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#286766 - 05/08/17 11:48 AM What's up with the America's Cup  
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Timbo Offline
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I just found some You Tube videos from "World on Water" that show the boys practicing in Bermuda.

This is from yesterday and it also shows the pedal power training for ETNZ, they are going to use their feet instead of their arms to grind the hydraulic pressure.

I'm wondering why they are using big heavy guys over 200lbs with big upper bodies instead of some out of work Tour De France types that only weigh 135lbs and can pedal harder, all day?

https://www.youtube.com/watch?v=Yzh5VfDN80E


Blade F16
#777
-- Have You Seen This? --
#286767 - 05/08/17 12:26 PM Re: What's up with the America's Cup [Re: Timbo]  
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Mn3Again Offline
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fl
easy - bicyclists are afraid of the water

but now my baseless guess would be that they need "power lifters" vs. "endurance guys"





Originally Posted by Timbo
I just found some You Tube videos from "World on Water" that show the boys practicing in Bermuda.

This is from yesterday and it also shows the pedal power training for ETNZ, they are going to use their feet instead of their arms to grind the hydraulic pressure.

I'm wondering why they are using big heavy guys over 200lbs with big upper bodies instead of some out of work Tour De France types that only weigh 135lbs and can pedal harder, all day?

https://www.youtube.com/watch?v=Yzh5VfDN80E


Mn3
#286768 - 05/08/17 04:23 PM Re: What's up with the America's Cup [Re: Mn3Again]  
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Timbo Offline
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Look at how bow down they all seem to be when they are on the foils. At the beginning of that video you see the Brit team stuff a bow during a tack/gibe. At first I thought it was a Brit boat only thing, but later in the video you see all the boats are sailing like that, almost all the time when they are foiling. I wonder why.


Blade F16
#777
#286770 - 05/09/17 07:43 AM Re: What's up with the America's Cup [Re: Timbo]  
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I was curious about that bow-down hull attitude as well.

Perhaps it is the best way to keep the mast as vertical as possible? I presume with a wing you don't have as much mast rake as you would with a sail since the draft profile would be much different.


Jay

#286771 - 05/09/17 07:45 AM Re: What's up with the America's Cup [Re: waterbug_wpb]  
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in something totally not related (cuz i'm the king of hijack)... Timbo I've got the Naples - Key West race this week (Thursday down, Sunday back), so I could use your help next year if you can keep your calendar clear... & Carlos if he's still alive


Jay

#286772 - 05/09/17 08:54 AM Re: What's up with the America's Cup [Re: waterbug_wpb]  
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How does the bow-down attitude surprise you? Did you all forget that these are sailed by non-catsailors???

All kidding aside, don't forget that the platform (including crossbars) is another important foil at these speeds. I'm willing to bet that plays a role.

Mike

#286773 - 05/09/17 09:36 AM Re: What's up with the America's Cup [Re: brucat]  
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Mn3Again Offline
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fl
if you look real close ... you can see a fat bastard on the bows
he's probably weighing it down
[img]https://www.thebeachcats.com/galler...p;g2_itemId=127684&g2_serialNumber=4[/img]


Mn3
#286774 - 05/09/17 11:37 AM Re: What's up with the America's Cup [Re: Timbo]  
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mbounds Offline
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The bow down attitude is the result of restrictions in the angle of the rudder foils and the different speeds upwind vs. downwind.

Upwind, the boats are relatively level; the boats are moving 25-30 kts. A higher angle of attack is required on the rudder foils to lift and stabilize the back of the boat.

Downwind, the speed increases to 35-40 kts; a lower angle of attack on the rudder foils is required to achieve the same lift, so the boats assume a bow-down attitude.

#286775 - 05/09/17 12:11 PM Re: What's up with the America's Cup [Re: waterbug_wpb]  
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Originally Posted by waterbug_wpb
in something totally not related (cuz i'm the king of hijack)... Timbo I've got the Naples - Key West race this week (Thursday down, Sunday back), so I could use your help next year if you can keep your calendar clear... & Carlos if he's still alive


Remind me to bid it off next year, tell me around April 5th, when our May bidding opens!

I just saw Carlos last Saturday, he's now in Miami going through 737 school, he'll be flying for Miami Air, and he's looking to move to somewhere down there. He might be available next May, heck, he may be retired, again, and again by then! grin


Blade F16
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#286776 - 05/09/17 12:14 PM Re: What's up with the America's Cup [Re: mbounds]  
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Originally Posted by mbounds
The bow down attitude is the result of restrictions in the angle of the rudder foils and the different speeds upwind vs. downwind.

Upwind, the boats are relatively level; the boats are moving 25-30 kts. A higher angle of attack is required on the rudder foils to lift and stabilize the back of the boat.

Downwind, the speed increases to 35-40 kts; a lower angle of attack on the rudder foils is required to achieve the same lift, so the boats assume a bow-down attitude.


I wonder why they don't change the rudder foil angle of attack by raking the rudders just a little bit, like they do the main foils, unless changing the rudder rake is prohibited by the new rules.


Blade F16
#777
#286777 - 05/09/17 07:38 PM Re: What's up with the America's Cup [Re: Timbo]  
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mbounds Offline
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Originally Posted by Timbo
changing the rudder rake is prohibited by the new rules.

There's your answer. Limited to 3 degrees of movement.

#286778 - 05/09/17 08:01 PM Re: What's up with the America's Cup [Re: mbounds]  
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Any ideas on why it's so restricted?

Mike

#286779 - 05/09/17 08:45 PM Re: What's up with the America's Cup [Re: brucat]  
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Timbo Offline
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Yeah that seems like kind of a dumb rule considering they want a balls out foiling catamaran going as fast as possible, why restrict the rudder rake when so much other stuff is made for going fast?


Blade F16
#777
#286782 - 05/10/17 12:54 PM Re: What's up with the America's Cup [Re: Timbo]  
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David Parker Offline
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For a detailed answer to the bow-down attitude watch this short video by Slingsby. Sign up for the Oracle Facebook page and get regular news videos from them. Really well done and some great video of them flying (and of Jimmy falling off ...again!).

Facebook link to Slingsby explaining bow-down

Latest news (May 10)...Oracle just capsized (again!) but no damage and nobody hurt.

#286783 - 05/10/17 06:53 PM Re: What's up with the America's Cup [Re: David Parker]  
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Originally Posted by David Parker
Latest news (May 10)...Oracle just capsized (again!) but no damage and nobody hurt.


Link to video: https://twitter.com/i/videos/tweet/862441427120336897?

Mike

#286784 - 05/10/17 10:03 PM Re: What's up with the America's Cup [Re: mbounds]  
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Timbo Offline
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Originally Posted by mbounds
Originally Posted by Timbo
changing the rudder rake is prohibited by the new rules.

There's your answer. Limited to 2 degrees of movement.


3 degrees according to that video, but my question is, why are there any limits?


Blade F16
#777
#286789 - 05/11/17 01:38 PM Re: What's up with the America's Cup [Re: Timbo]  
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I'm sure part of the box rule that the defender put together. The question of "why" is probably best left to them.

Maybe to limit the design options (and part of the arms-race)? In doing so, they may limit the wide variety of performance between boats/designs and therefore keep the racing somewhat close?


Jay

#286790 - 05/11/17 01:40 PM Re: What's up with the America's Cup [Re: waterbug_wpb]  
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I am looking forward to the possibility of watching fleet racing at 40+ kts downwind.

Can you imagine flying toward C-gate with 4-6 other boats and closing speeds on opposite gybes approaching 70 knots? yeehaw! Talk about the tactician having an anyerism


Jay

#286791 - 05/12/17 04:50 AM Re: What's up with the America's Cup [Re: waterbug_wpb]  
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Timbo Offline
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These cats are what, 45 feet long?

And they are making nearly the same speeds as the 72' cats from 3 years ago!

Wow.

It used to be that a longer waterline made for a faster boat, but once they get up on the foils I guess it comes down to weight and sail area for determining max speed. Foil mechanics and control are becoming more important than waterline length.


Blade F16
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#286794 - 05/12/17 12:53 PM Re: What's up with the America's Cup [Re: Timbo]  
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David Parker Offline
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More importantly than just momentary boat speed is the total time up on foils. Jimmy, Dean, and Ben have all said in recent interviews that foiling the entire race is possible. In recent practice races you could see examples of where one boat fell off foil and slammed down, slowing let's say from 40 mph to 20 mph, that the other boat picked up so many boat lengths that the race was basically over. That speed difference would give them 10 boat lengths in just 15 seconds of "down time".

Fast and steady wins the race.

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