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On 10/17/2020 at 12:09 AM, Loose Cannon said:

Well that was an exciting wheelie!  First impression of the boat the key design is obviously the bow to slightly past mast skeg. I think there are a couple drivers to that design:  aero, adding effective ‘wingspan’ via end plate on deck and the skeg below.  Hydro, at low speeds you get a break in Bernoulli suction, side resistance and the potential to pop out a bit faster in transition as a result.

How does the skeg/keel on the underside provide end-plating for the sail topside?

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6 hours ago, Kate short for Bob said:

You are assuming that the boat was fully tested.  It was clear from race 1 in San Francisco who had the quicker boat.  

By the time you get to the AC finals the fastest boat has been developed.  How did it get to that point?

no I am not 'assuming' it was fully tested, GD has been on record saying that the boat was fully wound up and they couldnt develop it any further only to watch oracle keep developing.

again this is likely entirely DB s fault..

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6 hours ago, JALhazmat said:

That  period where he with the rest of the team developed a foiling 72ft cat, learned to sail it developed a second boat that was ahead of the poodle and yet rather than keeping it too them selves and providing the killer blow that the other teams couldn’t react too.

the management decided to show off.. blowing the advantage and letting Oracle out develop them.

and that is Deans fault is it? 

News flash: 

AC yacht clubs’ management committees are political.

Ref: Tom Blackaller 

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9 hours ago, I14RACER said:

You can’t make an omelet without cracking a few eggs. There was no harm in doing it or they wouldn’t have. These guys are far more capable of judging their abilities than us keyboard jockeys.

They have capsized before like NZ and nothing horrible happened. I’m glad they went for it. It can help shake the nerves when the winds will be calmer.

Yes, and he said they only reason they didn't keep sailing was because they had some oil leaks.  

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4 hours ago, MaxHugen said:

How does the skeg/keel on the underside provide end-plating for the sail topside?

It creates another barrier to help hold windward pressure. This was an original supposition of LRs keel and ETNZ'S bustle, and why LR added theirs to the B1 and has been discussed in a few interviews with team representatives.

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6 hours ago, loneshark64 said:

News flash: 

AC yacht clubs’ management committees are political.

Ref: Tom Blackaller 

Never known any club's management committee not to be political..

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9 minutes ago, mikenz2 said:

Patriot has just headed out to go sailing.

1140654-01.jpeg

Have I been drinking or has that boom been drinking? 

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1 hour ago, mikenz2 said:

Patriot has just headed out to go sailing.

1140654-01.jpeg

Nice pic of the foil!

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1 hour ago, RMac said:

Have I been drinking or has that boom been drinking? 

That’s the new one. They shaped it to follow the deck and straighten out at the end to allow adjustment via outhaul/cars. It’s a pretty simple and elegant solution.

Engineering 101 motto: KISS keep it simple stupid.

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1 hour ago, RMac said:

Have I been drinking or has that boom been drinking? 

But is it articulated or not?

 

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7 minutes ago, Xlot said:

But is it articulated or not?

 

Doesn't look like it to me. I've been iffy on the articulated boom. If you can control your foot tensions independently I'm not sure how necessary craming a ton of extra camber is

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Thanks. Any clear picture of Te Aihe’s boom?

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That front fillet keel reminds me of Ineos B1 post-mod...

Its interesting to see the convergence of these designs.

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It is interesting how Patriot has a natural bow down position, just like Defiant did.  You do not see that on the other boats while being towed.

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6 hours ago, mikenz2 said:

Patriot has just headed out to go sailing.

1140654-01.jpeg

Amazing work across threads @mikenz2, much appreciated. Particularly the recent LR below deck stuff. Nothing close to that has been seen so far for that team.

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22 hours ago, amc said:

 

FBE86535-2ABF-4785-ABAC-B316E6A510F5.png

Thank you good sir, may fortune smile upon your pate !!

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On 10/17/2020 at 12:09 AM, Loose Cannon said:

...adding effective ‘wingspan’ via end plate on deck and the skeg below. .

How does a vertical skeg or keel contribute to the end plate effect on the mainsail?

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5 hours ago, barfy said:

Thank you good sir, may fortune smile upon your pate !!

Okay, Harbfy! 
 

Got any more dumb-ass Herbie videos to share? :D  :D :D 
I remember an NZ media guy asking JS about ‘Herbie’ and JS laughed out loud then made a comment about a silly children’s movie. 

 

 

 

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@MaxHugen

 

ok the 'sail' is a large vertical wing.

if there is a gap under it   (between the boom and the deck, the air on the windward side can slip under it disturbing the nice laminar flow that you want introducing a vortex of tumbling air to the leeward side  and this reduces the lift of the wing 

hence the obsession with teams 'end plating the sail to the deck'

the airflow is now unable to migrate under the boom so the next path of least resistance is around the sides of the boat and flowing (diagonally, approximately, due to apparent wind) under the hull

if you can reduce the gap between the water and the hull you reduce the escape route and reduce the creation of an untidy air vortex screwing with what is flowing neatly of your rig, thus reducing drag and maximizing performance.

 

end plating has nothing to do with ground effect or wing in ground effect as both of those are different principles.

 

that is literally the least technical explanation of it but that's the bare bones 

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7 minutes ago, JALhazmat said:

that is literally the least technical explanation of it

Does anyone think there may be a ‘wingsail’ effect created by the flying keels? Could they be so aerodynamic at 18 AWA that they even create a measure of forward lift? Ineos’s keel shape especially resembles an airfoil, a sail section. 

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6 minutes ago, JALhazmat said:

@MaxHugen

 

ok the 'sail' is a large vertical wing.

if there is a gap under it   (between the boom and the deck, the air on the windward side can slip under it disturbing the nice laminar flow that you want introducing a vortex of tumbling air to the leeward side  and this reduces the lift of the wing 

hence the obsession with teams 'end plating the sail to the deck'

the airflow is now unable to migrate under the boom so the next path of least resistance is around the sides of the boat and flowing (diagonally, approximately, due to apparent wind) under the hull

if you can reduce the gap between the water and the hull you reduce the escape route and reduce the creation of an untidy air vortex screwing with what is flowing neatly of your rig, thus reducing drag and maximizing performance.

 

end plating has nothing to do with ground effect or wing in ground effect as both of those are different principles.

 

that is literally the least technical explanation of it but that's the bare bones 

Thanks. I do understand the deck/sail effect, but I would have thought the resultant path of least resistance would continue to flow aft, rather than around the sides of the boat.

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2 minutes ago, JALhazmat said:

You have to account for the apparent wind angle 

That's what puzzles me. The high pressure airflow on the windward side of the sail would have to overcome the apparent wind, across a fairly wide deck area, in order to even get to the side of the boat?

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The air flow is deflected by the boat side before it gets to the rig, so it’s either going under the boat or onto the rig, if it can’t go under the hull then it joins up with the air flow moving back along the boat.

generally speaking the boats are fucking terrible aero devices so it’s all mariginal.

moving boat on moving surface with people moving about and not a huge speed make it hard to keep any air flow attached where you want it anyway never mind sealing the hull to the water 

but hey if you can get 5% from it and the other bloke can’t, it’s 5% in your pocket 

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31 minutes ago, JALhazmat said:

The air flow is deflected by the boat side before it gets to the rig, so it’s either going under the boat or onto the rig, if it can’t go under the hull then it joins up with the air flow moving back along the boat.

but hey if you can get 5% from it and the other bloke can’t, it’s 5% in your pocket 

OK, getting a better "mental picture" of this.  Cheers.

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I think the differences in hull design/keel size may indicate how much they want to rotate the boat across the direction of movement (some call it crabbing).

I always though that they do that to increase the righting moment from the rudder foil by increasing the lateral distance between the rudder and the main foils. Maybe it also helps opening the gap between the jib and the main. Of course the downside is that now you have more aero drag on the hull. They'll have to find the balance between minimizing drag and maximizing righting moment.

The differences in the keel size and roundness may indicate that AM plans to rotate the boat across the most with the smallest keel, INEOS the least with the big, sharp-edged keel and LR (and NZ B1) somewhere in the middle.

crab2.jpg

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On 10/19/2020 at 2:46 PM, The_Alchemist said:

From the Friday interview with TH 

https://www.facebook.com/SailingIllustratedBlog/videos/365766524779367/

 

TH said they had some adjustment issues on the first sail.  They just planed to tow B2 around a little that first day, but with the nice calm water, Dean convinced them to go for a sail.  TH said that they gave it a good stress test that first day.  

He said they are taking the weekend off and will most likely go sailing on Tuesday.  

It's an impressive effort to make an interview with the principle of a US AC Challenger such hard work. Highlights include

  • Terry Hutchinson continuing to be an absolute class act, calm, considerate, real and at times as candid as he could be given the circumstances.
  • TH having to answer if the Christmas Cup is going to be a fleet race, struggling to conceal his confusion. 
  • TH calling out TE for 'whinging' about Def and CoR on having the rule for 6 months - TH said, "we knew that coming in to it'.
  • A freeze-frame review of the champagne smashing - even TH looked like he had better things to do at that point.
  • In particular it was great to see TH call out the name Patriot in relation to Katelyn Choe as a first generation immigrant from Korea that was a living embodiment of what it means to be an American in terms of helping others to become citizens (making it clear where he stands such things).
  • Followed by TE having just heard the name pronounced multiple times, decides to absolutely butcher the pronouciation (Kamala Harris style?), causing TH to interrupt and literally spell it out for him. :rolleyes:
  • TH pointing out that GD has been awesome at keeping them up to date with what was happening in NZ, and the NZ Govt being super helpful with the logistics and immigration.
  • TH having to explain what blinder means, as well as pointing out, it's not a kiwi term. :lol:
  • TH explaining that the ETNZ capsize photo is a bit of a clueless cheap shot, that ETNZ were doing 'low 50s' with what TH thinks is "a pretty nice foil... smaller... aggressive and 'they have the cup for a reason'

Great to see TH set the record straight on so many things...

Bravo Zulu Croutons! LOL! :P

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^ Very interesting point.  I wish I could add something.

Maybe hull contributing to the force forward

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28 minutes ago, rh3000 said:

It's an impressive effort to make an interview with the principle of a US AC Challenger such hard work. Highlights include

  • Terry Hutchinson continuing to be an absolute class act, calm, considerate, real and at times as candid as he could be given the circumstances.
  • TH having to answer if the Christmas Cup is going to be a fleet race, struggling to conceal his confusion. 
  • TH calling out TE for 'whinging' about Def and CoR on having the rule for 6 months - TH said, "we knew that coming in to it'.
  • A freeze-frame review of the champagne smashing - even TH looked like he had better things to do at that point.
  • In particular it was great to see TH call out the name Patriot in relation to Katelyn Choe as a first generation immigrant from Korea that was a living embodiment of what it means to be an American in terms of helping others to become citizens (making it clear where he stands such things).
  • Followed by TE having just heard the name pronounced multiple times, decides to absolutely butcher the pronouciation (Kamala Harris style?), causing TH to interrupt and literally spell it out for him. :rolleyes:
  • TH pointing out that GD has been awesome at keeping them up to date with what was happening in NZ, and the NZ Govt being super helpful with the logistics and immigration.
  • TH having to explain what blinder means, as well as pointing out, it's not a kiwi term. :lol:
  • TH explaining that the ETNZ capsize photo is a bit of a clueless cheap shot, that ETNZ were doing 'low 50s' with what TH thinks is "a pretty nice foil... smaller... aggressive and 'they have the cup for a reason'

Great to see TH set the record straight on so many things...

Bravo Zulu Croutons! LOL! :P

Thanks for the highlights. Hutch has always struck me as a gentleman, and it's easy to see why NYYC appointed him in charge of their Challenge.

And I like how Team NYYC have got their heads down and concentrated on going about their business undistracted. My second favourite team.

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38 minutes ago, rh3000 said:

TH calling out TE for 'whinging' about Def and CoR on having the rule for 6 months - TH said, "we knew that coming in to it'.

Did he mention SR?

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56 minutes ago, Indio said:

And I like how Team NYYC have got their heads down and concentrated on going about their business undistracted. My second favourite team.

I like their chances for the Challenger Series. They look a strong prospect, with a good B2.

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24 minutes ago, I14RACER said:

Looks like the same thing on GBR...

 

90F2FB11-FAD3-48AF-B9DF-A5B2874DBCCF.jpeg

They all have it. It’s part of the cooling system for the foil canting hydraulics. 

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1 minute ago, Monkey said:

They all have it. It’s part of the cooling system for the foil canting hydraulics. 

Water cooled?

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The large benefit to end plating the sail to the deck is that if the sail is sealed to the deck, the center of effort moves lower when you twist the sail.  If there is cross flow, there is less effect.

On catamarans, you can have different pressure on either side ( windward /leeward) of the trampoline.  The leeward side pulling up and the Windward side pulling down.  A centerline spine as the AC 50 has can prevent these forces from mixing, resulting in more righting moment.  I don’t know if the AC 72 can create a similar effect, but the hull is far enough from the leeward foil to make aerodynamic down force a player in the righting moment sweepstakes.

Oh, and flying bow down helps too.

SHC

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7 minutes ago, Monkey said:

They all have it. It’s part of the cooling system for the foil canting hydraulics. 

The dc motor driving the hydraulic pump generating 600bar will heat up quite a bit quite rapidly in the belly of the beast, so they'd want to dissipate that heat quickly..

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On 10/20/2020 at 4:24 AM, rh3000 said:

It creates another barrier to help hold windward pressure. This was an original supposition of LRs keel and ETNZ'S bustle, and why LR added theirs to the B1 and has been discussed in a few interviews with team representatives.

Thanks, JALhazmat explained the same to me... I think I got confused trying to think in terms of end plate and the mainsail/deck interface. I had thought that NZ's bustle was mainly to minimise wetted area, but I guess it could be doing both?  I do wonder if additional leeward forces from long keels will offset gains in power from higher sail pressure.

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7 minutes ago, MaxHugen said:

Thanks, JALhazmat explained the same to me... I think I got confused trying to think in terms of end plate and the mainsail/deck interface. I had thought that NZ's bustle was mainly to minimise wetted area, but I guess it could be doing both?  I do wonder if additional leeward forces from long keels will offset gains in power from higher sail pressure.

I think you are are right too, because If wetted area wasn't a concern you'd see just a sharp curtain ala Ineo's B1.5.

It's what makes their B2 interesting, they've got for some displacement, but a hard bottom, I suspect to help 'plane' at speed if it touches down.

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On 10/19/2020 at 6:09 PM, mikenz2 said:

Patriot has returned to base after a morning on the water. 

 

Wow, that sucker sounds like a jet plane!

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3 hours ago, erdb said:

I think the differences in hull design/keel size may indicate how much they want to rotate the boat across the direction of movement (some call it crabbing).

I always though that they do that to increase the righting moment from the rudder foil by increasing the lateral distance between the rudder and the main foils. Maybe it also helps opening the gap between the jib and the main. Of course the downside is that now you have more aero drag on the hull. They'll have to find the balance between minimizing drag and maximizing righting moment.

The differences in the keel size and roundness may indicate that AM plans to rotate the boat across the most with the smallest keel, INEOS the least with the big, sharp-edged keel and LR (and NZ B1) somewhere in the middle.

crab2.jpg

Interesting. How would they "rotate" the boat like that?

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3 hours ago, rh3000 said:

It's an impressive effort to make an interview with the principle of a US AC Challenger such hard work. Highlights include

  • Terry Hutchinson continuing to be an absolute class act, calm, considerate, real and at times as candid as he could be given the circumstances.
  • TH having to answer if the Christmas Cup is going to be a fleet race, struggling to conceal his confusion. 
  • TH calling out TE for 'whinging' about Def and CoR on having the rule for 6 months - TH said, "we knew that coming in to it'.
  • A freeze-frame review of the champagne smashing - even TH looked like he had better things to do at that point.
  • In particular it was great to see TH call out the name Patriot in relation to Katelyn Choe as a first generation immigrant from Korea that was a living embodiment of what it means to be an American in terms of helping others to become citizens (making it clear where he stands such things).
  • Followed by TE having just heard the name pronounced multiple times, decides to absolutely butcher the pronouciation (Kamala Harris style?), causing TH to interrupt and literally spell it out for him. :rolleyes:
  • TH pointing out that GD has been awesome at keeping them up to date with what was happening in NZ, and the NZ Govt being super helpful with the logistics and immigration.
  • TH having to explain what blinder means, as well as pointing out, it's not a kiwi term. :lol:
  • TH explaining that the ETNZ capsize photo is a bit of a clueless cheap shot, that ETNZ were doing 'low 50s' with what TH thinks is "a pretty nice foil... smaller... aggressive and 'they have the cup for a reason'

Great to see TH set the record straight on so many things...

Bravo Zulu Croutons! LOL! :P

Great recap.  It is difficult to listen to TE do an interview, he constantly interrupts and points out how important he is...

I agree, TH continues to handle it with class and no excuses.  At time he points out a few items, but never as an excuse.  He knows the lay of the land and you have to make the best of it.  He did point out how they kind of "put the pressure" on NZ to make a decision by shipping the boat to NZ before it was approved. 

TH seems to be the only one of the team heads that isn't overlooking the other challengers when he talks about the cup.  It struck me a funny how LR and UK heaped so much praise on to the NZ effort, but totally ignore the other teams.  I know they are talking to the NZ press and want to play up to the NZ home audience, but to totally ignore any discussion of your first opponents is being a little arrogant.

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2 hours ago, MaxHugen said:

Interesting. How would they "rotate" the boat like that?

Watch one of the videos of NYYC she is pointing away from the camera and climbing radically to windward (starboard) for a long time.

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5 minutes ago, Kiwing said:

Watch one of the videos of NYYC she is pointing away from the camera and climbing radically to windward (starboard) for a long time.

I've seen that. I assumed that it was a factor of leeway vs windward lift from the foil, but the comment "how much they want to rotate the boat across the direction of movement" seems to imply they have some control over that?

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I guess they can "rotate" the boat at will to arrive at the best VMG.  It surprises me that they can and while the foils are the only things in the water it still looks radical to me.

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5 hours ago, Indio said:

Thanks for the highlights. Hutch has always struck me as a gentleman, and it's easy to see why NYYC appointed him in charge of their Challenge.

And I like how Team NYYC have got their heads down and concentrated on going about their business undistracted. My second favourite team.

Kudos to Hutch he is so easy to listen to and I believe gives AM a genuine chance to win this thing. You always need a little bit of luck and I would prefer Hutch talking to the Karma Gods than some of the others. LOL No he knows his stuff,  he is head down bum up getting the job done. Certainly a pretty boat they have in Patriot. Let's hope the have a "BLINDER"

Go American Magic.......! 

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3 minutes ago, terrafirma said:

Kudos to Hutch he is so easy to listen to and I believe gives AM a genuine chance to win this thing. You always need a little bit of luck and I would prefer Hutch talking to the Karma Gods than some of the others. LOL No he knows his stuff,  he is head down bum up getting the job done. Certainly a pretty boat they have in Patriot. Let's hope the have a "BLINDER"

Go American Magic.......! 

Yeah, so far I think AM and LR could both be a tough challenger. As for GB, I don't know if it will be a surprising success or dismal failure. If I had to bet, I'd say the latter. Still, I hope they are all competitive, even if I'll barrack for NZ.

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30 minutes ago, MaxHugen said:

I've seen that. I assumed that it was a factor of leeway vs windward lift from the foil, but the comment "how much they want to rotate the boat across the direction of movement" seems to imply they have some control over that?

I guess it's determined by the angle and lift of the main foil and then the rudder angle is adjusted accordingly. 

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6 hours ago, erdb said:

I think the differences in hull design/keel size may indicate how much they want to rotate the boat across the direction of movement (some call it crabbing).

I always though that they do that to increase the righting moment from the rudder foil by increasing the lateral distance between the rudder and the main foils. Maybe it also helps opening the gap between the jib and the main. Of course the downside is that now you have more aero drag on the hull. They'll have to find the balance between minimizing drag and maximizing righting moment.

The differences in the keel size and roundness may indicate that AM plans to rotate the boat across the most with the smallest keel, INEOS the least with the big, sharp-edged keel and LR (and NZ B1) somewhere in the middle.

crab2.jpg

Ignoring the water for a moment surely the right diagram gives more RM and power from the sails?

The foil is using it's flaps to generate amazing VMG for some drag?

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11 minutes ago, Kiwing said:

Ignoring the water for a moment surely the right diagram gives more RM and power from the sails?

The foil is using it's flaps to generate amazing VMG for some drag?

That's "assuming" that it can produce enough windward lift to maintain that VMG. And the flaps affect vertical lift - and drag - as well, so they can't overdo it. No doubt all teams have been extensively testing just which angle to the True Wind they can achieve best VMG, in varying wind strengths.

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4 hours ago, Monkey said:

They all have it. It’s part of the cooling system for the foil canting hydraulics. 

So what you are saying... is it's some kind of tray, where heat is expunged...

So.... by this definition it could be... A PIE WARMER?!

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36 minutes ago, darth reapius said:

So what you are saying... is it's some kind of tray, where heat is expunged...

So.... by this definition it could be... A PIE WARMER?!

More a pie cooler up there.IMG_1945.jpeg.b2988dcbf05272ee916e3a4c3e0c1ff8.jpeg pie 

 

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From Roger Mills YouTube channel

 

 

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On 10/20/2020 at 8:40 AM, mikenz2 said:

Patriot has just headed out to go sailing.

1140654-01.jpeg

I'm still not a big fan of the bulbs but the foil/flap & especially that tip looks very nice.

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Interesting point from the TH interview, is that if they were to win, they're going to go back to a non foiling mono box rule. Can't say I'd look forward to that, but then again I still think they're an outside chance to win the Prada cup.

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Magic win would = non-foilers?  Not sure I like the sound of that.  Do we know the position of the others?  I guess ETNZ and LR are a given...?

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2 hours ago, JustinL42 said:

From Roger Mills YouTube channel

 

 

Thanks. She looks sleek and steady..They won't suffer from a shortage of local knowledge or experience after the time they've spent on the water.

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On 10/20/2020 at 1:22 PM, The_Alchemist said:

It is interesting how Patriot has a natural bow down position, just like Defiant did.  You do not see that on the other boats while being towed.

She was towed past while I was on the ferry this morning and it is quite remarkable how bow down it is. I have video but it's from a distance.  

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spray pattern off the foil arms looks far smoother, could just be conditions or the distance effecting how it looks but looking good 

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1 hour ago, Teaky said:

Magic win would = non-foilers?  Not sure I like the sound of that.  Do we know the position of the others?  I guess ETNZ and LR are a given...?

ETNZ is. Not so sure about LR. The received wisdom on here seems to be that LR said mono, and ETNZ sprung the foiling mono on them.

But no real idea. Even ETNZ might want to throw the ball further

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3 hours ago, enigmatically2 said:

ETNZ is. Not so sure about LR. The received wisdom on here seems to be that LR said mono, and ETNZ sprung the foiling mono on them.

But no real idea. Even ETNZ might want to throw the ball further

I do not want to go down the rabbit hole, but....  I know the AC is a design showcase, but it doesn’t have to be a freak show.  I agree that these boats are exciting, but so would be boats like Hugo Boss, or something that does require a team of hamsters to keep it sailing.  It would be nice to go somewhat back to a design that can benefit from innovation, but also where it relies on more sailing skills and reading the wind.

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11 hours ago, Kiwing said:

Ignoring the water for a moment surely the right diagram gives more RM and power from the sails?

The foil is using it's flaps to generate amazing VMG for some drag?

 

10 hours ago, MaxHugen said:

That's "assuming" that it can produce enough windward lift to maintain that VMG. And the flaps affect vertical lift - and drag - as well, so they can't overdo it. No doubt all teams have been extensively testing just which angle to the True Wind they can achieve best VMG, in varying wind strengths.

You don't need more lift for this, and rotating the hull doesn't affect VMG directly either. Once the hull is in the air, VMG depends mainly on the efficiency or lift/drag ratios of the foils and sails. The rotation of the hull only affects hull aero and the geometry of how the foil vs rudder are positioned and how the sails are set relative to the hull. It doesn't have a direct effect on which direction the boat is moving. It's really just rotating the hull relative to the direction of movement.

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8 hours ago, JustinL42 said:

From Roger Mills YouTube channel

 

 

Looks like LR is following around 1:10. I guess with AM being the first out in B2 they will have all the syndicate’s eyes on them out there.

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8 minutes ago, erdb said:

You don't need more lift for this, and rotating the hull doesn't affect VMG directly either. Once the hull is in the air, VMG depends mainly on the efficiency or lift/drag ratios of the foils and sails. The rotation of the hull only affects hull aero and the geometry of how the foil vs rudder are positioned and how the sails are set relative to the hull. It doesn't have a direct effect on which direction the boat is moving. It's really just rotating the hull relative to the direction of movement.

I don't follow you. So, you're sailing on a given course, and you want to "rotate" the hull at 5° or 10° or whatever - whilst maintaining the same course. How do you do that?

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34 minutes ago, erdb said:

 

 

You don't need more lift for this, and rotating the hull doesn't affect VMG directly either. Once the hull is in the air, VMG depends mainly on the efficiency or lift/drag ratios of the foils and sails. The rotation of the hull only affects hull aero and the geometry of how the foil vs rudder are positioned and how the sails are set relative to the hull. It doesn't have a direct effect on which direction the boat is moving. It's really just rotating the hull relative to the direction of movement.

That is true and it brings up a interesting point.  The direction the hull points will be for optimal aero drag, RM, sail sets, etc and not an indicator of the direction the boat is moving.

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15 minutes ago, The_Alchemist said:

That is true and it brings up a interesting point.  The direction the hull points will be for optimal aero drag, RM, sail sets, etc and not an indicator of the direction the boat is moving.

Original post sounds like buzz word babble to me. How do you go about "just rotating the hull relative to the direction of movement" ?

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58 minutes ago, MaxHugen said:

I don't follow you. So, you're sailing on a given course, and you want to "rotate" the hull at 5° or 10° or whatever - whilst maintaining the same course. How do you do that?

The cats did it in Bermuda. Oracle discovered it first, and ETNZ followed suit. They effectively wracked or twisted the platform by tensioning the normally slack leeward shrouds.

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1 hour ago, erdb said:

 

 

You don't need more lift for this, and rotating the hull doesn't affect VMG directly either. Once the hull is in the air, VMG depends mainly on the efficiency or lift/drag ratios of the foils and sails. The rotation of the hull only affects hull aero and the geometry of how the foil vs rudder are positioned and how the sails are set relative to the hull. It doesn't have a direct effect on which direction the boat is moving. It's really just rotating the hull relative to the direction of movement.

Crab Walk

 

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8 minutes ago, Horn Rock said:

The cats did it in Bermuda. Oracle discovered it first, and ETNZ followed suit. They effectively wracked or twisted the platform by tensioning the normally slack leeward shrouds.

Didn't know that. Any articles describing that?

Still, the original  post was referring to a monohull, and somehow rotating it without changing the direction of travel... can't see that!

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7 minutes ago, MaxHugen said:

Any articles describing that?

I think it was Ken Read describing it in commentary. NZ spotted Oracle doing it, then asked the Measurement Committee for a ruling on it.

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30 minutes ago, MaxHugen said:

Didn't know that. Any articles describing that?

Still, the original  post was referring to a monohull, and somehow rotating it without changing the direction of travel... can't see that!

The two points of contact with the water determine the direction of travel, not the shape of the structure that connects them.  

It differs if the hull is in contact with the water like a typical boat, but since the hull is out of the water it is merely the connector that holds the foil and rudder together (ignoring air drag or sail lift, etc...).  

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Sure, but without rotating the foil arm on the horizontal plane, the question remains...

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15 minutes ago, The_Alchemist said:

Speed calcs of 36 to 38 knots

Nice work.  I couldn't even spot any seagulls.

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1 hour ago, The_Alchemist said:

Speed calcs of 36 to 38 knots

Are you able to calc the take-off speeds of any of the boats from previous videos? Just curious, after 19kn on one foil was mentioned, I think by Max Sirena. Still seems high to me... but maybe that's what it is.

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2 hours ago, MaxHugen said:

Sure, but without rotating the foil arm on the horizontal plane, the question remains...

If you watch the video you can see them doing it.
It seems wrong because the vertical profile of the foil would seem to have force leeward, but I guess the flaps on the foil change that.
Watch the video and you will see it happening.  I/we are guessing how they do it, and what benefits there might be - but they are doing it with very improved VMG.

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3 hours ago, The_Alchemist said:

That is true and it brings up a interesting point.  The direction the hull points will be for optimal aero drag, RM, sail sets, etc and not an indicator of the direction the boat is moving.

Exactly

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3 hours ago, Horn Rock said:

The cats did it in Bermuda. Oracle discovered it first, and ETNZ followed suit. They effectively wracked or twisted the platform by tensioning the normally slack leeward shrouds.

That's a different kind of rotation, more like twisting. But, the cats did some crab walking, too, which may have been for the same reasons - increase the lateral distance (across the direction of movement) between main foil and windward rudder that provided additional righting moment.

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2 hours ago, MaxHugen said:

Sure, but without rotating the foil arm on the horizontal plane, the question remains...

I guess the boats are designed to sail this way, so the foils are already angled accordingly, plus you can fine-tune with the flaps. Rudder is turned relative to the hull as if the boat was turning off the wind, but it goes straight, because the rudder is parallel with the direction of movement.

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3 hours ago, Horn Rock said:

The cats did it in Bermuda. Oracle discovered it first, and ETNZ followed suit. They effectively wracked or twisted the platform by tensioning the normally slack leeward shrouds.

 Not quite. What Oracle did in Bermuda, imitated by ETNZ, was to slacken the top shrouds/stays so that the platform would twist and the windward hull would point down (pitch plane). This solely for the purpose of increasing the windward stabilator’s AoA (and related downforce) beyond the Rule limits

 

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47 minutes ago, Stingray~ said:

The crabbing we’ve seen, could it have been simply tide? 

No

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