Emirates Team New Zealand.

atwinda

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The fact that folks are spending blogwidth on the management politics and not this marvel says a lot about the shit slinging and trolling here. I am surprised there was no additional second looks at this. We use to do this with skiff masts, Tornado masts, DN masts all the way up to G32 cats when we built the prototype sails and batten systems, but to do this for a AC mast is fucking impressive. You have to build a jig for the mast base a given distance off the ground, one that allows rotation, and then a loaded (hydraulic) system for the boom or to pull the foot tight, support the rig so it rotates at the spreader, a rotation system at the mast tip, and then what is not shown is how they are simulating load, either pushing or pulling down on the mast at the mid point or pushing at the mast tip. I suspect they are looking not only at the shape, which is a very basic way of looking at flying vs. design, which is most likely done with cameras on water, but more likely refining a batten systems where you can work with your feet on the ground or maybe the lower skin off. Maybe working on the reverse camber bits up top and not shown.
The picture shown was explained as part of the measurement process. Something along the lines of, the only way to accurately measure the CG of the mast + twin skin sail combo was to rig everything up and suspend it to get the measurements. I'm not saying they aren't doing more once it's all up in the air- setting initial batten tension would certainly be a ton easier when you can walk up to the batten, rather than fussing with an adjustment 10's of meters off the water.

 

Kate short for Bob

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Looking forward to seeing Argentina compete in the next AC.
Worst All Black team in 10 years.  Poor selections, poor coaching, poor game strategy and on field leadership no ability to change tactics.  I said that watching the first test and everyone in the pub laughed.

 
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SCARECROW

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Melbourne, Aus
I’m actually interested in what you just said. Can you explain that a little better for the common folk?  I’m genuinely clueless in this area, so would love some good info!  
1. (vibration) is easy if you have the props turning past each other at speed each time the blades pass each other other you get a an impulse. V8 engines and 4 bladed props (8 being divisible by 4) means the natural frequency of the engine and this vibration can line up and cause extra vibration through the boat.  On a twin engine boat there isn't much you can do about this so you'd default to a 3 or 5 blade prop on a V8 engine to reduce the likelihood.  You're not going to mismatch the port and stbd engines but one this quad rig they have the opportunity to tailor the solution.

2. Is a bit more complicated and you could write a PHD thesis on it. It is no secret that water accelerates (changes direction and speed) around a boat hull just like it does around a wing.  This is taken into account when designing/ specifying propellers, we don't assume the propeller is working in static water.  On a powercat the inner side of the hulls see quite different flow to the out because water forced away from one hull hits the water being forced away from the other.  This causes the water line to rise a little between the hulls and change speed resulting in the distinct wake you see behind planing power cats. (you'd think after designing cats for 20 years I'd be able to find a decent photo of this but nope).  The result is on a boat like these the inner engines are going to see more turbulent flow and the props will need to be a marginally different pitch.  Unlike large boat props outboard props don't tend to be made to order so the choice between 3 and 4 blade might be as simple as what off the shelf prop is closest to correct for that job.

 

MaxHugen

Super Anarchist
Looking forward to seeing Argentina compete in the next AC.
I'd like to see the French get into it.

They have some great designers, and already have tons of experience with foiling sail craft, eg Hydroptère , cats and tris in general, the IMOCA class... etc.

Oh, and I really wish an Aussie would stump up the mega bucks for another Challenge of course!

 

Stingray~

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Got a little nostalgic twinge from this post, takes me back to my (30 years younger) I-90 bridge days & the sound of twin V8s idling their way under the arches.

And of course that day in my 1st year on the bridge when a good sized sailboat motored under the east arch with a pair of topless young ladies on the foredeck, when the little brunette stood up & stripped off everything & gave us "twirl", well if I hadn't been hanging halfway up one of the bridge columns I would have dropped my tool belt & clothes & made the 50' leap to the water & joined them!

Probably would have been fired, but might have been worth it!
Fun memory! A couple years ago I was out on the lake for SeaFair and a whole boatload of ladies were cruising around just south of the I 90 bridge off Leschi and every one of them topless! 
 

Bro’s Donzi is moored at the marina at the north end of L Washington, next to the Kenmore Air float planes harbor. His house overlooks both, I think you mentioned you live in Lake Forest Park too? My family has belonged to the LFP Civic Club for decades, I’ve launched my Laser from there a lot. 

 

mikenz2

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Auckland
I was told this set up gets used on boats that care more about being able to turn predictably and without losing speed, as opposed to just all out top speed. Sounds pretty logical if your goal is to chase an AC75 around!
Not just chase an AC75, but "be" an AC75. They're the large chase boats to simulate AC75s and mock race against them (Luna Rossa do the same). So you're going to need all the help you can get to turn a big power boat on a dime like an AC75 does. 

Edit: Reminds me... LR uses the same motors on their large chase boat, I'll pay attention to the prop config they run next time I see them.

 
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animeproblem

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Seattle
Fun memory! A couple years ago I was out on the lake for SeaFair and a whole boatload of ladies were cruising around just south of the I 90 bridge off Leschi and every one of them topless! 
 

Bro’s Donzi is moored at the marina at the north end of L Washington, next to the Kenmore Air float planes harbor. His house overlooks both, I think you mentioned you live in Lake Forest Park too? My family has belonged to the LFP Civic Club for decades, I’ve launched my Laser from there a lot. 
I know the marina well, way back in the mid to early 70s (the place was called Davidson's in those days) I learned to use what would be common tools in my trade, my step Dad & i were helping a guy re-furbish an old fishing vessel.

The punchline here is said boatowner's funding ran out & even though my step Dad never was paid the bulk of what he had coming he paid me the 10% we had agreed on.

 
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