What exterior w/t door?
Port side tender bay seen hatch partly open in photo taken earlier that night….
You’ve actually been on this model/class of boat many times
I take it there are doors leading to the exterior on multiple decks. Are there multiple watertight doors?
Footage of a large sailing vessel being knocked down in Auckland Harbour. Clearly it has a much larger AVS than the Bayesian.
3 Likes
I have not been onboard Bayesian, just a few of its family members of the same general design. The only doors I am familiar with are the port side shell door, the engine room door, one between the crew mess/galley area, and one between the galley and the guest area. either of those last two were probably open and in use. There is a heavy deck hatch on the aft deck portside which leads to a stairway to the lazz area that is used to access the shell platform when in use. There is an escape hatch forward in the crew area and a door in the collision bulkhead for access to the chain locker if I recall correctly.
2 Likes
To my mind water coming into the engine room might cause a blackout but it would not cause the yacht to sink. Something prevented the people in the staterooms from reaching the deck and a wall of water would do it. I will join the speculation that the glass doors had something to do with it .
The glass doors do not appear to be very “weathertight”. Shower proof like the door of my local supermarket. At best if closed would only slow the ingress. Near the centerline under cover. A ways from the deck edge.
Presumably approved by someone in an official capacity at Class. (ABS? I had a higher opinion of ABS than others)
Pure guess and speculation. Probably will be found to be wrong in the end.
Me thinks, Free Surface Effect might have played a role. Water does not have to make it below deck to serriously effect stability if it gets trapped on deck. If the deck or cockpit is unable to shed water fast enough.
A bit of this a bit of that it all adds up. To in this case a catastrophic problem which was not contemplated by the applicable codes, design builder or operator. Ultimately the crew present on the day.
Quite honestly I don’t think I would have been prepared for this. A ship at anchor. A thunderstorm. No I wouldn’t have anticipated this. Or been prepared for it.
Initial approach, Appears to have been noticed. By Watch, By crew, Including Master Mates Engineer and some Pax or guests.
The crew were responding to a mess created by a storm. Which brought them up on deck, Some Pax must have been concerned enough to come up on deck or been on deck for some other reason.
This saved their lives. Some were probability injured by falling a significant distance, when the deck suddenly became a bulkhead. Or the fell OB.
The people bellow deck appear to have been guests. Possibly awakened, Possibly asleep. ietherway not concerned enough. Why not? They are on a big safe ship, They have people to deal with this.
They would have possibly been suddenly thrown or fallen to the low side. possible quite a few meters enough to injure. Disorientated. The Deck is now a bulkhead. You have to climb to the exit if you can even find it. It may have gone dark.
What was the required EM lighting, signage ect?
Look at reports for other other vessels which suffered a sudden catastrophic loss of stability.
Princes Victoria.
Herald of Free Enterprise.
Estonia.
The Sewol.
There was no effective response.
On deck you had a chance.
Bellow deck,
The Herald Didn’t completely capsize or sink. Some got out.
The Others not so much.
The Storm winds arrived.
The wind direction and speed increased dramatically.
The ship heeled to the wind.
The Ship started dragging her anchor.
The anchor dragged very quickly or cable parted.
Bow fell off down wind.
If the anchor had kept her “Head to wind”? She might have had a chance. Beam on?
The “out burst” or “down burst” on the beam wasn’t just a coincidence.
Wind keep increasing and as she turned down wind heel got much worse.
Force on mast should get less a ship heels.
Unfortunately its a down burst. Force on mast still increasing as ship heels.
Somewhere in this deck edge immersion occurs.
Water on deck, Water Ingress Begines Water Down Bellow.
The water goes to the low side. making things worse
When did she go to 20? 40? 80? 90?
From upright to 20 ish. Appears to have been some time, as crew responded trying to deal with blowing stuff on deck.
Very quickly from 20 on
Prior to 20. It’s a Sailing vessel. “Crew guests, We are not alarmed”. Yet. “Or some of us are just getting there”.
Suddenly an unexpectedly she goes way past 20.
40 and its going bad fast. and getting worse.
50 ish. The power to resist is getting less and water is making it worse.
By 80 its gone.
Once she gets to 80 or 90 the water is coming in quickly through all the exits. holding closed hatches shut and pouring into open hatches.
She past the point of recovery. even as the wind eases changes and switches the other way. The ship is doomed.
The liferaft hydrostatic release activates.
The people in the water are able to find some floatation jackets the raft.
It’s now a rescue and recovery.
3 Likes
Uricane,
Yup. That’s a chillingly good description of a possible scenario and I speculate the final report will read in similar fashion to some degree.
Those sliding doors you mentioned are often about 400-600 kg per leaf. Here on a larger yacht they are about a ton per moving leaf. The glass is between 25-40mm thick, in some positions more.
They typically include rated laminated glass and often inflatable seals, although the seals can be deactivated to decrease operating cycle time. The standards applied are the same as a weathertight door on a ship, althoflag state may allow a slight relaxation where doors are located in a sheltered position.
They are definitely engineered and tested to load line requirements- some with amazing construction details to meet those requirements. Never seen a slider tested while rotated 90 degrees however, be it an ABS, LR or DNV classed yacht. The door factories I’ve been in could definitely do it however if it was a requirement.
It must be borne in mind that WT and Weathertight doors and closures are generally intended to be effective against water rising from a hull breach and boarding seas respectively. Not flipping an operating, undamaged ship at anchor on an otherwise calm night - on its side near instantaneously and flinging the crew overboard.
In addition to the ship design, the timeline and details of the forecast weather will prove key in this incident. Methinks.
1 Like
Interesting and plausible analysis.
Personally I think social media commentary in the yachting community has become too invested in a knockdown which makes sense logically but doesn’t fit with the CCTV, if the footage is indeed of the Bayesian, which I am not entirely sure it is.
If the CCTV footage is genuine then we are seeing the following: heeling followed by the mast lights going out, leaving the masthead light alone on a different circuit or emergency battery.
Setting aside catastrophic power failure cause unknown, this could indicate water has reached the generator and knocked out the power even at this early stage. So it could be that the boat is listing not heeling.
Accounts from survivors have understandably been tight-lipped although both passengers and crew have reported a “tilting”or “heeling to 20 degrees” when suddenly the ship heeled some more and they found themselves in the water.
Yes, they are not your neighbor’s sliding patio doors. There is a video on Superyacht News that shows a door with a failed closure: https://www.youtube.com/watch?v=oU3Te6i8Ado
What is very evident if you know what you are looking at is the cogged belt that has either broken or slipped off its rollers. That is what synchronously opens and closes the doors.
But what works best to stop belt squeaking 
?
Cats are a very different thing. You can find photos of them being lifted out of the water and flung ashore in hurricanes. They can turn into lifting bodies if the wind is strong enough. The basic issue of towing a Hobie Cat with the bow angled up on the trailer instead of down scaled way the hell up!
If you look at the video it includes a cat AND it shows a yacht being knocked down. There’s a longer version of the video on this thread that also shows the yacht righting.
This is a good video, nothing new but a good summary, includes the CCTV footage for the knockdown in a waterspout, in Auckland. It also has a recording of the AIS track of both vessels,
2 Likes
A lot of common sense, finally.
The cat wasn’t knocked down, it was flipped over, end for end.
That must have been exciting.
1 Like
Mr Cutfield said the boat tilted by 45 degrees and stayed in that position for some time, then it suddenly fell completely to the right, the newspaper reported.
From here:
1 Like
What seems to be coming together is not the wind laying the boat over to 90 degrees, but more like this:
Wind
Boat heals over about 45 degrees
Rapid flooding
A free-surface aided fast roll to 90
1 Like
KC,
Thanks for the link. It would appear to me that this thread and its contributors are not the only ones who will be hypothesising and running on assumptions. A thorough and accurate investigation will be difficult to produce owing to no fitted VDR allied with the correct establishment of time frames and hull/mast aspect throughout the sinking. Additionally, the available CCTV footage is of little help.
“ Mr Cutfield said the boat tilted by 45 degrees and stayed in that position for some time, then it suddenly fell completely to the right, the newspaper reported.”
Some time……….during which downflooding was occurring effectively reducing the inherent 77 degree AVS. One could also assume that there would be an initial amount of trapped air buoyancy within the 75m mast preventing the entire vessel from rolling further than 90 degrees. This may explain why the vessel has settled on its starboard side with the rig fully intact.
There have been a significant number of dives made on the wreck and one could naturally assume that a quantity of photographic evidence has been taken to assist the investigation. The divers have accessed the full accommodation internal areas via the two cockpit doors and one can only assume that, on arrival, found the starboard door open and the port door closed…….a sufficient opening for significant ingress in short time. She was on her beam ends and low in the water as the progressive downflooding continued.
Hopefully, like the “Dali”, all will be revealed in the fullness of time. In 12 months we will all have moved on and forgotten about it……….
4 Likes
I don’t know how good these numbers are but I’ve not seen a calculation of dangerous wind speed for the Bayesian elsewhere.
Why Did the Bayesian Sink? Video of Palermo Storm That Hit the Lynch Superyacht
its righting moment would be approximately 12,750,000 Newton-meters (Nm). The dangerous heeling moment would be where a 75m mast is hit with 170,000 Newtons of wind force (F x 75 = 12,750,000).
To calculate a dangerous wind speed (V²), we use air density (1.225kg/m3), mast drag coefficient (1.2), mast surface area (200m²), and that wind force. The equation looks like this:
170,000 = 0.5 x 1.225 x 1.2 x 200 x V²
Solving for V, we find that a dangerous wind speed is 34 m/s.
This means a sideways wind at around 80 mph could be strong enough to tip the yacht over far enough to take on water in a sudden instant,
34 m/s is 66 kts
80 mph is 70 kts.
Also from the same site:
Looking at the weather history, we see some of this evidence. A predominant westerly breeze of 10-15 after midnight suddenly jumps 90 degrees from the north and over 40mph at 3:50AM.
Wind Speed Palermo. Source: WunderGround 2024-08-19
This graph is not readings at the Bayesian’s actual location.
Don’t know about these numbers or some of the key assumptions. Anyone seen better calculations?
EDIT: (F x 75 = 12,750,000): Is the assumption here that the force is acting on a point at the top of the mast?
You idea is a good basic illustration.
The windage area of mast/boom plus the standing rigging must be considered, plus the hull & superstructure.
The force applied by a wind would of course depend on the direction of application and would be reduced as the ship heeled and the horizontal vector of the wind force applied is reduced. So that is a bit of an integrated solution.
The resultant force is not at mast tip although it could be expressed that way.
This will prove an interesting technical investigation and a good defense. No one knows nor can anyone prove what the wind speed was at the time and place of the incident….
I would think the force should be calculated as acting at the center of lateral area of the mast.
Another observation: from this picture, it appears that the cabin deck is at about one meter below the sheer line, and the distance between the opening and the sheer line is half a meter or so. This might have had an effect on when flooding began and what the actual righting moment was after ingress.
Earl
2 Likes