The Sea Demonstrates Again It Doesn't Care - Yacht Bayesian

Perhaps you are stuck in the Gyre of Effluvia. Might want to try shifting the helm Cap’n, but by dim recollection you’ve been stuck in adverse currents for quite some time.

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Heiwa’s stability has been heeled beyond recovery for a long time.

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This does!

I’m surprised of a downflooding angle of only 40-45 degrees. Sailboats are designed to sail heeled over. It is their normal operating condition. Sailing with the rail nearly submerged is normal for a sailboat.

It is not unusual for sailboats to be knocked down, i.e. hit with a gust of wind with too much sail area up, such that it capsizes the boat. Sailboats survive this provided they seal hatches/vents ahead of time.

So, for a sailboat to begin downflooding at an angle of 45 degrees sounds unusual, unless an unusual number of hatches/vents were left open

30 years ago I sailed on a boat (motor steel, 180 feet) that would roll 40-45 degrees underway in Bering Sea/GOA storms. SOP. She was notorious for this. Notorious also for the vicious snap roll she had getting upright. We never took on water. And this was a motor vessel. Not a sailboat designed to list 20 degrees in normal operation and survive knockdowns.

In a post above I theorized Bayesian’s crew may have left hatches/vents open because of loss of AC plant. While that exact eventually may not have occurred I still think something like this may have. A luxury yacht is going to keep AC on all the time, meaning doors/windows must be kept closed. So, how does a vessel suddenly sink so quickly if everything is closed up? Also, a number of people were sleeping on deck. Which may or may not be indicative of loss of AC.

Just a theory.

Same article here,

How the vessel came to be taken outside her operation limits is what the investigators will need to determine, which I’m sure they will.

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The air intake for the generators would be left open. Probably a small exhaust &/or supply air vents for the engine room to keep ambient temperatures down as well. The heads would have exhaust vents leading to somewhere outside the vessel. Also, a “make up” air inlet for the HVAC system to let fresh air into the vessel for odor/humidification reasons.

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A good read for those interested in some facts about the yacht.

Note the part where he indicates details about swing keel use.

So apparently no class or flag requirement for lowering the keel when the yacht would be located at anchor 0.5 n-m offshore. Hmmmm.

Now for „outside the operating envelope“ think about the near instant application of 8.4 million Nm overturning moment being applied via rig windage alone - at just 120 kts. Try 13.3 million Nm overturning moment at 150 kts. Okay …. Puts the effect of strong downdrafts or tornadic winds on large classed sailing vessels that possess adequate intact stability into a little more perspective.

So - was it unreasonable to have the yacht configured in such a manner given information available to the Master?

Would the yacht have suffered a full knockdown if the keel was deployed at the time ? What was the wind velocity acting on the rig, hull & superstructure and how long was the attendant overturning moment applied?

Did these conditions exceed the operational envelope and if so by how much ? 5% or 300% ? Hmmmm

In the USA the VHF bad weather alarm would be going off and maybe a security call on 16 too if they (NOAA) saw the weather in time.
I am in the cognitive dissonance phase here where “sailboats” are not really in danger from thunderstorms when anchored and can pop right back up from 90 degree knockdowns but this vessel is more a small ship than a big sailboat and back in the day a 90 degree angle of heel was fatal to sailing ships.

Some excellent and definitive information in this video.

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This is the link to the ANSA news feed (in Italian) updates on the Bayesian including salvage:

Sailing vessels I dealt with usually get the toerail in the water around 20°, max 25°, at which point you would start to depower to keel the heel in check. So 40°-45° of downflooding angle still gives a good margin in normal sailing conditions.
Obviously what happened was NOT normal sailing conditions.

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THere was a statement yesterday or the day before from the a spokeperson from the Italian weather service that said the a storm was predicted with winds of about 30kts, if I recall correctly, but the overall conditions did not forecast for possible downbursts or waterspouts.
It seemed to me a clear statement that was happened was completely unpredicted.

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In Italian (from the link @Skua provided):
Che lo yacht si sia ritrovato al centro di un fenomeno meteorologico di straordinaria violenza, definito downburst, lo conferma l’Istituto di scienze marine del consiglio nazionale delle ricerche (Cnr-Ismar) sulla base della registrazione di un simile evento avvenuto nel luglio del 2008 nell’alto Adriatico e misurato dalla piattaforma oceanografica. Lo studio, pubblicato nel 2012, dimostra che a seguito di un temporale il vento è passato in pochi minuti da una velocità di 3 metri al secondo a una velocità di 30 metri al secondo (pari a 108 chilometri orari), con le raffiche che per 15 minuti sono andate ben oltre il massimo rilevabile dallo strumento (40 metri al secondo).

Using Google traslate (sorry at work and don’t have time to do it myself):
“That the yacht found itself at the center of a meteorological phenomenon of extraordinary violence, called downburst, is confirmed by the Institute of Marine Sciences of the National Research Council (Cnr-Ismar) on the basis of the recording of a similar event that took place in July 2008 in the upper Adriatic and measured by the oceanographic platform. The study, published in 2012, shows that following a thunderstorm, the wind went from a speed of 3 meters per second to a speed of 30 meters per second (equal to 108 kilometers per hour) in a few minutes, with gusts that for 15 minutes went well beyond the maximum detectable by the instrument (40 meters per second).”

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Sorry, but I find the information that he gives misleading and not understanding of how a sailing yacht works.
The issue with the sliding doors and lowered cockpit, it seems a non-issue to me as they are in centerline and even if heeled to 90° the door would most likely be completely out of the water. I’d be surprised if that were not a case analysed in the design phase when doing intact stability.
He also says the angle of vanishing stability is the angle when the yacht does not come back up and it stays down. Unless the GZ magically stays at zero, passing the AVS will result in capsize, not just staying down.
Also is take on the stability book, he says the keel “should” be in the raised position at anchor, which is wrong, the stability book says when it must be lowered and when it can be raised, doesn’t says it must be raised.
Regarding the legal case, the Captain exercise the right to not answer questions, according to his lawyer, because he is still recovering, and not all relevant information has been disclosed by the prosecution. No admission of anything.

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Not a problem. I am not a fan of his style of presentation and having viewed many of his contributions……remain in that mindset.

What I did find interesting was the quoted commentary from the previous Master, Stephen Edwards, who makes reference to the “Stability Information Book” which had been approved by the flag state.
Quote…”The operational limitations MUST be adhered to at all times”.
Quote……”One section of the Bayesian stability book related to the use of the moveable keel…and defines when it MUST be lowered”.
Quote….”in this vessels case it was required to be lowered when using sails and/or when more than 60 nautical miles offshore regardless of whether sailing or only using engines”.
Quote….”at all other times, it COULD be in the raised position…”

The AVS, in this instance, was 77 degrees (keel up) according to the vessel’s builder….and there is only a 11 degree AVS differential between keel up and keel down! Modern day offshore sailing vessels are somewhere between 110~120 degrees. Once again, good definitive information.

Allied with a DFA of 40~45 degrees her fate was sealed.
Quote from an engineer who had worked on the sister vessel……”you would not consider to close any of the many dampers at anchor as they all needed to remain open for the HVAC and running generator”.

One could also surmise that once downflooding commences the AVS is effectively reduced…….

A quoted section from a UK Sailing Ship Stability Forum……

Downflooding & intact freeboard:
Given that circumstances can result in knockdown for even the best vessel, maintaining her intact freeboard and minimising the risk of resultant downflooding is critical to her ability to recover. There are many features that can improve ‘intact’ stability at large angles of heel, such as watertight deckhouses. Downflooding creates free surface effect, and thus transforms a difficult situation into an irrecoverable one. A good range of stability is indeed essential, but it must be combined with maximum resistance to downflooding.
The size of opening that will cause critical downflooding is calculated from a formula related to the ship’s displacement. The angle at which these openings submerge is called the downflooding angle, and it is an important figure for sailing ship stability. UK regulations preclude submergence at less than 40o of any such openings. A downflood angle of more than 65o is both achievable and regarded as best practice.
Many certifying authorities require that the shipside should not be pierced for opening scuttles, in order to protect intact freeboard. Excessive water trapped on deck is a related potential problem. The modern recommendation is that ships should be able to free their decks of water in a time close to (better still – less than) their period of roll.”

Note……”UK regulations preclude submergence at less than 40 degrees of any such openings”.

Note……” A down flood angle of more than 65 degrees is both achievable and regarded as best practice”.

All of this information has been available since this post: The Sea Demonstrates Again It Doesn't Care - Yacht Bayesian - #228 by ombugge

I will confess to not having read many of the posts. Was Stephen Edwards quoted in #228?

Yikes!
A boat(ship?) like that would need a vastly different mindset to manage if you grew up on sailboats where 110 degrees AVS* would be considered low and a 90 degree knockdown meant yelling at the deck apes to please get the f-n preventer off any time now.

  • mine is 125 degrees or so
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Yes. As Joseph Conrad noted, “And yet I have known the sea far too long to believe in its respect for any decency. An elemental force is ruthlessly frank”