56M Perini S/Y Bayesian Sinks During Palermo Storm

The Italian Air Force have concluded (or disclosed ) that it was a microburst rather than a tornado,

That was what I mentioned a few pages back. I think you and I both know the energy of a micro burst as airplane pilots. I do still wonder if the anchor drug the boat under as the time frame on sinking is so short?

A dragging anchor is not a set anchor, that’s why it’s dragging. I can’t imagine any scenario where that would take the boat down. Even if it were to reset. And as others mentioned here, I don’t believe it’s ever happened.

Minor point: a dragging anchor during extreme conditions will allow the bow to fall off the wind, to what extent depends on the residual resistance provided by the ground tackle.

Of course, the bow will not be submerged to any degree during such an event. Even if the anchor(s) were fully set and holding, bow submergence to the point of taking solid water over the foredeck is not a realistic scenario.

You guys are thinking about anchor drag on an upright boat. From the crew the boat was listing 20-25 degrees for some time before it went over. The crew also said the bow went down first. That really suggests the anchr MAY have had some impact on the sudden sinking. I don't know if you folks remember an AHTS that went to the bottom because of an anchor The Burbon Dolphin

With all due respect, stability concerns arising from typical loads experienced during offshore rig scale commercial anchor handling operations have little relevance in this case imo.

I wouldn't be surprised to see heel angles around 20-25° given sufficient wind strength beam-on, although probably quite unsettling to the crew and guests. The CEO's comments (though undoubtedly in bad taste) have some merit that something else, e.g. flooding, must've accounted for the more extreme heel angles and non-recovery.

Form a former Capt., I think down flooding was the most likely cause of the sinking, more so than the knock down.

The Angle of Vanishing Stability is the angle of heel at which the vessel righting moment reaches zero, meaning that the vessel will not return to upright. Again, I forget the actual numbers for this, but the figures would be around 90 degrees with the moveable keel lowered and 75 degrees with it raised.

The Downflooding Angle is much more important though in the scenario we are talking about. This is the angle of heel at which water will start to enter the vessel (usually through engine room or accommodation ventilation ducts)… once this starts the vessels is in serious trouble as stability is quickly reduced or lost due to the flooding.

The downflooding angle for Bayesian was around 40-45 degrees… much less than the AVS. So, unless the vent dampers are closed (which with HVAC systems and generator running they would NOT be as they need to be open for that), the vessel will start to flood rapidly if heeled more than the downflooding angle.

Actual article is here: https://www.sailingscuttlebutt.com/2024/08/27/former-bayesian-captain-offers-insight/

More crew members under investigation, phones seized, Sky News:
https://news.sky.com/story/two-brit...esian-superyacht-under-investigation-13204664

Since they all ended up in the salt bath, you've gotta wonder what they're collecting.

Yes, very familiar with microburst on sailboats, been knocked over twice but no drama as she popped right up when I steered into the wind. (While holding on and bracing with a leg sideways and the rudder barely in the water)
Also had micro burst airborne but modern airplanes and modern airports have so much sensing equipment and early warnings that no metal was bent.
The big one was @ DFW airport when a Delta 1011 crashed and killed most of the crew and pax in 1985. That one was the big wake-up call for downdrafts and microburst and the industry took it seriously and did a lot of research on the phenomenon.
I spent 15 years of my life flying 747s, lucky as no 747 has ever crashed due to microburst, too much mass in motion according to the experts.
(In the simulator however we had some close calls practicing the DFW crash)

As for this thread and the big sailboat: All the holes in the Swiss cheese lined up she just sank really fast.
I am guessing future BiG sailboats will have automatic locking air intakes when the critical 45 degree angle is coming close, the generators shut down and the emergency power for pumps, steering, controls, etc will be handled by a big battery bank in water proof compartments. Pretty low tech really, submarines has been built that way for 100 years.

In all forms of transportation graveyard legislation/rulemaking is the standard.

Really unthinkable that the class societies didn't have the vents close automaticly. A simple system even years ago. Yea, saddly all the holes in the cheese lined up on this one!

Yes, the USCG is as guilty as the FAA: Remember the California dive boat that burned, perfectly legal
to have a death trap as long as a crew member was awake and in charge, but no plan B in case the night watch took a nap, 33 dead bodies..
The FAA writing different rest and duty time limitations between pax and cargo pilots inviting abuse from cargo operators, fly till you die. Not impressed.

At any rate, back to the subject, this huge sailing yacht that sunk as fast as swamped rowboat in a rain storm.
Not impressed, but hopefully lessons will be learned, present boats modified and future boats improved..

Today there is an article/interview with a former captain of the ship, who describes some construction details and limits. Article in German, but translate with google, deepl, etc works just fine: „Bayesian“-Havarie: Einschätzungen des Ex-Kapitäns | YACHT

My understanding is that E/R access was limited to the aft bulkhead/corridor crew-only spaces, likely part of the internal 'garage' accessible via the hull side opening. If the E/R door were open, it may have been for ease of access and/or to help dissipate heat, as probably only one genset was running so would be easier/quieter than the main ventilation fans. Genset likely to be reliable NL-equivalent without any history of major malfunction, fire, etc.

As a side note, I cannot imagine the hull side was actually open at that time/location so very unlikely to be a source of initial flooding.

I understand there were no openings whatsoever in the E/R fwd bulkhead, other than typical penetrations for services, electrics, etc which would have been verified to maintain WT integrity.