America's Cup ask the experts: Sails and Spars

[@CharlesWhitten-md6gz]

Dear Mossy, thank you for your incredible insight and generous knowledge, i worked as skipper 20 years in this environment (IOR, IMS maxies back in the day 1990’s, early 2000’s) but some of your coverage and comments have opened my mind and eyes….keep it up…i’ll definitely be tuned in…..Charles…

[@nickl2681]

Mozzy, a great session!. More please! Also, overlaying the conversation with the illustrations is really helpful, as even for experienced sailors, there's a lot of info coming from the experts and it helps process these nuggets. Fantastic and thank you !

[@Gefionius]

Awesome! Great interviews and insight! Can’t wait for more and the racing to start

[@PatrickJohnston-i2s]

Advanced wing systems, we built our first double skin soft wing in 1986. We also have control of thickness, camber and twist over the entire span. You guys are still learning.

[@glennmartin2403]

Thanks for feeding the arm chair watchers with great content - appreciated and great to see the channel grow.

[@simonpuxley7374]

Thank you Mozzy! Really fascinating to learn more!!

[@stephenfromspielberg]

Outstanding work form you, again! It is really amazing to see what kind of deep, insightful answers one can get by asking informed, intelligent questions. Keep going, I'll be watching.

[@firstnamelastname2669]

What I wonder is kind of magnitude aero advantage the twin skin allows? I'm not aware of any other classes using these, though Moths & WS have the partial double surface. I guess the high apparent wind makes these more worthwhile here than in any other applications. It is fascinating that the concept has gone from nerdy discussion (and often dismissed), seemingly straight into the fastest class of all.

[@peterwilson6363]

I think you could make some comparison to early microlights and even hang -gliders which initially were single surface wings. Clearly double surface allows a "proper" aerofoil shape but then that shape is highly dependent on the phase of "flight". A slower speed a deeper section and high speed shallower -once they are foiling these boats are so fast that really they probably would not require any depth of section. Would there be any gains for all the gear involved in a variable section. My guess is very little. Anyway certainly interesting concepts. Cant wait for the action to start. Go ETNZ!!

[@Gottenhimfella]

@@peterwilson6363 I think that the main benefit, once foiling, is still indirectly related to the depth of the section. What I mean is that the athwartships strength required from the mast, given the apparent wind strength is generally hurricane force, inevitably forces the leading portion of the aerofoil profile to be deep, with the result that two skins are the only way to provide a sufficiently fair profile on both windward and leeward surfaces to maintain laminar flow all over . Otherwise, for one thing, the drag at those ultra high apparent wind speeds would kill the chances of a foiling tack.

[@jamesaron1967]

Excellent talk, much I didn't know about the AC rig details. Looking forward to the next video for the group discussion. Should be very interesting to hear what everyone thinks now that all the teams have their boats on the water.

[@brentminshull]

Great work as usual. Wish it was longer, but maybe you can get to some of the other suppliers in the future. Thanks from an old sailer here in Nova Scotia.

[@ChrisPlow]

Absolutely fascinating and thanks for an awesome insight, looking forward to the teams discussion video, you definitely ask the right questions and know as much as anyone I have spoken too. Just booked a ferry to Bilbao in September, a little road trip via Rioja region then onto Barcelona for the semi’s ⛵💨

[@ypsaj]

Go Mozzy!

[@simonolsen1158]

Awesome video! If seperate twin main sheet controls might only benefit lower part of sail plan, that is still an advantage in a sport of marginal gains

[@samlook]

When you're at the point of chasing 0.x gains even the bottom 20% of the sail would be huge if there was any significant benefit.

[@freeaccess5905]

Doesn't it depend upon how much energy it takes to make these changes and how rapid it is needed? It could be to a point of diminishing returns

[@TheCruisingKiwis]

I reckon that main sheet mechanism will still have an impact on the result. Go ETNZ!!

[@Gottenhimfella]

Yes, I think the thing they failed to factor in is active mast rotation, which I don't doubt is being used(with careful detailing of the battens and their connections to the mast) to deepen, flatten and even invert the draft up high, while the cunning twin sheet system can do the first two things for the bottom section.

[@charlottescott7150]

Great video as usual thanks

[@alx-vla4986]

You could get interesting information from the people of Advanced Wing Systems in Perth (AUS); they have been battling with D mast and double main from the beginning.

[@Silvius.2]

I saying it since before Auckland thats doubble main Sails cut and even more controll systems for chamber are one of most important. Cut sails to controll best chamber giving power. Look like mantas or birds change they fins or wings to speed up or controll slow flying....

[@8cervezas648]

Brilliantly confused as always after that video but loved it!

[@UnkleSi]

Awesome! Thanks mozzy

[@carbonarne675]

Thanks for that amazing Video!

[@TheZitherish]

Yes. More beach huts plz.👍

[@MozzySails]

😁

[@jonathanseal5155]

That’s a beach??🥵🥵

[@davidtydeman1434]

Good questions meant we got an interesting discussion 👏👏

[@uberseehandel]

I loved the reference to the Merlin Rocket. Does anybody outside of the UK know anything about these boats?

[@MozzySails]

Ha, I'd spent the week before sailing a Merlin and was chatting to Dave about it before we pressed record so it was likely stuck in his head!

[@real2gone]

Great interviews, Tom. Question: Given the complexity, weight and expense of the twin skin mains'ls and D section masts, how much slower might a conventional rig be, do you suppose? Keep up the great work, mate. EDIT: Obviously excluded in the Rule.

[@zlm001]

Thanks.

[@TobinWheeler-b7t]

The comments rightly thank you for these cool and informative videos, so I'm just going to skip straight into a super noob sort of question: What are the guesses by the more informed and knowledgeable America's Cup nerds as to which boats look fast and which not so fast? In all the interviews I've seen everyone side steps that question; but I'm hoping you might be able to get one or two informed opinions. No one knows who's going to win; but which boats look fast?

[@finaboykm]

Waiting for your thoughts on NZ boat and the crane dropping the boat 6+ meters on to the cradle?

[@c42cly]

Fascinating

[@youroddsox]

Great content as always Mozzy. As you say, it came across like the twin mainsheet design potentially doesn't have that great an increase in performance over a single skin. Would be really interesting to know how the twin mainsheet compares to an equivalent wing sail as from the comments sounds like the twin mainsail is very expensive and complex for not a huge gain and I was under the impression the reason for it was to essentially have a collapsable sail you could get really good control over the shape like a wing

[@rydenkaye9735]

nah they never said that the twin skin was more efficient than a wing. it's not. the reason they introduced it is to try and quiet some of the haters saying bring back the old 12 meters by bringing it closer to traditional sailing so people can relate to it more, while still preserving some performance benefit.

[@CarkeekW]

The bottom percentage of the main skins that can be affected by sheet manipulation is how much of the total sail area though ? The bottom section also has the least leverage for the most power , i think it is a more more significant advantage than it suggests.

[@davidpicken6879]

Please can you have a look at differences in mast rake between the teams, im guessing there is a quite a lot going on here too.

[@steveray4708]

I didn't understand about 50% of the technical stuff that was shown .. But .. ! Thank you.. Loverly.. go NZ

[@peterwor]

As a long time sailmaker, this is my favorite interview. I've noticed the rather twitchy traveler movements on this gen of both the 40's and 75's. I will say the leeches are surely more refined this go round.

[@strongarm_aus5486]

Fantastic

[@justinmatthiashintze2575]

I know it’s been a month since this video, but can someone explain this to me: If the apparent wind is coming from the front in both the upwind and downwind leg, why do we still call it gybing, and aren’t tacking and gybing essentially the same now given you’re moving the bow through apparent wind regardless.

[@strozzascotte]

Why you didn't ask about the Alinghi broken mast?

[@TheLDunn1]

I thought that too!

[@MozzySails]

I did, but conclusions are still internal to Red Bull

[@BRMCaptChaos]

But if the laminate thickness has minimum limits, is this not a common issue?

[@Silvius.2]

​@@BRMCaptChaos And how mutch load and bend your mast. Of course every team could break his mast.. with to mutch pressure on it.

[@Errol.C-nz]

@@Silvius.2 much ! .. but yeah agree'd

[@henry.742]

Do you follow the TP 52 super series at all?

[@uflux]

When you say that the ability to shape the bottom portion of the sail isn’t that significant is a bit weird. That is where all the power is generated. So obviously for the transition to take off and foiling it is immensely important. Your comment about whether ETNZs sail controls then are that much of a game changer….Well look at their foils. That sail control system allows that use of those small foils and still foil at low wind speeds. That is pretty significant IMHO

[@Silvius.2]

It not allowed controll chamber inside up the sails then? 🤷

[@MozzySails]

No, not this time. Last cut you could actively control the top 3m, but actually moat teams didn't and chose to save weight

[@JohnLaMonte]

It would be good for The Cup if England could pull it off!

[@nedoneil123]

Did you ask about the Alinghi mast breakage?

[@jameslittlewood7821]

TNZ mentioned an inflatable bag between the skins in one recon interview. Kind of interested to know more about that.

[@MozzySails]

That's a buoyancy bag to stop the yachts turtling if they capsize. They're one design so not really for sail shapes although I guess could impact it a bit if inflated to much

[@madstruelsen7863]

⁠my guess is the rule-writing Kiwis will show up in Barcelona, with a surprisingly adaptable safety-balloon between the main skins. Maybe it just overinflate, can be moved around or it is attached to the rotating mast for effect in the upper part of the sails. Really cool if the bladder controlled little valves so the twin-skin main could blow up like a foilkite for 3d shape in the middle/top section.

Why does everyone have their garden sheds near the sea?

[@MozzySails]

Haha! Beachhuts

[@tristankiddie1710]

Thanks Mozzy. Really appreciate the content. I don't suppose you have found any images etc of the new kiwi foils? The lack of coverage now from the official channels is pathetic now that the spy program has finished.

[@robertbaird4822]

Yep these KIWIS ARE A CLEVER BUNCH,way ahead of the rest of the world

[@RobertBinedell]

From the start of these boats,all the hoo haa about how fast they would be.Its not spoken about much .Have these boats hit the wall where 50 knots is about it 🤓🤓🤓🤓

[@Gottenhimfella]

Are you saying that's not fast? Or is your point that they should be able to continue indefinitely raising the bar, with no ceiling imposed by the laws of physics? The only sailboats which currently go faster do so with virtually no other objective than speed. No practicality, no ability to manoeuvre, mostly they can only sail unassisted on one tack and one true wind angle, and in flat seas next to the beach with very strong offshore winds, conditions either found almost nowhere, or hardly ever. And with all those limations, they're only a shade faster, maybe 12 percent at most. What's more, that record has not been matched for three times as long as the new AmCup rule has been in operation. Physics is a tough mistress...

[@RobertBinedell]

@@Gottenhimfella ,I’m asking ,what are the present top speeds?Basically,went away from cats that cost a fraction of these boats that don’t have any PRACTICAL use.Clever technology but the spin off to the general boating community 🧐🧐🧐🧐

[@Gottenhimfella]

@@RobertBinedell Couldn't agree less. Top speeds are limited by cavitation to about the same for both classes, and size for size the cost is similar, so that's not a decision factor, but these foiling monos seem to me far more likely to spin off tech to other sailing, firstly because of the fact they allow rapid and safe reduction or removal of sails, (compared with wings which require low wind, sheltered water and a massive crane to get rid of the "sail" area), and secondly because you can recover from a capsize in a matter of minutes, and usually without damage.

[@otm646]

You guys need to work on normalizing your volume, it's all over the place. Makes it very difficult to listen.

[@floodo1]

Fascinating