Big sailboat sunk by tornado

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sunchaser said:
Any thoughts on vessel’s initial stability with centerboard - ballast raised while at anchor and +gale force winds?
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It would certainly be reduced, the question is how much. In my mind, a ballasted lifting keel should be left down at anchor or any other time and only raised when in water too shallow to permit leaving it lowered.
 
For races AvS is calculated with daggerboards and centerboards up. In open water survival conditions boats with boards up are more likely to survive. They can slide on a wave front and not “trip”.
This is a different situation where only static stability is relevant. Seems reasonable to assume calculations are based if board is up vessel is on a run or stationary or under power. With board down when on a reach or beat to counteract center of effort of the sailplan more righting arm is required. Boat was built in 2008. A different world with different rating systems. Probably built under commercial passenger ship rules as likely designed to be used as charter at some point. No suggestion in available information as to whether she was recently chartered or what rules she followed recently.
Think sailboat mega yacht design has been distorted in recent decades. Less split rigs and more sloops, solents, cutters. You occasionally see a ketch in the red light district but increasingly rare. Split rig was demanded with wooden sticks but then the conversion to Al and now CF that’s changed. For the same sail area the center of effort is higher for a sloop than a split rig. In the past something this size would be a three (or four) masted schooner. Yes possibly more mast area facing the wind and more rigging so more wind resistance. But likely acting at a lower height. The mast on this boat is longer than loa. Also would think mast if currently built would be CF. Much less weight. That single mast make for a beautiful vessel but likely contributed to this tragedy.
 
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sunchaser said:
Any thoughts on vessel’s initial stability with centerboard - ballast raised while at anchor and +gale force winds?
Click to expand...
Haven't seen any engineering data yet, but the biggie is whether the center/daggerboard was ballasted or whether it was more just a sailing performance appendage.

Hard to believe the centerboard was balasted at 20 feet for this vessel which was considered a "A well-designed, 56-meter heavy-displacement yacht" in the Yachting mag review link above.
 
It has now been reported after police interviews with the captain that the lifting keel was definitely in the 'up' position.
 
psneeld said:
Actual strength of waterspout and distance from wall (similar to hurricane) can have a lot todo with probable danger/damage.

Look at the aftermath of tornadoes on land where one house is literally torn off its foundation and the one across the street has minor damage.
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Tornados/Waterspouts do cause damage from high-speed winds, but the much bigger danger and source of damage is from the extreme low atmospheric pressure inside the vortex (which is what is creating those winds as a secondary effect. With the tornado damage you describe, where a house is blown to splinters and one next to it is intact, this is caused more by vortex decompression than wind. There may be something similar involved here if it was a direct strike by a waterspout. Waterspouts form as the low-pressure vortex inside a tornado hits water and sucks it up into the air.
 
sunchaser said:
Any thoughts on vessel’s initial stability with centerboard - ballast raised while at anchor and +gale force winds?
Click to expand...
In the Netherlands a nautical engineer explained why the keel may have been raised and what that would do to stability.
Reason for raising it is most likely because a lowered keel would make noise while moving with the waves. The keel is not fixed solid, it can move, so it makes a sound when the boat moves with the waves. This is uncomfortable for the guests to they raise the keel.
He then stated that the COG with a raised keel would change drastically and that means that in freak storms the boat could become unstable.

The question then becomes: 'did the captain lower the keel again when the thunderstorm arrived or did he leave the keel in the raised position ?'.
Does the keel have only 2 positions (up or down) or are there intermediate stops as well ?

But the main question, which will be answered shortly by the crew is: 'what happened ?'
 
Mambo42 said:
...
Reason for raising it is most likely because a lowered keel would make noise while moving with the waves. The keel is not fixed solid, it can move, so it makes a sound when the boat moves with the waves. This is uncomfortable for the guests to they raise the keel.
...

The question then becomes: 'did the captain lower the keel again when the thunderstorm arrived or did he leave the keel in the raised position ?'.
Does the keel have only 2 positions (up or down) or are there intermediate stops as well ?
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On a super yacht YouTube channel that was covering this incident, a crew member on a sister ship said they kept the keel raised at anchor. This was to not disturb the guest with the keel making noise and vibration when it was lowered.

The man who helped rescue the survivors said they had hurricane force winds and then the ship was hit by a waterspout.

The AIS data shows the keel was up and I think I read that has been confirmed.
 
Ertyqway said:
Tornados/Waterspouts do cause damage from high-speed winds, but the much bigger danger and source of damage is from the extreme low atmospheric pressure inside the vortex (which is what is creating those winds as a secondary effect. With the tornado damage you describe, where a house is blown to splinters and one next to it is intact, this is caused more by vortex decompression than wind. There may be something similar involved here if it was a direct strike by a waterspout. Waterspouts form as the low-pressure vortex inside a tornado hits water and sucks it up into the air.
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Got a link to another supporting view?....

Here is mine...

question..... does the low pressure in tornadoes destroy houses or just wind?
Answer......
High winds
Equalizing pressure in a house to keep it from exploding was the basis of this myth. It's useless and you'd be wasting precious time to get to real safety before a tornado strikes. It's the high winds and flying debris that cause damage to structures, not a pressure difference.

10 Tornado Myths Busted | Weather.com - The Weather Channel​

 
There was a quote from the boat builders executive in the NYT that was posted on the Cruising Forum that was interesting and answers one of my questions, which was, what was the AVS of the ship? The executive said, "...the yacht had been specifically designed for having a tall mast — the second-tallest aluminum mast in the world. He said the Bayesian was an extremely safe and secure boat that could list even to 75 degrees without capsizing."

C&N managed yacht sinks off Sicily, 7 missing - Page 12 - Cruisers & Sailing Forums

Please, please, lets not let facts intrude on a good conspiracy. Hows this: HP wins big fraud case; perpetrator beats related criminal rap. Revenge killers wipe out conspirators two days apart.
www.cruisersforum.com

75 degrees is not a good AVS for a sail boat/ship. The NZ video showing the sailing ship being knocked down in a marina sure looks to have been down to 80 degrees or so. It is not clear if that ship was held up by a dock or other vessels.
 
psneeld said:
Got a link to another supporting view?....

Here is mine...

question..... does the low pressure in tornadoes destroy houses or just wind?
Answer......
High winds
Equalizing pressure in a house to keep it from exploding was the basis of this myth. It's useless and you'd be wasting precious time to get to real safety before a tornado strikes. It's the high winds and flying debris that cause damage to structures, not a pressure difference.

10 Tornado Myths Busted | Weather.com - The Weather Channel​

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It's both. Which is how it's taught in structural and architectural engineering classes regardless of what "weather.com" says about it.
 
dannc said:
75 degrees is not a good AVS for a sail boat/ship. The NZ video showing the sailing ship being knocked down in a marina sure looks to have been down to 80 degrees or so. It is not clear if that ship was held up by a dock or other vessels.
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Yeah. That really stands out. An AVS under 80 is "calm waters only" level of stability, and certainly not something offshore rated, let alone self-righting.
 
Ertyqway said:
It's both. Which is how it's taught in structural and architectural engineering classes regardless of what "weather.com" says about it.
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Got a link to any engineering studies as it's many more places I looked at than just wearther.com. Maybe they changed what they are teaching as a lot of sources state that it's primarily the winds /blowing debris

This from NOAA

Myth: Low pressure with a tornado causes buildings to "explode" as the tornado passes overhead. Fact: It is the force of the horizontal wind and debris slamming into buildings that causes structural damage during a tornado. It is not the pressure change. The air pressure will drop near a tornado. Many people near a tornado tell of their ears "popping" due to the pressure change.

Not saying pressure differentials can't be somewhat damaging but the vote seems to go more to wind damage.

Ay any rate, sounds like the boat was not dismasted or "exploded from low pressure" so knockdown and massive progressive flooding sounds like a high possibility. I would think we might start seeing pictures from underwater cameras/vehicles sooner or later that might tell the story.
 
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I didn't say it was "exploded from low pressure". I said the combination of high winds and vortex pressure differentials can yield much more extreme localized forces on a boat than even a hurricane. That's clearly what happened here, though it now sounds like a combination of design characteristics (AVS less than 80) and circumstance (the keel being up) are major contributing factors in this tragedy.
 
Ertyqway said:
I didn't say it was "exploded from low pressure". I said the combination of high winds and vortex pressure differentials can yield much more extreme localized forces on a boat than even a hurricane. That's clearly what happened here, though it now sounds like a combination of design characteristics (AVS less than 80) and circumstance (the keel being up) are major contributing factors in this tragedy.
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I will get off the subject after my one last comment on tornadic pressure and winds.....that is because I like the readers to understand the bigger picture.

Your post #35 is quoted as "but the much bigger danger and source of damage is from the extreme low atmospheric pressure inside the vortex (which is what is creating those winds as a secondary effect.".

Repeatedly on the net from reliable sources, say that while pressure is involved, it is not to the extent that wind is. So the myth about pressure being a big enough danger that people should opening doors and windows to equalize the pressure (which actually allows wind in to blow off roofs and level walls) creates the danger of people wasting time instead of immediately seeking shelter. This is why I insist that people who don't believe me, take the opportunity to look it up themselves.

Hopefully cruising boaters understand that WIND.... IS.... generated between high and low pressure areas, and the more extreme the stronger the wind. So yes, pressure plays a PART...but from my readings (having never been in a tornado but quite a few waterspouts and dust devils) many sources still blame the wind.

As in this case, it was the wind that low pressure caused that probably knocked down the boat so maybe we can just settle on semantics. But still, the recommendation is not to equalize the pressure as the myth has it, it to get your butt in a safe location.
 
The builder is suggesting that the crew left some doof open, the large doors for launching water toys. Didn’t say for sure though.
 
Comodave said:
The builder is suggesting that the crew left some doof open, the large doors for launching water toys. Didn’t say for sure though.
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Yeah, he is accusing the Captain for the sinking, which to some extent is true, since the Captain is the Captain, but, it seems a bit early to be throwing stones at the crew.
 
Depends on what the builder knows about the status of the boat before and at the time of the sinking.

Can't say for sure but the builder may have pretty good insight if some things weren't done in preparation, and during the storm. How the Owner and or Captain was supposed to know any safety issues is going to come to light sooner or later.

Here is one recent headline I just saw....

"Yacht Sank in Sicily Due to ‘Endless Chain of Errors,' Ship Maker's Owner Speculates: ‘Everything Was Predictable’

"A series of activities should have been done to avoid finding oneself in that situation," argues Giovanni ."



​


Profile Picture
 
dannc said:
Yeah, he is accusing the Captain for the sinking, which to some extent is true, since the Captain is the Captain, but, it seems a bit early to be throwing stones at the crew.
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As soon as a company starts blaming anyone else but themselves you know they are signing their own death sentence. This company is not going to get a lot of business anymore from customers.
Just saw the video of Esysman where he explains that on sister boats the doors to the salon don't remain closed when the boat heels over when under sail. The doors are heavy and open up under their own weight.
If that is true the CEO is basically talking cr*p.

That said I think we should stop speculating. Let's just simply wait what the accident investigation board is going to conclude. It is basically the same as in an aircraft accident, no need to do their work in a forum.
I guess the preliminary report will arrive in a month or so and the final report in about one to 2 years. Until that report comes in, all we do is speculating and although that could be fun, it is not really useful.
 
Typical forensics after a knock down show failures on the opposite side of the house that goes into the water. That side and overhead shift away from the water causing the opposite side to distort. Glass, port lights, doors and any framing of any piercings of the house can totally or partially pop out. The junction of the house to the deck can fail as can bulkheads. Materials tend to be stronger in compression so when subjected to the opposite may pull apart. The wide open spaces of modern yachts makes it more difficult to create a rigid structure. Of course the side that’s immediately immersed can have direct failures as it’s subjected to water pressure. But when the opposite side structurally fails it greatly contributes to the failure of the immersed side as the house is no longer a rigid structure.

Yes 75 degrees is an unacceptable AVS. Modern keel center board ocean sailboats, both racing and cruising, usually have an AVS of 120-130 with board UP. As it’s with board up their survival is improved in an open water storm. This vessel is NOT a boat. It is a ship. Rules are different. It is designed for comfort and aesthetics. Absent are structural watertight bulkheads pierced by watertight doors as you would see in military vessels and some explorer yachts. This makes getting to a rigid structure more difficult. It further makes loss of integrity of all house piercings (glass, doors, etc.) more likely . For multiple possible reasons beyond a poor AVS one can think of reasons this ship did not survive a knock down.
 
Have we seen a solid answer as far as whether this boat had a centerboard or daggerboard, or was it a ballasted lifting keel where AVS may change significantly with the keel lifted?
 
I saw that headline of the builders throwing the crew under the bus.

It seemed pretty tasteless on their part, this soon. Wait for the inevitable court case. I didn't read the article.
 
CaptTom said:
I saw that headline of the builders throwing the crew under the bus.

It seemed pretty tasteless on their part, this soon. Wait for the inevitable court case. I didn't read the article.
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I think his input might be good, but agree it was pretty accusatory unless he/authorities have lots of info exchanged that the press doesn't have yet. ...like exactly what has been seen underwater by the divers, or remote vehicle cameras.

The builder says he has the weather reports for the incident and that seems to be confirmed in other reports about the weather and probability and how these storms occur regularly in the area. That goes against some "expert" opinions early on that it was "unexpected". There have been indices that discuss stability of the atmosphere around since before I went to flight school in the 70's.
 
psneeld said:
I think his input might be good, but agree it was pretty accusatory unless he/authorities have lots of info exchanged that the press doesn't have yet. ...like exactly what has been seen underwater by the divers, or remote vehicle cameras.

The builder says he has the weather reports for the incident and that seems to be confirmed in other reports about the weather and probability and how these storms occur regularly in the area. That goes against some "expert" opinions early on that it was "unexpected". There have been indices that discuss stability of the atmosphere around since before I went to flight school in the 70's.
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Brings to mind ”Aeolian Triangle”
aleta.life

Triangles, Myths, and Volcanoes - The Adventures of Aleta

Rod Heikell proposed the area bounded by Ustica, the Straits of Messina and the Aeolians be designated the ‘Aeolian Triangle’.
aleta.life aleta.life
 
rslifkin said:
Have we seen a solid answer as far as whether this boat had a centerboard or daggerboard, or was it a ballasted lifting keel where AVS may change significantly with the keel lifted?
Click to expand...

I saw a video where they had photo of a lifting keel with a ballasted bulb but I am not sure if that was from the ship. The builder said in the video linked below, that the AVS with keel up was 73 degrees and 88 with the keel down. 73/75 degrees vs 88 is not much of a difference.

There is some very interesting information in this video,
. This video then links to another video,
which has a comment from Chis Freer.(@chrischamberlaine4160 )which is mentioned in the first video.

The ship's mast has huge windage, see Freer's comments.

The other interesting piece of information is from a person who served on these ships. The doors, and the photos shown in the video, were glass doors, would swing open when the boat heeled... The doors in the video were huge, maybe 6-8 feet wide and tall.

Accusing the captain and crew is not justified until the final report is published. The captain is responsible at some level simply because he is the captain but everything is pointing to a very specific chain of events, some in the captains control, the keel position being the main one, but many of the issues are pointing at the ships design and build.
 
dannc said:
I saw a video where they had photo of a lifting keel with a ballasted bulb but I am not sure if that was from the ship. The builder said in the video linked below, that the AVS with keel up was 73 degrees and 88 with the keel down. 73/75 degrees vs 88 is not much of a difference.

There is some very interesting information in this video,
. This video then links to another video,
which has a comment from Chis Freer.(@chrischamberlaine4160 )which is mentioned in the first video.

The ship's mast has huge windage, see Freer's comments.

The other interesting piece of information is from a person who served on these ships. The doors, and the photos shown in the video, were glass doors, would swing open when the boat heeled... The doors in the video were huge, maybe 6-8 feet wide and tall.

Accusing the captain and crew is not justified until the final report is published. The captain is responsible at some level simply because he is the captain but everything is pointing to a very specific chain of events, some in the captains control, the keel position being the main one, but many of the issues are pointing at the ships design and build.
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It matters if opening posts/doors or weak points are in that narrow range.
 
At 73/75 degrees house piercings may well be awash even in the absence of boarding waves. Most catastrophic would be water ingress on the windward side. Then that weight going to leeward side and further compromising stability. Especially if the knockdown closed any openings on the leeward side. Then at an initial 73/75 degrees what water is inside the vessel and above the waterline momentarily all on one side would further compromise stability If so stability would be driven below 73/75.
 
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