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Brendon Dobroth is good in, among other things, keels. It is not common that a yacht designer reveals the methods for strength calculation. However, he was involved in this failure investigation. Something similar can be performed for the stuff that risk to come loose. This is a minimum that must be analyzed:

https://assets.system.tamus.edu/files/communications/cynthiawoods/Cynthia-Woods-Report-SIAD-OGC-FINAL.pdf?fbclid=IwAR0YjWGbyVV5NPbbE2sUK7jC0qhK9IJ8sGdZQDDJL89ni2oh5xIiZkwAEcY

 

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On 1/21/2021 at 2:21 PM, SimonN said:

Again, you show your lack of knowledge of this type of sailing. They went into the bear away down speed. They had just tacked and were not going at 40+ knots. They were going low 20's when they begun the bear away, which is very much down speed. The problems with most high performance, over canvassed boats bearing away is the difference between the speed you go into that bear away and the speed you come out - the bigger the difference, the more difficult it is. This is why Goodie wanted they to do a bear away, gybe. They would have come in a little hot (deliberately), so something like 34/5 knots and they would have accelerated to, say, 45 knots a difference of 10 knots which is nice and manageable. Instead, they came in down speed and in a very short period, went from low 20's to 45 knots. You see the stern lift significantly, too much for the flight controller to correct, until the rudder winglets stall and the arse comes down, increasing the angle of attack of the main foils so the boat leaps out. At this time, the apparent wind is still well forward of the beam, probably from about the same direction as upwind (note how when you watch most bear aways in this class their sails don't really ease). Then the boat comes crashing down, almost stops and the apparent wind swings aft, by about 150 degrees - no forward motion means that the apparent and true wind become one and the same. You the have 2 problems. The first is that it is impossible to ease the sails fast enough to stop the inevitable. The second is that even if you can, these boats are not designed to go downwind at that sort of wind angle and the main cannot be eased enough. From the moment they lost the rudder, they were doomed. In 10 knots less wind, they might have got away with it but with that squirt, no chance. That is why Goodie didn't want to do the tack, bear away. The most experienced foiler on the boat knew what might happen, and he was right.

It's actually not a lot different to the cause of the ETNZ capsize. They went into the gybe slower after a touchdown, rig loaded up, apparent swung aft and they were pushed over their bow. The problem was being downspeed and the apparent swinging aft. In the case of ETNZ, they eased their main as far as it could go and that didn't help at all because by then, it was too late and the apparent was too far behind.

I would say that a significant majority of foiler capsizes are due to that sudden shift in apparent wind direction from the boat slowing quickly, and in almost all cases, there is little you can do once the events begin and you are just along for the ride.

I understand downspeed bear aways and have wiped out plenty of times on a foiler doing them, but also have learned how to avoid eating it. I also understand that they were doing 40 knots when the bow was at the mark. They were up to speed. The tape clearly shows elevation was steady until they hit the point of no return when they could bear away no more due to the runner. 

And that call for a bear away gybe..... how is one supposed to bear away gybe when you cant bear away in the first place? They clearly could not get low enough before they ate shit. 

I still contend all of it was caused by the leeward runner. Everything after was a direct result.

Pic below:
- 40 knots at the mark

- Hooked and fluttering main leach

- Jib clearly eased

- Elevation steady



 

bear.PNG

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18 hours ago, Priscilla said:

Complete and utter bullshit post.

Entering the approach to a mark and encountering a squal whilst rounding  and attempting to bear away that’s all it was.

You're lack of experience shows. 

 

The gust had nothing to do with the mark rounding decision made prior the mark.

The decision made by barker over ruled the correct call made by the smarter sailor on the boat.

 

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4 hours ago, Strategery said:

I understand downspeed bear aways and have wiped out plenty of times on a foiler doing them, but also have learned how to avoid eating it. I also understand that they were doing 40 knots when the bow was at the mark. They were up to speed. The tape clearly shows elevation was steady until they hit the point of no return when they could bear away no more due to the runner. 

And that call for a bear away gybe..... how is one supposed to bear away gybe when you cant bear away in the first place? They clearly could not get low enough before they ate shit. 

I still contend all of it was caused by the leeward runner. Everything after was a direct result.

Pic below:
- 40 knots at the mark

- Hooked and fluttering main leach

- Jib clearly eased

- Elevation steady



 

bear.PNG

I call bullshit on you foiling. You keep posting too many things that are wrong.  For example, it doesn’t matter what speed they are going when the bow passes the mark. By then, they have already turned over 90 degrees from their tacked, close hauled position. The important speed is when they exit the tack and start to turn downwind. All you have shown is that exactly as I said, they accelerated very quickly from the end of the tack to that point. We have seen the speed all these boats exit racks so we know they exited going about 23/24 knots. You show that in little more than a boat length they had hit 40 knots. We know the flight controller says he lost control when the rudder stalled, which happened due to excess lift caused by the acceleration. 
 

How can I be sure you don’t foil? Because you have called one of the basics of foiling completely wrong. One of the first things you learn when foiling is that sheet on or fail to ease pushes the bow down while easing brings the bow up. If your comment that it all went wrong because of the runner, that would have pushed the bow down, levelled out the rudder winglets and led to a big nosedive. Instead, exactly the opposite happened, which tells us that by the time they couldn’t ease the sail any more, it was all over.

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58 minutes ago, SimonN said:

Instead, exactly the opposite happened, which tells us that by the time they couldn’t ease the sail any more, it was all over.

Some things in sailing are truisms.

One of them is, if you get the runner caught on a batten after a gybe, bad things happen.

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53 minutes ago, astro said:

Some things in sailing are truisms.

One of them is, if you get the runner caught on a batten after a gybe, bad things happen.

Yes, but they hadn’t gybed so what’s your point?

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Just now, SimonN said:

Yes, but they hadn’t gybed so what’s your point?

The Emperors New Clothes...heard that fable at school?  I think not, but you should look it up.

When a snagged runner lays a lead mine flat, how the fuck is a foiler supposed to stay upright?

 

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On 1/22/2021 at 11:34 PM, SimonN said:

I call bullshit on you foiling. You keep posting too many things that are wrong.  For example, it doesn’t matter what speed they are going when the bow passes the mark. By then, they have already turned over 90 degrees from their tacked, close hauled position. The important speed is when they exit the tack and start to turn downwind. All you have shown is that exactly as I said, they accelerated very quickly from the end of the tack to that point. We have seen the speed all these boats exit racks so we know they exited going about 23/24 knots. You show that in little more than a boat length they had hit 40 knots. We know the flight controller says he lost control when the rudder stalled, which happened due to excess lift caused by the acceleration. 
 

How can I be sure you don’t foil? Because you have called one of the basics of foiling completely wrong. One of the first things you learn when foiling is that sheet on or fail to ease pushes the bow down while easing brings the bow up. If your comment that it all went wrong because of the runner, that would have pushed the bow down, levelled out the rudder winglets and led to a big nosedive. Instead, exactly the opposite happened, which tells us that by the time they couldn’t ease the sail any more, it was all over.

Your description of what happened is inaccurate and your assessment of what I have sailed is incorrect. This was not a down-speed bear away. If it were a down-speed bear away, I would agree that easing the main too much could have made for a tripping hazard, but they were fully up to pre-bear away speed and level before making the turn.

Don't take my word for it, watch the video: They tacked and barely touched 25 knots for a nano second during the tack, then accelerated steadily and predictably back towards 40. After sailing 5-7 boat lengths, Barker says "Turning down in 3,2,1, turning down now" when he says "now" they are doing 40+. Dean is driving from the leeward side and doesnt see the runner issue. The boat turns down and the climb towards 50 happens, but the important main twist needed to keep the boat underneath the mast couldnt happen because the lee runner is fucked. 

Here's another shot of the lee runner continuing to prove my point. 

Believe what you want, I could care less, but don't disparage me from your keyboard, that's a bitch move.

 

leech_fw.png

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On 1/23/2021 at 8:34 AM, SimonN said:

We know the flight controller says he lost control when the rudder stalled, which happened due to excess lift caused by the acceleration.

I have a problem with that: I understood stall is just tied to AoA, irrespective of velocity (other than in the way it varies the profile Reynolds number). I keep maintaining that the stabilator never stalled, on the contrary it violently pushed the transom down when the counterbalancing moment fron sail forward thrust decreased - or possibly when the boat pitch was excessive

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On 1/22/2021 at 1:23 AM, number7of3 said:

I've only seen a perfect shape like that on a boat hull once before. Its not going to be as simple as fixing the whole hole. This is from a fish. A bad fish. It's not like going down to pond chasin' blue gills or tommy cots. They've got a big issue deal with.

D72JUYBWsAAp2fy.jpg

So they just need a bigger boat?

Simples.

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Apologies if this was already posted, but Nathan Outteridge and Ken Read do a breakdown of hte capsize, including some fascinating overhead shots of how AM spins in midair to land on the side. For what it's worth, I was wrong on the tack vs gybe call, but do stand by the lee runner overtrimming the middle of the main before and during the capsize. Not sure they wouldn't have still wiped out in that huge puff, but am convinced that the runner hooking the main (it's luffing above and below the runner) was a huge issue that led to the capsize. Also think the way AM is set to handle the main is limited by their traveler in a way that other teams aren't. 

 

 

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At 5:40 do I hear something about a runner from the on board comms? These guys seem to confirm that the

Tack bear away was a poor decision and that the runner was then the cause of the capsize

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3 hours ago, RMac said:

Apologies if this was already posted, but Nathan Outteridge and Ken Read do a breakdown of hte capsize, including some fascinating overhead shots of how AM spins in midair to land on the side. For what it's worth, I was wrong on the tack vs gybe call, but do stand by the lee runner overtrimming the middle of the main before and during the capsize. Not sure they wouldn't have still wiped out in that huge puff, but am convinced that the runner hooking the main (it's luffing above and below the runner) was a huge issue that led to the capsize. Also think the way AM is set to handle the main is limited by their traveler in a way that other teams aren't. 

 

 

Exactly! 

And I too was wrong on the tack/bear away vs bear away/gybe. I wonder if that double take from Deano was because he was so locked on the port gate that he thought it was a call to do a tack / bear away / gybe around the port gate?

How bout that power slide shot from above! Done that plenty of times on much less expensive toys, but damn....thats a 72' boat doing that.  Insane!

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39 minutes ago, Lynch said:

At 5:40 do I hear something about a runner from the on board comms? These guys seem to confirm that the

Tack bear away was a poor decision and that the runner was then the cause of the capsize

I think he said "Oh I lost the rudder here". 

Yeah, decades of sailing boats that dont go 45 knots probably clouded the judgement there as they were  physically closer to the port gate. The bear away to the stbd gate would have been awash....probably even faster than tacking plus theyd be one ladder rung lower on that left shift after they gybed. 

If ifs and buts were candy and nuts... 

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I got to ask a friend who sails foilers at a very high level, he confirmed that he would have gone for the gybe instead of the tack. Reasoning was that getting up to speed after the tack would mean extra distance going sideways to the finish, that the gybe would be easier and you'd stay in the puff longer, and never have the apparent wind aft.  

If you look at the shots of the main, you can see the area where the runner hits it is essentially trimmed in, with luffing and flutter about and below.  I don't know how you can see that and insist it didn't play a big part in the tip.

Asked a friend on the AM team about it, he responded by very deliberately sending me pics of the kids, the sunset, pretty much everything BUT any inside info, sorry!

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4 hours ago, RMac said:

I got to ask a friend who sails foilers at a very high level, he confirmed that he would have gone for the gybe instead of the tack. Reasoning was that getting up to speed after the tack would mean extra distance going sideways to the finish, that the gybe would be easier and you'd stay in the puff longer, and never have the apparent wind aft.  

If you look at the shots of the main, you can see the area where the runner hits it is essentially trimmed in, with luffing and flutter about and below.  I don't know how you can see that and insist it didn't play a big part in the tip.

Asked a friend on the AM team about it, he responded by very deliberately sending me pics of the kids, the sunset, pretty much everything BUT any inside info, sorry!

+1 for your friend! Nice to know integrity still exists in some Americans.

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