Article: Bayesian Skipper Couldn't Have Known How Vulnerable She Was, Investigators Say

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JackConnick

JackConnick

Senior Member
Joined
Aug 19, 2022
Messages
288
Location
Seattle, WA
Vessel Name
Paradox
Vessel Make
1991 Grand Banks 36 Classic
But that is in direct contradiction to the boats builder who said it was a very safe boat…
 
Oh it's a tangled mess. Everyone is pointing their finger at the skipper, but the stability manual wasn't onboard.
My biggest question is when the wind reached 30 kts., why wasn't the centerboard lowered?
 
And maybe, the hatches closed. A knockdown by itself would not have sunk the boat.
 
From what I read, a knock down would have sunk the boat. It's all in the stability calculations in the report. Of course the builder figured a good offense is the best defense, but I don't see how they're going to avoid some responsibility. We still have to wait for the final report, and of course all the lawsuits to work their way through the system.
 
JackConnick said:
Oh it's a tangled mess. Everyone is pointing their finger at the skipper, but the stability manual wasn't onboard.
My biggest question is when the wind reached 30 kts., why wasn't the centerboard lowered?
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Probably because they didn’t want to inconvenience the guests. When down apparently it makes some noise.
 
Comodave said:
Probably because they didn’t want to inconvenience the guests. When down apparently it makes some noise.
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I wonder if the skipper might have thought that 'board up' was the best condition at anchor.
Less possibility of grounding in an emergency lee shore situation, i.e. anchor tackle failure.
That's what I would be thinking if I wasn't aware of the instability issue in very high winds.
 
They were in 50 meters deep water. Not much chance of grounding. One article I read remarked about the noise from the keel bothering some guests.
 
Comodave said:
They were in 50 meters deep water. Not much chance of grounding. One article I read remarked about the noise from the keel bothering some guests.
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You miss my more obvious point that 'board up' may have been the correct condition any
time the boat was anchored or moored in an area that also had a shore or shoal nearby.
If swinging on a single hook, the centerboard could also have posed a rode wrap possibility.
 
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No, I didn’t. From the charts shown on TV it doesn’t look like they were really close to shore. The vessel was almost a mile offshore when it sank. However on these super yachts they do whatever is requested by the guests within reason. If the guests were bothered by the noise of the keel then they would likely pull it up. Yes the captain might decide not to accede to the guests requests but there is a lot of pressure to do so.
 
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Comodave said:
No, I didn’t. From the charts shown on TV it doesn’t look like they were really close to shore. The vessel was almost a mile offshore when it sank. However on these super yachts they do whatever is requested by the guests within reason. If the guests were bothered by the noise of the keel then they would likely pull it up. Yes the captain might decide not to accede to the guests requests but there is a lot of pressure to do so.
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Agree to disagree.
 
The keel position is not really important, last year, the builder said that the AVS with keel up was 73/75 degrees and 88 with the keel down. 73/75 degrees vs 88 is not much of a difference.

The bigger issue is that It was reported that down flooding would occur at 40-45 degrees.
 
dannc said:
The bigger issue is that It was reported that down flooding would occur at 40-45 degrees.
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If you read the MAIB report, including the crew's evidence, the vessel went directly to a complete knockdown (90 degrees) and the water entered via passenger entries.

The calculations cited in the report said that no downflooding was necessary to allow it to reach 90 degrees in the case of a 64 knot wind on the beam.
 
The report is very damming for the builder.

A 70% angle of vanishing stability is terrible for a sailboat. It is often double that.

Chat GPT:
1747423295088.png

True, the 70º AVS in Bayesian is with the keel up.

But I recall reading that Bayesian's "boat manual" specified that the keel only needed to be down under sail or when motoring off-shore. It was not a whim of the skipper that it was up at anchor.

Although the boat had a some kind of "stability manual" it only applied to keel-down. So no relevant info for the owner or the skipper while at anchor.

And 60+ knot gusts in the Mediterranean are common during late-summer squalls. (Ask me why I know.) Yet this is the wind that was calculated in the report needed to exceed the AVS.

An accident waiting to happen ...
 
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Xlantic said:
The report is very damming for the builder.

Although the boat had a some kind of "stability manual" it only applied to keel-down. So no relevant info for the owner or the skipper while at anchor.


An accident waiting to happen ...
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The Stability Booklet covers both the keel up and keel down conditions. It gives AVS for both conditions. It also states that keel down is only required for when sails are raised or for extreme weather (I forget the exact wording).

I read the Stability Booklet via Loose Cannon, but it now behind a (minor) paywall. and I have not paid to get further access. It is a very readable document - especially the "Instructions to Master". If someone has access to it, please post!
 
Nick F said:
The Stability Booklet covers both the keel up and keel down conditions. It gives AVS for both conditions. It also states that keel down is only required for when sails are raised or for extreme weather (I forget the exact wording).

I read the Stability Booklet via Loose Cannon, but it now behind a (minor) paywall. and I have not paid to get further access. It is a very readable document - especially the "Instructions to Master". If someone has access to it, please post!
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According to the report, it covers only keel-up, at least for these situations:

1747425596188.png
 
SuperYacht News on Youtube has a video discussing the MAIB report.
 
It's astonishing how quickly it all happened. Basically over the course of 10 minutes the wind went from calm to 30kts, then 70 kts, then they were irreversibly on their side. It's also amazing that 50% of the side windage in from the mast.

Here's a question for everyone; if you were hit with a 70 kts beam wind, do you think your boat would be at risk of getting flipped over? To me, it's a scenario that I would never even consider possible. It's not something I would even remotely consider.
 
I think Bayesian flipped because the huge mast gave it a double whammy: instability and windage.

Trawlers have neither.

At least this what I am telling my family …
 
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Windage from a mast and rigging is a lot more than it looks like. People frequently assume that a sailboat has less windage at anchor or docked than a powerboat, but it's often a huge difference.

I certainly wouldn't worry about 70 kts on the beam flipping my boat. Shredding some canvas sure, but not flipping. Based on the amount of heel we get from 40 kts on the beam, even if 70 kts were to produce 3 - 4 times as much heel it wouldn't be concerning, just maybe a little annoying.
 
Nick F said:
If you read the MAIB report, including the crew's evidence, the vessel went directly to a complete knockdown (90 degrees) and the water entered via passenger entries.

The calculations cited in the report said that no downflooding was necessary to allow it to reach 90 degrees in the case of a 64 knot wind on the beam.
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I think you missed the point.

People have been talking about the keel being up or down. That seems to be irrelevant, since even if the ship was only knocked down to 60 degrees, there would have been down flooding. Since the ship was knocked down past the AVS of the ship, keel up or keel down, the keels position seems to be a who cares.

Since there would be down flooding with the ship heeling 40-45 degrees, any heeling past that angle would be serious. The keel position does not seem to matter if the ship heeled past 40-45 degrees. Given that the ship was blown down past its AVS, even with the keel down, which is well past the ship's down flooding angle, the ship would seem to be doomed.
 
Getting into the downflooding range is iffy, but in a short gust you won't necessarily take on a catastrophic amount of water before it comes back up. The bigger issue if you get hit again before you've pumped all of the water out, as the water will negatively impact your stability.

Having the keel down will help. It doesn't just increase AVS, but also the righting arm. So it'll take more force to heel the boat to 45 degrees with the keel down than with it up.
 
The down flooding angle is a problem. A well found offshore sailboat won't founder even if upside down, and there are countless examples of that.
 
DDW said:
The down flooding angle is a problem. A well found offshore sailboat won't founder even if upside down, and there are countless examples of that.
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Please read the report. The intial downflooding angle appears to have been irrelevant in the case of the Bayseian's loss.
 
The point is, with closed hatches on a well found offshore sailboat, there is no downflooding angle. It is watetight on a 360 degree roll. So unless it got holed by a rock or other boat, it shouldn't have sunk, certainly not quickly. Might have ended up upside down, still not good for the people inside, but not on the bottom in minutes.
 
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