"Bayesian" s/y sinks in Palermo

[RunAgroundHard]

The boats are built to standards and tested, frequently inspected, and retested after major modifications, has been stated elsewhere.

Divers have looked through windows and noted bodies, The Guardian or BBC today.

 

[billskip]

Oh right, I thought it was down to a pressure difference,

You could well be right...but what pressure difference? Possibly atmospheric pressure on one side, and less than atmospheric pressure on the other..therefor there woud not be, as you said "after one big window coming out pressure would equlise". Atmospheric pressure could reman, and the possibility of a less than atmospheric pressure could remain on another big window...giving as you say a pressure difference.

 

[doug748]

To be honest, I those seeking to assign blame to boat design etc are maybe a little guilty of assuming that we really can tame nature.

Looking at footage of waterspouts etc, then imagining one hitting a boat, even a really big one, unseen in the dark, I'm wondering if you just have to put that down to "there but for the grace of God" and be thankful that some people, especially the kid, survived.

Your restraint does you great credit, I think some folk are on the wind up.

 

[Time Out]

Being in the industry myself some of the comments on here are laughable.

Good job the media is relying on the expertise of the Sailing Today Editor …

As with all these things the real reason will be known soon.

In the meantime 6 are still Missing and one ( crew) dead.

 

[Baggywrinkle]

The sea has a long history of destroying human creations, whatever way you look at it, every boat is a compromise of hundreds of different requirements. You can't expect a superyacht manufacturer to put the levels of comfort and seaworthiness of a severn class lifeboat into a luxury superyacht - it would compromise comfort and luxury too much.

Everything can be sunk or washed onto the rocks given the right circumstances, and you can't foresee the circumstances that will destroy your boat, or necessarily predict when they will occur.

Best to wait for the investigation to complete, read the recommendations, and see if any of them are relevant to normal cruising yachtsmen.

 

[john_morris_uk]

Yes.
Cockpit hatches giving access to the engine: closed.
Bottom washboard in as a minimum, (usually both boards in and the hatch closed to keep the midges out).
Sheolin doesn't have a garage on the waterline for jet skis and the like, nor does she have any watertight bulkheads with hatches that can be secured.

May I humbly suggest you’d either need air conditioning or you’d make your boat uninhabitable in the tropics. We’re like most everyone else who lives on board their yacht in the Caribbean. Companionway is open but a mosquito net over it (when necessary). Hatches are open with hatch tents over them if there’s a chance of rain.
Any comparisons with the sort of yacht this thread is about are risible. Completely different boating experience.

One of our regular race crew is the chief engineer on a superyacht. I think you'd be surprised. At a minimum they'd need to bring generators etc on-line, the engineer would have a whole load of hydraulic pumps etc to monitor, etc etc.

I think you’ll find that on a yacht this size, there’s at least one generator running 24/7 unless they’re alongside plugged into mains. (Of suitable capacity!)

 

[john_morris_uk]

Being in the industry myself some of the comments on here are laughable.

Good job the media is relying on the expertise of the Sailing Today Editor …

As with all these things the real reason will be known soon.

In the meantime 6 are still Missing and one ( crew) dead.

Agree totally. I humbly suggest people should stop and think before they compare experience of 30-45’ boats with a 55 metre super yacht.

 

[flaming]

I think you’ll find that on a yacht this size, there’s at least one generator running 24/7 unless they’re alongside plugged into mains. (Of suitable capacity!)

Oh yes I know, like I say I know a chief engineer on a very similar boat. However I'd assume that they'd need a lot more oomph than the domestic generator to raise or lower the keel.

I just can't imagine that there was any perceived risk in leaving the keel up at anchor after exiting the port, especially if planning to re-enter in the morning, and I can fully understand a decision to leave it up vs going through the procedure to lower it. It certainly will not be as simple as pushing a button marked "lower keel".

 

[pcatterall]

[QUOTE="Sea Change]
I'll put my hand up and admit that, unless we're expecting heavy rain, we sleep with every hatch open

+1
At least the companionway open; in normal circumstances, I find the ability to get out on deck ASAP to check whatever is happening a lot more useful than trying and maximise chances to resist a waterspout/tornado.
[/QUOTE]
Gin palace, air con, close hatches? The big window lights would be vulnerable though? What a bloody tragedy though.

 

[Mark-1]

I just can't imagine that there was any perceived risk in leaving the keel up at anchor after exiting the port, especially if planning to re-enter in the morning, and I can fully understand a decision to leave it up vs going through the procedure to lower it.

This, AFAIC. *If* the keel does provide ballast, then there would be no reason to have it down when not sailing, safely at anchor. Apparently waterspouts occur during weak storms and have the nickname "fair-weather tornadoes" so they might not have been anticipating heavy weather at all, just a thunderstorm.

Tornadoes and waterspouts: Europe's underestimated extreme weather threat?
Waterspouts typically occur during relatively weak storms, Groenemeijer says. "We even call them fair-weather tornadoes,"

It's a freak event. I suspect nobody did anything out of the ordinary to create this disaster and the boat design is totally adequate.

 

[XDC]

It’s a body recovery operation. No one is coming up alive.

They are at 50m, which means 6 bars of pressure. Ear drums would have exploded. Total disorientation. Ppo2 of 1.2 for prolonged time means convulsions and thus drowning from oxygen toxicity. Even if you could bring them up, it would be a very slow decompression assent.

Is that absolute fact?

This guy survived for three days at 98 feet.

Rescued and spent 60 hours in a decompression chamber.

 

[AntarcticPilot]

Oh right, I thought it was down to a pressure difference, that's entirely based on intuition and I'd be happy if you could explain where I'm going wrong.

A tornado is an extremely local area of low pressure. The water pressure is always higher than atmospheric pressure. Therefore any effect would be to lift the boat out of the water, not to sink it.

 

[Frogmogman]

Apparently waterspouts occur during weak storms and have the nickname "fair-weather tornadoes" so they might not have been anticipating heavy weather at all, just a thunderstorm.

There are two types of waterspout; non tornadic (aka fair weather waterspout) and tornadic, which are pretty much like a land tornado and totally devastating.

We had a waterspout that came ashore and ripped all the trees out…if one crosses the path of a boat I don’t see how you could survive….they are quite narrow so a boat nearby might escape unscathed

About 35 years ago, when we lived near Duras (in the south west of France) a tornado cut a swathe across our area. Everything in its way was totally destroyed, cars chucked in the air, and seven pylons of the main high voltage grid completely crumpled. IIRC they were designed to withstand wind speeds of up to 230Km/hr. The astonishing thing was that the other side of the road from the devastation were intact trees and vines with all their grapes still on them.

 

[Fr J Hackett]

Yes.
Cockpit hatches giving access to the engine: closed.
Bottom washboard in as a minimum, (usually both boards in and the hatch closed to keep the midges out).
Sheolin doesn't have a garage on the waterline for jet skis and the like, nor does she have any watertight bulkheads with hatches that can be secured.

I think you are confusing a 56M boat with a 32M boat, the former doesn't have washboards nor cockpit hatches for access to the engine.

 

[Mark-1]

U

There are two types of waterspout; non tornadic (aka fair weather waterspout) and tornadic, which are pretty much like a land tornado and totally devastating.

I don't doubt that waterspouts are devastating but that article says that the conditions that create them are not. So, based on that, the crew shouldn't be expected to have prepared for extreme weather.

Mind you, chatgpt reckons that you are right and the bbc is wrong:

Is it true that non tornadic water spouts are referred to as fair weather waterspouts?

Yes, that is correct. Non-tornadic waterspouts are commonly referred to as "fair-weather waterspouts." These waterspouts form under relatively calm and stable conditions, often on warm, sunny days with light winds. They are usually associated with cumulus clouds and do not require the severe weather conditions that are necessary for tornadic waterspouts, which are essentially tornadoes that form over water.

Fair-weather waterspouts are generally weaker than tornadic waterspouts, and while they can still be hazardous to small boats or swimmers, they typically dissipate quickly and pose less of a threat compared to their tornadic counterparts.

 

[Mark-1]

I think you are confusing a 56M boat with a 32M boat, the former doesn't have washboards nor cockpit hatches for access to the engine.

The principle is the same. It's a sailing boat and will have openings and those openings will (surely?) be reasonably well sealable - certainly sealable enough to handle a 120 second knock down because it might get caught in a massive storm or knocked down under sail at sea and will be designed to handle that.

Given that there are three possible ways water got in:

Openings left open. (Quite reasonably IMHO.)
Something broke (Possible).
Design flaw. (Unlikely)

We've seen a similar vessel knocked down and pop right back up.

I don't buy the idea that a 56m vessel is 'different' to a 32ft vessel. The detail might be different but in principle they are the same and the physics is the same. In normal use it won't sink from a knock down and it should recover fast from a knockdown. If you're calmly anchored in conditions were a knockdown is highly unlikely you might leave all openings open and a lifting keel up and that's not unreasonable because we can't live life catering for freak events. (Of course, houses aren't tornado proof and we don't regard that as too risky.)

 

[Sea Change]

A tornado is an extremely local area of low pressure. The water pressure is always higher than atmospheric pressure. Therefore any effect would be to lift the boat out of the water, not to sink it.

The point being made was that low pressure could suck a large window out of its fixings. I don't know how likely that is, but my intuition was that once one window gave way, the pressure difference would immediately reduce and it would become increasingly unlikely that further windows would pop out.
But apparently it doesn't work this way.

 

[Portofino]

A boat like that would have had its genys running to cover the Aircon + general other 220 v requirements like fridges / freezers and all those mast lights .So let’s drop all this open hatch and crew running around nonsense .
Even our 15 M mobo we slept at anchor geny running + Aircon + closed up boat .

My theory looking at the design and considering the water spout thingy is as the storm approached there would have been a pre storm whereby the neighbours crew got on deck then this boats crew .
Either the rear patio doors were opened at the exact time or indeed blown out / blown in = breached as the full force of windage tipped the hull .The lower in effect free board of this stern “ beach club “ = tonnes of water entered the saloon and flooded it .
The surviving wife wheel chair bound is due to lacerations on her feet from broken glass escaping seconds before it was too late .
Wether the rear patio doors blew in or blew out or were opened ( in error ) doesn’t matter and indeed we will never know unless the survivors can shed light on this .

As it tipped furniture May have smashed those pilot house glass on the deck level after the rear door breach .

Divers report intact boat on its side nothing missing and are entering through the rear lower deck level albeit they report furniture kinda blocking access to proceed much further deeper into the boat .

I mean the patio doors might have even dropped off there runners when the hull was 70-90 degree knocked over by the storm ? Or because they are not made of 3 cm armoured glass like the hull and side windows ( why would they ? ) so with say 1 m of water pressure say a 45-60 degree list increasing simply shattered and let the sea in , more sea as it was further knocked to 90 degree = sank gone in 60 seconds .Only survivors those already on deck thrown in as it sank .

They ( builders + class society’s ) would have done static water pressure calcs on the patio doors but only likely scenarios not a knock down + extra pressure or indeed “ suction “ of a water spout / tornado etc .

Against all this to add perspective in the world Approx 5 airliners crash each yr . You , the civil aviation authority, designers , manufacturers ( think Boeing doors ! ) can’t make planes 100 % safe .

Nor can boat builders there’s a always tiny residual risk .

In my book large glass areas is one of those , wether holes in the hull , glass down to the side decks , patio doors etc .
Some can see it others can’t because today at boat shows that’s mostly what you see acres of glass theses day .

Just scroll back and study that rear beach club / patio door arrangement. Ludicrous imho …..considering it the type of boat crew are likely to asked to moved it across oceans for the owners to fly in .The “Blue water “ thingy.

My 0.02 C worth .

Obviously like the rest will read with interest the reports when they transpire .

 

[Fr J Hackett]

The principle is the same. It's a sailing boat and will have openings and those openings will (surely?) be reasonably well sealable - certainly sealable enough to handle a 120 second knock down because it might get caught in a massive storm or knocked down under sail at sea and will be designed to handle that.

Given that there are three possible ways water got in:

Openings left open. (Quite reasonably IMHO.)
Something broke (Possible).
Design flaw. (Unlikely)

We've seen a similar vessel knocked down and pop right back up.

I don't buy the idea that a 56m vessel is 'different' to a 32ft vessel. The detail might be different but in principle they are the same and the physics is the same.

That 56M vessel will have large sliding doors at Bothe the rear saloon and forward accommodation access, there are two explanations why this might be open or unsecured:
They were purposely left open or unsecured during the night, it's quite probable that the air-conditioning to the main saloon, dining and recreational areas was switched off during the night with individual cabins using air conditioning. I have been on large motor yachts 23M and 35M where this was the case.

The second and most plausible reason is that the crew were brought on deck as the weather quickly deteriorated and the doors were closed but not locked ( secured) as the ship heeled the doors could have slid open. This explains why most of the crew were saved, they were on deck ready to attend the anchor and possibly deploy fenders should they be blown into the proximity of the other vessel. All crew members including stewards and stewardess's on such vessels are trained in deck work.

As I have said once those doors are open with a gap of 2to 3M the quantity of water entering would be enormous and overpowering and the vessel would founder very quickly.

 

[westernman]

Yes and with 10 minutes bottom time they are not going to get very far inside or get a body out. It will be down to clearance divers using trimix to do that.

Sounds like it would be much easier to lift it from the bottom first.
That would only need a few inflatable bags.....