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7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

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Tone
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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby Tone » Tue Jun 13, 2017 12:55 pm

Starsky wrote:
Tue Jun 13, 2017 12:22 pm
longwhitecloud wrote:
Tue Jun 13, 2017 11:36 am
they get scared when it is above 20 knots - i can see why...
Who, the sailors or the accountants ?
both!

Ben Ainsley was interviewed and when asked was it fun, he said he wouldn't go as far as to say it was fun.

These boats are going so fast that it is easy to get blown off, they turn so fast that you can get thrown off. Above 20 knots they are so lit up that if there is a malfunction with the running gear you can throw the entire crew into the water at 30+ knots. I know how much it hurts to fall foiling at 30 knots, from 3ft. Imagine falling from 8-10ft at 45 knots.

Some of the mark roundings that have gone wrong have resulted in parts of the boats being ripped off.

This is formula 1 with 6 people involved!

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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby FrederikS » Tue Jun 13, 2017 1:56 pm

On an upwind downwind course they would probably be equally fast. The VMG up and downwind look very similar to what the top HF racers are doing if you look at the VMG in the races with sub 10 knots wind. Even with the reach start and finish I think the top racers will be fine, the AC50s peak at around 40 knots on a reach in light winds.

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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby Kamikuza » Tue Jun 13, 2017 3:17 pm

Lokihel wrote:
Tue Jun 13, 2017 11:26 am
If they were allowed to have a smaller rigid wing-strut for the very strong winds they would still win.
There, I fixed it

Tone
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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby Tone » Tue Jun 13, 2017 4:21 pm

FrederikS wrote:
Tue Jun 13, 2017 1:56 pm
On an upwind downwind course they would probably be equally fast. The VMG up and downwind look very similar to what the top HF racers are doing if you look at the VMG in the races with sub 10 knots wind. Even with the reach start and finish I think the top racers will be fine, the AC50s peak at around 40 knots on a reach in light winds.
You're wrong.

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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby BWD » Tue Jun 13, 2017 4:32 pm

Agree with tone (who should know)
I saw the SWE boat hit 46 last week in lightish wind.
These guys are match racing, usually covering each other tactically so rarely spend a lot of time at Vmax, max VMG...
They get on foil at what is a "good" speed for a kitefoiler, and then build another 10-25 knots on top of that, when they have clear course, tactically sensible, and compatible with not dying!

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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby Lokihel » Tue Jun 13, 2017 5:39 pm

Kamikuza wrote:
Tue Jun 13, 2017 3:17 pm
Lokihel wrote:
Tue Jun 13, 2017 11:26 am
If they were allowed to have a smaller rigid wing-strut for the very strong winds they would still win.
There, I fixed it
Now people will just get completely confused: it has foils AND a mast.
Or does it have two masts? :?:
Or is the mast the thing connecting the foils to the boat, and the thing on top the hulls a 'wing'? :o

How are we ever going to understand anything when they double the number of unknown parts.

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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby gbrungra » Tue Jun 13, 2017 6:04 pm

Seems like a kitefoiler would win in winds too light for the AC to foil, so 6kts?

And seems like the kitefoiler wins by default when the wind is too strong for the AC to be safe with its wingsail.

It does seem that the wind range sweet spot of the ACs has expanded now that they have multiple foils to choose from. I think kitefoil racing will get there at some point too.

But why are we comparing max speeds instead of VMGs? (Also, swell should not be considered since ACs only race on flat water)

It would be great to be able to watch kitefoil racing with the same level of video and computer analysis that the AC gets...

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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby Tone » Tue Jun 13, 2017 6:18 pm

gbrungra wrote:
Tue Jun 13, 2017 6:04 pm
Seems like a kitefoiler would win in winds too light for the AC to foil, so 6kts?

And seems like the kitefoiler wins by default when the wind is too strong for the AC to be safe with its wingsail.

It does seem that the wind range sweet spot of the ACs has expanded now that they have multiple foils to choose from. I think kitefoil racing will get there at some point too.

But why are we comparing max speeds instead of VMGs? (Also, swell should not be considered since ACs only race on flat water)

It would be great to be able to watch kitefoil racing with the same level of video and computer analysis that the AC gets...
You say they only race on flat water? I think you will find that the water they are on is flat for a AC50 but if a kiter were to go over the same surface at 45 knots it would be far more spectacular!

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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby pākihiroa » Tue Jun 13, 2017 9:50 pm

It is drag, not weight, that will ultimately limit top speed. When lift = drag, no more acceleration and at max speed. Wing sail has got to be way more aerodynamically efficient (configurable shape, greater lift to drag, etc) than a kite and therefore can sail closer to the (apparent) wind. Advantage AC45, methinks.

Caveat: Both craft are on foils so assumes differences in the underwater drag is not the deciding factor (once everything is scaled).

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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby tegirinenashi » Tue Jun 13, 2017 10:08 pm

Hydrofoil performance is not equal. Kiter just leans the board and counteracts the pull, while a sailboat has to have negative lift on some wings to keep sail mast vertical. Therefore, the force on the remaining lifting wings is higher than the boat weight.

There is youtube video of racer kitesurfing smoking up the small hydrofoil sailboats competition (3 different classes), which link unfortunately I fail to recover. Admittedly, those small crafts are no match for AC45F with its rigid (=aerodynamically superior) sail.


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