Bayesian sinking--the mystery continues

[Christian Williams]

Crew statements are being withheld for legal reasons, but I find compelling this information volunteered by a former captain.

Looking at the enormous boat it's hard to imagine it suddenly going to the bottom when anchored. But the tall mast presents challenges. And it had a "downflooding" limitation of only 45 degrees heel. Downflooding is apparently when water begins entering, and can enter fast. No Ericson floods at 45 degrees of heel.

 

[Loren Beach]

That whole "insisting on the tallest aluminum spar plus the 45 degree downflooding angle begger belief.
For instance, I had a spreader tip in the water once in my former Ranger 20, when hit by a spring time line squall, and decades later was on a delivery with an Islander 36 where we took a hard roll from a big gust while crossing the outer Columbia River Bar, and briefly had water over a low side cabin fixed port. No water entering the interior in either case. Exciting, tho!
Gotta add... both of those designs were from respected naval architects. (Raymond Richards N.A.M.E, and Alan P. Gurney, respectively)
I wonder if the hyper wealthy clients for "super yacht" projects just keep shopping until they get the answers they want?

 

[Shankara]

This one has some interesting points about angle with keel retracted:

 

[Bepi]

Years ago a waterspout hit Huntington Beach, nearly where my Gondola business was. When it hit land it turned into a tornado. It rolled cars in the parking lot and went over the building tearing off tiles. I rushed down to find my boats were fine, but a few docks down there was a lot of damage. Strangely, a week before, one of my gondoliers, who was very experienced, hit the front of a small docked Runabout and made a half dollar size chip in what appeared to be brand new turquoise topside gelcoat. I was getting the repair funds together and formulating a letter of explanation, but after all I came to find that that vessel was picked up by the twister and carried a mile away into the nearby Seal Beach Naval weapons station... so I didn't feel the need to send the letter.
In the case of this super yacht, I believe that the waterspout grabbed and held the mast down giving enough time for a fatal amount of water to get in before the vessel could right herself. And once the water was in, the weight of the mast finished the job and rolled her over.

 

[Alan Gomes]

Some more info on the role the yacht's design may have had on the sinking.

 

[N.A.]

That is a sobering link from @Alan Gomes ... I had seen that the AC and engine vents would have been open, but had not made the connection to how much water could come in.

It does not surprise me that a crazy weather event could hold a boat down at 90 deg for over a minute; I once watched a big (40'+) racing boat on SF Bay at ~90 deg for quite a while (went down, stayed, came up, went back down... I thought it was going to sink for sure, but it didn't) due to a spinnaker broach coupled with (I presume) figure-8'ed spinnaker sheets. There is a reason sailing schools train you to put no stopper knots in those : ) Anyway, that boat definitely had its mast only a few degrees above the water. I think the water was about halfway up the cockpit. For a ling time. It was startling.

Which makes me wonder... how/do you secure your hatchboards when offshore to prevent flooding if knocked down?

I put this question on a different thread to avoid repurposing this one:

Securing hatchboards

Offshore racing rules here (SF Bay) require the hatchboard(s) to be in and secured to a level such that a wave filling the cockpit cannot empty down the companionway entrance... Do any of you do this? How? I just tie mine down, but the more I think about it the more I wonder if some easier way...

ericsonyachts.org