Americas Cup AC75 fully foiling mono unveiled ...

[Scotty Kiwi]

Originally Posted by Don C L

Does anyone know of any boat currently sailing that employs these lifting foils as they are drawn here?

Good question. I'll ask on some of the local NZ discussion groups when I get the chance.

[Polux]

Originally Posted by Don C L

Does anyone know of any boat currently sailing that employs these lifting foils as they are drawn here?

No. I don't think there is any. The Quant has nothing to do with these foils since this ones are also keels and carry the ballast.

The Quant as a keel with ballast and foils that cannot move the way the ones on the America's cup move.





The Quant is however the more stable flying monohull the only one that don't need a very special sailor to sail it.

https://www.youtube.com/watch?v=--DN0vEB0vg

[Don C L]

So a design that has no analog and is theoretical at this point will be ready to race in 2021? Kinda sounds like a moon shot to me but then again with the kind of money they have to work with....
I don't mean to sound too negative. Just don't have a good image of the lifting, canting, hinging mechanism for this in my head that is robust enough.... given the way it is drawn...

[Polux]

Originally Posted by Don C L

So a design that has no analog and is theoretical at this point will be ready to race in 2021? Kinda sounds like a moon shot to me but then again with the kind of money they have to work with....
I don't mean to sound too negative. Just don't have a good image of the lifting, canting, hinging mechanism for this in my head that is robust enough.... given the way it is drawn...

I find it difficult....but don't forget that this proposal comes not from a lunatic but for the design teams of two of the teams that were involved in the last America's cup designing the flying cats.

They have for sure made studies and computerized analysis and they should know what they are talking about.....I hope

[fxykty]

Lots of design and engineering experience exists for canting keels and their range of motion of 120 degrees or so. Similarly, lots of experience with lifting and/or canting foils.

The next step is a combined lifting foil and canting keel. Given the budgets and sizes of the design and engineering teams I don’t expect it’s anything like a moon shot, more like a progression from a known base of knowledge. I’m also confident that they wouldn’t be releasing a boat design that they don’t know how to build.

For the poster that claimed America’s Cup is old tech is missing the point. Sure, I accept the boats haven’t always been the most advanced. However, the technologies on large scale (not single or one-off boat building) of sail making, electronics, and boat hardware absolutely have trickled down from the massive R&D budgets that America’s Cup teams provide. And I don’t think the last three generations of foiling cats can be considered not bleeding edge - again for scale and size. Moths and Hydroptere and C class cats and you name it notwithstanding.

[Mirror16]

Looks like a dog cocking its leg to pee. But racing these things is sure to get alot of media coverage. People will love to watch decapitations by the windward foil.

[Pelagic]

Originally Posted by Cheechako

If it's foiling then I don't think it really matters if it's mono or cat. So whatever works. But I'm sure it must preclude whatever the traditionalist's wanted out of going back to monos. Why not just a grid structure with longitudinal air bags to float until it gets on the foil? Why does it need a hull at all?

They are not always on the foils as in tacks and light winds.....Curious if the mono can point higher during the tacking duel at starts?

[Scotty Kiwi]

How long does it take to build a prototype of this kind of technology? It's only been four months (or so) since the conclusion of Bermuda. Is that enough time to get a test boat into a testing tank?

Fxykty - have Aucklanders seen anything weird of Rangitoto lately? <grin>

Would be very surprised if Team NZ went ahead and announced something purely theoretical or without 100% certainty of its workability.

And imho they've been very quick with the announcement. From memory it took years for Oracle to come to announce the foiling cats concept. Confidence or Stupidity? Given their track record it can only be confidence, with a strong sense of fair play.

Fxytky has to be correct here - it's an advance on canting keel + lifting foils, maybe with also some 1960's powered hydrofoil knowledge thrown in. If each foil is properly balanced around a pivot point then, while overall weight would increase, the need for extraordinary hydraulic power would reduce.

[Just Another Sa]

Originally Posted by Scotty Kiwi

My guess is that computer control will be banned, all controls manual. Otherwise the class is not sustainable (susceptable to computer breakdown) or cheap, or able to be easily migrated to other classes.

If these guesses are close, then there'll be severe sailing skill required in 6 to 8 positions, instead of in two positions as in the last AC.

Severe sailing skill required in 6 to 8 positions makes the boat at least 10 times more expensive than computer control would. There will be no trickle down due to that into any other class. That kind of foil system can only be sustainable with 100% computer control, and they are not doing that.

[Just Another Sa]

Originally Posted by Suijin

I can see these being faster around the whole course. More maneuverable, probably lighter overall in terms of the hull. I think the premise is that if the boat is flying on foils you don't need two hulls...just put the foil outboard on an arm.

I do have a feeling this may make for some spectacular wipe-outs.

As for the technology "trickling down"..yes, maybe to other racing designs and the odd day sailor but I can't see a cruising foiler anytime soon...

More likely AC75 is only faster in conditions where AC50 as built would have been severly limited to avoid pitchpoling, and slower in every other condition.
Most difference is in light winds, AC75 weighs 3 times as much, has 2 times righting arm, and only 10% higher mast height above water. More sal area only helps when it is slower and heading downwind, and thus having wideer apparent wind angle. My guess is that in 8 knots true, AC50 was capable of 32 knots, and AC75 will only achieve 16 knots of boat speed or less in any point of sail. Of course AC50 would have been faster and capable for sailing in higher winds, if it had a a smaller and shorter wing, but still limited by wave height in short chop.

[Just Another Sa]

Originally Posted by Cheechako

If it's foiling then I don't think it really matters if it's mono or cat. So whatever works. But I'm sure it must preclude whatever the traditionalist's wanted out of going back to monos. Why not just a grid structure with longitudinal air bags to float until it gets on the foil? Why does it need a hull at all?

It's not going to be foiling in light air. Without boatspeed for the foils to produce significant lift, the righting moment is very low for it's size, compared to any other sailboat, ballasted monohull or multihull. That is why the mast is so short. Only 90ft high for a 75ft boat, even shorter than in most cruising monohulls of that size.
Not foiling mean you need a hull (or several) to race at all. You also need a hull to accelerate to a speed required for the foils to lift a boat. Without an efficient hull, it wouldn't take off even in 15 knots true.

[Just Another Sa]

Originally Posted by Utahsailor

the raised windward foils are the scariest part- imagine aggressive luffing with those daggers raised to windward.

They only need to luff enough to get a penalty on the other boat. If the penalty is not given by human umpires but by the computer, they will instantly know when the penalty is given, and don't need to keep luffing after that. The rules can be such that there is no contact at that point, or even too close to be dangerous. There is no guarantee they will do so, but the technology needed for that was already there in 2 previous ACs.

[james247]

Originally Posted by Scotty Kiwi

Looks exciting.



They say the design concepts include:



- ability to fit into a standard berth

- design able to "trickle down" to other classes of racers and cruisers (emphasis added by me).

- affordable and sustainable.

- stable.

- self righting.

- potentially faster than the AC 50 (catamarans).



https://www.msn.com/en-nz/sport/more...cid=spartandhp



Call me biased, but this seems to me to be the start of one of the biggest advances in sailing, and potentially cruising, since .... papyrus! OK how about since .... any other suggestions?

Simply brilliant by every test for me. And I thought a Marconi rig would never replace a gaff rig. That was a few years ago

[Polux]

Originally Posted by Just Another Sa

It's not going to be foiling in light air. Without boatspeed for the foils to produce significant lift, the righting moment is very low for it's size, compared to any other sailboat, ballasted monohull or multihull. That is why the mast is so short. Only 90ft high for a 75ft boat, even shorter than in most cruising monohulls of that size.
Not foiling mean you need a hull (or several) to race at all. You also need a hull to accelerate to a speed required for the foils to lift a boat. Without an efficient hull, it wouldn't take off even in 15 knots true.

How do you know that the righting moment will be low to the boat displacement?

[Just Another Sa]

Originally Posted by Polux

How do you know that the righting moment will be low to the boat displacement?

It's not low then foils are lifting, it will be very high.
It is low when they are not, as the ballast is only dimensioned to provide self righting, not to provide much righting moment. A wide hull with a lot of form stability would also have high drag, preventing it achieving enough speed for the foils to lift the boat, since the rig is so short. That means the hull hasn't got proportionally as much form stability like IMOCA60 for example.
Would you use a short rig in a AC racing boat having a lot of RM and ability to self right?
There can only be one reason for the decision makers to do that.