Boats and foils comparison

Stingray~

Super Anarchist
10,390
2,685
PNW
That's to install Python package. It requires python installed on your PC, and works with any OS. Once installed, access the boats telemetry data with Python command:
"data = ac36data.get_boats('ac2021',1)"
where 'ac2021' - event name, "1" - race number.
Thanks, very cool.

Should the data be easily importable into database tables? 

 

The Advocate

Super Anarchist
supercavitating foils will only ever be useful at >20-30kt wind speeds, and never if there isn't a lot of time spent reaching. Those winds speeds are very infrequent almost everywhere in the world, and generally come with big waves too that destroy their utility on sailing yachts.  Their profile lift to drag maxes out in low teens, where conventional foils can exceed 100.  As a practical thing you would need to switch between supercavitating and conventional foils at lower speeds to make them useful for sailing.
IKR, just like a handful of years back when they said 70 ft yachts would foil one day, dreamers.

 

Tornado-Cat

Super Anarchist
16,290
1,025
TR has smaller foils than LR so can go faster but makes a longer course.

With light wind conditions LR should be favoured however both boats are equal, so can TR be faster in stronger winds ? perhaps, but in stronger winds LR can point higher and go deeper so it is a tough answer. Let's say that TR would be favoured downwind and LR could do as well or better upwind and during manoeuvers.

So what strategy for LR ? The best for them would be to use their manoeuvrability to make the kiwi fall of their foils in the prestart or even bring them to a capsize, that would not please to some but could be interesting.

 

Tornado-Cat

Super Anarchist
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Pure gold, Guillaume Verdier himself give very simple answers with a lot of common sense for a lot of questions debated here, by the two Italians, Mozzy. You have to understand French though.

I'll come back with some points when I have time, unless somebody does it before.

https://voilesetvoiliers.ouest-france.fr/regate/coupe-de-l-america/america-s-cup-guillaume-verdier-du-vendee-globe-a-la-coupe-de-l-america-sur-tous-les-fronts-16505d9a-7daf-11eb-a530-8257a05e6295?fbclid=IwAR1NxsAj3wAuWdzn6_P7iVTxshZyq76ZeZcZfnogKPj0O9F0JBzZQrROne8

 
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Tornado-Cat

Super Anarchist
16,290
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Pure gold, Guillaume Verdier himself give very simple answers with a lot of common sense for a lot of questions debated here, by the two Italians, Mozzy. You have to understand French though.

I'll come back with some points when I have time, unless somebody does it before.

https://voilesetvoiliers.ouest-france.fr/regate/coupe-de-l-america/america-s-cup-guillaume-verdier-du-vendee-globe-a-la-coupe-de-l-america-sur-tous-les-fronts-16505d9a-7daf-11eb-a530-8257a05e6295?fbclid=IwAR1NxsAj3wAuWdzn6_P7iVTxshZyq76ZeZcZfnogKPj0O9F0JBzZQrROne8
TNZ

-          My first meeting with TNZ was in 2009

-          I begain to work in 2010

-          I have aneye on everyting on the boat but works part time because busy on other projects

-          I give ideas but it’s a lot of work, you have to develop it each idea

-          I like a small team because it’s efficient, we are even too many, lots of people coding, too many, we have to keep a global vision

AC75

-          One day day Ray Davis asks me to meet Howard Spencer, willing to get a fun 40 ft.

-          I design a foiling mono

-          Ray says that the keel is too much

-          I tell him it’s possible, however we need stability

-          I remember that a french architect, Martin Defline has made two queels boats who are pretty efficient, so we can do the same thing with ballast at the end of the foil

-          It’s counter intuitive to put weight where we want a lift but calcules show it is 50% more efficient that with the keel for the same mass.

-          The project doesn’t work as too expensive

-          The Italians want a big mono for AC36, we could have a had a smaller boat for economic reasons

-          Ray Davies puts my drawing on the table, everybody laugh. He tells us: I give you one month to test the concept to test If it works in a simulator. I was not there, I did not test, Bobby tested the design and they said it was a fun concept and it works

-          They tried other concepts but came back to the initial one

AC75 rule

-          I was willing two rudder foils for better stability to avoid diagonal heel instability like the hydrotère.

-          I was against it but we went to one rudder for a good reason: to avoid cutting a crew falling in the water. That is also why the rules prevent going on the bow.

-          I did not write the rule, Dan Bernasconi did it, I gave my advices.

-          We chose a close rule to avoid mistakes, it took us a year

-          We were very reassured to see that the british model worked, simulation works but is not always reassuring.

-          We surely took some advance compared to the other teams but I don’t think it was so much

-          Once I chose a concept I like to push it to the end.

-          We got symetric foils at the end only in order to learn as much as possible

-          The bulb at the end of the foil arm is just to put ballast, it has nothing to do with hydro but with the rule

Our AC75

-          We are given a rule that I hate, the inertial stability in the harbour that imposes a wide flotation beam

-          I understand it but it was not required with the ballasted foils in the water, we did not need that. 10’17

-          I understood that it was obvious that we have to make a central tube like a trimaran hull and a wide ass for the rule and stability, I don’t think other teams understood it right away: narrow hull and wide as far on the back as possible.

-          So we have a narrow hull in the front like a trimaran and a wide ass for static stability in the harbour.

-          Not a big evolution between B1 and B2, B2 is even more like a multi

-          We want a boat easy to foil that lift the stern first and get early on the foils for lower drag asap

-          The brits were capsizing when bearing away as they could not get enough lift from the foil vs the pressure. They were afraid of the transition and they were right to have a first boat with more stability.

-          B1 was an hydro dynamic concept, B2 an aero + hydro

The foil

-          The dihedral is more equlibrated and does not require a big “shaft” that maintain the foil and which creates drag

-          On the other hand a flat design is simpler and has lower drag. Both concepts are good.

B  

 
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dorox

Member
138
217
Races 7 and 8 are uploaded https://ac36.herokuapp.com/map
Italians got really unlucky getting stuck in 6kn of wind contrary to NZL in 7kn.

image.png

 

dorox

Member
138
217
Race 9 is uploaded. I've included course-VMG to see how each team handles the wind.

The screenshot shows the 6kn CVMG advantage for NZL at the 5th leg when they got the lead.

image.png

 

erdb

Anarchist
755
557
As we are getting closer to the end, I ran the "summarize all races" algorithm again to see how the boats ranked and how much improvement was made by LR and ETNZ.

LR's and ETNZ's AC races are marked by triangles and darker red and green trend lines vs their previous ACWS and Prada cup races.

VMG vs TWS: vmg.png

Altogether, ETNZ were always superior both upwind and downwind. They did improve since the ACWS, but LR actually improved a lot more - they got very close. Sandbagging or just careful scheduling of improvements?  Intentional or not, they did manage to surprise everyone with their evolution.

Interestingly, they're actually closer to ETNZ in the mid-range, not in the light. Maybe a good sign for them for today.

TR has superior Speed and TWA in most conditions (except for LR in mid-range upwind).

bs.png

rtwa.png

AWA vs TWS:

awa.png

I guess it's not surprising it's the Kiwis who can sail with the tightest AWA in all conditions showing their superior efficiency and lift/drag ratios. Again, check out the improvement by LR!

Effective foil cant (heel+cant angle) vs TWS:

efcant.png

 I thought this was interesting how their techniques evolved. LR increased effective cant angles both up- and downwind, while ETNZ increased it downwind and in light upwind. AM were using some crazy angles in strong upwind. That's probably the batwing main / low CoE setup. I'd love to see what ETNZ would do in that range.

Pitch vs TWS: pitch.png

Pitch angle (positive is forward pitch here) doesn't really correlate with wind speed for most boats, but there are some interesting differences between the teams with AM and ETNZ sailing the most bow-down.

 

erdb

Anarchist
755
557
Here is the data from the last race, just for the record. No surprises, ETNZ clearly dominated both upwind and downwind:

uw vmg.png dw vmg.png

They've sailed some amazing apparent angles:

uw awa.png dw awa.png

For me the most remarkable is how ETNZ switched to a whole new level of performance within a few days. The two boats were matched pretty good on the first two days, and then ETNZ figured out something. They not only started to tack better, but somehow found an extra gear in straight line speed.

I think this sums it up pretty well  :D :

etnz.gif

What an amazing machine and a group of sailors / engineers who figured out how to tame it. Congrats to ETNZ!

Also thanks for everyone for all the wonderful discussions here. I've learned a lot.

 

Kiwing

Super Anarchist
3,309
512
Bay of Islands
Core I hope all you geniuses keep analysing all this stuff and future stuff.

I for one will have a bit more time to go through all this amazing analysis and clear out my thoughts.

Then there will be the new boats (or maybe the new rules for these boats?).

Hope there is a new life for this thread/forum

 

Paddywackery

Super Anarchist
1,112
438
Ireland
Here is the data from the last race, just for the record. No surprises, ETNZ clearly dominated both upwind and downwind:

View attachment 435023 View attachment 435024

They've sailed some amazing apparent angles:

View attachment 435025 View attachment 435026

For me the most remarkable is how ETNZ switched to a whole new level of performance within a few days. The two boats were matched pretty good on the first two days, and then ETNZ figured out something. They not only started to tack better, but somehow found an extra gear in straight line speed.

I think this sums it up pretty well  :D :

View attachment 435027

What an amazing machine and a group of sailors / engineers who figured out how to tame it. Congrats to ETNZ!

Also thanks for everyone for all the wonderful discussions here. I've learned a lot.
Thank you for the incredible data and insights you prepared for our benefit. Interesting that Dan Bernasconi admitted to being disappointed that we didn't get to see these AC75's in strong breeze. I suspect there were a few more surprises in store. 

In the aftermath of SFO, one key learning rammed home to all involved with ETNZ was the need to be able to improve performance through the match Final. And beyond race practice, which mattered, it suggests that they were tinkering every day to get better sailing/boat performance.

 

jaysper

Super Anarchist
10,144
1,282
Wellington
Here is the data from the last race, just for the record. No surprises, ETNZ clearly dominated both upwind and downwind:

View attachment 435023 View attachment 435024

They've sailed some amazing apparent angles:

View attachment 435025 View attachment 435026

For me the most remarkable is how ETNZ switched to a whole new level of performance within a few days. The two boats were matched pretty good on the first two days, and then ETNZ figured out something. They not only started to tack better, but somehow found an extra gear in straight line speed.

I think this sums it up pretty well  :D :

View attachment 435027

What an amazing machine and a group of sailors / engineers who figured out how to tame it. Congrats to ETNZ!

Also thanks for everyone for all the wonderful discussions here. I've learned a lot.
My thinking is that as they learnt to manouvre better, they were able to keep out of Luna Rossa's gas more often, freeing them up to realise the superior VMG they had to begin with.

But ya know, could be wrong  :lol:

 

mauriciogfj

Member
228
122
Brazil
Here is the data from the last race, just for the record. No surprises, ETNZ clearly dominated both upwind and downwind:

View attachment 435023 View attachment 435024

They've sailed some amazing apparent angles:

View attachment 435025 View attachment 435026

For me the most remarkable is how ETNZ switched to a whole new level of performance within a few days. The two boats were matched pretty good on the first two days, and then ETNZ figured out something. They not only started to tack better, but somehow found an extra gear in straight line speed.

I think this sums it up pretty well  :D :

View attachment 435027

What an amazing machine and a group of sailors / engineers who figured out how to tame it. Congrats to ETNZ!

Also thanks for everyone for all the wonderful discussions here. I've learned a lot.
Thanks mate, keep them coming.

 

Blitzkrieg9

Member
220
62
Interesting that Dan Bernasconi admitted to being disappointed that we didn't get to see these AC75's in strong breeze. I suspect there were a few more surprises in store.
I'm in the camp that believes at the highest range (19-21 knots) LR might gain the advantage.   At top wind speeds, hydro drag becomes irrelevant since every boat is over powered/ over canvassed (hence the bat-wing sails and reverse camber on the mainsail head).   If boats are desperately trying to shed power, then the excess hydro drag from larger foils becomes moot. Right?

 
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