouette over the water, she’s streamlined with a harmonious deckhouse situated astern of a special 60 metre Southern Spar mast which can carry approximately 2,000 square metres of canvass. The ensuing strong lateral push with the canvass set is balanced more by the hull’s shape than by anything else as the 60 tons worth of ballast is not a great deal when compared to a 265 ton displacement. So as to remain on the same subject, it would be safe to say we’re looking at a hull which is slightly below the mark that separates light displacement range from middle ones and promises therefore hi-performance levels.

https://www.superyacht.eu/shipyard-alloy-yachts/ay45-encore-sea-trial/

Smaller than Bayesian, but didn't stand up to the microburst that hit her very well.

 

[Mark-1]

The superyacht laid flat in the Westhaven, Auckland, under bare poles in the video I posted earlier was the 44m "Encore" .... mast was 60m and it seems she relied on form stability as well as carrying 60 tons of ballast.



https://www.superyacht.eu/shipyard-alloy-yachts/ay45-encore-sea-trial/

Smaller than Bayesian, but didn't stand up to the microburst that hit her very well.

Of course, "balanced more by the hull’s shape " isn't inherently a flaw. It still ought to keep the thing upright. I guess a water spout was outside the design criteria for Encore. Perhaps it's the same for Bayesian.

 

[Chiara’s slave]

Of course, "balanced more by the hull’s shape " isn't inherently a flaw. It still ought to keep the thing upright. I guess a water spout was outside the design criteria for Encore. Perhaps it's the same for Bayesian.

Joshua Slocum, Admiral Lord Nelson, and the good ship ‘Chiara’ are all entirely form stable, though with internal ballast in 2 of the cases.

 

[ylop]

I don't think you fully understand what the role of an accident investigation board is.

I think I do. Its quite clearly defined: The sole objective of the investigation of an accident under the Merchant Shipping (Accident Reporting andInvestigation) Regulations 2012 shall be the prevention of future accidents through the ascertainment of its causes and circumstances. It shall not be the purpose of an such investigation to determine liability nor, except so far as is necessary to achieve its objective, to apportion blame. [my bold]

What I am saying is that actually they seem to wander off looking for things to criticise which were not the causes of the accident. Sometimes they comment on rescue service response and sometimes they don't. Of course that is never a cause but it might mitigate the outcome.

One of the problems is the MAIB essentially define "best practice" by default - its hard for an industry or an individual operator to question or not follow their recommendations without being criticised. But its easy to define good practice sitting behind a desk in an ideal world.

 

[Fr J Hackett]

The yacht would have had a large, very large saloon with accommodations and service areas off it. Highly unlikely that doors between them would have been closed. If any of the entrance doors either at the stern or in the forward area were open as is likely, tonnes of water per second could have entered.
Water tight doors and bulkheads at bow and stern would be for collision damage, other watertight doors internally are most likely to have been open whilst at anchor. The air conditioning would have been running in the cabins and almost certainly switched of in the larger areas, dinning room, saloon etc whilst at anchor overnight hence the probably of external doors being open.

 

[Sea Change]

Re: lifting keels, I agree that this could be a red herring. In a boat of that size it would make the engineering much simpler if it was an unballasted plate, in which case there will be no real effect on the AVS.
In fact, it's well known in the dinghy scene that a boat with the board up can slide sideways over the water, whereas a lowered board can trip the boat and contribute to a capsize. That might not apply at this kind of scale though.

To add to the almost baseless speculation, remember the recent sinking of a large motorboat in Greece- that was caused by a low level side door being left open. These kinds of boats carry lots of toys so there are openings to allow launch and recovery of jetskis etc.

 

[stu9000]

If everything was open the watertightness is largely irrelevant.

These vessels are designed for the mega affluent who are risk averse in their design choices. Even if the doors and windows were open and water was flooding in due to a knockdown, she should not have sunk. There are built in water tight compartments. Utility areas would not just be left open. I cannot think of another example of a vessel like this going down so quickly.

 

[stu9000]

The yacht would have had a large, very large saloon with accommodations and service areas off it. Highly unlikely that doors between them would have been closed. If any of the entrance doors either at the stern or in the forward area were open as is likely, tonnes of water per second could have entered.
Water tight doors and bulkheads at bow and stern would be for collision damage, other watertight doors internally are most likely to have been open whilst at anchor. The air conditioning would have been running in the cabins and almost certainly switched of in the larger areas, dinning room, saloon etc whilst at anchor overnight hence the probably of external doors being open.

This vessel had around 10 crew for up to 12 guests. Even with open plan areas there would be a range of utility areas that are closed off and build in buoyancy.

 

[Mark-1]

These vessels are designed for the mega affluent who are risk averse in their design choices. Even if the doors and windows were open and water was flooding in due to a knockdown, she should not have sunk. There are built in water tight compartments. Utility areas would not just be left open. I cannot think of another example of a vessel like this going down so quickly.

Well it did sink (fast) and the eye witnesses say it was on its side due to the tornado.

So occams razor says a shed load of water got in quickly while it was on its side.

 

[Richardab1967]

Beginner question, but how does a yacht get laid flat when at anchor. The video at the beginning of this thread looks like a yacht tied up, so I get that, but surely a yacht at anchor would pretty much face into the wind?

 

[onesea]

Interesting discussion it will be interesting when the report comes out.

Her AIS history seemed to show her at anchor then drifting before she sank.

My thought is:
Anchor dragged or parted rode?
Lying beam to extreme winds being pushed along in its path? pinned, down flooding would continue.

Anyone who’s been caught by a squall knows that feeling.

If so extreme the mast hit water and/ or she lost part of it.
With rigging and other hazards on deck and potentially a hole in hull or deck, it’s not going to be a good place for survivors.

Even if she recovered briefly those below are going to have a struggle to get out with water dark / reduced lighting and furniture movements.

Go to a marina during a gale and watch the various boats heel, it’s surprising which heal most.
Those that heel most is that just lack of initial stability, When heeled further would they get more resistance?
Those that remain stiff, would they loose stability if pushed further?

Without complete stability data and design it’s very hard to know.

A little more info here:
Divers 'open hole' in sunken superyacht - but have just 10 minutes to search for bodies
Appear to have 4 main sub divisions:
Garage area aft,
Machinery Space,
guest accommodation,
Crew Quarters,

My guess is machinery space and garage area had water tight door to separate other would be compartments.

A little more here:
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