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And we have liftoff!!

I for one was happy to finally see an American team that didn’t just reek of assholes. Terry was a great bloke to have in front of the cameras and the intimate videos behind the scenes I found quite f

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36 minutes ago, wlrottge said:

It may have one hull, however the whole design is based around how to get more righting moment with less weight.  The configuration with the canting arms is meant to mimic the beam of a catamaran; one area where it falls short however, is that the foils need to be ballasted.  Without the additional weight of the ballasted foils, the lever arm/righting moment would only be the weight of the hull  and the length of one of the arms.  The extra beam and inherent stability is already baked into a cat/tri, they just tried to obtain similar results out of a dissimilar design. 

I think there are a couple of other problems as well that will add up to why the AC75's won't be as fast as the AC50/F50.  Single vertical rudder; suspect that this will prove to be the number one problem (expect spin outs).  Dual skin soft sails won't be as efficient as a rigid wing for a couple of reasons (aspect ratio, shape control, chord depth).  Power to weight and RM.  Did I mention that they only have one rudder?

They did their best to design a single hull platform with the benefits of a multi hull, but didn't get there.  The only saving grace might be the ability to provide RM with the windward foil, but... they still had to make them heavy, so...

"why the AC75's won't be as fast as the AC50/F50"

This is the basis of your comment. You prefer the AC50/ F50 over the AC75. 

The rest is white noise.

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3 minutes ago, Forourselves said:

"why the AC75's won't be as fast as the AC50/F50"

This is the basis of your comment. You prefer the AC50/ F50 over the AC75. 

The rest is white noise.

AC50/F50:  0.043 m^2/kg on a beam of 8.5m with ability to provide differential lift with the rudders (more RM)

AC75:  0.031 m^2/kg on a 5m wide hull with 4m of additional beam/side with the arms and potential for additional RM with windward foil

My preferences aside, physics says that the AC50/F50 will be faster.

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4 hours ago, Purple Headed Warrior said:

I thought the arms did not look quite as radical as the original rendered video we were shown... I expected them to appear longer and deeper.

The reason is that your eyes associates the support with the hull making it look much bigger than in reality. The zoom allows you to make the difference.NYYC.PNG.bdc50e538306f6b6aeada141b84865a1.PNG

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27 minutes ago, wlrottge said:

AC50/F50:  0.043 m^2/kg on a beam of 8.5m with ability to provide differential lift with the rudders (more RM)

AC75:  0.031 m^2/kg on a 5m wide hull with 4m of additional beam/side with the arms and potential for additional RM with windward foil

My preferences aside, physics says that the AC50/F50 will be faster.

Reality may prove differently.

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52 minutes ago, wlrottge said:

AC50/F50:  0.043 m^2/kg on a beam of 8.5m with ability to provide differential lift with the rudders (more RM)

AC75:  0.031 m^2/kg on a 5m wide hull with 4m of additional beam/side with the arms and potential for additional RM with windward foil

My preferences aside, physics says that the AC50/F50 will be faster.

Those physics are missing key data...  The only purpose of all that RM and power is to overpower drag.

I actually think the AC75 will be an extremely slippery beast, perhaps less so the twin skin rig, but even that may not be so bad.  We know both would be effectively overpowered once up on the foils in any amount of breeze, getting rid of drag is going to be key.

Aero as it was last time is going to be a really big component,  I think fundamentally getting it all into one single point of entry on the AC75 is going to be way better than the three points of entry complicated by the crossbeam of an AC50, the width of the AC75 is probably still narrow enough that you can get clean airflow along the entire length and really just have to deal with the foils, the bottom is competely smooth!  The crew, equipment and rig and essentially the same problem on both platforms (although there are more crew on an AC75), although once again you may be able to hide a lot more away in the AC75.

The other major component is two points of entry versus three, yes the AC50 generated some small RM with the windward rudder, but it did come at the expense of having another point of entry and increased drag.

Soooooo much maths! Best to believe the computers here methinks!

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9 hours ago, Ex-yachtie said:

I don't think it's permanent.  It looks to be a few sheets of plywood protecting something, either from damage, or view.

I agree, it looks like a temporary ramp to help with the mast set-up.  The boards don't align evenly.

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1 hour ago, NeedAClew said:

AM trimmer Paul Goodison talking about RM, power, wing twist, and more. Have to grind like crazy before liftoff. Lots of surfaces to control.

Nice piece. AM look to be getting a real handle on this boat. Expect them to be strong contenders. Development of the power source and how to control it could be where the cup is won and lost, even more so than the foil geometry.

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8 hours ago, wlrottge said:

AC50/F50:  0.043 m^2/kg on a beam of 8.5m with ability to provide differential lift with the rudders (more RM)

AC75:  0.031 m^2/kg on a 5m wide hull with 4m of additional beam/side with the arms and potential for additional RM with windward foil

My preferences aside, physics says that the AC50/F50 will be faster.

You butchering of the numbers says you are way out 

the 75 has more RM than the 50s

it was a design goal from the outset and one that has gone through to implementation. 

Question it what do they do with it all now they have it. 

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22 hours ago, Boybland said:

Those physics are missing key data...  The only purpose of all that RM and power is to overpower drag.

Agreed, but time being what it is and I'm not payed to analyze this stuff, lol.

Look at the aspect ratio of the sails and foils (nice visual comparison here: https://chevaliertaglang.blogspot.com/?fbclid=IwAR1l66HKa4VDw-B31R54h3CnlWzH4jYuEG9qQ8aPsleCp_Cvk35zem6v3-g)

The 75 is a lower aspect rig and although, yes it lowers the CE, which decreases lateral load on the foils and therefore drag, that would tell us that it isn't going to be as efficient as the AC50 wing (yes, the wing is heavier).  Same goes for the foil shape.. and considering that L/D are as the square of the velocity, again the lower aspect suggests that it would be slower (yes, I know, the shape is open and we won't see what's been developed until they hit the water, but it is an anecdotal piece of evidence).

Another consideration is the distribution of sail area; maybe this is because they're targeting lower wind speeds, I don't know, but... check out the size of the headsail AND the code zero.  Thinking back to the AC72 and AC50, they started with longer sprits and reaching head sails, but as development progressed, they found that the apparent wind moved forward and built to the point where those sails both didn't work and were unnecessary.

To the point about the third water entry and the rudder; you'll see the same thing if the windward foil is used for RM on the AC75, but it's going to be a bigger foil and "vertical".  The question is of course, is the drag penalty overcome by the additional power you can bring to bear?  Since the AC50/F50's are light without any ballast beyond the crew, the additional RM easily overcomes the drag.  You see this with the A class and Vampire where they use differential rake to the same effect.

@JALhazmat, what did I miss?  Not including the CZ for the 75?  It was just meant to be a simple comparison, I wasn't going to start working up VPP data.  An aircraft carrier has more RM, does that mean it's going to be faster?  Like @Boybland said, it's more complicated than that.  Ok, more RM, what what about the power, sail/foil efficiency, etc.?

Regardless though, I think this quote tells you something:  “The AC75 Class Rule sets the parameters for the teams to develop and race the fastest sailing monohull on earth. The rules are the result of a close collaboration and a true partnership between Emirates Team New Zealand and Luna Rossa,” said Martin Fischer, Design Coordinator for Luna Rossa Challenge.

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Seeing as I was blessed with the intellectual ability known as rational thought, I can’t wait to see which box rule ends up quicker!  That’s why I love the AC!  
 

I actually feel bad for the damaged folks like Smackdaddy and SClarke. When they wake up in the morning, their day is only as good as the press releases.  Poor guys. 

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21 hours ago, Monkey said:

Seeing as I was blessed with the intellectual ability known as rational thought, I can’t wait to see which box rule ends up quicker!  That’s why I love the AC!  
 

I actually feel bad for the damaged folks like Smackdaddy and SClarke. When they wake up in the morning, their day is only as good as the press releases.  Poor guys. 

"Seeing as I was blessed with the intellectual ability..." sure, what ever you say.

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On 8/27/2019 at 8:22 PM, Ex-yachtie said:

I don't think it's permanent.  It looks to be a few sheets of plywood protecting something, either from damage, or view.

ETNZ used plywood on the central fairing of their AC50 while testing in New Zealand. Of that’s what it is, expect it to go when they officially launch or after a while in testing. 

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Ex-Yachtie posted this article in the new twin sail thread:

https://www.sailingworld.com/intel-on-ac75s-twin-skin-main/

It gives some insight into how the sail will need to be adjusted to control the boat.  

It is really telling about how "unique" these boats will be:

The one big challenge with this type of boat will be the takeoffs. In 7 knots of breeze, if you sheeted the sails on, the boat would capsize because there’s so little righting moment available at that speed. With so little righting moment, both sails are almost luffing and it feels wrong. You’re trying to accelerate, but you have to ease the sails so the boat doesn’t heel over. The way the foil geometry works, as soon as you heel over, you lose a lot of righting moment very fast. So it’s about trying to accelerate with a flat boat, and this is where the big top-panel inversion and the deeper cambers to start the acceleration come in. Then, very quickly, you have no sort of righting moment. As soon as it accelerates above 10 knots, the foil flap is acting like a sail-trimming tool. Righting moment comes very quick, so you have to then generate a lot more power in the sails to push it over the hump and get airborne. Then it’s about getting quite flat or else you heel over quickly. The takeoffs will really hurt the grinders because there will be a lot of power required to do this.

The comment about the foil geometry many be why some have tested the Y shaped foils vs the T shaped foils in order to keep more righting moment under various conditions.

This is going to be a very awkward boat to get up on the foils.  It sounds like the design gives you a virtual righting moment that can be lost instantly once boat slows or touches down.  That could be one of the reason why AM built a boat with such a "whale bow".  It could certainly enter into the strategy of trying to force your opponent down off their foils based upon right of ways, etc...  It sounds like crashing off of the foils will be a much larger penalty than with the AC50's.

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2 hours ago, JoeBleaux said:

It’s been about two weeks since we saw pictures of the NYYC boat with the rig up and foil arms attached. Any word on when they’re launching? Maybe they were waiting for the kiwis to go  first?

Can’t see them rushing into the launch whilst Hap, Terry and co are all in Sardinia.

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1 hour ago, JoeBleaux said:

TE said the hurricane has held them up, which makes a lot of sense. 

Hmmm I wonder how long it'll be before one of the foil hat wearers comes on and tells us the hurricane is all part of an ETNZ conspiracy.

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1 hour ago, Sea Breeze 74 said:

Wow, no pomp and ceremony for these guys!

Great! Its been a long time since the Americas Cup has been this exciting!

From these photo's, which admittedly are pretty grainy, the stern at least, looks very IMOCA - esque.

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10 minutes ago, Forourselves said:

Great! Its been a long time since the Americas Cup has been this exciting!

From these photo's, which admittedly are pretty grainy, the stern at least, looks very IMOCA - esque.

First ever in-water spy shots of this Cup yacht, they’re supposed to be grainy!  It’s boxier than IMOCA, almost looks like the box she came in.

Definitely not as sexy as the Kiwi weapon, but fast is not always pretty. 

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23 minutes ago, Forourselves said:

Great! Its been a long time since the Americas Cup has been this exciting!

From these photo's, which admittedly are pretty grainy, the stern at least, looks very IMOCA - esque.

Surprising then. Fat arses are redundant with full foiling, I'd have thought. Much better to be pinched (ETP). But what would I know?

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4 minutes ago, JoeBleaux said:

Wow, from the earlier pics, I didn't expect the bow to be so pointy. Crazy looking port foil. Foil arm hinges look more conventional than NZL. 

That bow looks like it'll slice right through a Russian Akula-class nuclear sub...

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33 minutes ago, Southern Cross said:

0A8326B5-5216-4479-939D-6CF7EBA8F0A1.jpeg

Few thoughts;

 

1) Not sure if its the perspective, but it almost looks like the deck slopes back as a whole, rather than having 'pits' as in the ETNZ boat

2) No 'dimples' around the tops of the foil arms.

3) Definitely dig the plain, almost 'stealth' paint job 

4) Not sure about the bow shape - looks almost 'wrinkled'. An organic shape for aero maybe?

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2 minutes ago, TimmyHate said:

2) No 'dimples' around the tops of the foil arms.

 

The rule allows very little horizontal (and vertical) movement in the axis of the foil arms.  The lack of dimple and presence of bump, suggests that the hull is narrower at this point than ETNZ.

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12 minutes ago, Ex-yachtie said:

The rule allows very little horizontal (and vertical) movement in the axis of the foil arms.  The lack of dimple and presence of bump, suggests that the hull is narrower at this point than ETNZ.

Correct, ~ in a recent video interview a member of the NZ design team mentions (notable) they have not designed a Hull (prior to recent launch)  for some ? time ...................

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32 minutes ago, Southern Cross said:

Correct, ~ in a recent video interview a member of the NZ design team mentions (notable) they have not designed a Hull (prior to recent launch)  for some ? time ...................

Their rockstar designer Verdier has taken up the slack in that department it would appear...

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27 minutes ago, Costro said:

That port foil is crazy looking. Looks a very small area.... Super-cav? Could be what defines this cup? 

Was watching gd say, it will for sure do 50. Like a lot of other water craft. If you can do 55, well, you'd win I reckon.

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Definitely smaller area foils than what TNZ showed, looks like a bullet fairing rather than keeping the leading edge ahead of the strut like TNZ.

Potato quality pic but that section appears to have max camber a really long way aft.

Less of a cut-down on the arms but does appear to be a step there.

 

I'm not so convinced that the hull is actually narrower than TNZ: there is more bulge outboard but they've also got a much bigger diameter of barrel so the axis is a lot further inboard than the barrel surface on TNZ.

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Well, the boat is pretty ugly compared to the beautiful TNZ, but it may not mean slow.

- The bow is much thinner than in the first photos

- The hull is narrower at the foil level as the indents seem non existent

- the hull is flat as the boat "sticks" to the water while the TNZ one doesn't

- the foils are serious shit or just a set for photos that may never be used

Capture.PNG

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21 minutes ago, Tornado-Cat said:

Well, the boat is pretty ugly compared to the beautiful TNZ, but it may not mean slow.

The bow is ugly, the rest above the water seems to be following the same trends the others are (tapered sheerline toward the stern, aero deck with likely some sealing of mainsail foot). Interesting that their foil axle nacelles stick out whereas ETNZ have them set into the hull more, which points to more curved sides than ETNZ.

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2 minutes ago, RobG said:

The bow is ugly, the rest above the water seems to be following the same trends the others are (tapered sheerline toward the stern, aero deck with likely some sealing of mainsail foot). Interesting that their foil axle nacelles stick out whereas ETNZ have them set into the hull more, which points to more curved sides than ETNZ.

Agreed, but I see straight inclined sides and a narrower but flatter bottom.

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8 hours ago, Southern Cross said:

0A8326B5-5216-4479-939D-6CF7EBA8F0A1.jpeg

This photo makes the boat look way more aggressive than the first spy shots - and as mentioned does a good job at hiding the finer details of the hull shape.

I actually prefer the monocolour/mat finish to Magic than the Kiwi 'swirls'....

That deck/cockpit slope seems interesting - keen to see how grinders are positioned do deal with the angles....

Foredeck hatch for furled Code 0 launch/recovery?

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5 hours ago, Tornado-Cat said:

Well, the boat is pretty ugly compared to the beautiful TNZ, but it may not mean slow.

- The bow is much thinner than in the first photos

- The hull is narrower at the foil level as the indents seem non existent

- the hull is flat as the boat "sticks" to the water while the TNZ one doesn't

- the foils are serious shit or just a set for photos that may never be used

Capture.PNG

It is interesting also that while etnz has horizontal bulbless in front of the vertical, they went for the completely opposite approach, with a small bulb and horizontal at the back.

 

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6 hours ago, Tornado-Cat said:

- The bow is much thinner than in the first photos

Its not, just that bow photo was an unusual angle with telephoto lens flattening making it look odder than it is.

It is pretty odd but not as much as it looks in that other pic

 

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Well, very interesting.

I think we can say the aero on the boat is not as promising as ETNZ, which surprises me a bit. I guess the jury is out on the foil arm mounting, but I cannot see this is a huge concern either way.

My feeling is that, you can have the best boat in the world taking into consideration all the parameters we talk about on these forums. But I guess what is key, is that this new breed of yacht needs to be race-able and the first to nail the technique will have a benefit going into boat #2

Great to see AM on the water and cannot wait to see how this unfolds.

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1 hour ago, Purple Headed Warrior said:

Well, very interesting.

I think we can say the aero on the boat is not as promising as ETNZ, which surprises me a bit. I guess the jury is out on the foil arm mounting, but I cannot see this is a huge concern either way.

My feeling is that, you can have the best boat in the world taking into consideration all the parameters we talk about on these forums. But I guess what is key, is that this new breed of yacht needs to be race-able and the first to nail the technique will have a benefit going into boat #2

Great to see AM on the water and cannot wait to see how this unfolds.

I doubt it'll stay that way. Odds are Boat 2 will be all aero and clean and smooth. Same goes for the other teams I guess. 

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25 minutes ago, Raptorsailor said:

I doubt it'll stay that way. Odds are Boat 2 will be all aero and clean and smooth. Same goes for the other teams I guess. 

Absolutely! Interesting to see two different approaches. ETNZ feel that their first boat is radical and they might have the reign it in and we are suggesting that AM are doing the opposite.

I am happy to bet that ETNZ are fooling us by suggesting the above, I cant see them being less radical unless the boat really is too much of a handful, which would make it a very risky first build. So, I am assuming they are very happy with what they have on the simulator. 

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Don’t forget that ETNZ haven’t told the others of any wind limits, top or bottom.

If they are planning a lower limit that will be high enough to be on the foils then they can be less conservative than the others, who didn’t know that. AM look to be making sure that they have enough shape to stay upright and sail in low wind speeds that may not be needed.

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1 hour ago, Chimp too said:

Don’t forget that ETNZ haven’t told the others of any wind limits, top or bottom.

If they are planning a lower limit that will be high enough to be on the foils then they can be less conservative than the others, who didn’t know that. AM look to be making sure that they have enough shape to stay upright and sail in low wind speeds that may not be needed.

Seems plausible, since the ETNZ foils appear to be lower aspect than AM

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15 hours ago, Southern Cross said:

0A8326B5-5216-4479-939D-6CF7EBA8F0A1.jpeg

This is not the same bow we saw in the other “spy” photo.  Looking back at the other picture there looks like a vertical “line” just in front of the foils.  It looks like the whale bow could be a slip on attachment over the ribbed bow.  Maybe they have several attachments to test changes in the bow?  

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21 minutes ago, Herfy said:

This is not the same bow we saw in the other “spy” photo.  Looking back at the other picture there looks like a vertical “line” just in front of the foils.  It looks like the whale bow could be a slip on attachment over the ribbed bow.  Maybe they have several attachments to test changes in the bow?  

Sort of like a ribbed condom ?

:ph34r:

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59 minutes ago, Herfy said:

This is not the same bow we saw in the other “spy” photo.  Looking back at the other picture there looks like a vertical “line” just in front of the foils.  It looks like the whale bow could be a slip on attachment over the ribbed bow.  Maybe they have several attachments to test changes in the bow?  

makes perfect sense that they built a foiler and engineered a changeable bow that they are going to change everyday to test. FFS. If you are not drunk you need to find a mirror and have a good look at yourself.

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58 minutes ago, tinga said:

makes perfect sense that they built a foiler and engineered a changeable bow that they are going to change everyday to test. FFS. If you are not drunk you need to find a mirror and have a good look at yourself.

Maybe but I'm pretty sure there's a rule - somewhere - prohibiting this. Otherwise you could just make one type of bow for one type of weather condition which is not something ETNZ want this time round, more of an all rounder set up I believe. Hope the changeable bows are actually a thing though. 

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4 hours ago, underperformer said:

So this US boat was out on a sunday afternoon and all we got is 2 grainy pics that show exactly nothing? Almost hard to believe

You’re kidding, right?  Opening day of the NFL season was the best cover imaginable to sneak out onto the water!

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17 hours ago, Raptorsailor said:

Odds are Boat 2 will be all aero and clean and smooth.

Agree with first part, not necessarily with second. Boat 2 will be all aero and optimized for handling but that could include aero elements which are not clean and smooth as such. Looking at F1 cars, they create outwash effect from front wings and other elements to avoid tire wake. They might do similar things in the AC to minimize the impact of crew or maximize the lift they get from the hull (ground effect to help lift off or pure lift to keep airbone if wind drop).

I wouldn't be surprise that the slope seen at the end of the deck on both AM and TNZ is to try to create some lift. As long as airflow stay attached to that slope, it should create some succion and some lift..

I don't believe that it is there to help the water clear the desk as mentioned before (as the water will most likely go into crew tranches anyway) or to avoid a fight between crew members (more annoyance than anything for the crew).

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I've talked to some people who have seen the boat up close, been given the tour by the design team, and the summary I got was "it's like nothing I've ever seen, it looks like a fucking airplane."  The intention was to design a boat that is fast above the water.

 

The official launch of the boat is later this week, tickets were distributed to invitees last week.  Today is race day 1 of the Invitational Cup, so I'm sure teams on the water may see some movement on the American Magic front.

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