potentillaCO32
Well-Known Member
The report says it was in over 50M of water
Bayesian Interim Report
- Thread starter DreadShips
- Start date
DreadShips
Well-Known Member
Yeah, but the mast was 72m high!
potentillaCO32
Well-Known Member
A mast hitting the ground isn't going to stop a boat rolling over. Having.lost a mast they are designed to be strong in certain directions only
Chiara’s slave
Well-Known Member
If we couldn’t invert, ie 14 metres of water or less, then the boat would just invert as afar as possible, and still float. We don’t really have a downflooding angle. Heeled to 90 degrees, the hatches are at least 3m off the water. Who’d have thought our numbers were better than a superyacht? Thing is, we are well aware of the stability curve of our boat. Seems that is the problem here, nobody thought of it, it didn’t seem relevant to such a craft.
westernman
Well-Known Member
The mast on my entreprise dinghy did stop it rolling over. And it came up some what bent.
I would be surprised if the mast on Bayesian was not supported well enough to not break if the boat were to try to invert.
I got my enterprise mast straight enough by spreading it across some trestles and jumping on it few times.
It was not perfectly straight, but you would have to look closely to see the slight S bend.
DreadShips
Well-Known Member
If the mast is hitting the bottom in 50m of water I'm going out on a limb to suggest that whether it snaps or not is the least of your concerns!
Literally nothing about this vessel seems to match intuition though.
billskip
Well-Known Member
Well it's all irrelevant...the boat sank, as did the unsinkable Titanic.....
The monitoring of the AVS probably wasn't being thought about and nowt could be done I suspect at that moment in time.
This to me puts threads like...downsize your anchor/downsize your chain...do this do that,....lot of bad advice imho....all from the comfort of the armchair.
Bottom line for me is always prepare for the worst and then some...
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billskip
Well-Known Member
Doubt many think of it on any boat...I've experienced the spreaders dipping the water a couple of times and I was not casually calculating the AVS at the time, my mind was on other things...tipped a hobie cat upside down once, that was a struggle getting it back.
westernman
Well-Known Member
Only once?
I have done that quite a few times.
May be I was more daring - or just a slow learner.
But boy, did that thing (Hobie FX One) move on a broad reach in a decent bit of wind with the asymmetric up.
There is a knack to getting it up. You have to have it facing the right way with respect to the wind.
The wind from the wrong side, you will never get it up. The wind on the opposite side, it will come up and flip right back over again. The hard bit is actually getting back on it again.
KevinV
Well-Known Member
Is there any chance we could keep a topic about a fatal tragedy on-topic? Please?
ylop
Well-Known Member
You are well aware of the curve or you are well aware of what the manufacturer said the curve is?
Do you know what heel you get under bare poles if you end up beam to the wind? And thus what your critical wind speed is to prevent being flipped at anchor?
It’s easy with 20:20 hindsight to say the designer/builder, regulator, captain should have questioned the impact of the keel on stability curve, but even if you had I’m not sure that when retiring to bed with 8kts asking to be woken at 20kts that the captain would have anticipated that gusts (beyond the forecast) were likely to reach that level of heel whilst anchored, and certainly not to go from F1-F8+ in less time than you can lower the keel.
billskip
Well-Known Member
For me, the keel should (would most certainly if I were skipper ) be down at all times with obviously allowing for port or shallow water manoeuvre.
Chiara’s slave
Well-Known Member
Well, we don’t heel, being a multi. But yes, there are numbers for beam winds, folded, and unfolded. But why wasn’t ‘keel down’ the default configuration? We only ever reduce our stability by folding when we must. Then the first thing we do when the need has passed is unfold. For stability reasons.
ylop
Well-Known Member
Interestingly the MAIB refer to a “motoring condition” with the keel up - so presumably that is considered fairly normal on such boats? I expect the reduced drag has a significant difference of fuel cost on something that bunkers by the ton rather than the litre. I guess none of us have much experience of actually sailing a superyacht but that it spends most of its life motoring except when conditions make for fun comfortable sailing? The keel in the “ready to sail” position would therefore be part of getting ready to said rather than just going to sea unless the captain understood the stability information that the designed and builder had never provided and the regulator hadn’t asked for.
Without wanting to start a spat your argument that you are “well aware” of your numbers would have been more convincing if you had actually stated the windspeed where beam on you were at risk of flipping (without looking it up). Knowing the data is there and being well aware of it, are slightly different. The data is also in the “as supplied” form - stick a liferaft on deck, a sprayhood up, or a big radar reflector 2/3rds of the way up the mast and things will be different. Our foam luff Genoa doesn’t pack as neatly as the original so we will have more windage high up than the Builder ever imagined.
And yet if a newbie asked here for pros and cons of lift keel I think many would say access to shallower anchorages was an advantage of lifting keels. Perhaps I’ve missed it, I don’t read every thread, but I don’t recall anyone saying: you might end up beam on at anchor and being knocked down. That feels like being smart after the event - I assume many sailing super yachts are reviewing their SOP right now. I wonder how many already had a rule that the keel should be down at anchor in forecast F4-5 conditions, never mind the F1 it was when they anchored.
dunedin
Well-Known Member
In the previous thread at the time that got pulled, it was identified that most superyachts tended to overnight with the keel up, and only put fully down when sailing.
But it does now seem from the MAIB that the skippers may not be fully aware of the stability limits which is the surprise.
Boathook
Well-Known Member
I haven't read many MAIB reports but the ones I have, have been interesting in that they deal with facts.
I suspect that owners and skippers of super yachts will be looking at keel down, stability curves plus instructions on what wind speed to call skipper, engineer, etc.
benjenbav
Well-Known Member
Is the issue around a ketch rig much more that, had Bayesian been built with such, the masts would have been considerably lower than the very high single mast of Bayesian’s sloop rig and the leverage exerted in the exceptional wind conditions would have been less?
flaming
Well-Known Member
Yes, quite possibly.
It’s just the suggestion that a riding sail is a good tactic for winds of 70 knots that I find quite so odd…
billskip
Well-Known Member
Doubt it for much longer....
How many do?
Are you aware of the traction limitations of your tyres at every stage of ware
Yes it's human nature, I read some of your posts are inspired by others.
It's how lessons are learnt, isn't it?
If I was skipper I would probably get knocked for being over cautious.
It's my belief if I protect my life it gives security to those around me.
billskip
Well-Known Member
Possibly being the magic word, there are some designs that retain main mast hight with or without a mizzen.