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      Abbreviated rules   07/28/2017

      Underdawg did an excellent job of explaining the rules.  Here's the simplified version: Don't insinuate Pedo.  Warning and or timeout for a first offense.  PermaFlick for any subsequent offenses Don't out members.  See above for penalties.  Caveat:  if you have ever used your own real name or personal information here on the forums since, like, ever - it doesn't count and you are fair game. If you see spam posts, report it to the mods.  We do not hang out in every thread 24/7 If you see any of the above, report it to the mods by hitting the Report button in the offending post.   We do not take action for foul language, off-subject content, or abusive behavior unless it escalates to persistent stalking.  There may be times that we might warn someone or flick someone for something particularly egregious.  There is no standard, we will know it when we see it.  If you continually report things that do not fall into rules #1 or 2 above, you may very well get a timeout yourself for annoying the Mods with repeated whining.  Use your best judgement. Warnings, timeouts, suspensions and flicks are arbitrary and capricious.  Deal with it.  Welcome to anarchy.   If you are a newbie, there are unwritten rules to adhere to.  They will be explained to you soon enough.  
rh2600

Dan Bernasconi Describes The Three AC75 Concepts

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41 minutes ago, nav said:

^ Haven't they already said that the Class Rule is to be decided on and written between now and March, in conjunction with LR, i.e. there is no class rule yet!?

Please go ahead and rephrase the questions as required to make the point clear. I'm trying to ask what Dan thinks the intention of rules are gonna be and/or what he wants them to be regarding the issues raised. I'm sure there are room for improvement and additions to be made. This is a discussion forum and you are welcome to contribute as well as anyone else and I don't mind any of them being changed for something better. (but not by me)

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I was multitasking at the time the Q from here got asked and missed some of it (will watch the replay) but I ~think~ ‘Dr Dan’ said RM from an immersed ww foil will be ruled out; both because the forces would be too dangerous and because of the structural requirements that it would take.

Nice interview! He sounded reassuringly confident about this boat.

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37 minutes ago, Terry Hollis said:

My question is ..

Will the contestants be required to have their vessels in stability mode until they cross the start line?

If it's an upwind start I think it's kind of going to be a bit of a moot point anyway.

The amount of jockeying and manauvering on the line will probably rule out getting fully powered up on one tack or another until right before the gun anyway.

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At https://www.sailingillustrated.com/single-post/2017/11/28/Tuesdays-with-TFE-Watch-a-replay-of-todays-lively-and-enlightening-netcast-with-ETNZ-Technical-Director-Dr-Dan-Bernasconi-GBRNZL

Tuesdays with TFE: Watch a replay of today's lively and enlightening netcast with ETNZ Technical Director Dr Dan Bernasconi (GBR/NZL)

SAN FRANCISCO – An hour packed full of insight into the radical new AC75 yacht planned for the 2021 America's Cup, thanks to ETNZ Technical Director Dan Bernasconi who joined TFE live via Skype from the ETNZ base in Auckland, NZL. Watch a replay on our SI Facebook page here

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Q1: will the rule allow to use only one rudder T foil or 2 ?

Q2: If yes, will they be able to use dowforce to increase the righting moment or improve longitudinal the stability ?

Q3: Will the minimum hull weight be limited ?

Q4: Will the minimum width of the hull be limited ?

Q5: If not, will it be authorized to have longer arms for the foils ?

Q6: Will the winward foil be allowed to be left down for better stability in some wind conditions ? if yes, will it be necessary to fill the foil with weight or could it be hollow ? or filled with lighter than air material ?

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17 minutes ago, Boybland said:

If it's an upwind start I think it's kind of going to be a bit of a moot point anyway.

The amount of jockeying and manauvering on the line will probably rule out getting fully powered up on one tack or another until right before the gun anyway.

The point of having them in stability mode during the prestart is that it satisfies the needs of spectators who crave for the "traditional" lead mines.

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4 minutes ago, Terry Hollis said:

The point of having them in stability mode during the prestart is that it satisfies the needs of spectators who crave for the "traditional" lead mines.

You have a point, but if it had been their intention they would have organized starts on the reach. I would say that the game in the prestart will be to put the other "down" while been able to foil, IF..........any is able to foil upwind with this concept, and if yes, after what wind limit. Remember: 9 kts of wind to fly, but presumably not upwind...

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1 hour ago, ~Stingray~ said:

I was multitasking at the time the Q from here got asked and missed some of it (will watch the replay) but I ~think~ ‘Dr Dan’ said RM from an immersed ww foil will be ruled out; both because the forces would be too dangerous and because of the structural requirements that it would take.

Nice interview! He sounded reassuringly confident about this boat.

It is at around 36:00 of the replay

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29 minutes ago, Tornado-Cat said:

Did he ? I had not read that before using the word "foil arm" !

Good for you, yes they got into the terms and that’s the exact one Dan led TE to.

The Rule for the shape of that arm is also under discussion, I hope they leave some design room both there and especially so in the ‘foil wing.’

Interestingly, the intention already seems to be to allow a lot of room around the hull shape - partly as a nod to fans. WetHog will be among those who love that.

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23 minutes ago, ~Stingray~ said:

 

The Rule for the shape of that arm is also under discussion, I hope they leave some design room both there and especially so in the ‘foil wing.’

 

Oh, thanks for making me thinking, I have another question:

Q7: Will it be authorized to have arms equipped with flaps with positive and negative incidence ?

No question for foil wings, it seems obvious it will be authorized.

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Yes, great question although it didn’t come up. But if the foil arms have to be S shaped for any reason, it’d be quite a design challenge to pull that off.

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14 minutes ago, ~Stingray~ said:

The Rule for the shape of that arm is also under discussion, I hope they leave some design room both there and especially so in the ‘foil wing.’

It was made clear in this interview that there will be only one (not 2) rudder with elevator, and no down force by wing of the windward foil. It has been made clear earlier that windward foil is allowed in the water during a race and called as stability mode. This time it was referred only as a temporary measure, but that doesn't indicate any change, just that alternative was not discussed again.

I can't see any way to make those things happen without very restrictive rules and some one-design part for foils (wing, arm, and orientation of canting pin and flap range for the wing)

But Dan just said foil hydraulics and pin will probably be one design and they are still considering if rest of the foils are one design or not.

They can not allow windward foil in the water and just write a rule to forbid using down force, because there is no way to police such a rule. they have to choose at some point in time:

1) either not to allow windward foil in the water for any predetermined period of time while foiling

OR

2) make foil parts one design and with very restrictive rules what can move and at what direction/axis and at what range. That makes down force impractical and inefficient, but leaves some fuzziness for very small down force in some situations.

7 minutes ago, Tornado-Cat said:

Oh, thanks for making me thinking, I have another question:

Q7: Will it be authorized to have arms equipped with flaps with positive and negative incidence ?

No question for foil wings, it seems obvious it will be authorized.

Flap wings will obviously be authorised, has been made clear earlier. But their range of deflection can not be open, if windward foil is allowed in the water for a long time while racing and down force is not intended to be possible in any significant amount.

 

Did I got the interview correctly in all those items? Can someone conform? 

 

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57 minutes ago, Tornado-Cat said:

You have a point, but if it had been their intention they would have organized starts on the reach. I would say that the game in the prestart will be to put the other "down" while been able to foil, IF..........any is able to foil upwind with this concept, and if yes, after what wind limit. Remember: 9 kts of wind to fly, but presumably not upwind...

I'm pretty sure that the minimum wind speed to allow taking off is more than minimum allowing maintaining flight. If they can take off in 9 knots in a reach it will be very probable they can also sail to windward in 9 kts if already flying. I thought the mentioned 9 kts was referring to the take off wind speed, not minimum flying wind speed. But then all those are just estimates at this time, as there is no boat or even a design, just a concept. 

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1 hour ago, Terry Hollis said:

The point of having them in stability mode during the prestart is that it satisfies the needs of spectators who crave for the "traditional" lead mines.

The meaning of stable sail mode is referring to both foils being in foiling position symmetrically. That would not result anything like the "traditional" lead mines.

But might allow fast foiling tacks in some wind conditions, like AC50.

Perhaps you were referring to dock mode instead, as in both foils fully down under the boat? Slow mode, and heeling over easily, like narrow lead mines with too much sail on.

And allowing changing modes after start, policing by sensors with radio transmitters to the umpires, so they can call it if someone uses foils too early, but not visibly, just close to the surface?

 

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6 minutes ago, NotSoFast said:

The meaning of stable sail mode is referring to both foils being in foiling position symmetrically. That would not result anything like the "traditional" lead mines.

But might allow fast foiling tacks in some wind conditions, like AC50.

Perhaps you were referring to dock mode instead, as in both foils fully down under the boat? Slow mode, and heeling over easily, like narrow lead mines with too much sail on.

And allowing changing modes after start, policing by sensors with radio transmitters to the umpires, so they can call it if someone uses foils too early, but not visibly, just close to the surface?

 

You are right .. I was referring to "Dock Mode" as they cannot foil in Dock Mode.

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I wonder how fast the foil arms will be able to rotate? It could be a big-time differentiator, perhaps it accounts for the idea to OD all that part of it? Battery power remaining could get interesting too.

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2 hours ago, ~Stingray~ said:

Good for you, yes they got into the terms and that’s the exact one Dan led TE to.

The Rule for the shape of that arm is also under discussion, I hope they leave some design room both there and especially so in the ‘foil wing.’

Interestingly, the intention already seems to be to allow a lot of room around the hull shape - partly as a nod to fans. WetHog will be among those who love that.

The do a lot of things I do like.  I love that they allow the hull shape to be open.  See if anyone comes up with some wild ideas that are both visually and possibly functionally very different.  I loved when Oracle brought out the "Bat Boat", which was visually and functionally significantly different than ETNZ, LR, and AR, with the central pod for structure and end-plate.  there may be some very innovative ways that the hull shape can change the way the foils work.  Oh, yeah, and for simpletons like me, the boats may actually LOOK different.

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My notes from the interview:(apologies for double post..) 

Hull:
Hull design will be open (to box rule). A big part of design challenge will be hull efficiency, who can get on foils first and who can accelerate fastest. Plus, fans are interested in different looking boats. The hull will ride only 1-2feet above water in normal foiling. 

Foils:
Main Foils: (Foil Arm + Foil Wing) 
- Fixed Wing with Trim Tabs controlling ride height. 
- Electric / Hydraulic controls will raise the Foil in estimated 3-5 seconds. 
- Max Draft in Mooring Mode will be 5m (16ft)

T Foil: will have 2 independent control surfaces (apart from rudder). Either the whole foil will cant fore & aft like AC50, or, the whole elevator (horizontal wing) will pivot. With either system there will also be trim tabs on the elevator.
There is minimal load on T foil, due to being very close to balanced on the Main Foil. DB says, you could almost remove the T foil and have the boat continue sailing (before imminent wipe out..) 

Mast: One design to stop syndicates having to build and test multiple iterations. 

Sails:
Main: Still under development. Mast likely one design (or at least its shape). Reefing is still being determined, but more likely a 2nd smaller main with same loft height but shorter chord will be allowed. 

Sailing:
- Windward Foil will not be allowed to be used submerged for wing generated downforce adding to righting moment (probably above a minimum windspeed). This is to stop syndicates building light air / heavy air boats (with heavy & very strong rig for extra load). This way the RM loads don't increase much over the wind range and all racing remains competitive.
- Wind range upper limit will not be finalised until initial boats are tested, but DB suggested 25 knots as an initial indicator.
- Prestarts - Boats may sail with 2 Main Foils submerged (stability mode). Unknown as yet if it's a benefit. 

Grinding:
Cyclors banned. Grinders efforts will be focussed on sail lofting and trim. 

One Design:
Many parts will be one design to reduce cost. e.g.: Electric / Hudraulic Foil lifting system, controls, bearings etc., possibly the Main Foil Arms (but not wings), the Mast (but not sails). 

Cost:
DB disputed Dennis Connors $US140M cost estimate, saying something like "if that is the case ETNZ don't have a show of competing." He expects costs to be substantially lower through One Design components and that the Protocol will allow syndicates to purchase designs off existing syndicates (e.g. ETNZ, Luna Rossa, BAR)

Dates:
- Design Rule Released March 2018
- First date boat launch March 2019
 

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26 minutes ago, zillafreak said:

Foils weigh 1.5 tons each? How the F you gonna move 1.5 tons with any speed?

Powerful hydraulics apparently.. 

They're going to have to find a way to do it fast or tacking duels and pre-starts will be a bore.. 

They'll be a lot quicker to drop though.. 

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Another thing they mentioned was the "diamond" exclusion zone. 

From memory, it will be the 4 points of the perimeter (bow, stern, P foil, S foil) with maybe a small offset. 

DB says the GPS monitoring they have on the boats is accurate to millimetres, so boats will know when they're close to fouling the virtual diamond. 

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3 hours ago, NotSoFast said:

The meaning of stable sail mode is referring to both foils being in foiling position symmetrically. That would not result anything like the "traditional" lead mines.

But might allow fast foiling tacks in some wind conditions, like AC50.

 

And foiling downwind stable and deep in light. At least this configuration could be compared to the other mode.

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20 minutes ago, Tornado-Cat said:

And foiling downwind stable and deep in light. At least this configuration could be compared to the other mode.

That was the only area of DB's explanations that I didn't get. 

How Stable Mode - 2 foil sailing is allowed, but generating RM via downforce is not.. How will they police that.. Load or angle sensors on the foil trim tabs? 

DB has said stability mode is definitely allowed in pre-starts and "difficult conditions", but hasn't specified when (or if) it's disallowed. 

Maybe difficult conditions is large chop or low wind. 

.. Perhaps the design protocol will only allow Main Foil Trim tabs to pivot between neutral and flaps down and if so, could ride height still be controlled... 

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Listening to the Dan Bernasconi interview it was interesting to hear that Grant Simmer gave his him his start whilst at Alinghi. Given the fact that Bernasconi via TNZ defeated Oracle for the AC I wonder if Dan knew what was needed to defeat a team led by Simmer after working under him for so long? 

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8 minutes ago, waterboy42 said:

That was the only area of DB's explanations that I didn't get. 

How Stable Mode - 2 foil sailing is allowed, but generating RM via downforce is not.. How will they police that.. Load or angle sensors on the foil trim tabs? 

DB has said stability mode is definitely allowed in pre-starts and "difficult conditions", but hasn't specified when (or if) it's disallowed. 

Maybe difficult conditions is large chop or low wind. 

.. Perhaps the design protocol will only allow Main Foil Trim tabs to pivot between neutral and flaps down.. 

I did not listen to the interview but I agree with you, by all means, and whatever the solution, they will have difficulty to control that when both foils are down.

Even if they have sensors, how to prevent a foil from pulling down, they will have to introduce some kind of rule "for no more than 4 seconds". Anyway, they have a lot to figure out.

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31 minutes ago, terrafirma said:

Listening to the Dan Bernasconi interview it was interesting to hear that Grant Simmer gave his him his start whilst at Alinghi. Given the fact that Bernasconi via TNZ defeated Oracle for the AC I wonder if Dan knew what was needed to defeat a team led by Simmer? 

Yeah, he applied to ETNZ as well, but was turned down as he didn't know anything about sailing and was just a Mech Engineer at the time. Alinghy sponsored him through his PhD in Aerodynamics & Mathematical Modeling (or similar) as he tailored his research to their Sail Development Program. 

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1 hour ago, Tornado-Cat said:

I did not listen to the interview but I agree with you, by all means, and whatever the solution, they will have difficulty to control that when both foils are down.

Even if they have sensors, how to prevent a foil from pulling down, they will have to introduce some kind of rule "for no more than 4 seconds". Anyway, they have a lot to figure out.

I think he said that it was max 10 sec on the 50's . Apparently the problem is the rig. An extra rig would be needed to deal with the pressure in heavy winds

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13 hours ago, NotSoFast said:

The meaning of stable sail mode is referring to both foils being in foiling position symmetrically. That would not result anything like the "traditional" lead mines.

But might allow fast foiling tacks in some wind conditions, like AC50.

Perhaps you were referring to dock mode instead, as in both foils fully down under the boat? Slow mode, and heeling over easily, like narrow lead mines with too much sail on.

And allowing changing modes after start, policing by sensors with radio transmitters to the umpires, so they can call it if someone uses foils too early, but not visibly, just close to the surface?

 

Two foils in stability mode, will allow the boat to foil at a slower speed, which may be beneficial pointing to windward... ie pointing higher to windward at slow speed rather than reaching at high speed the wrong way. 

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35 minutes ago, dachopper said:

Two foils in stability mode, will allow the boat to foil at a slower speed, which may be beneficial pointing to windward... ie pointing higher to windward at slow speed rather than reaching at high speed the wrong way. 

I think the idea was that it would add maneuverability in the pre-start

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11 hours ago, waterboy42 said:

My notes from the interview:(apologies for double post..) 

 

Foils:
Main Foils: (Foil Arm + Foil Wing) 
- Electric / Hydraulic controls will raise the Foil in estimated 3-5 seconds. 
 

Grinding:

... Grinders efforts will be focussed on sail lofting and trim. 

 

Thanks for the summary.

The two points left above suggest motor powered rather than arm powered canting

Was that your impression? Is that what you meant by Electric / Hydraulic controls?

Was this addressed any more directly, i.e. batteries/motors/fuel cells etc

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45 minutes ago, nav said:

Thanks for the summary.

The two points left above suggest motor powered rather than arm powered canting

Was that your impression? Is that what you meant by Electric / Hydraulic controls?

Was this addressed any more directly, i.e. batteries/motors/fuel cells etc

Agree, very good summary by waterboy.

While Dan strongly suggested that the power will be from batteries (and GD already ruled out combustion engines, making this choice the obvious one), he said they were still considering whether to handle the loads through hydraulics or electric motors. Either way, the whole arm-lifting operation is likely to be OD.

In one brief comment Dan also alluded to a likelihood of boats not changing modes, raising and lowering the foil arms, too frequently for the reason it could use too much of the stored energy.

My guess is they have had to think hard about how big to make the batteries; lighter is better for performance but means less power available, which may also play into how much the foils should get in ballast weight, thereby reducing RM. A weight vs RM trade-off.

He did say they'll have 'plenty' of RM anywhere in that 1-2 ton per foil ballast range, so maybe the weight difference between either hydro or electric-motor is already sorted and they can go either way and the choice is more about viability, electric motors being a much newer option.

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1 hour ago, jonas a said:

I think the idea was that it would add maneuverability in the pre-start

Maybe, but if you can't change the foil sizes depending on wind like the ac50s, then the next best thing would be underspec the thickness so that in lower winds you require two foils down , til say 20kts boat speed, then  1 could take the load with minimal drag..

 

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19 minutes ago, dachopper said:

Maybe, but if you can't change the foil sizes depending on wind like the ac50s, then the next best thing would be underspec the thickness so that in lower winds you require two foils down , til say 20kts boat speed, then  1 could take the load with minimal drag..

 

But wouldn't lift fron windward foil drastically (long arm) eat into the very RM that's propelling the boat forward?

 

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1 hour ago, ~Stingray~ said:

I don't think Dennis is right, but I don't think ETNZ will achieve their goal of making it more affordable either.

 

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4 hours ago, ~Stingray~ said:

Agree, very good summary by waterboy.

While Dan strongly suggested that the power will be from batteries (and GD already ruled out combustion engines, making this choice the obvious one), he said they were still considering whether to handle the loads through hydraulics or electric motors. Either way, the whole arm-lifting operation is likely to be OD.

In one brief comment Dan also alluded to a likelihood of boats not changing modes, raising and lowering the foil arms, too frequently for the reason it could use too much of the stored energy.

My guess is they have had to think hard about how big to make the batteries; lighter is better for performance but means less power available, which may also play into how much the foils should get in ballast weight, thereby reducing RM. A weight vs RM trade-off.

He did say they'll have 'plenty' of RM anywhere in that 1-2 ton per foil ballast range, so maybe the weight difference between either hydro or electric-motor is already sorted and they can go either way and the choice is more about viability, electric motors being a much newer option.

Again to clarify, if you have batteries you have electric motors doing the work either way - the difference being whether they cant the foils directly or they pump oil - right?

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So they are removing athletes from the boats and replacing them with batteries because the blazer brigade would rather watch rail meat aggressivly perching on the side of the hull than blokes on bikes?

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16 hours ago, waterboy42 said:

That was the only area of DB's explanations that I didn't get. 

How Stable Mode - 2 foil sailing is allowed, but generating RM via downforce is not.. How will they police that.. Load or angle sensors on the foil trim tabs? 

DB has said stability mode is definitely allowed in pre-starts and "difficult conditions", but hasn't specified when (or if) it's disallowed. 

Maybe difficult conditions is large chop or low wind. 

.. Perhaps the design protocol will only allow Main Foil Trim tabs to pivot between neutral and flaps down and if so, could ride height still be controlled... 

16 hours ago, Tornado-Cat said:

I did not listen to the interview but I agree with you, by all means, and whatever the solution, they will have difficulty to control that when both foils are down.

Even if they have sensors, how to prevent a foil from pulling down, they will have to introduce some kind of rule "for no more than 4 seconds". Anyway, they have a lot to figure out.

I see 2 very different approaches to that:

1) One-design foils, and flaps and deflection range control by the rules. Also foil arm cant axis orientation defined by the rules. This limits any static down force to be generated directly, but with limitations do design freedom.

2) Let the wing of the foil free to produce down force as much as you want, but prevent the boat receiving any RM from it. Meaning that there is a pressure relief valve in the one-design hydraulic system, that controls foil arm canting. Dimension it so, that it can support weight of the foil, but not much more. Then if you try to use down force, the foil arm will simply move down, thus delivering no more RM to the boat or mast & sails.

In all cases, there will always be instantaneous down force as a gust response when ever windward foil is in the water. Wing gust induces rolling motion to the boat, the windward foil move upwards together with the boat rolling, and down wards hydrodynamic lift is generated as a result regardless if wanted or not. This can not and should not be penalized. Only that there is no static down force, ie the time integral of the instantaneous value can't exceed value caused by gravity on the foil alone in any significant period of time.

 

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6 minutes ago, SunFroggy said:

So they are removing athletes from the boats and replacing them with batteries because the blazer brigade would rather watch rail meat aggressivly perching on the side of the hull than blokes on bikes?

No. All sail control is by human muscle power, but only arm muscle, not legs. Only foil control receiving energy from batteries. 

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5 hours ago, Xlot said:

But wouldn't lift fron windward foil drastically (long arm) eat into the very RM that's propelling the boat forward?

 

Not when the wind is so light that the boat is under powered, and not capable of using all RM it has due to lack of sail area and mast height. It's reasonable that the boat can foil in such conditions when using some lift from windward foil as well. At least when going downwind, when heeling moment is low with significant driving force.

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3 minutes ago, NotSoFast said:

Not when the wind is so light that the boat is under powered, and not capable of using all RM it has due to lack of sail area and mast height. It's reasonable that the boat can foil in such conditions when using some lift from windward foil as well. At least when going downwind, when heeling moment is low with significant driving force.

 

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Just re-listened to parts of DB interview on Sailing Illustrated. 

A couple of clarifications below, as finer points are easy to misinterpret... 

T Foils:
Either complete foil will cant fore & aft, or there will be trim tabs on elevator (but not both) 

Main Foils (Arm + Wing):
It sounds like the 1 - 1.5 tonnes of ballast is in the Foil Wing alone (I initially took it to mean in the combined Foil Assembly (Arm + Wing)).
I have re-watched it a few times and it definitely comes across like that..

You would need 88 litres (about the body volume of a large 90kg male) of pure lead, or 127 litres of steel, for just 1 tonne, and presumably (if lead) encased in a structurally strong shell. This sounds huge, but I guess the in scale of a 75ft boat even a foil is larger than it appears.

Stability Mode:
Dan has done a lot of sailing simulation on this. Dan says "this mode is nice in a pre-start as you can do lots of manoeuvres without using up energy & time raising / lowering foils. It's quite easy to mode sail if you are controlling the altitude or flap angle on both foils."

Dan later says although you won't be allowed to generate downforce from windward foil, they haven't worked out exactly how they will limit this. 

Canting Operation:
Likely to be battery powering a hydraulic motor. Tom asks to clarify if electric or hydraulic motor? Dan says in AC they have traditionally used hydraulic motors for high loads, but electric motor options will also be looked at. The foils will raise in a few seconds

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Tell me again how this is “relatable” to us sailors? Sorry. Just kicking my high chair. 

Foiling is cool, mono is good. But will J and Bene be able to use any trickle down? At least the last several cycles have inspired  small cat foilers. 

 

Docking my future mono-with-lizard-legs will be a hoot. 

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2 minutes ago, dogedog said:

Tell me again how this is “relatable” to us sailors? Sorry. Just kicking my high chair. 

Foiling is cool, mono is good. But will J and Bene be able to use any trickle down? At least the last several cycles have inspired  small cat foilers. 

 

Docking my future mono-with-lizard-legs will be a hoot. 

Actually, I think it's partly why they've gone this route, i.e.- they need foiling for public interest and sponsors / TV, but they want to make tech that can trickle down. 

- These will be narrow and stable (in mooring mode) and fit in a standard marina berth (unlike most cats) 

- Soft wing tech that can be raised / lowered will be usable by mainstream sailors

 

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I’m sure that’s why they are trying to appease both sides (mono / foilers) but the lizard legs are whacky... why not ‘boards’ that are pulled up and and down vertically w L foils through the hull? Swinging legs is crazy. (I know if you told me 10 years ago I would have no problem getting in a strangers car and prearranged payment called Uber I wouldn’t have believed it...)

 

just saying I hope the swinging lizard legs innovates a more ellagant approach in the future. 

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Btw - the last cycle was the first to get the stink pot owners at the club excited and saying “man, they are really going that fast?!” You could tell their twin cat 600 hp motors were feeling a little envious ;-)

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1 hour ago, NotSoFast said:

 

I see 2 very different approaches to that:

1) One-design foils, and flaps and deflection range control by the rules. Also foil arm cant axis orientation defined by the rules. This limits any static down force to be generated directly, but with limitations do design freedom.

2) Let the wing of the foil free to produce down force as much as you want, but prevent the boat receiving any RM from it. Meaning that there is a pressure relief valve in the one-design hydraulic system, that controls foil arm canting. Dimension it so, that it can support weight of the foil, but not much more. Then if you try to use down force, the foil arm will simply move down, thus delivering no more RM to the boat or mast & sails.

In all cases, there will always be instantaneous down force as a gust response when ever windward foil is in the water. Wing gust induces rolling motion to the boat, the windward foil move upwards together with the boat rolling, and down wards hydrodynamic lift is generated as a result regardless if wanted or not. This can not and should not be penalized. Only that there is no static down force, ie the time integral of the instantaneous value can't exceed value caused by gravity on the foil alone in any significant period of time.

 

1) I'm think foil wings (& flaps) may be open design (to box rule), while foil arms (and mechanisms) may likely be one design for cost reasons. This potentially allows teams multiple wing configurations if they independently attach to arms, and keeps a critical part of design innovation / differentiation and light / heavy air selection. However, unless they allow a ballast range (eg 1-1.5t) then a range of light / heavy wind profiles will be limited, and will take a mini crane to swap out.

2) Interesting solution. I was thinking of some sort of electronic limiter that sensed the wing encountering greater  positive lift force to be the leeward foil and limited the opposite foil flap to only neutral to negative range of motion, but a PRV could be simpler and more elegant solution. 

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18 hours ago, waterboy42 said:

Another thing they mentioned was the "diamond" exclusion zone. 

From memory, it will be the 4 points of the perimeter (bow, stern, P foil, S foil) with maybe a small offset. 

DB says the GPS monitoring they have on the boats is accurate to millimetres, so boats will know when they're close to fouling the virtual diamond. 

Ah, yes, the virtual diamond exclusion zone measured by GPS systems. Part of the grand trickle down vision by GD. 

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50 minutes ago, waterboy42 said:

 

- Soft wing tech that can be raised / lowered will be usable by mainstream sailors

 

My reading (of your notes) is that they've given up on that,  will go for a wing mast and battened main(s)

 

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4 minutes ago, Xlot said:

My reading (of your notes) is that they've given up on that,  will go for a wing mast and battened main(s)

Dr Dan (mad scientist) used the word ‘hoist’ a few times - presumably for the trailing edge.

Click the link (close your eyes if you feel the need to) it’s a pretty good listen once they get into it.

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23 minutes ago, Nauti Buoy said:

Ah, yes, the virtual diamond exclusion zone measured by GPS systems. Part of the grand trickle down vision by GD. 

And wait until they start mentioning boundaries ...

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26 minutes ago, Nauti Buoy said:

Ah, yes, the virtual diamond exclusion zone measured by GPS systems. Part of the grand trickle down vision by GD. 

Not that it makes too much difference but Dan B suggested it could be more ellipse than diamond and also made the reasonable point that despite the Ben Hur Chariot looks, it’s not actually much different an obstacle than what the flying AC50 hulls were.

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21 minutes ago, Xlot said:

My reading (of your notes) is that they've given up on that,  will go for a wing mast and battened main(s)

 

 

The way I understand it is that they plan for a soft wing, or partial wing main, that you can raise & drop. Part of the reason is tech trickle down to mainstream and part is cost reduction, i.e.- shore crew don't need to step & remove daily with a crane. 

Also, instead of a reefing function, they talked of a 2nd smaller main, same height but shorter chord. 

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1 hour ago, NotSoFast said:

No. All sail control is by human muscle power, but only arm muscle, not legs. Only foil control receiving energy from batteries. 

Precisely. Batteries, not people or wind (ie sailing) to power the foils and artificial restraints on what the crew is allowed to do, so they may not be used to best advantage. Will they put the grinders in restraints so they can't use their leg muscles at all?  Excuse me umpire that man appear to be standing. The rules specifically state.....

On the other hand I suppose ooching is also not allowed.

Maybe I should buy a blazer.

 

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7 minutes ago, SunFroggy said:

Precisely. Batteries, not people or wind (ie sailing) to power the foils and artificial restraints on what the crew is allowed to do, so they may not be used to best advantage. Will they put the grinders in restraints so they can't use their leg muscles at all?  Excuse me umpire that man appear to be standing. The rules specifically state.....

On the other hand I suppose ooching is also not allowed.

Maybe I should buy a blazer.

This boat simply can’t work without being powered since raising and lowering the ballast will take so much work. Aside from the AC 33 DoG Match it will be the first time an AC Class will be going this way; we may never see fully Manual-powered AC boats again. Big change.

The grinders will still be busy with Code 0 hoists, Jib furls, tacking and trims, mainsail trim and travelers and maybe leech load, and of course foil and rudder wing tab-trims - which could take considerable effort. Dr Dan suggested they may need to go even above 12 crew and are still thinking about that.

 

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With Dan saying stable mode in pre starts may avoid using too much energy, it will be interesting to know how many foil lifts the batteries will do in a race and at what point it becomes a limiting factor on your manoeuvring ability and tactical decisions, eg, "I can't engage in a tacking duel now as I used up too much juice in the pre-starts"... 

A substantial amount of energy could be returned to the battery (like regenerative braking on EV) when dropping the foil.

As far as I know, to do that you need a hydraulic motor that will work in reverse (as a pump) and an electric motor that will work in reverse (as a generator) 

Don't want the crews getting range anxiety.. 

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8 minutes ago, waterboy42 said:

With Dan saying stable mode in pre starts may avoid using too much energy, it will be interesting to know how many foil lifts the batteries will do in a race and at what point it becomes a limiting factor on your manoeuvring ability and tactical decisions, eg, "I can't engage in a tacking duel now as I used up too much juice in the pre-starts"... 

A substantial amount of energy could be returned to the battery (like regenerative braking on EV) when dropping the foil.

As far as I know, to do that you need a hydraulic motor that will work in reverse (as a pump) and an electric motor that will work in reverse (as a generator) 

Don't want the crews getting range anxiety.. 

I'm still holding onto the hope that these boats will NOT require batteries for the actuation of foils etc.

If they do, how is this a step forward from cyclors?

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The more I learn about this, the less I like it which is a low bar to get under...

 

This... thing... seems designed to appease both sides of an argument while it solves NONE of the issues they raise.

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5 minutes ago, RMac said:

The more I learn about this, the less I like it which is a low bar to get under...

 

This... thing... seems designed to appease both sides of an argument while it solves NONE of the issues they raise.

I'm taking a wait and see approach and I don't think that we will know absolutely for sure until they race. In fact, given the many diverging opinions over  the AC50s that we see on this boar, we probably won't know AFTER they have raced.

But at least each of us individually will know if the AC75 has delivered on our wants. Personally, I didn't like the AC50s and on the face of it, the AC75s seem to solve none of the issues with it from my perspective.

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For the mono folks:

you don't get traditional match racing, instead you get very likely huge speed differentials both between boats and from manouvers, probably worse than the AC50s. 

you don't get boats that look or act like everyman's boat

Is this a mono? Enjoy debating that for the next couple years (at least! who is going to challenge for this?) and trying to explain why this boat doesn't look at all like any boat your non sailing friends have ever seen

For the foiling is fun folks 

It remains to be seen, but does anyone really think this will be faster? 

With a few rule changes the AC50 could have been opened up to allow for safer and faster boats, instead it's starting from scratch on a new concept with highly debatable benefit

For the sailing purists

Cyclors was an issue, but the batteries, exclusion zones between boats, and all the moving appendages aren't? 

For the people that thought the AC was supposed to trickle down to them:

Enjoy your canting ballasted foils, your wing mast, your rotary pumps, your big batteries you'll be pulling every night... 

For the "can we please save the B$ some money crowd"

I don't think the design effort could possibly be less for this boat than for the AC50, nor the systems knock up, nor the developement of completely new technology.  

The crews are going to be larger,  probably more than enough to offset any reduction in shore crew, and is it much less effort to crane an AC50 than to bring the boards off this thing?

 

Im sorry to be a downer, but the more thought i give this the weirder it seems and the more I worry about what the AC is going to be like

 

 

But... the NZ team has been pretty good at pulling out miracles so lets hope it extends to this design brief, and we get some cool lizard leg racing.  If you squint real hard, and imagine the preview video on boats that actually make it work, it's quite a spectacle. 

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21 minutes ago, RMac said:

The more I learn about this, the less I like it which is a low bar to get under...

 

This... thing... seems designed to appease both sides of an argument while it solves NONE of the issues they raise.

Face it.. The sailors will all be AI Robots within a decade..

Let's enjoy it while there's still some human input.. ;)

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5 hours ago, RMac said:

For the mono folks:

you don't get traditional match racing, instead you get very likely huge speed differentials both between boats and from manouvers, probably worse than the AC50s. 

you don't get boats that look or act like everyman's boat

Is this a mono? Enjoy debating that for the next couple years (at least! who is going to challenge for this?) and trying to explain why this boat doesn't look at all like any boat your non sailing friends have ever seen

For the foiling is fun folks 

It remains to be seen, but does anyone really think this will be faster? 

With a few rule changes the AC50 could have been opened up to allow for safer and faster boats, instead it's starting from scratch on a new concept with highly debatable benefit

For the sailing purists

Cyclors was an issue, but the batteries, exclusion zones between boats, and all the moving appendages aren't? 

For the people that thought the AC was supposed to trickle down to them:

Enjoy your canting ballasted foils, your wing mast, your rotary pumps, your big batteries you'll be pulling every night... 

For the "can we please save the B$ some money crowd"

I don't think the design effort could possibly be less for this boat than for the AC50, nor the systems knock up, nor the developement of completely new technology.  

The crews are going to be larger,  probably more than enough to offset any reduction in shore crew, and is it much less effort to crane an AC50 than to bring the boards off this thing?

 

Im sorry to be a downer, but the more thought i give this the weirder it seems and the more I worry about what the AC is going to be like

 

 

But... the NZ team has been pretty good at pulling out miracles so lets hope it extends to this design brief, and we get some cool lizard leg racing.  If you squint real hard, and imagine the preview video on boats that actually make it work, it's quite a spectacle. 

To be fair, big batteries are probably part of the future though ;)

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Big batteries.

The power needed to raise one 1.5 ton keel/foil from under the boat to out of the water(about 6m) in the claimed 3 seconds is something like

1500kg * 9.8m/s/s * 6m divided by 3 seconds  = about 30 kWatts. 

Maybe half that for a tack because the foil would only be half way down in the foiling position.

Lithium batteries are about 4kg per kWatt. So they need 60kg of battery for every tack.

If they do 2 hours of racing a day (one long or several short races) and tack or gybe every 4 minutes, 30 tacks/gybes? 

Battery minimum size is 60kg times 30 = 1800kg, probably more like 2500kg allowing for some reserve and the damage done if you flatten lithium batteries. 

2.5 Ton of batteries. No need for other internal ballast then.

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8 minutes ago, Phil S said:

Big batteries.

The power needed to raise one 1.5 ton keel/foil from under the boat to out of the water(about 6m) in the claimed 3 seconds is something like

1500kg * 9.8m/s/s * 6m divided by 3 seconds  = about 30 kWatts. 

Maybe half that for a tack because the foil would only be half way down in the foiling position.

Lithium batteries are about 4kg per kWatt. So they need 60kg of battery for every tack.

If they do 2 hours of racing a day (one long or several short races) and tack or gybe every 4 minutes, 30 tacks/gybes? 

Battery minimum size is 60kg times 30 = 1800kg, probably more like 2500kg allowing for some reserve and the damage done if you flatten lithium batteries. 

2.5 Ton of batteries. No need for other internal ballast then.

Very much what I've been thinking...

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19 minutes ago, Phil S said:

 

Lithium batteries are about 4kg per kWatt. So they need 60kg of battery for every tack.

 

I suspect you're mixing up units: you should consider energy per tack, expressed in W.h

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21 minutes ago, Phil S said:

Big batteries.

The power needed to raise one 1.5 ton keel/foil from under the boat to out of the water(about 6m) in the claimed 3 seconds is something like

1500kg * 9.8m/s/s * 6m divided by 3 seconds  = about 30 kWatts. 

Maybe half that for a tack because the foil would only be half way down in the foiling position.

Lithium batteries are about 4kg per kWatt. So they need 60kg of battery for every tack.

If they do 2 hours of racing a day (one long or several short races) and tack or gybe every 4 minutes, 30 tacks/gybes? 

Battery minimum size is 60kg times 30 = 1800kg, probably more like 2500kg allowing for some reserve and the damage done if you flatten lithium batteries. 

2.5 Ton of batteries. No need for other internal ballast then.

I think it would be best for you to learn the difference between energy and power.

If you need 15 kW of power to lift the foil, you do not need 1500 kW to lift the foil 100 times, only the same 15 kW.

It's only required energy that needs to be multiplied by the number of lifts, not power!

30 lifts each 3 sec long, total 90 sec or 1.5 min. energy required 15 kW times 1.5 min = 22.5 kWmin = 0.375 kWh = 375 Wh = 12 V * 31.25 Ah.

No need for 2500 kg of batteries for that , even if lead acid is used, just one car battery.

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2 minutes ago, NotSoFast said:

I think it would be best for you to learn the difference between energy and power.

If you need 15 kW of power to lift the foil, you do not need 1500 kW to lift the foil 100 times, only the same 15 kW.

It's only required energy that needs to be multiplied by the number of lifts, not power!

30 lifts each 3 sec long, total 90 sec or 1.5 min. energy required 15 kW times 1.5 min = 22.5 kWmin = 0.375 kWh = 375 Wh = 12 V * 31.25 Ah.

No need for 2500 kg of batteries for that , even if lead acid is used, just one car battery.

Do you really think they're going to use a 12V system for this!?

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Just now, Colomba said:

Do you really think they're going to use a 12V system for this!?

No, but that has no effect on the weight of battery needed for the job.

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21 minutes ago, NotSoFast said:

I think it would be best for you to learn the difference between energy and power.

If you need 15 kW of power to lift the foil, you do not need 1500 kW to lift the foil 100 times, only the same 15 kW.

It's only required energy that needs to be multiplied by the number of lifts, not power!

30 lifts each 3 sec long, total 90 sec or 1.5 min. energy required 15 kW times 1.5 min = 22.5 kWmin = 0.375 kWh = 375 Wh = 12 V * 31.25 Ah.

No need for 2500 kg of batteries for that , even if lead acid is used, just one car battery.

No Im sure he is right.

The boat has a righting moment of 500 kilometres too :D

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53 minutes ago, hoom said:

A single car battery sounds insufficient to me :blink:

It won't give you 15 kW of power, but a same weight Li-Ion might. 30 lifts during the race might not be enough either, but same weight of Li-Ion will give you more than that.

60 kg will more than adequate for the job using quality batteries.

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1 hour ago, hoom said:

A single car battery sounds insufficient to me :blink:

Well, you'd be surprised ... #2 Son tells me battery energy density for the current crop of electric powered planes/helos is around 300 W.h/kg, less about 20% overhead (battery management system, frame/enclosure) but improving 4-5% every year. In the AC75 application, the fact it's not continuous discharge but a series of peak loads also significantly affects sizing, but in any case we're talking kgs, not tons - somebody tell mechanical engineer Dan :)

In this connection, I'm betting against Indio this time we'll finally see purely electric (EMA) actuators rather than electro-hydraulic ones

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https://en.wikipedia.org/wiki/Power-to-weight_ratio#Electrochemical_.28galvanic.29_and_electrostatic_cell_systems

Panasonic CGA103450A 1.95Ah LiCoO2 Lithium-ion battery[57]

 

20 °C 641 kJ/kg 2C to 2.75 V 356 W/kg 2C

1 kg rechargeable battery can provide 356 Watts of power continuously 30 min or 1800 seconds or 600 times 3 second lifts. Plenty longer than needed for one race.

60 kg of such batteries can provide 21360 Watts of electric power the same 30 min. That can deliver 15 kW of mechanical power to the ballasted foil with a real world efficiency.

Same table lists others with more power / kg, but with reduced energy / kg. One of those might do the job with even less weight, but significantly less number of lifts.

A123 Systems 26650 Cell 2.3Ah LiFePO4 Lithium-ion battery[65][66]

390 kJ/kg 27C to 2 V

3300 W/kg 27C

6 lifts for each kg and min 6 kg for required power.

 

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22 hours ago, Xlot said:

But wouldn't lift fron windward foil drastically (long arm) eat into the very RM that's propelling the boat forward?

 

Yes but we are talking low wind speeds when the hull is draggy and wont leave the water, Rm isn't an issue until wind picks up.

How much time did the ac50s waste trying go get up on the foil and build speed on the lighter days

You could foil in conditions that provide less RM with 2 foils vs 1 foil.

 

U could even set the angle of attack of upwind foil to produce CL=0, to give the full rm available once your up, without retracting the foil.

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