What will AC75 v 2 look like

[Piet56 202]

Assuming that ETNZ / INEOS are the next defender challenger combo - how or what do these boats look like? How do you improve on these things?

[hoom 640]

No bowsprit or allow some kind of underway code-0 deployment/retrieval system.

Foil arm revision for more span/thinner profile (if there is margin?)

FCS revision for better reliability/less weight based on experience in use.

Probably either ban TNZ style sunken deck or make it more viable.

Maybe adjustment to the min waterplane area to help them be less sticky in displacement? (Verdier seemed to be not happy about that in the recent French interview or did I misunderstand?)

IMO should allow a 4th pair of main foils & similar limit on rudders.

I think an option for smaller mast has been mentioned for better moding.

Some kind of crash/capsize proof VIP pod? This class was supposed to have the return of the VIP passenger but that got abandoned. IMO I think they're better off sticking to no VIP though.

 

Personally I reckon a bit of a down-scale could help cut costs/attract more competitors.

Alternately/also an AC45-style easily transported OD variant for ACWS & start-up teams.

[southseasbill 159]

Get rid of running backstays?

[shebeen 478]

it will have female sailors on it

[Milli 65]

Down-scale to 60 feet. 

[Perpetual Toil 64]

Change the helm setup so that teams aren't having to choose between going with two-person steering and scampering across the deck at 45kts. 

[NotSoFast 19]

1) FCS revision to automate a foil in full up position to gradually move downwards relative to the boat, to compensate for excessive heeling angles, thus keeping the foil at the position to continue producing maximum righting moment. Currently the foil heels with the boat, until it's located right above the centerline, see the American Magic case where the boat got seriously damaged as a reference. The required movement of the heavy foil does not require electric power in that case, only power for electronic unit of FCS. In fact the electric motor adjusting foil cant could even be used as a generator to produce necessary power for FCS electronics should the battery fail or be empty in such situation. But I don't see that last one as important, just as a possibility.

With that kind of system modification of FCS, the center of gravity of the foil will not be allowed to raise higher than the cant axis due to increasing heeling angle, as the current status.

2) Ban movement of crew members across the centerline above deck during a race. There were several times during racing then crossing took place in front of another boat coming close from behind at fast speed. Should a crossing crewmember fallen over board he would have been run over by the other boat with no time to avoid. Potential death as a result. There is no need to risk killing crewmembers due to such practice, as it provides nothing to improve racing.

 

[JALhazmat 1,615]

not sure its a potential death more like certain, being hit by 6.5 tonnes through a small surface area, (Foil or rudder leading edge) moving at 35+kts, you would burst on impact 

[alphafb552 625]

7 hours ago, hoom said:

...

 

Personally I reckon a bit of a down-scale could help cut costs/attract more competitors.

...

 

3 hours ago, Milli said:

Down-scale to 60 feet. 

Downscaling will only save a few square meters of carbon - none of the expensive technology and development costs will be affected so savings will be minimal.

Unless you suggest also reducing crew sizes, then there might be a few savings on personnel costs

[alphafb552 625]

Not necessarily related to the boats, but the penalty system needs to be revised to make the competition more like match racing, less like pure speed trials

[SloopJohnB 361]

Fully autonomous.

[Varan 2,137]

Virtual. All done on simulators to reduce costs and increase entries. 

[amc 101]

9 hours ago, alphafb552 said:

Not necessarily related to the boats, but the penalty system needs to be revised to make the competition more like match racing, less like pure speed trials

Personally I prefer it to be a design race, there are lots of other match racing regattas in identical boats to watch if that is your preference. Nothing wrong with watching match racing I might add, it is super exciting when things are close. 

[dg_sailingfan 70]

Terry Hutchinson in an Interview suggested that the Crew will be reduced and "Grinding" will entirely done by Batteries just like the SailGP Boats.

There are also Rumors that Team New Zealand might incorporate a "Self-Tacking Jib" so the Jib Trimmers will fall over the wayside.

Basically you only have to push some buttons to win AC Races and hang onto the wheel.

Not sure if that's Sailing anymore then!

[Chobani Sailor 199]

56 minutes ago, dg_sailingfan said:

Terry Hutchinson in an Interview suggested that the Crew will be reduced and "Grinding" will entirely done by Batteries just like the SailGP Boats.

There are also Rumors that Team New Zealand might incorporate a "Self-Tacking Jib" so the Jib Trimmers will fall over the wayside.

Basically you only have to push some buttons to win AC Races and hang onto the wheel.

Not sure if that's Sailing anymore then!

I thought Terry said that the grinders will be cut about in half - 3 to 4 grinders.  I suspect all teams go to the dual helmsman so that nobody is running back and forth.  There is a rumor swirling in at the Sail GP event in Denmark - TH may be talking to a helmsman who may or may not drive the Aussie boat.

[dg_sailingfan 70]

24 minutes ago, Chobani Sailor said:

I thought Terry said that the grinders will be cut about in half - 3 to 4 grinders.  I suspect all teams go to the dual helmsman so that nobody is running back and forth.  There is a rumor swirling in at the Sail GP event in Denmark - TH may be talking to a helmsman who may or may not drive the Aussie boat.

Not sure how that is going to work? Given the new Nationality Rules incorporated by TNZ & INEOS only an American can drive a Boat for an American Challenger in AC37!

[pusslicker 664]

2 hours ago, dg_sailingfan said:

Terry Hutchinson in an Interview suggested that the Crew will be reduced and "Grinding" will entirely done by Batteries just like the SailGP Boats.

There are also Rumors that Team New Zealand might incorporate a "Self-Tacking Jib" so the Jib Trimmers will fall over the wayside.

Basically you only have to push some buttons to win AC Races and hang onto the wheel.

Not sure if that's Sailing anymore then!

It's a design race. Who cares about the the crew? There are tons of other sailing skill contests available out there. I hope they leave this last design race alone.

[pusslicker 664]

On 3/16/2021 at 7:22 AM, Milli said:

Down-scale to 60 feet. 

8 foot reduction seems meaningless. If they did this I think they would have to go further. 

[Chobani Sailor 199]

1 hour ago, dg_sailingfan said:

Not sure how that is going to work? Given the new Nationality Rules incorporated by TNZ & INEOS only an American can drive a Boat for an American Challenger in AC37!

One would assume that he has a US passport.

[dg_sailingfan 70]

2 minutes ago, pusslicker said:

It's a design race. Who cares about the the crew? There are tons of other sailing skill contests available out there. I hope they leave this last design race alone.

No, it is a DESIGN & SAILING Race. I dunno if you can still call it the AC if you just have to push buttons!

[Zaal 694]

In a recent interview Max Sirena told that there has been an informal chat between teams of the last edition to gather ideas and suggestions for the next AC. He said that the grinders might be reduced and that there is the intention to widen up the AC75 wind range. In a interview made in Auckland during the Prada Cup Checco Bruni said that one possible solution to this was to use different masts, just like in Sail Gp.

Personally, I think that there will be more one design parts in the next rule, since one of the main goal for the next edition should be to attract new teams. Foils rudders and sails will be designed by teams, maybe the hull could be one design ? 

[basketcase 802]

35 minutes ago, Zaal said:

 

Personally, I think that there will be more one design parts in the next rule, since one of the main goal for the next edition should be to attract new teams. Foils rudders and sails will be designed by teams, maybe the hull could be one design ? 

so..... same as the AC50?

[NeedAClew 1,786]

3 hours ago, dg_sailingfan said:

Not sure how that is going to work? Given the new Nationality Rules incorporated by TNZ & INEOS only an American can drive a Boat for an American Challenger in AC37!

Slingers mother is American. Even though he is a proud Aussie, technically he can claim citizenship via her. For all I know, he has a US passport in his sock drawer.  

[trt131 268]

Yes he has one but it is the underpants drawer.

[Gissie 1,758]

Make the boats one design, all built by the company willing to pay the most to Team What Ever Country Pays The Most.

This will ensure dozens, or at least double figures, of challengers. This will enable the country paying billions to hold the event to pretend it is worth it. Or not.

[sailman 412]

On 8/15/2021 at 7:18 AM, Gissie said:

Make the boats one design, all built by the company willing to pay the most to Team What Ever Country Pays The Most.

This will ensure dozens, or at least double figures, of challengers. This will enable the country paying billions to hold the event to pretend it is worth it. Or not.

Isn't that what SailGP is?

[NeedAClew 1,786]

I doubt there would be 10 challengers making it to Prada or equiv if the boats were free. 

[Zaal 694]

On 8/14/2021 at 1:19 AM, basketcase said:

so..... same as the AC50?

Yeah, maybe something like that. But I'm not so convinced, a on one design hull could be too restrictive on systems and sails. 

[basketcase 802]

40 minutes ago, Zaal said:

Yeah, maybe something like that. But I'm not so convinced, a on one design hull could be too restrictive on systems and sails. 

when we had the AC50s, people bitched that there should be no one design component.  the cup is a design/build/race competition.

[Zaal 694]

4 minutes ago, basketcase said:

when we had the AC50s, people bitched that there should be no one design component.  the cup is a design/build/race competition.

And I absolutely agree on this. But I expect ETNZ and COR to focus a lot on bringing in new teams, hence the fact they they could impose some more one design components to cut expenses. I don't  think that a "one boat" program could be enough, because you save on boat construction costs, but you have only one shot to get the boat right, so you spend more on designing it (a better simulator, a bigger design team, for example) and you still have to build the smaller surrogate boats. 

[Chimp too 392]

On 8/17/2021 at 10:41 PM, Zaal said:

And I absolutely agree on this. But I expect ETNZ and COR to focus a lot on bringing in new teams, hence the fact they they could impose some more one design components to cut expenses. I don't  think that a "one boat" program could be enough, because you save on boat construction costs, but you have only one shot to get the boat right, so you spend more on designing it (a better simulator, a bigger design team, for example) and you still have to build the smaller surrogate boats. 

If they are all the same, they don't have to be right. 

[chesirecat 721]

This beastie could fit the bill. Change the format with some passage stuff and round the buoys, Circuit already set up. 

Post launch shakedown showing some impressive numbers 

Trimaran SVR Lazartigue and Francois Gabart

 

[idontwan2know 230]

If they want to have any challengers, the differences need to be minor enough that v1 boats can be brought up to v2 spec reasonably. Most of the rumors from the teams seem to be along those lines....reduce grinders, maybe some expanded rig options. I'd be surprised if improved FCS isn't on the agenda though that really falls into more of a fix than a design change since they're one design anyway.

[Boybland 560]

Mandate the code 0 be on board at all times (maybe a deck channel or similar).

Work towards making it easily deployable / retrievable mid race.

On it's own this would massively improve racing in low end conditions.

Clear up what is and isn't allowed as far as deck height goes.

Otherwise as mentioned, ensure any changes are not so drastic that we have to throw away the existing boats, they need to be at least viable as training platforms for new teams.

[terrafirma 1,341]

Making the boats one design would be the best move to reduce costs and have all the boats built at the same factory. A bit like the VOR65's. The money that is needed to be spent on designing your own boat is so stupid you have NZ going offshore in an attempt to raise the money. If the AC continues in this manner it will capitulate eventually as the costs vs the return simply don't make sense. One Design would see twice as many teams if not more entering the regatta. The best sailors win is what we want to see. 

[Terry Hollis 441]

12 minutes ago, terrafirma said:

Making the boats one design would be the best move to reduce costs and have all the boats built at the same factory. A bit like the VOR65's. The money that is needed to be spent on designing your own boat is so stupid you have NZ going offshore in an attempt to raise the money. If the AC continues in this manner it will capitulate eventually as the costs vs the return simply don't make sense. One Design would see twice as many teams if not more entering the regatta. The best sailors win is what we want to see. 

If you make it one design it will no longer be the America's Cap, in would be just another regatta.

[Stingray~ 2,280]

While rig power and aero-drag reduction matter too, the tastiest 'secret sauce' with the AC75's is in the foils and their shape controls. That's where I'd like to see the Design Rule envelopes opened up wider.

[Terry Hollis 441]

Luna Rossa says that NZ had the fastest boat because of it's superior aero-drag.

[Sailbydate 3,613]

3 hours ago, terrafirma said:

Making the boats one design would be the best move to reduce costs and have all the boats built at the same factory. A bit like the VOR65's. The money that is needed to be spent on designing your own boat is so stupid you have NZ going offshore in an attempt to raise the money. If the AC continues in this manner it will capitulate eventually as the costs vs the return simply don't make sense. One Design would see twice as many teams if not more entering the regatta. The best sailors win is what we want to see. 

Exactly the wrong strategy. The AC must maintain its design/sailing competition origins/traditions to remain relevant. "The best sailors win is what we want to see", we already get every 4 years at the Olympics, not to mention World Championship every year.

[barfy 1,305]

4 hours ago, Terry Hollis said:

Luna Rossa says that NZ had the fastest boat because of it's superior aero-drag.

Foil profiles were unique as well.

[Sailbydate 3,613]

 

41 minutes ago, barfy said:

4 hours ago, Terry Hollis said:

Luna Rossa says that NZ had the fastest boat because of it's superior aero-drag.

Foil profiles were unique as well.

I got the impression, Te Rehutai's full potential was never on display during the AC36 match, while Luna Rossa was fully tapped out. There was more to that speed edge than just aero-drag, that's for sure.

[Terry Hollis 441]

6 minutes ago, Sailbydate said:

I got the impression, Te Rehutai's full potential was never on display during the AC36 match, while Luna Rossa was fully tapped out. There was more to that speed edge than just aero-drag, that's for sure.

I am sure that you are right but I was merely quoting their main competitor ..

Interview with Max Sirena in the Luna Rossa thread ..

"Q: What would you take from the other boats?

Horacio : The aerodynamics of Te Rehutai. Anyway, I'm confident that we have both the people and the means to develop this sector a lot, perhaps the only one we were a little behind on. We are already active right now to improve ourselves."

[Priscilla 2,804]

25 minutes ago, Sailbydate said:

 

I got the impression, Te Rehutai's full potential was never on display during the AC36 match, while Luna Rossa was fully tapped out. There was more to that speed edge than just aero-drag, that's for sure.

Gotta wonder wether the teams lining up for a tilt at AC37 will come within a bulls roar of licking Te Rehutai’s rather broad ass considering they are limited to campaigning only one new boat…

[Jethrow 411]

Yes the one boat rule will mandate some varying degree of a "roll of the dice" when it comes time to press the GO button.

How far out on that limb is a team prepared to go...

[Stingray~ 2,280]

16 minutes ago, Jethrow said:

Yes the one boat rule will mandate some varying degree of a "roll of the dice" when it comes time to press the GO button.

How far out on that limb is a team prepared to go...

A lot will surely be loosened up on hull mods you can make, foils you can build, masts, sail cards etc.

[atwinda 206]

I recall the ETNZ sail designer mentioning how difficult it was to measure the sails in (specifically the mainsails) as they had to fitted and loaded on the spar.. I'd bet they change that up to measure off the rig somehow.

[Stingray~ 2,280]

2 minutes ago, atwinda said:

I recall the ETNZ sail designer mentioning how difficult it was to measure the sails in (specifically the mainsails) as they had to fitted and loaded on the spar.. I'd bet they change that up to measure off the rig somehow.

Sounds like a good idea too.

The sails must surely be a cost-saving are too though. Fewer parts allowed maybe, to simplify things.

[Priscilla 2,804]

13 minutes ago, Stingray~ said:

The sails must surely be a cost-saving are too though. Fewer parts allowed maybe, to simplify things.

Hah Stinger this is the AC "cost saving" and "simple" just ain't in the vocabulary.

[Stingray~ 2,280]

26 minutes ago, Priscilla said:

Hah Stinger this is the AC "cost saving" and "simple" just ain't in the vocabulary.

Hah, true. But if this double-mainsail thing is supposed to trickle down then maybe simplify the contraptions? Better yet, go with practical and more-efficient solid wings somehow?

[atwinda 206]

41 minutes ago, Stingray~ said:

Sounds like a good idea too.

The sails must surely be a cost-saving are too though. Fewer parts allowed maybe, to simplify things.

I'd be willing to bet the primary cost saving factor for the sail inventory will be the elimination of the code zeros. Other refinements might be a wider range of tolerances on the main sails to accommodate the excessive hollow AM were running with their bat wing main. ETNZ at least tried it, so they'll likely have modeling data, and real world data to asses that. I doubt they would open it up to multiple height rigs, doubling the rig and sail inventory wouldn't cut any costs- but it might be justified to sail in the lighter air days that saw the boats glued to the water.

[Priscilla 2,804]

5 minutes ago, Stingray~ said:

Better yet, go with practical and more-efficient solid wings somehow?

Pretty hard to find a solid wing on a monohull anywhere suggesting there are issues.

 

[atwinda 206]

7 minutes ago, Stingray~ said:

Hah, true. But if this double-mainsail thing is supposed to trickle down then maybe simplify the contraptions? Better yet, go with practical and more-efficient solid wings somehow?

Care to explain practical? the solid wings are only more practical in a modular sense, but are far more complex to build, store, and fix when you capsize.

At least when the AC75's capsized they could be righted with help and join the next race. The solid wing sails are always going to break.
 

[Stingray~ 2,280]

52 minutes ago, atwinda said:

At least when the AC75's capsized they could be righted with help and join the next race. The solid wing sails are always going to break.

Has that been true in SailGP? Honest question.

[accnick 1,745]

24 minutes ago, Stingray~ said:

Has that been true in SailGP? Honest question.

Usually but not always.

[enigmatically2 1,483]

On 3/16/2021 at 9:10 AM, hoom said:

 

Alternately/also an AC45-style easily transported OD variant for ACWS & start-up teams.

Well you certainly got that pretty bang on.

I think most of your other suggestions were also good. Though I would allow even more foils and allow them to pick on the day

[Priscilla 2,804]

On 3/16/2021 at 10:56 PM, shebeen said:

it will have female sailors on it

Not if it is sailed in the Evil Empire

[Priscilla 2,804]

Can't wait to see the MKII version of Te Rehutai.

 

[The_Alchemist 1,433]

On 9/21/2021 at 9:57 PM, terrafirma said:

Making the boats one design would be the best move to reduce costs and have all the boats built at the same factory. A bit like the VOR65's. The money that is needed to be spent on designing your own boat is so stupid you have NZ going offshore in an attempt to raise the money. If the AC continues in this manner it will capitulate eventually as the costs vs the return simply don't make sense. One Design would see twice as many teams if not more entering the regatta. The best sailors win is what we want to see. 

Oh, you mean like SailGP?

[The_Alchemist 1,433]

Well, we at least know what the racing protocol and hosting negotiations looks like:

 

 

 

[arneelof 17]

On 3/16/2021 at 5:42 PM, alphafb552 said:

 

Downscaling will only save a few square meters of carbon - none of the expensive technology and development costs will be affected so savings will be minimal.

Unless you suggest also reducing crew sizes, then there might be a few savings on personnel costs

Downsizing (to 45) makes shopping much cheaper.

[Boybland 560]

On 9/23/2021 at 7:53 AM, Stingray~ said:

Hah, true. But if this double-mainsail thing is supposed to trickle down then maybe simplify the contraptions? Better yet, go with practical and more-efficient solid wings somehow?

How many times did you see a team lower their solid wing on the water after a race, NEVER.
How many times did you see a team lower their double skin on the water after a race, ALWAYS.

Tell me again how solid wings are more practical?

[Raptorsailor 313]

On 9/23/2021 at 1:00 AM, Priscilla said:

Pretty hard to find a solid wing on a monohull anywhere suggesting there are issues.

 

*Built by the boatyard with beer

[Raptorsailor 313]

On 9/25/2021 at 11:31 PM, Priscilla said:

Can't wait to see the MKII version of Te Rehutai.

 

If you were to improve the hull of Te Rehutai, here's what I would do. Based on my gut feeling and zero experience in aerodynamics. Although I am very interested in it, maybe I understand it better than the average joe... idk, aerodynamics is so fucking complicated. Anyway here goes. 

-'pinch' the stern around the blue lines to reduce surface area, a bit like Prada B2.

-increase the radius of the edge around the yellow line to reduce pressure around that area when tacking/gybing, creating a smoother transition for the air that's not doing anything to the air around the cockpits and middle part where work is being done to the air. 

-Smooth/blend the entire area in the orange box for a similar reason as above. To further reduce the drag as the wind ain't coming straight on. The problem here is the sharp edge in that box is there for a reason: to help air go underneath the hull. Careful balance to be made here, 

-Increase the surface area of the purple line to increase its ability to float and relieve the foils of some of the workload. 

-Make the edge around the red line sharper to create a nice teardrop shape for the skeg from a top-down view, and to better seal that area.

 

And will come with bigger pie warmers so you can have more pie per unit pie so you can pie while you pie. 

[barfy 1,305]

On 10/17/2021 at 9:48 AM, Raptorsailor said:

-increase the radius of the edge around the yellow line to reduce pressure around that area

 

On 10/17/2021 at 9:48 AM, Raptorsailor said:

Smooth/blend the entire area in the orange box for a similar reason as above. To further reduce the drag as the wind ain't coming straight on. The problem here is the sharp edge in that box is there for a reason: to help air go underneath the hull. Careful balance to be made here, 

More use of pie in the radii calculations in these areas I think you are asking for.

[Raptorsailor 313]

10 hours ago, barfy said:

 

More use of pie in the radii calculations in these areas I think you are asking for.

Yes, meat pie to be specific.

[Fiji Bitter 1,976]

12 hours ago, barfy said:

 

More use of pie in the radii calculations in these areas I think you are asking for.

Wie, o dies π (pi, pronounced pie)
Macht ernstlich so vielen viele Müh,
(Lernt immerhin, Jünglinge, leichte Verselein,
Wie so zum Beispiel dies dürfte zu merken sein!)

Urban translation: "We are all getting fooking tired of that stupid pie warmer".

Or in short, approximately:  3.14 (159 26535 89793 23846 26433 83279 50288 41971 69399 37510 58209 74944 59230 78164
06286 20899 86280 34825 34211 7067).

Pi Thagoras.

 

[shebeen 478]

Quote

I suspect you see all teams go with dual helmspersons for AC37 - there is no reason to run back and forth and take a potential tumble like Ben did.

Quote

How they gonna do that with only 8 People? You don't need to be a flintstone to know that a Dual Helm with only 8 People ain't going to work. You need one Main Trimmer as well and I think 6 Cyclors or Grinders, 3 on each Side.
Dual Helmsman is GONE my friend.

some debate elsewhere as to how the boats will be crewed with just 8.

If you have helm and main + 6 cyclors, then you will have a lot of jobs done by cyclors.

instead i think you'll see some more hybrid options.

4 big guys to do power stuff (and maybe jibs + tactic/nav eyes).

   then the other 4 to juggle this somehow.

2 flight control add some power

2 (main + helm)

 

 

i see both dual helm and a single crossing helm possible

 

We never saw extended tacking duels between LRPP and ETNZ in AC36 final, but surely Pete needing to run across in front of the mast each time would have been an issue here. I don't think this was a limitation in muscle power, as the FCS is battery operated. The potential gain here is getting your competitor off foils, a huge tool to use really.

 

[enigmatically2 1,483]

So now we have had the new rule for a while, perhaps its time to start looking in more detail at it.

Firstly foils. This was after all widely held to be the deciding factor in why NZ were fast last time around, and is sure to be key this time.

Most obviously there is a bigger box, so they can have a bigger span. Everyone last time went to the max, so it does seem likely that this will be taken advantage of. That will give more righting moment, and can give more lift in lower wind speeds. However they presumably won't want to increase drag so it seems likely that either or both of cord length and thickness will decrease. 

So we are likely to see increased aspect ratio, which can worsen the cavitation problem. There seems to be no significant change to the finish restrictions so hydro-phobic finishes to reduce cavitation are out.

I do note however that the rule on deforming foils has been completely re-written. It seems to still prohibit it (13.12) but is now written quite differently. I think it should allow better smoothing between the foil and the flap. I also note that deformation due to external forces is still permitted (though re-written). Given that Red Bull and Merc-AMG F1 teams have spent a lot of time this year accusing each other of such deformation (which is banned by F1) I wonder whether this an area that they might consider. I suspect its unlikely because unlike F1 the AC boats can move the flaps and change the angle of attack (of the boat and thus) of the foils. Nevertheless if there is something that could be done to increase onset of cavitation it could be worth it

Nevertheless overall, it seems like the obvious change of span length and thus reducing cord and/or thickness does seem to be the most significant. That could  give structural problems and will also likely mean that better control will be required as such a higher aspect ratio foil will be inherently less stable.

One one hand NZ were already further in this direction so have an advantage, you can bet that the other teams have a good model of what NZ did last time by now, but whether they have caught up with NZ is another matter given that NZ will have progressed. Presumably UK and NZ also have an updated model (and tank testing?) of a foil with the new sizes since they would have wanted to confirm the impact before the rules was agreed. On the other hand I wonder whether such control systems are an area where the F1 teams can bring innovation. They also may bring advantages in strength given their very refined in-house manufacturing techniques etc,

Thus I suspect we might get a bit more crash and burn. We already had some issues last time with uncontrolled increase or decrease in lift. I suspect we will get more next time- at least initially

[enigmatically2 1,483]

Mainsails.

I can't see many significant rule changes here. There is the Batwing clarification that was mentioned. Next most critical is that the max number of full length battens has increased from 6 to 10 (plus unchanged 6 shorter ones).  That is quite an increase. Not sure what drove it, but plainly it will be taken an advantage of.

I think the biggest visible difference we will see is in the mainsheet/boom arrangement. Obviously each team had different arrangements last time, with various benefits and drawbacks. I suspect we will see a hybrid of all of them.

I also think there will be a lot more work down in the lower and top mainsail control systems. Unfortunately so much of this is hidden that I don't think we know everything that went on, and won't next time. Which is a shame because I suspect that is where most of the development will take place wrt mainsails

[enigmatically2 1,483]

Materials for rudders and foils. There are now limits on the metals used,. There was always an upper limit on density, but now there are limits on the amount of metal other than lead which is high or low strength (rule 2.9). I guess the intent is to control costs by limiting exotics, but this could in theory at least cause further problems with structural integrity of the higher aspect foils

[enigmatically2 1,483]

p.s. none of this is definitive, I may easily have missed other significant rule changes so please pipe up if you spot any

[Xlot 1,162]

5 hours ago, enigmatically2 said:

I also think there will be a lot more work down in the lower and top mainsail control systems. Unfortunately so much of this is hidden that I don't think we know everything that went on, and won't next time. Which is a shame because I suspect that is where most of the development will take place wrt mainsails

Read somewhere (but haven’t checked) that now mainsail controls do not allow camber inversion - which wasn’t being used anyway. True?

[enigmatically2 1,483]

1 hour ago, Xlot said:

Read somewhere (but haven’t checked) that now mainsail controls do not allow camber inversion - which wasn’t being used anyway. True?

Haven't seen anything so far, and neither inverse or camber come up in search, but I'm on my phone now so hard to check throughly

[enigmatically2 1,483]

14 hours ago, Xlot said:

Read somewhere (but haven’t checked) that now mainsail controls do not allow camber inversion - which wasn’t being used anyway. True?

It seems you are correct. I had missed that. The whole concept of the controls in the upper part of the mainsail has gone

Rule 19.5:

Quote

Rig controls are restricted to:

(a) mast rotation permitted by Rule 15.9 (a);

(b) degrees-of-freedom of control systems that are attached to or bear upon the mainsail within the mast lower zone;

(c) jib sheet degrees-of-freedom, including car position;

(d) jib cunningham extension and retraction; and

(e) jib leech line adjustment via force input devices permitted by Rule 19.10 (c)

I'm quite shocked by that

[enigmatically2 1,483]

The lower mast zone (where controls are allowed within main) has been extended from 1.2m to 1.5m so expect more going on there - but still invisible to us unfortunately.

The rules on connections between skins have been changed

Old rule

Quote

 

Battens may be connected to a batten on any other sail skin however such connections are restricted as follows:

(a) rigid or linked connections between battens are permitted only within 0.400 m of the leech or luff of any sail skin;

(b) tethered connections between battens, or battens pockets, are permitted anywhere provided such connections are no longer than 600 mm and can not take compressive forces; and

(c) with the exception of battens that are entirely within the mast lower zone and mast upper zone, batten connections shall not be adjusted

 

New rule

Quote

 

With the exception of fairings permitted by Rule 17.16 (b), connections between skins of a mainsail or between battens of a mainsail above the mast lower zone may only:

(a) be entirely within 400 mm of the luff or the leech of a sail skin;

(b) span no more than 150 mm vertically with the mainsail in an unloaded state; and

(c) be no closer than 2.0 m for any leech connection permitted by Rule 17.18 (a). Within the mast lower zone there is are no restrictions on connections between sail skins or battens.

 

So it seems to may that there can be more connections, not just at the battens, but along all of the luff and leech, and they can take compressive forces. 

I'm not quite sure what they are going to do there but it feels important. Any suggestions?

[enigmatically2 1,483]

Digging further, the restrictions on number of mainsails, and amount of the mainsail that can be modified have gone. Thus it will be possible to develop mainsails with these connections set separately - e.g. with linkages to keep the skins further apart for a high power, high drag sail for light winds. 

As you would have to get them pre-measured I don't think you could adjust them. But you can have as many as you like pre-measured and then pick the one you want up to the warning signal.

This removes the unfairness of AC36 that the defender had brand new sails for the final, whereas the challengers had to use them up through the Prada Cup.

On the other hand it puts costs up. I wonder why they didn't allow adjustment of these connections. It seems like it would have reduced costs.

Additional considerations of these changes

1) that this will increase the power of the sails to closer to that of a wing rig, albeit without so much control

2) It could take the design further away from the skillsets of sail designers and into more of unknown. We know that the F1 teams have excellent skills and models around aero-forces. I wonder whether they will get involved with this aspect

So as well as knocking the weight off, I think these new more powerful sails will improve the light air performance, whilst allowing for different sail connection for medium or upper end winds

[enigmatically2 1,483]

I thought this might stimulate more discussion. No-one interested?

[Stingray~ 2,280]

7 minutes ago, enigmatically2 said:

I thought this might stimulate more discussion. No-one interested?

You’re doing a great job - thank you!! 

[Sailbydate 3,613]

3 hours ago, enigmatically2 said:

I thought this might stimulate more discussion. No-one interested?

Wow. Real boat shit. Not nearly as much fun as politics and character assassination.

[enigmatically2 1,483]

One thing I have noticed is that a lot of the rules have been rewritten quite heavily, even when there seem to be no substantial changes in meaning.

So were they closing down loopholes that were discovered during AC36; opening new ones up for themselves to exploit; or just rewriting for the hell of it? 

[Stingray~ 2,280]

5 minutes ago, enigmatically2 said:

One thing I have noticed is that a lot of the rules have been rewritten quite heavily, even when there seem to be no substantial changes in meaning.

So were they closing down loopholes that were discovered during AC36; opening new ones up for themselves to exploit; or just rewriting for the hell of it? 

Is it your impression that control rules have been opened up in the upper mast control zone?

[enigmatically2 1,483]

47 minutes ago, Stingray~ said:

Is it your impression that control rules have been opened up in the upper mast control zone?

The upper mast control zone seems to have gone

[Stingray~ 2,280]

3 minutes ago, enigmatically2 said:

The upper mast control zone seems to have gone

Wow! Maybe the new batten rules make the wing more controllable/shapeable across more span than before?

[enigmatically2 1,483]

I have been pondering these rules on batten connections more and maybe they do have the controls they need to adjust whilst sailing via the clew outhauls.

If we consider leech first, then the (crude) pictures below show 3 options for the 2 skins. The top shows when the outhauls are even. At this point if the 2 skins can be separated by the length of the connectors (or if necessary can be forced apart by those connectors). This makes for a big separation, i.e. a very thick wing all the way back with high lift but also high drag. Possibly perfect for lifting the boat onto the foils in light winds

The middle shows when the windward skin outhaul is tightened. In this case it means that windward clew is further aft, which also means that skins come closer together at the leech. However that pulls the windward skin tighter and so increases the separation further forward. This will provide a wing which still provide a lot of lift, but less drag than the first (and is less susceptible to stalling due to changes in angle of attack).

The last option shows the leeward skin outhaul being tightened. This narrows the gap between the skins all the way along the sail and thus decreases lift, but also minimises drag. If the outhauls are adjusted so that they are separated by the same as the connector distance then the skins will of course come together at the leech. So as the wind rises this would be the preferred option.

Control can also be exerted on the separation near the luff by under or over rotating the mast.

These connections can only be within 0.4m of the luff or the leech, and given that I have no experience of twin-skin sails (like pretty much everyone here I expect) and have no model, its hard to estimate exactly what will happen with the rest of the sail, but logically it should allow a big trade-off with lift and drag - more so than last time

[enigmatically2 1,483]

Hull;

Min hull volume has dropped from 70m3 to 60m3. And correspondingly the forward watertight tank is now 35m3 down from 40m3. Surprised by that. I thought they might have increased reserve buoyancy after the AM incident but they have dropped it. 

Fairing flaps are now allowed on the drainage holes (they weren't last time)

All up weight we know is down. Mostly from loss of code 0 and reduction in crew

That reduction in hull volume could result in a big change to how the hulls look

[Schakel 262]

With solar cells... 1% win is already closer to victory,
In nobodies way, might take over all the grinders + their weight on a sunny day.
Makes competition 10 times smarter.

Green or blue flag rule: No shore power lurking allowed on sunny days.
Good for rersearch, one of the propelling powers behind the experimental cup idea.
It is, in someway, a design contest.

Really a good idea, IMHO.

[pusslicker 664]