Emirates Team New Zealand.

MaxHugen

Super Anarchist
New video by Pietro and Vittorio, I'm sure they're gonna do the English Version, so I'll do just a preview translation :

- Due to the lowered deck configuration, with the two high "pods" at both sides, ETNZ added mainsail area could be not performing at best (Venturi Effect doesn't apply)

- The last interpretation (N.91) about the rudder seems to show that they wants to change the hight of the rudder between races, or just before the beginning, so they can have always the same flight altitude in every sea condition. This is something very clever, that LR could try to copy
Will be interesting to listen to the English version... I'm not clear as to what they mean by venturi effect?
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The change in rudder height indeed sounds worthwhile. The foils have an Angle of Incidence (I think it's ~2°). From around 35 knots boat speed, they would want the foil to be at neutral AoA, and use just a slight flap angle for boat altitude, and longitudinal balance.

An increased sea state means they need to fly slightly higher, which would reduce the depth of immersed rudder if keeping the boat at it's design pitch, so using an extended rudder stock counters this nicely.      IMO. :)

 

MaxHugen

Super Anarchist
AC75s have shedloads of RM, 7.5 tonnes of boat x a lever arm between the centre of gravity and the centre of lift of somewhere around 2.5, maybe even 3 metres.  The Centre of lift (CL) will in theory be on to the straight line between the lift centres of the immersed foil and rudder, and given that the foil carries most of the boat's weight the overall CL will be just behind and inside the foil.
Sounds like you are only considering the forces in the "z" plane.

When looking at Heel vs RM moments, it's a different problem. The RM can only vary by a slight amount, governed by the ± forces from the rudder foil.  However sail forces can vary enormously. The resultant Heel moment has to be balanced by the RM moment.  You will have noticed that they reduce sail area in just moderate wind strengths, and even then still need to use more twist and less upper camber to help minimise Heel moment, thus lowering the CE.

 

The Advocate

Super Anarchist
Sounds like you are only considering the forces in the "z" plane.

When looking at Heel vs RM moments, it's a different problem. The RM can only vary by a slight amount, governed by the ± forces from the rudder foil.  However sail forces can vary enormously. The resultant Heel moment has to be balanced by the RM moment.  You will have noticed that they reduce sail area in just moderate wind strengths, and even then still need to use more twist and less upper camber to help minimise Heel moment, thus lowering the CE.
But these boats don't heel in the tradition sense, they just fly higher. Once you are at the desire flight height, you can reduce sail area therefore reduce drag gaining efficiency. That is what DD is talking about with the rotational centre being so far to leeward.

 

KiwiJoker

Super Anarchist
3,734
324
Auckland, NZ
More personally, Emirates Team New Zealand chief executive Grant Dalton faces the question of what his life in sailing has been for.
I suspect that it's a mixture of clickbait and over-thinking the position.  GD is a fiercely proud Kiwi with a ton of smarts and so are the rest of the movers and shakers in ETNZ.  He's quite correct not to share motives and strategy as that will reduce leverage.  He understands how much it means emotionally to the NZ public and financially to NZ business interests.  I'd lay money that  if and when it all comes out, there won't be anything which damages NZ in any way (subject to us act.. ually winning the cup).  It might well take a slightly different direction in terms of the lead-up though to get a stronger world-wide interest and number of competitors. 
Nice Going.  Well said.  Grist for the rumour mill but not much more. It seems this all springs from Matthew Hooten's twisted and unsubstantiated ramblings from behind the NZH paywall. We seem to have most of it here courtesy of Barnyb although without attribution. 

Yes, Dalts has been testing the international waters with a comprehensive document through a third party re hosting rights for the next Cup.  Good for him, I say,  It sets him up with background and expressions of interest before he has to wrestle with slow-to-act local interests for cash and support.  Hooten boldly labels Dalton's ploy as "shopping around." I prefer to think of it as knowing where you stand and strengthening your negotiating position.

And as for Dalton going it alone, without a nod to the Squadron.  Foooie! The RNZYS will always appear aloof from the day-to-day but they will be well briefed on the CEO's thinking. From Barnyb's post:  "Were RNZYS and Team New Zealand ever to clash in the New York courts, both sides know the squadron would win. Should it choose, RNZYS can confidently assert its rights."  Now we're really in the weeds. Tell us something we don't know. This will never happen. Just more evidence of the pure waffle and speculation from Hooten.

 
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jaysper

Super Anarchist
10,172
1,295
Wellington
Nice Going.  Well said.  Grist for the rumour mill but not much more. It seems this all springs from Matthew Hooten's twisted and unsubstantiated ramblings from behind the NZH paywall. We seem to have most of it here courtesy of Barnyb although without attribution. 

Yes, Dalts has been testing the international waters with a comprehensive document through a third party re hosting rights for the next Cup.  Good for him, I say,  It sets him up with background and expressions of interest before he has to wrestle with slow-to-act local interests for cash and support.  Hooten boldly labels Dalton's ploy as "shopping around." I prefer to think of it as knowing where you stand and strengthening your negotiating position.

And as for Dalton going it alone, without a nod to the Squadron.  Foooie! The RNZYS will always appear aloof from the day-to-day but they will be well briefed on the CEO's thinking. From Barnyb's post:  "Were RNZYS and Team New Zealand ever to clash in the New York courts, both sides know the squadron would win. Should it choose, RNZYS can confidently assert its rights."  Now we're really in the weeds. Tell us something we don't know. This will never happen. Just more evidence of the pure waffle and speculation from Hooten.
ETNZ will have a cast iron contract that tells RNZYS to do whatever the fuck they say.

Why would ETNZ do all the work and have it any other way?

You think RNZYS chose mono foilers?

 

LB 15.1

Member
326
55
Sanxenxo
Daltons either a dick or knows his boat is so superior it will trounce Prada.

The time to sus out the next AC venue is after you've won it.

Dalton is all about Dalton.

He is after the best deal for what his new billionaire sponsor demands.

He is also after the biggest pay packet he can get.

Dalts is just positioning his organisation to put pressure on the NZ govt to give out millions to rich white guys to lather up Thier overindulged egos.

 

nroose

Super Anarchist
5,314
331
Berkeley
4 hours ago, Mozzy Sails said:

I've had a week off videos, but I thought this video from Vittorio d'Albertas is worth a watch as a balance to the video I put out about the mast foot on ETNZ. 

Myself and Rob actually debated back and forth about the issues the Italian raise. How valuable is the sail area in the 'trench'? The ETNZ chaps were running tell tales on those pods just after the launch, so it's surely been an area of validation for the team themselves. 

My initial thought was aligned with the Italians, in that the windward pod would create a bit of an obstacle for the air arriving to the sail, and that the tunnel may create a 'choke point' which the air spills out of. 

Rob on the other hand was more convinced. He feels the pods are far enough aft they the wind isn't really going over them. And that the leeward pod may help keep flow attached around the leeward side.

Hard to know for sure... I guess answering these questions is why we have boat races! 


Yes, it will be very interesting to see the racing! I am guessing the low deck, pods, and sail on NZ are really great for the end-plating, but probably not resulting in extra sail area that is particularly effective. Admittedly just based on my imagination.

 

LB 15.1

Member
326
55
Sanxenxo
ETNZ will have a cast iron contract that tells RNZYS to do whatever the fuck they say.

Why would ETNZ do all the work and have it any other way?

You think RNZYS chose mono foilers?
Rnzys is just a race hosting club.... Unlike new York..  who get the cash for team America Magic.

Dalton could choose the dannevirke yacht club ( a $500 shed on a farm) if he wanted.

The club don't even manage the races.

 

jaysper

Super Anarchist
10,172
1,295
Wellington
Rnzys is just a race hosting club.... Unlike new York..  who get the cash for team America Magic.

Dalton could choose the dannevirke yacht club ( a $500 shed on a farm) if he wanted.

The club don't even manage the races.
I'm not sure NYYC has much more say quite frankly.

He who pays the piper calls the tune.

 

LB 15.1

Member
326
55
Sanxenxo
Yes, it will be very interesting to see the racing! I am guessing the low deck, pods, and sail on NZ are really great for the end-plating, but probably not resulting in extra sail area that is particularly effective. Admittedly just based on my imagination.
Youre right the low curved deck, boom end detail, cowling design, and even small things like the fineness of the transom corners where the backstays enter are just so superior and so well engineered... It's all to reduce laminar separation / end plate effect.

These guys could build awesome planes!

Mind you Hasn't every boat except prada capsized, spun out...    Which tell me that prada is an excellent controllable package.

ETNZ outside hull shape looks like it has far to much surface area friction and area of high air turbulence zones compared to pradads smooth lines.

 

jaysper

Super Anarchist
10,172
1,295
Wellington
Rnzys is just a race hosting club.... Unlike new York..  who get the cash for team America Magic.

Dalton could choose the dannevirke yacht club ( a $500 shed on a farm) if he wanted.

The club don't even manage the races.
I'm not sure NYYC has much more say quite frankly.

He who pays the piper calls the tune and the NYYC aren't the ones paying the piper.

 

LB 15.1

Member
326
55
Sanxenxo
The yacht club aren't the sponsor, the rich fuckers who belong to it are.
Correct but the contract with the sponsors gives the sponsors advertising profile in return for the NYYC setting the rules and how they spend the money.

Believe me the NYYC call the shots fiscally based on a plan developed between them and the CEO of team AM. Basically the sponsors get naming rights and a few perks. Just like emerates 

Billionaire sponsors are different and are team owners and the team CEO is an employee of the Billionaire.

 
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