yacht sunk in med

Having seen some of the security camera footage, it appears to me that the vessel rolled about maybe 60 to 70 degrees then started righting itself. My guess is that by the time it did so, enough water came in through the ventilation system to doom it.

I don't think the extra tall mast was by itself to blame. But I suspect that the combination of it and the placement of AC and engine vents proved to be a lethal combination.

I suspect that a boat with a two-masted rig behaves better than one with just one at anchor.

It would have been smart for the crew to close off all of these vents at the mere hint of possible trouble. But I think such would be sociologically impossible. Doing such would have turned the vessel into a floating oven. Then, what if the squall never happened? Would that be the end of the captain's career and that of his crew?

I think, though technically sound (this vessel could be configured to handle such a squall), this design presented human factors which helped seal its fate.

But all of this conjecture on.my part is based on the security camera footage I have seen. There may well be footage I have not seen. How many times was this vessel heeled over during this advent?

All I could see from the on-shore footage was that she disappeared behind the rain squall. I didn't see any timestamped footage and I can't tell if she was dragging yet. It's also unclear what the geometry was - the AIS showed her pivoting 180 and drifting off, but that has been questioned. The AIS doesn't always get vessel headings correct. I think the film probably shows her drifting/dragging and turned as depicted in AIS data, but I'm not sure. (I believe the video of a knockdown was of 43 meter Encore in Auckland a few years back.)

The most recent video by Yacht Report blogger esysman did post a list of 8 questions they would like to see answered by investigators.

It's a reasonable list, to which I would add: was there any evidence that any of the emergency egress hatches were accessed, or attempted to be accessed, by those on board?

There is also an investigation opened up by the British. I guess someone asked how Bayesian got flagged British, triggering yet another CYA scramble.

Hi Tad & everyone (I saw where Tad was quoted in a SuperYacht News video).
I wonder this: if the s/v Bayesian had had side water ballast tanks, like a Class 40, and if they had been empty at anchor, would they have kept the vessel from sinking entirely?
Also: is there any reason to think a motor yacht of similar size would have survived what hit Bayesian?

Stephen Ditmore said:

I wonder this: if the s/v Bayesian had had side water ballast tanks, like a Class 40, and if they had been empty at anchor, would they have kept the vessel from sinking entirely?

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The general assumption is that wind heeled the boat over far enough that she downflooded and sank. So if there had been large side tanks that limited the flooding to centreline, possibly she could have survived, but that's nothing that's possible as every inch on these yachts counts towards luxury, not safety.

Also: is there any reason to think a motor yacht of similar size would have survived what hit Bayesian?

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There is every reason to think a similar sized motoryacht would have survived this storm as it would not carry the gigantic windage that Bayesian does. There is every reason to think Bayesian's windage increased as she heeled due to the numerous large spreaders.

See The Yacht Report (youtube) from two days ago. It seems that AIS data was incomplete - no heading data - and defaulted to showing track data.
EDIT I made this comment because it implies that the boat could have been heading into wind (while dragging anchor?), not pointing downwind.

Tad said:

The general assumption is that wind heeled the boat over far enough that she downflooded and sank. So if there had been large side tanks that limited the flooding to centreline, possibly she could have survived, but that's nothing that's possible as every inch on these yachts counts towards luxury, not safety.

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Very interesting observations, Tad - thank you for your serious engagement concerning this tragedy. I'm going to push back a bit on "nothing that's possible", though, with a quick sketch:
Also note that the Philippe Briand designed Mari-Cha III has both an award nominated interior and ballast tanks: Interior Refit of the 44.7m luxury yacht Mari Cha III by Clear Yacht Interiors — Yacht Charter & Superyacht News

Stephen, the arrangement of Bayesian is different. The deckhouse is set down in the deck at least 3' and there is owner's and guest accomodation under it. Under the guest deck is solid tankage and the centerboard case. The machinery space is aft of the owner/guest cabins and takes full width and depth of the hull. In almost all guest cabins the bed is a giant walk-around, a couple are up against the hull but most are not.

Again, thank you for your earnest information. I'm being a little flip in suggesting, with only indirect relevance, side water tanks be considered for future vessels, but I just asked ChatGBT what other superyachts have side water ballast tanks. It said:

Maltese Falcon was, line Bayesian, built by Perini Navi, but in the case Maltese Falcon an outside naval architect was involved.

[The ChatGBT quote was edited after ChatGBT and I had a little 'talk'.]

I'd also like to point out that the primary engine vents on many motor vessels are located on the sides of a centerline stack. It's common on most classic sailboats for interior spaces to be vented using dorades on cabin tops. I am suggesting that lower downflooding apertures are irresponsible on any sailing vessel.

My 30,000 foot view brings it home a little different.

Looking at the ais, other boats much less formidable on paper survived in the surrounding area.

Hang out on the forums long enough and you'll find a never ending line of folks wanting to reinvent the boat. Appears it's human nature from the poorest to the billionair, the desire to have something unique or different to stand out from the rest. Surface level it appears the consequences hit both just as hard.

My take home will continue to remain, that boats established slowly over time for good reason the way they are. Heavy deviation from that norm will have some consequences, financial or otherwise.

most superyacht owners grew up in houses, thats why their boats resemble almost everything you would find in a plastic kitchen and almost nothing traditionally seaworthy

Stephen Ditmore said:

side water tanks be considered for future vessels, but I just asked ChatGBT what other superyachts have side water ballast tanks. It said:

Here’s a list of sailing superyachts [besides Mari-Cha III and IV] with side water ballast tanks:

Magic Carpet 3 (2013) - Designed by Reichel/Pugh, this 30.47-meter performance yacht incorporates side water ballast tanks to enhance its sailing capabilities and stability.

Hetairos (2011) - Designed by German Frers, this 66-meter yacht incorporates side water ballast tanks to enhance its sailing capabilities and stability.

Maltese Falcon (2006) - Designed by Dykstra Naval Architects, this iconic yacht features side water ballast tanks to support its innovative DynaRig and improve overall performance.
​

Maltese Falcon was, line Bayesian, built by Perini Navi, but in the case Maltese Falcon an outside naval architect was involved.

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Don't believe anything from that bot, it has no clue about boat design. Hetairos was designed by Dykstra (as was Maltese Falcon) with the hull form by Reichel/Pugh. Her side tanks are on the one hand huge, but I would really question if they are big enough to make a difference in a downflooding situation. There is no evidence of side ballast tanks in Maltese Falcon's GA.

I'd also like to point out that the primary engine vents on many motor vessels are located on the sides of a centerline stack. It's common on most classic sailboats for interior spaces to be vented using dorades on cabin tops. I am suggesting that lower downflooding apertures are irresponsible on any sailing vessel.

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While it's common for the very largest motoryachts to have a centreline stack today, most small to medium sized vessels have underwater and transom exhausts, engine ventilation is through deckhouse sides (better), or through topside vents (worst). The Typical Powerboat is Not Seaworthy https://blog.tadroberts.ca/2011/11/the-typical-powerboat-is-not-seaworthy/

Thank you for your corrections, Tad. I have edited my post to reflect the correct designers for Hetairos (while your quote of my post continues to record my mistake, which is fine).

About a third of the way down this Yachting World article on Maltese Falcon is the heading "On the weight budget".
The last part of the first paragraph under that heading ends with the sentence:


So my questions become: is Maltese Falcon a safer boat than (was) Bayesian? Why or by virtue of what (and might Bayesian statistics play a role in the analysis)? If neither is safe, what modifications could be made to future vessels to prevent their rapid capsize and sinking?

Thank you for your observations about the typical powerboat. Where a superyacht is concerned there's no excuse for features that undermine the whole point of subdivision, and there's no excuse for carrying these poor features into sailing yacht design.

comfisherman said:

My take home will continue to remain, that boats established slowly over time for good reason the way they are. Heavy deviation from that norm will have some consequences, financial or otherwise.

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Agreed.

My take home simply confirms my belief that "There is no correlation between brains and money".

comfisherman said:

My take home will continue to remain, that boats established slowly over time for good reason the way they are. Heavy deviation from that norm will have some consequences, financial or otherwise.

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These are classed vessels, though - subdivided, the works. And I expect the classification rules will be revisited in light of this sinking. Down flooding angles are not a new concept. Marine industry professionals should act professional, not blame the deceased owner (perhaps that's a response to BlueBell rather than comfisherman).

Not enough foam flotation at that scale to keep the boat afloat, of course, but that's my point. Deliberately empty tanks or tanks used for other purposes when underway can function, when the keel is up, like foam flotation. What I'm wondering is whether we should look at the whole problem in terms of the hull's ability to trap air as much as keep water out.

A long time ago Art Paine (Chuck Paine's twin brother) wrote a series of articles arguing for jettisonable keels. Would a jettisonable keel have helped in this case? What about that in combination with empty flotation tanks?

Waterspouts and downbursts are location specific, so I'm not persuaded boats in the surrounding area prove anything.

It was difficult to find a precedent, but I found these:

Sinking of Dongfang zhi Xing - Wikipedia <-- major loss of life

VIDEO: Microburst Caused Tilghman Storm Damage | Chesapeake Bay Magazine

Tad said:

There is every reason to think Bayesian's windage increased as she heeled due to the numerous large spreaders.

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@Tad
Yes, and the way the LY2 standard handles this is very bad. It ignores both the windage of spreaders and the increase in height due to form stability. The design space of the gust response requirement is rather flat. Designs such as Bayesian would be expected to be hard against the design limit, and if you provide an allowance for spreader drag and form stability, such as changing the formula for "derived wind heeling lever" from a factor of theta to a factor of theta - 4 degrees, the static stability would need to be quite a bit larger to provide the same notional gust reserve.



This was clipped from LY3, but LY2 had the same requirement.