America's Cup 2021 Defense

Forums › Sports › America's Cup 2021 Defense

1 | ... | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | ... | 26

Networkn
32884 posts

Uber Geek
+1 received by user: 15483

ID Verified

Trusted

Lifetime subscriber

#2675770 16-Mar-2021 20:48

I was talking to a food vendor operating in the waterfront, she cannot be more delighted the racing was cancelled. They were pretty much at break even point for their investment to be down there, tomorrow is where they make their actual money. She said most of the food vendors down there were in the same boat.

Whilst once they have open air ETNZ seem so quick, it all seems to be pretty much relying on errors by LR to get to that point. Without the error today, would they have had the gas to beat them? I guess it doesn't really matter, but despite our winning advantage, it seems less about us than it does about what LR does.

itxtme

2102 posts

Uber Geek
+1 received by user: 557

#2675800 16-Mar-2021 21:14

networkn:

Whilst once they have open air ETNZ seem so quick, it all seems to be pretty much relying on errors by LR to get to that point. Without the error today, would they have had the gas to beat them? I guess it doesn't really matter, but despite our winning advantage, it seems less about us than it does about what LR does.

I dont think thats true at all. LR could have just as easily decided to keeping going out to the right and we would not have followed them. The difference in the boat between the start of the regatta and now is the modes and the ability to roll tack with our extreme cant angles. We were being destroyed on manoeuvres and now that is a strength. TR has smaller foils, and so winning starts in low breeze is always going to be difficult. The move by LR at the bottom mark to take us past the mark was sensational match racing. They are a good competitor, their boat just isnt fast enough.

I also call BS on Peter Leister suggesting the wind shift at the end was pure local knowledge. By there very nature they shift back and forth, thats what gets you a gain as opposed to the other guys. Not following them is what led to the passing opportunity. What did seem crazy about that tack LR made back to the left side was the giving up of the starboard right of way position, crazy when they are that close to each other.

networkn

Networkn
32884 posts

Uber Geek
+1 received by user: 15483

ID Verified

Trusted

Lifetime subscriber

#2675804 16-Mar-2021 21:29

itxtme:

networkn:

Whilst once they have open air ETNZ seem so quick, it all seems to be pretty much relying on errors by LR to get to that point. Without the error today, would they have had the gas to beat them? I guess it doesn't really matter, but despite our winning advantage, it seems less about us than it does about what LR does.

I dont think thats true at all. LR could have just as easily decided to keeping going out to the right and we would not have followed them. The difference in the boat between the start of the regatta and now is the modes and the ability to roll tack with our extreme cant angles. We were being destroyed on manoeuvres and now that is a strength. TR has smaller foils, and so winning starts in low breeze is always going to be difficult. The move by LR at the bottom mark to take us past the mark was sensational match racing. They are a good competitor, their boat just isnt fast enough.

I also call BS on Peter Leister suggesting the wind shift at the end was pure local knowledge. By there very nature they shift back and forth, thats what gets you a gain as opposed to the other guys. Not following them is what led to the passing opportunity. What did seem crazy about that tack LR made back to the left side was the giving up of the starboard right of way position, crazy when they are that close to each other.

Well, you've sort of said it's quite true.. If LR had stayed on the side of the course we passed them on, we would have tacked away (is that the right term?), they would have got the boost in speed, we would not have, and the gap between us and them would have opened up and they would have won, surely?

I do think we have the faster boat, but I don't see us having won today without the decision by LR which you mentioned above, and the commentators on YT were surprised about as well.

I am certainly no expert, you sound like you know more than me, but as a casual observer, I see us mostly winning off LR errors. It's a valid strategy, because you have to be good enough to take your chances I guess.

ezbee

2662 posts

Uber Geek
+1 received by user: 3110

#2675839 16-Mar-2021 21:52

LR get a chance to reset overnight and make their boat wider.
Reminds me of someone once I passed out west with a 1.5m stick poking out the side of his bike.
Protection their rightful space ?

Our superpower is we can remain close enough despite getting gassed to be able to pick up on any mistake.

I wonder if foils need patching, the mention of cavitation made me wonder...
If they suffer the erosion you see with propellers given velocity of water over them.
The stress on the whole system going onto those tiny foils.

Oblivian

7347 posts

Uber Geek
+1 received by user: 2117

ID Verified

#2675845 16-Mar-2021 22:06

Wider? Fix foils?..

They can't really touch them. And if they do they have to get permission to use their pre-approved ones and appeal to get re-measured and certified, with the opponent given the same option each time to make sure. The only thing they can change, is the sails. And that is up until only about 15min call.

Monday 1 March at 16:03 local time was the deadline for both teams to define and finalise the configuration of their boats for the Match. With that deadline now passed, both teams will have laid out precisely the boat that they will use for the series with specific details on all the key areas such as the hull, rig, foils and many other areas of the boat including its precise weight.

Within these key areas there are various subsections that define each element in more detail. And while the AC75 and the rules that define it are complex, the bottom line is that there is barely any wriggle room once a team has staked its claim to the type of boat that they intend to race.

https://www.americascup.com/en/news/1141_DECLARATION-TIME

There was a heck of a shakeup to stop tweaks between races like we have seen previously (and still not written out as what went down..)

eracode

Smpl Mnmlst
9345 posts

Uber Geek
+1 received by user: 6228

ID Verified

Trusted

Lifetime subscriber

#2675847 16-Mar-2021 22:07

ezbee:

I wonder if foils need patching, the mention of cavitation made me wonder...
If they suffer the erosion you see with propellers given velocity of water over them.
The stress on the whole system going onto those tiny foils.

I don’t think the commentators are necessarily using the term ‘cavitation’ in its true technical sense. I think they loosely mean the foils have lost lift because they’re close to the surface and are getting aerated (or less-dense) water around them. If I’m correct this doesn’t mean that the foils are being damaged in the true sense of cavitation. However IANA Fluid Dynamics Engineer.

Sometimes I just sit and think. Other times I just sit.

AliExpress

Shop now on AliExpress (affiliate link).

Handle9

11937 posts

Uber Geek
+1 received by user: 9699

Trusted

Lifetime subscriber

#2675849 16-Mar-2021 22:09

eracode:

ezbee:

I wonder if foils need patching, the mention of cavitation made me wonder...
If they suffer the erosion you see with propellers given velocity of water over them.
The stress on the whole system going onto those tiny foils.

I don’t think the commentators are necessarily using the term ‘cavitation’ in its true technical sense. I think they loosely mean the foils have lost lift because they’re close to the surface and are getting aerated (or less-dense)water around them. If I’m correct this doesn’t mean that the foils are being damaged in the true sense of cavitation. However IANA Fluids Dynamics Engineer.

It was Spithill that mentioned cavitation.

networkn

Networkn
32884 posts

Uber Geek
+1 received by user: 15483

ID Verified

Trusted

Lifetime subscriber

#2675850 16-Mar-2021 22:09

I must say it wasn't until someone here mentioned it, just how one sided the commentary on YT is. It certainly favours LR, almost to the exclusion of everything else. They sound almost disappointed when ETNZ wins, or bored, or something. It's not the end of the world of course, everyone has their preferences, but it was noticeable.

Oblivian

7347 posts

Uber Geek
+1 received by user: 2117

ID Verified

#2675851 16-Mar-2021 22:10

eracode:

I don’t think the commentators are necessarily using the term ‘cavitation’ in its true technical sense. I think they loosely mean the foils have lost lift because they’re close to the surface and are getting aerated (or less-dense)water around them. If I’m correct this doesn’t mean that the foils are being damaged in the true sense of cavitation. However IANA Fluids Dynamics Engineer.

That was the case yesterday, the air pocket that is created can sit underneath them and possibly support the change over, Until it doesn't and releases out in rush... :P

Handle9

11937 posts

Uber Geek
+1 received by user: 9699

Trusted

Lifetime subscriber

#2675852 16-Mar-2021 22:12

networkn:

I must say it wasn't until someone here mentioned it, just how one sided the commentary on YT is. It certainly favours LR, almost to the exclusion of everything else. They sound almost disappointed when ETNZ wins, or bored, or something. It's not the end of the world of course, everyone has their preferences, but it was noticeable.

I don't find it that way. Most home commentaries are terribly parochial as that's what the yokels want to hear.

The YouTube team seem to want close races and they get that with Prada in front.

eracode

Smpl Mnmlst
9345 posts

Uber Geek
+1 received by user: 6228

ID Verified

Trusted

Lifetime subscriber

#2675865 16-Mar-2021 22:37

Handle9:

It was Spithill that mentioned cavitation.

Then the commentators must have picked up on it. It doesn’t matter who mentioned it, my point is whether the term is being used loosely or in its true sense that results in physical damage to the component being subjected to it - as @ezbee implied.

Sometimes I just sit and think. Other times I just sit.

Mighty Ape

Shop now at Mighty Ape (affiliate link).

tdgeek

30048 posts

Uber Geek
+1 received by user: 9455

Trusted

Lifetime subscriber

#2675879 16-Mar-2021 23:21

ezbee:

LR get a chance to reset overnight and make their boat wider.
Reminds me of someone once I passed out west with a 1.5m stick poking out the side of his bike.
Protection their rightful space ?

Our superpower is we can remain close enough despite getting gassed to be able to pick up on any mistake.

I wonder if foils need patching, the mention of cavitation made me wonder...
If they suffer the erosion you see with propellers given velocity of water over them.
The stress on the whole system going onto those tiny foils.

I just watched a video when searching for cavitation, also includes ventilation. I do know about wings, I assumed cavitation was stalling the foil, thats ventilation

https://www.youtube.com/watch?v=x_CzbAvQaZE

Very interesting. Layman's guide, ventilation is when the foil gets too high so the low pressure water flow on the top of the foil which is generating the lift, is disturbed by the lack of water and surface bubbles over the top of the foil as it gets shallow in the water. Same has stalling an aircraft wing

Cavitation is when the water across the top of the foil, boils. yes it boils, but not the same temp as a jug. Sea level air temp, water boils at 100 C. Sea has different pressure and the top of the foil at speed has very low pressure (water boils in a vacuum at room temperature.) So this boiling water, which is not actually super hot temperature (I assume), is boiling and all the bubbles disturb the low pressure across the too of the foil and it loses lift. These bubbles are exploding so yes they can cause damage. This is an issue at about 50 knots.

Very interesting stuff

tdgeek

30048 posts

Uber Geek
+1 received by user: 9455

Trusted

Lifetime subscriber

#2675881 16-Mar-2021 23:23

eracode:

I don’t think the commentators are necessarily using the term ‘cavitation’ in its true technical sense. I think they loosely mean the foils have lost lift because they’re close to the surface and are getting aerated (or less-dense) water around them. If I’m correct this doesn’t mean that the foils are being damaged in the true sense of cavitation. However IANA Fluid Dynamics Engineer.

I thought that, what you described is ventilation, that happens at/near surface. Cavitation that I explained just now is different and it happens at normal depth.

tdgeek

30048 posts

Uber Geek
+1 received by user: 9455

Trusted

Lifetime subscriber

#2675883 16-Mar-2021 23:39

Wondering why LR allowed a split twice and got burned twice. I can't see that they would move away from covering off TNZ as we have proven we have the speed to hang with them if they block us and we will run away if we get clear. It can only be they saw a wind shift and were wrong. Commentators on YT stated that its harder to see the shifts at boat level (obviously) but the Sun was low so harder again. In the chopper its very easy, so we hear there is a shift on starboard, which probably implies to most of us, that they missed it, but it seems its difficult to see at low Sun. Maybe easier with no cloud, or cloud, I don't know, but this theory seems logical.

eracode

Smpl Mnmlst
9345 posts

Uber Geek
+1 received by user: 6228

ID Verified

Trusted

Lifetime subscriber

#2675891 17-Mar-2021 05:24

tdgeek:

eracode:

I don’t think the commentators are necessarily using the term ‘cavitation’ in its true technical sense. I think they loosely mean the foils have lost lift because they’re close to the surface and are getting aerated (or less-dense) water around them. If I’m correct this doesn’t mean that the foils are being damaged in the true sense of cavitation. However IANA Fluid Dynamics Engineer.

I thought that, what you described is ventilation, that happens at/near surface. Cavitation that I explained just now is different and it happens at normal depth.

Yes, that’s my point. What happens when a foil loses lift near the surface, or when only partially submerged, is not cavitation - even though Spithill and others have used that term.

Sometimes I just sit and think. Other times I just sit.

1 | ... | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | ... | 26