"Bayesian" s/y sinks in Palermo

[Sea Change]

Do you do that every time you anchor?

I'll put my hand up and admit that, unless we're expecting heavy rain, we sleep with every hatch open, and fans running.

 

[E39mad]

If the boat was anchored at the bow and stern, ie not free to swing, and was hit on the beam, I can see how it might get blown over.

And those anchor chains are going to create a -ve righting moment.

It could still get blown over without a kedge anchor if the waterspout came at say a 90 degrees to the angle in which she was anchored. It would take a boat of that size some time to "readjust" to a new wind angle.

 

[E39mad]

To me, the elephant in the room is the huge mast. If they designed these extreme boats as a ketch I guess the main mast height could have been very much shorter with all the stability benefits that should give.

Not sure that a ketch would have been any different in this situation - a ketch adds another mast, rigging, and sail to the windage over a sloop. You could argue there is more windage with a ketch.

 

[Baggywrinkle]

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

Seen them a number of times in the Adriatic over the years, probably about 10-15 in total, and sightings can be reported on the Croatia Meteorological and Hydrological Service website (where the marine forecast can also be found) ....



You don't want to get hit by something like this in the middle of the night ...



PHOTOS: Epic Croatia Weather Photography Stuns The World - Total Croatia

It's always something in the back of my mind when the marine forecast predicts "isolated thunderstorms". I usually head somewhere where I know it is sheltered with very good holding, or head for a marina.

This was Rovinj in 2013 ... within spitting distance of where I was anchored in the earlier video .... (not my video)

 

[cherod]

My guess is that lightning struck the mast in addition to the boat being tilted on it's side. The voltage blew a hole through the bottom of the boat. The boat settled o. Her bottom the puncture on her bottom cannot be seen.

This guess is based on no fact, science, or evidence.

That was my first suspicion , tho no facts

 

[cherod]

As I understand it she'd only come out of the harbour (where she would definitely have needed the keel to be raised) that evening. If they were expecting a calm night and then to go back into the port the following day, would they bother lowering it? I doubt it's a quick procedure.

I would expect it to be a “ press button “ procedure .

 

[flaming]

I would expect it to be a “ press button “ procedure .

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.

 

[dunedin]

To me, the elephant in the room is the huge mast. If they designed these extreme boats as a ketch I guess the main mast height could have been very much shorter with all the stability benefits that should give.

Lots of amateur naval architects on here. For the same sail area, I suspect that the twin masts of a ketch could easily have MORE weight and windage aloft. A lot of careful design engineering and calculations will have been done - otherwise the rig would not have survived to date. Using carbon rather than aluminium would certainly have reduced weight aloft though.
Whether there was too much reliance on assuming “hatches closed at sea” may be a differnt matter.

 

[Chiara’s slave]

Lots of amateur naval architects on here. For the same sail area, I suspect that the twin masts of a ketch could easily have MORE weight and windage aloft. A lot of careful design engineering and calculations will have been done - otherwise the rig would not have survived to date. Using carbon rather than aluminium would certainly have reduced weight aloft though.
Whether there was too much reliance on assuming “hatches closed at sea” may be a differnt matter.

Plus of course weight isn’t necessarily the overriding factor. Weight in the rig, the right amount, is also a part of stability calculations, on the positive side. It resists momentary forces such as wave motion.

 

[Sandydog2]

I think it’s remarkable that by the time the boat in front of them had noticed they were missing the liferaft was deployed and 15 survivors safely on board. Only a few minutes it seems. I hope the crew get a lot of credit for that.

I also hope no one is injured in the search for bodies. It’s not worth taking risks for.

 

[billskip]

Discipline. Unless tied up alongside ensure all watertight hatches and doors are closed,

Is it possible the tornado sucked the windows and doors out? These doors and windows are designed to resist external pressure, not a vacuum.

 

[billskip]

If boats could resist tornadoes all property in tornado ally would be redesigned.

We don't even know if the tornado lifted the boat and dropped it...these things don't happen in slow motion

 

[dunedin]

Is it possible the tornado sucked the windows and doors out? These doors and windows are designed to resist external pressure, not a vacuum.

Sounds like some / most of the windows are still in place according to the diver reports -

• Divers are unable to see inside the yacht as 3cm (1.2inch) thick glasswindows are preventing access (BBC News)

 

[Mark-1]

Is it possible the tornado sucked the windows and doors out? These doors and windows are designed to resist external pressure, not a vacuum.

The divers that have been down have mentioned they can't see through the windows (according to the BBC) so you'd think they'd probably mention if windows were broken or missing. But who knows....

 

[Trident]

Is it possible the tornado sucked the windows and doors out? These doors and windows are designed to resist external pressure, not a vacuum.

My boat went through hurricane Irma and lost two windows - no idea if the forces sucked them out or over pressure inside blew them out but both were pushed out not in so very possible

 

[Bouba]

The water pressure under a waterspout might create suction that sucks the boat under

 

[Fr J Hackett]

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.

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.

 

[billskip]

Sounds like some / most of the windows are still in place according to the diver reports -

• Divers are unable to see inside the yacht as 3cm (1.2inch) thick glasswindows are preventing access (BBC News)

Possible so...we don't know how the wreck is laying.
After reading all this thread, I get the impression that many don't realise the energy force's that can be involved.
This boat could have been 50 metres in a different position and escaped, if (as it appears to have been) in the wrong place allowing for the full force of the tornado energy to disrupt all the cog/design ballance then nature took its course.

 

[Mark-1]

Possible so...we don't know how the wreck is laying.

Good point, it's likely to be lying on the side with the smashed windows if there are some.

I'm still in the 'there were things open that let water in' camp, but the 'windows/doors sucked out' theory seems by far the best of the "something broke" theories. Consistent with Trident's experience.

 

[Roberto]

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