Why was OTUSA faster ?

[Tornado-Cat]

These polars show that OTUSA began to be faster after race 8

http://www.cupinfo.com/cupstats/index-ac34-statistics-polar-plots-02.php#VMG-races-17-18

 

[Grind4Beer]

For some insight into the determination of the final race, check out the NYT's sweet visualization-http://www.nytimes.com/interactive/2013/09/25/sports/americas-cup-course.html?ref=sports

The graphic really shows the turning point...At tack 3 of the upwind leg (around the 8:00 mark), Oracle tacked onto port on the city side, and moments later, ETNZ tacked onto starboard on the Alcatraz side. Their crossing after that tack was still super tight. 3 tacks from the leeward mark, Oracle had only made a couple of boatlengths...but for the next 2 tacks (4 and 5), Oracle's point was better, and they walked away.

Yanno, squinting at that NYT graphic, US shows higher point than NZ on most of both tacks.

Same speed, better point, that pretty much wins the whole ball game ...

G4B

better point - or less leeway?
Maybe a better expression would be the US had better 'track' than NZ almost the entire race?

After playing with the graphic a bit more, the US track appears higher upwind with two exceptions; the close P/S duck at the beginning of the beat, and a long stbd near the top gate. On the runs, the US track looks deeper ...

Interesting, that ...

G4B

 

[George Hackett]

i noticed that the jib on oracle was a little smaller than etnz? would that have anything to do? the reason i ask is that i remember a LV race in which etnz cut away their jib and actually sailed faster. i am guessing that without the jib, the airflow was attached and more effective for the whole length of the luff of the foil?

 

[JMOD]

for the people interested in the tracks of the last race, higher upwind and deeper downwind for oracle and especially less speedseeking coming out of the tacks and gybes

 

[BalticBandit]

For some insight into the determination of the final race, check out the NYT's sweet visualization-http://www.nytimes.com/interactive/2013/09/25/sports/americas-cup-course.html?ref=sports

The graphic really shows the turning point...At tack 3 of the upwind leg (around the 8:00 mark), Oracle tacked onto port on the city side, and moments later, ETNZ tacked onto starboard on the Alcatraz side. Their crossing after that tack was still super tight. 3 tacks from the leeward mark, Oracle had only made a couple of boatlengths...but for the next 2 tacks (4 and 5), Oracle's point was better, and they walked away.

Very cool. So notice the increadibly costly TACTiCAL move that ETNZ makes after going around the SE mark. Instead of heading for the Curent relief cone under Alcatraz they instead sail across the adverse current. And notice how at this point they start out higher but then fall off lower than OTUSA (5 mins to 7 mins). And once OTUSA has dragged ETNZ across the bad current, they tack and then for the next few minutes the boats sail relatively similar angles

The diff starts to happen around the 11 min mark when its clear that ETNZ is out of phase with the wind pattern on the course essentially tacking into headers while OTUSA is tacking into lifts The big one you see at 13 mins to 15 mins is were ETNZ foots off to cross bad current and then dials it up when Ainslee calls for it Whereas ETNZ at this point is demoralized and just sails into the header on the beach.

This was TACTICS not straightline speed

Utter BS, look at the graph and you will see that OR was increasing the gap at each tack after Alcatraz.

And that is inconsistent with what I wrote how? when you are "out of phase with the wind pattern on the course essentially tacking into headers" - tell me what happens to you vs. the boat that is on the opposite phase and crossing tacks witth you???? on each tack?

 

[BalticBandit]

for the people interested in the tracks of the last race, higher upwind and deeper downwind for oracle and especially less speedseeking coming out of the tacks and gybes

hmm I see downwind the tracks are essentially overlaid. Yes there is a slight boathandling advantage, but you don't get 703 meters out of that. But do notice how on the upwiind leg, OTUSA is in phase with wind shifts (after each tack OTUSA winds up about 1/4 of the way into the tack and ETNZ on the opposite tack gets headed about 1/4 of the way into the tack) And OTUSA's course spends less time in adverse current - in particular on the first tack and just before and after the last tack

Ashby made THE WRONG CALL after the downwind mark. Instead of sailing into the "Alcatraz Cone" he opted to "tack to cover" - a classic match racing move but one that made ETNZ sail twice the distance of OTUSA across the worst of the flood at the bottom of the course.

Now that was an 11 minute leg. .... now if net overall OTUSA managed to sail in water that was 2 knots less current during that time then they would have gained 0.33 nautical miles on the upwind leg. And how much shorter a distance did they sail upwind? According to ACStats roughly 0.34.. if the difference is 1 knot (more reasonable given the respective courses) then 50% of the upwind gain is due to sailing in slightly better current

Now is all of that current? of course not. Some of that iis being in phase with the wind - remember that the wind on the course in that area is more geographically driven than oscillating (though there is some oscilatory component as well) - so it matters a whole lot as to WHERE on the course you make your tacks. And if you look at where OTUSA makes tacks and her course afterwards vs ETNZ, OTUSA comes out of each tack roughly the same height as ETNZ does for the same relative board.

Both then sail about 1/4 of that tack on similar CMG. but then about 1/4 of the way into each tack, OTUSA winds up, and ETNZ falls off. That's a wind shift, (well it could be a mode change and in some cases it is but that too is tactics).

and THAT is probably good enough for 300 meters of gain

So why would Jobson and Reed not call this out?

1. Its hard enough to explain to thick-headed sailors who (supposedly) understand "tack on median" and "wind phase" and "current header" - try explaining it to folks who are, as one announcer admitted "stick and ball" persons.
2. It was not obvious at the time in part because of how the video was shot, in part because of how exciting the crosses were
3. Speed Dominance vs, just sailing a smarter course - is more emotionally satisfying explanation of the 7 straight winning streak.

 

[BalticBandit]

Reed is not an idiot. Jobson knows his audience - it is not you. Jobson's job has been to seem to be the sailing guru for NASCAR watchers. The gotcha in this series was that he had Nathan and Kenny to contend with. But both were struggling to explain the sport to the average person.

 

[Tornado-Cat]

For some insight into the determination of the final race, check out the NYT's sweet visualization-http://www.nytimes.com/interactive/2013/09/25/sports/americas-cup-course.html?ref=sports

The graphic really shows the turning point...At tack 3 of the upwind leg (around the 8:00 mark), Oracle tacked onto port on the city side, and moments later, ETNZ tacked onto starboard on the Alcatraz side. Their crossing after that tack was still super tight. 3 tacks from the leeward mark, Oracle had only made a couple of boatlengths...but for the next 2 tacks (4 and 5), Oracle's point was better, and they walked away.

Very cool. So notice the increadibly costly TACTiCAL move that ETNZ makes after going around the SE mark. Instead of heading for the Curent relief cone under Alcatraz they instead sail across the adverse current. And notice how at this point they start out higher but then fall off lower than OTUSA (5 mins to 7 mins). And once OTUSA has dragged ETNZ across the bad current, they tack and then for the next few minutes the boats sail relatively similar angles

The diff starts to happen around the 11 min mark when its clear that ETNZ is out of phase with the wind pattern on the course essentially tacking into headers while OTUSA is tacking into lifts The big one you see at 13 mins to 15 mins is were ETNZ foots off to cross bad current and then dials it up when Ainslee calls for it Whereas ETNZ at this point is demoralized and just sails into the header on the beach.

This was TACTICS not straightline speed

Utter BS, look at the graph and you will see that OR was increasing the gap at each tack after Alcatraz.

And that is inconsistent with what I wrote how? when you are "out of phase with the wind pattern on the course essentially tacking into headers" - tell me what happens to you vs. the boat that is on the opposite phase and crossing tacks witth you???? on each tack?

Look at 2 graphs:

- the polar shows OR sails higher and often with more speed (after race 8)

- the US newspaper also shows OR is sailing higher and increasing his advance.

 

[Tornado-Cat]

My take, based on my observation on the place, then on TV and Russell's comments

- I could watch and take pictures of OR until sept 12, when I left, I was puzzled to see how much water they were pushing upwind. I commented here and posted the pictures I took, IMO there was no way they could win that way.

- they began to win after and it is corroborated by the polar of race 8 on sept 14

When I looked at next races then, I was amazed to see how they were lifting sooner and higher than TNZ on their foils. It was the beginning of the end for the kiwis.

How can they foil earlier with the same boat ? well, there are not too many possibilities:

- unloading the main foil with more wing racking and loading the rudders, and modify its AoA

- modifying the trimming of the wing

- changing the AoA of the main foil

- reducing the aero drag ir order to have a lighter boat

That is pretty much what Russell said. Basically they succeed to exploit the lower aero drag of the boat, which they had not been able to do before.

As for the SAS, I don't have a clue if they used it and if it worked.

 

[floater]

My take, based on my observation on the place, then on TV and Russell's comments

- I could watch and take pictures of OR until sept 12, when I left, I was puzzled to see how much water they were pushing upwind. I commented here and posted the pictures I took, IMO there was no way they could win that way.

- they began to win after and it is corroborated by the polar of race 8 on sept 14

When I looked at next races then, I was amazed to see how they were lifting sooner and higher than TNZ on their foils. It was the beginning of the end for the kiwis.

How can they foil earlier with the same boat ? well, there are not too many possibilities:

- unloading the main foil with more wing racking and loading the rudders, and modify its AoA

- modifying the trimming of the wing

- changing the AoA of the main foil

- reducing the aero drag ir order to have a lighter boat

That is pretty much what Russell said. Basically they succeed to exploit the lower aero drag of the boat, which they had not been able to do before.

As for the SAS, I don't have a clue if they used it and if it worked.

JS said one of the "gutsier" changes they made was to (remove - lighten?) the forward spine.

 

[BalticBandit]

For some insight into the determination of the final race, check out the NYT's sweet visualization-http://www.nytimes.com/interactive/2013/09/25/sports/americas-cup-course.html?ref=sports

The graphic really shows the turning point...At tack 3 of the upwind leg (around the 8:00 mark), Oracle tacked onto port on the city side, and moments later, ETNZ tacked onto starboard on the Alcatraz side. Their crossing after that tack was still super tight. 3 tacks from the leeward mark, Oracle had only made a couple of boatlengths...but for the next 2 tacks (4 and 5), Oracle's point was better, and they walked away.

Very cool. So notice the increadibly costly TACTiCAL move that ETNZ makes after going around the SE mark. Instead of heading for the Curent relief cone under Alcatraz they instead sail across the adverse current. And notice how at this point they start out higher but then fall off lower than OTUSA (5 mins to 7 mins). And once OTUSA has dragged ETNZ across the bad current, they tack and then for the next few minutes the boats sail relatively similar angles

The diff starts to happen around the 11 min mark when its clear that ETNZ is out of phase with the wind pattern on the course essentially tacking into headers while OTUSA is tacking into lifts The big one you see at 13 mins to 15 mins is were ETNZ foots off to cross bad current and then dials it up when Ainslee calls for it Whereas ETNZ at this point is demoralized and just sails into the header on the beach.

This was TACTICS not straightline speed

Utter BS, look at the graph and you will see that OR was increasing the gap at each tack after Alcatraz.

And that is inconsistent with what I wrote how? when you are "out of phase with the wind pattern on the course essentially tacking into headers" - tell me what happens to you vs. the boat that is on the opposite phase and crossing tacks witth you???? on each tack?

Look at 2 graphs:

- the polar shows OR sails higher and often with more speed (after race 8)

- the US newspaper also shows OR is sailing higher and increasing his advance.

Well its really hard to actually say what the polars tell us. Because remember those are GPS based polars, not Course Steered polars. IOW It could well be that the 30 degree upwind polar for ETNZ is the same Course Steered as the OTUSA 35 degree polar because of the leeway OTUSA makes when steering 30 degrees. We are missing an important data point for accurately interpreting the upwind data. And given that on almost every other part of the polar the speeds are almost identical, I'm skeptical of reading too much into that incomplete data. A foil that generates too much drag upwind is also going to generate too much drag off the wind. A foil that generates similar top speed off the wind is going to have the potential for similar top speed upwind. What then matters is mode and technique, not raw technological advantage

You can see this if you go to Multihull Anarchy and look at the C class Little AC thread and the uStream video of Hydros vs. GroupAma. There you have radically different foils and radically different perf. Upwind Groupama is higher but slightly slower but with much better VMG. Offwind Groupama is Also higher, but also slower than Hydros. And Hydros just flies downwind, but is much less stable.

But you don't see that kind of diff between ETNZ or OTUSA at any point in time.

 

[floater]

for the people interested in the tracks of the last race, higher upwind and deeper downwind for oracle and especially less speedseeking coming out of the tacks and gybes

(well it could be a mode change and in some cases it is but that too is tactics).

well, when OR rode right over the top of ET - they were pretty much on the same heading. OR up on foils. ET in the drink - slow by comparison.
What's the difference? Does it take OR a while down low - up on foils - build apparent - bring it up higher - smoke ET?

 

[Daimond]

JS said one of the "gutsier" changes they made was to (remove - lighten?) the forward spine.

Seems a bit odd to me. All four teams played with the shorter sprit with LR being the first. I was told the loss in forestay tension didn't justify the weight saved/pitching moment of the shorter sprit.

 

[Tornado-Cat]

Very cool. So notice the increadibly costly TACTiCAL move that ETNZ makes after going around the SE mark. Instead of heading for the Curent relief cone under Alcatraz they instead sail across the adverse current. And notice how at this point they start out higher but then fall off lower than OTUSA (5 mins to 7 mins). And once OTUSA has dragged ETNZ across the bad current, they tack and then for the next few minutes the boats sail relatively similar angles

The diff starts to happen around the 11 min mark when its clear that ETNZ is out of phase with the wind pattern on the course essentially tacking into headers while OTUSA is tacking into lifts The big one you see at 13 mins to 15 mins is were ETNZ foots off to cross bad current and then dials it up when Ainslee calls for it Whereas ETNZ at this point is demoralized and just sails into the header on the beach.

This was TACTICS not straightline speed

Utter BS, look at the graph and you will see that OR was increasing the gap at each tack after Alcatraz.

And that is inconsistent with what I wrote how? when you are "out of phase with the wind pattern on the course essentially tacking into headers" - tell me what happens to you vs. the boat that is on the opposite phase and crossing tacks witth you???? on each tack?

Look at 2 graphs:

- the polar shows OR sails higher and often with more speed (after race 8)

- the US newspaper also shows OR is sailing higher and increasing his advance.

Well its really hard to actually say what the polars tell us. Because remember those are GPS based polars, not Course Steered polars. IOW It could well be that the 30 degree upwind polar for ETNZ is the same Course Steered as the OTUSA 35 degree polar because of the leeway OTUSA makes when steering 30 degrees. We are missing an important data point for accurately interpreting the upwind data. And given that on almost every other part of the polar the speeds are almost identical, I'm skeptical of reading too much into that incomplete data. A foil that generates too much drag upwind is also going to generate too much drag off the wind. A foil that generates similar top speed off the wind is going to have the potential for similar top speed upwind. What then matters is mode and technique, not raw technological advantage

You can see this if you go to Multihull Anarchy and look at the C class Little AC thread and the uStream video of Hydros vs. GroupAma. There you have radically different foils and radically different perf. Upwind Groupama is higher but slightly slower but with much better VMG. Offwind Groupama is Also higher, but also slower than Hydros. And Hydros just flies downwind, but is much less stable.

But you don't see that kind of diff between ETNZ or OTUSA at any point in time.

Polars are measured to the ground with both vmg and speed, in the same conditions, same race, boats sometimes at a few meters from each other. They are consistent in all races after R8.

The comparison with Gpma and Hydros is irrelevant. Hydros have more vertical lift, Gpma more dihedral angle, which explains why they are safer and slower downwind. Hydros tried ot go out today and...broke.

 

[BalticBandit]

GPS based polars are. But if you sail the same GPS polars when sailing against a 2 knot current as when sailing with it (on the same point of sail), you will be sailing both legs wrong. There are two kinds of polars: The ones the model tells you to drive to, and the ones that are measured based on CMG WRT ground

When going for boat on boat performance the former are the ones that matter. But when tracking with GPS the latter are what you get. And given that the polars from From both Race 18 and 19 are NOT from boats that are next to each other, you cannot make that claim.

BTW which Hydros broke (I missed today's racing)?

and no they are not irrelevant as the differences between them are what you are claiming also exists WRT ETNZ and OTUSA. But we don't see that sort of radical difference in performance on the AC 72s.

 

[zvikingz]

They had their engine running to charge the batteries and "accidentally" put it in gear.

This fits in with what most of those have posted on here. hahaha

 

[lazybone]

Grant Dolton's big ego.

"I'm too fucking old and feeble to do two races in one day but I'm in charge so the team will have to deal with the musical chairs"

 

[Tornado-Cat]

And given that the polars from From both Race 18 and 19 are NOT from boats that are next to each other, you cannot make that claim.

If you want to troll, at least do it intelligently.

http://www.nytimes.com/interactive/2013/09/25/sports/americas-cup-course.html?ref=sports

 

[SimonN]

My take, based on my observation on the place, then on TV and Russell's comments

- I could watch and take pictures of OR until sept 12, when I left, I was puzzled to see how much water they were pushing upwind. I commented here and posted the pictures I took, IMO there was no way they could win that way.

- they began to win after and it is corroborated by the polar of race 8 on sept 14

When I looked at next races then, I was amazed to see how they were lifting sooner and higher than TNZ on their foils. It was the beginning of the end for the kiwis.

How can they foil earlier with the same boat ? well, there are not too many possibilities:

- unloading the main foil with more wing racking and loading the rudders, and modify its AoA

- modifying the trimming of the wing

- changing the AoA of the main foil

- reducing the aero drag ir order to have a lighter boat

That is pretty much what Russell said. Basically they succeed to exploit the lower aero drag of the boat, which they had not been able to do before.

As for the SAS, I don't have a clue if they used it and if it worked.

Well here's a first. T-C and I agree on something!

It seems pretty clear to me that hey found a way of setting up the boat that unloaded the foils. Simply put, the wave/spray making is visible drag. Even a small gain in reducing drag is going to produce a big result. Going back to when we first saw ETNZ foiling, I suggested that the reason why we couldn't be sure that foiling was faster was because this drag was very high. Simply put, ETNZ didn't manage to reduce that drag by as much as OR did.

So what happened? I think there were a number of things. First off, they re-moded the boat, probably by raking the rig but I also suspect that they changed the twist profile they were using. If you consider the comments that Coutts ius said to have made, namely that they should foot off and go for speed, and combine that with blading out the top more and grunting up the bottom, it all feels like it should have less load on the foils. I also suspect that the low mode actually allowed them to gain more height once up to speed, as the foils worked more efficiently at the higher speeds. It's surprising how often you see that work in high performance boats. Finally, I think they put the boat on the biggest diet they could. The conventional wisdom was that you wanted the boat towards the top end of the weight limit because righting moment was more important than the extra drag from weight. Once they decided to favour unloading the foils, the diet was a logical conclusion. We saw the visible stuff like the removal of the pole, but I wonder what we didn't see. One guess would be that they fixed the rudders and removed the ability to change the rake on the water or maybe at all.

So why didn't they do it earlier? I suspect it is because it only worked really well in a narrow (higher) wind range and they hadn't had time to perfect it. There was also a feeling that you couldn't give away too much downwind (or was that only on this forum) and that the race might be won by the faster downhill boat. Once it was clear it was about upwind, the game changed. In addition, low mode needs different tactical thinking. I believe that the mode change and BA went hand in hand. He probably had the most experience of this "new" mode as they are more likely to have tried it more on the first boat, particularly if there was any element of "risk" involved. I believe that BA's experience on the helm allowed him to be more in touch with what mode to sail in and therefore, which way to go. All told, a high risk strategy that nearly didn't pay off when they were outclassed in a lighter wind race and were only saved by the time limit.

Lots of speculation, but it also stacks up with things we are seeing in the Little AC. Not only are Groupama's foils conservative, butmany elements of their program seem to me about reducing how hard the foils work. Things like the canting rig and deck sweeping would all contribute. At the end of the day, I am sure it was a very ballsy move backed by a huge amount of data and a little desperation!

 

[BalticBandit]

I agree Simon that all that stuff was important. But essentially it only got them "up to speed" The upwind story for Race 19 is that OTUSA aveaged roughly 0.5 knots slower, but sailed 600+ meters shorter distance.