I got it in the neck about my last post for being 'condescending, hypocritical, misogynistic, mummy, a bloke' and a whole bunch of other things besides (maybe it was the suggestion that every one of us is partially responsible for this sinking which got people's backs up? It's fine to keyboard away, leaping on suggestions that the crew did something wrong - but more painful to acknowledge that us burning fossil fuels leading to a 25% rise in atmospheric CO2 levels in the last 50 years is making our atmosphere and surface sea temperatures warmer and increasing the power and frequency of extreme weather events such as Bayesian experienced. And no-one wants to feel like it's actually THEM that is responsible for this loss of life, even if, in fact, mutually - we ALL are.) So with the caveat that I'm expecting yet more roasting for making posters feel bad for their own part in this tragedy (go and put more insulation in your house & use public transport & bikes over planes & cars if you want to take your own learning from this), here goes. I'll try to put some links in so that anyone who's interested can follow up for themselves instead of just telling me I'm preachy though!
I stand 100% by my previous comment that Bayesian sank because of an 'act of god'. From the limited CCTV footage which has been released into the public domain, m.youtube.com/watch?v=5RyhkSWM2nM the boat was clearly weathering a storm front ("storm force" is a defined meteorological term for those who were querying this - it is sustained winds of 55 knots or above Beaufort Wind Scale although 'storm' or 'storm front' can be used more generically to describe winds forecast from "near gale" up, with or without a forecast of thunderstorms developing, which they did). The boat was happily weathering winds which looked like c.40-55 knots or so just fine (nearby weather stations & boats will confirm the underlying wind strengths at the time). Then a localised, far more powerful downburst occurred as essentially a 'direct hit'. This would have been more akin to having a jet engine directed at the boat from the sky - and unless you're deep enough into the conspiracy vibe to think that HP hired an italian plane to point its engines directly at the yacht (and the Italian air force confirmed a downburst event in the immediate area, so I'm not suggesting that this won't be written off as a plausible explanation by the conspiracists!) - no boat is coded to survive a direct 100 knot hit, and it will have been a question of doing what was possible to survive the effects of it.
NOAA have a very good explanation of how downbursts occur in thunderstorm fronts here Weather Hazards - Downbursts the problem is they are fleeting and exact locations are just about impossible to predict and can't be seen in advance - even around thunderstorm cells which themselves form & dissipate very quicky (but which do show up on radar).
Incidentally, one area of the planet where downbursts most frequently occur is along the edge of the gulf stream as it flows out into the atlantic. They occur more frequently here because of the margin between extremely high water temperatures flowing up from the gulf of mexico, the colder atlantic waters, and the effect of storm fronts as they roll out to sea from the continental US. It has resulted in many unexplained sinkings over the centuries, along with way above average aircraft losses. These are grouped in an area which came to be known colloquially as 'The Bermuda Triangle'.
There have been comments above about the yacht 'breaking anchor'. I think it may help here to clarify that any vessel can drag anchor in almost any condition if it's not laid correctly. There's no suggestion that it wasn't laid appropriately for the forecast storm front, and CCTV appears to show it holding well initially. It's not unusual that it may drag a little in stronger gusts. This in itself is not even a problem - the boat was anchored with enough sea room to drag a little. At some point it appears to have lost hold & the boat dragged faster - this would be expected if it experienced an 80-100 knot downburst! The distances identified on AIS only translate to about 7 boatlengths in c.10 minutes or so - not unexpected if it was experiencing that kind of wind strength. It's entirely possible the anchor was still down and still connected to the boat, just dragging. Or the anchor rode (chain/rope) may have snapped under extreme load - I'm sure the investigation will conclude on this. There's been a lot of assumptions the engines weren't already on too. I don't know why. Again, the investigators timeline will conclude.
What I have found extremely distasteful and premature though, is the passionate italian protestations from the Chairman of The Italian Sea Group . Perini Navi make extremely high quality ocean going yachts. You can see in CCTV footage how little the boat was moving at anchor right up until the final, very rapid, heel & sinking. The job of a Chairman of a listed business is to protect the interests of shareholders and keep the share price up. Giovanni Costantino has certainly gone out all guns blazing doing this job - in front of anyone who will point a TV camera at him.
I hope all the investigators are thorough enough to see through all the bluster & bullshit he's come up with about 'unsinkable boats' (next job for him - chairman of White Star Lines, perhaps?) and that they will do what they're trained to do & go through all of the evidence & timeline methodically. It doesn't help that he's gone on record with some falsehoods like 'the yacht should have had it's anchor fully down for that weather forecast'. My understanding based on info the yacht's previous skipper has shared is that the stability book allows for the keel fully up in all cases except sailing or well offshore. The book is assessed by the American Bureau of Shipping (the classification society under which this yacht was built) and the stability condition at anchor was keel up not down (whether these assessments will change based on investgators' recommendations in due course remains to be seen). However it's likely the yacht would behave (move) better at anchor, and be LESS likely to drag anchor with the keel up than down. (There's a fairly longwinded reason I say this, if anyone's actually interested then ask & I could try to diagram it to explain.)
What is relevant & not mentioned by Chairman Costantino, is that the downflooding angle of the yacht at anchor is significantly less than the angle of vanishing stability (when it would capsize). Apparently the downflooding angle is somewhere around 43• wheras the boat wouldn't capsize until 77• Downflooding is where ventilation openings in the ship's hull are submerged while open (which they would at anchor to run air conditioning) & start to take on water.
However what I've seen on the CCTV suggests there was initially some flooding at a lower level, then it got to a level the generators stopped working (main mast lights go out and only masthead light & stern light remain lit from emergency backup power), then the boat heeled as a result of a powerful gust, then the free surface effect of the existing water in the boat made the boat heel further. A simple explanation of the free surface effect of water inside a hull is given at https://tc.canada.ca/en/marine-transportation/marine-safety/free-surface-effect# If at this point the boat has now heeled to the downflooding angle, it will take on more water rapidly, sinking lower & putting at risk even more rapid flooding through any broken deck level windows & main saloon doors.
But she seems to have gone down EVEN faster than that. And where did the initial flooding water come from? Well again, it's completely disingenuous of Chairman Costantino to describe a boat as unsinkable - they are riddled with through hull openings. This yacht had 2 engines - so 2 drive shafts to propellers and presumably also 2 rudders. If any of these 4 items had snagged on the anchor line of the Baden Powell behind them in the anchorage (or loose fishing gear, or a floating tree trunk, or any other storm debris) & bent, that would have been firehose pressure water coming in through a half-metre square or so opening to start with. Or any of the through hull pipes for engine & generator cooling, toilets & other plumbing may have come loose when the boat was shaken around like a ragdoll by the downburst (remembering this is a yacht that would sit quite happily in 50-60 knots of steady wind at anchor, so the force required to shake it around like a ragdoll is truly exceptional, and not in any way a normal design condition to withstand).
So there are a number of possibilities as to how an initial hull breech may have occurred to initiate flooding. Once there is that much force of water coming in through a small opening, it is possible that while the yacht was still being shaken in the downburst, structural damage occurred around that opening (or around the connection of the mast from the shroud plate down the starboard side, or longitudinally along the edge of the keel), causing part of the hull to 'unzip'. Again, this isn't saying the boat was badly built in any way - just that this event was so far outside the design condition envelope that experiencing it on board doesn't bear thinking about.
IF part of the structure gave way once the boat heeled from the wind & free surface effect impact of initial flooding, this WOULD explain how the boat took on so much water so quickly & sank so fast.
It's also possible that any torque on the hull as the ship heeled MAY have meant any closed cabin doors became far harder to open, if the frames had pressure on them because of the way the boat twisted once it heeled. So if an alarm was sounded as soon as the boat heeled by the 20-30 degrees or so shown on CCTV before visibility became worse - it's possible that structural effects within the hull and/or movement of furnishings & matresses were enough to prevent the remaining 6 guests from making their way up to the top deck. As tragic as that is.
I do understand the public interest in this case. It's terrifying as a sailor to contemplate. There is some conjecture above - but I'm trying to keep it in the context of what MAY have happened, rather than what definitely did. The investigation will go through all the detail to try to come up with a full timeline and explanation.
While it is entirely possible that there were many human errors, it is also entirely possible that they did absolutely everything by the book and yet STILL this happened. No ship is unsinkable (well the big orange ocean lifeboats on container ships with no through hull openings & only a bucket for toileting come close - but I think we can all agree that that's probably a little removed from the luxe billionaire experience your average superyacht owner is hoping to wow his guests with, eh?).
It has been deeply disturbing to hear Chairman Costantino leap to blaming the crew for leaving the garage or major hatches open, not having the engines on, having the keel in the wrong position (it wasn't), and not sounding an alarm. We don't know that ANY of those statements he's gone public with are true. Yet. He also blamed the crew for not responding to the forecast by waking the guests & having them sat around for hours with life jackets because c.50 knot winds were due (this absolutely wouldn't be standard). We can't tell yet whether there was any structural damage or not. It also troubled me to hear the local investigator state at a press conference that culpable homicide was 'probable' rather than simply 'possible' - I hope he doesn't leap too quickly along lines of enquiry without an excellent investigator's open mind! However he had already had some discussions with crew at that point, so maybe he does know the crew were disorganised, badly managed & not following procedures properly.
BUT as I said in my first post, it's entirely possible that none of the captain, crew, or builder did anything wrong within current operating legislation. And yet still she sank as fast as she did. There will no doubt be some recommendations for improvements to classification and/or operating standards within the final investigation repot.
Downbursts are terrifying super-localised weather events, and the exact location they may develop within a wider storm system cannot be predicted or seen.
There is a reason for the phrase 'worse things happen at sea'. I hope the investigators can complete their thorough investigation unhampered, and some explanations can ultimately be given to the poor families of the victims and the crew & guests that experienced this horror show.
You may also find the reasonable, balanced analysis at
https://m.youtube.com/playlist?list=PLkp667XjXLBm-kov9BltFvCnCy1SxPc30 of interest.