| Re: AC72 Oracle Team USA Spaceship has landed
[Re: P.M.]
#261633 07/23/13 11:18 PM 07/23/13 11:18 PM |
Joined: Jun 2001 Posts: 3,293 Long Beach, California John Williams
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Posts: 3,293 Long Beach, California | I've taken some private flak for picking NZL early; I hope some of the folks who may be bent at my surety realize that, not only do I believe that they have the fastest boat upon the sea (tip o' the hat, Cap'n Nat), but I also feel some national pride in the work done by Nat Shaver, Bobby Kleinschmit and Pete Melvin, all members of my Club, who picked up sticks to live in New Zealand for over two years to get to this point. Hat's off.
John Williams
- The harder you practice, the luckier you get - Gary Player, pro golfer
After watching Lionel Messi play, I realize I need to sail harder.
| | | Re: AC72 Oracle Team USA Spaceship has landed
[Re: P.M.]
#261639 07/24/13 05:17 AM 07/24/13 05:17 AM |
Joined: Jun 2009 Posts: 524 Petten Netherlands northsea junkie
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Posts: 524 Petten Netherlands | I think something is lost in the translation and/or the transmission of this remark.
Look, apparent wind is the resultant of the true wind in the sail and the boatspeed in opposite direction. The last is derived from the so-called groundspeed.
So, when the current is with you, your groundspeed will be higher then in the situation when the current is against you.
This will certainly effect the apparant wind; this app.wind will increase and will be turned more to the bow (more close-hauled).
If you will lose boatspeed because of that effect, will finally depend on the boat. The boatspeed will even want to be higher because of this increased (apparant) wind (the speed was already higher because of the current).
Only problem is the direction of the apparant wind which is more and more close-hauled!
ronald RAIDER-15 (homebuilt)
hey boy, what did you do over there, alone far out at sea?.. "huh....., that's the only place where I'm happy, sir.
| | | Re: AC72 Oracle Team USA Spaceship has landed
[Re: Tony_F18]
#261644 07/24/13 06:33 AM 07/24/13 06:33 AM |
Joined: Dec 2006 Posts: 2,490 On the Water P.M. OP
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Posts: 2,490 On the Water | I think one of the Oracle sailors told them about it so some information may have gotten lost in translation.
I'm guessing has more to do with less efficiency/lift of the foils. Probably does sound like it was lost in translation.
Philip USA #1006 | | | Re: AC72 Oracle Team USA Spaceship has landed
[Re: John Williams]
#261646 07/24/13 06:55 AM 07/24/13 06:55 AM |
Joined: Jun 2002 Posts: 1,658 Florida Suncoast, Dunedin Caus... catman
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Posts: 1,658 Florida Suncoast, Dunedin Caus... | I've taken some private flak for picking NZL early; I hope some of the folks who may be bent at my surety realize that, not only do I believe that they have the fastest boat upon the sea (tip o' the hat, Cap'n Nat), but I also feel some national pride in the work done by Nat Shaver, Bobby Kleinschmit and Pete Melvin, all members of my Club, who picked up sticks to live in New Zealand for over two years to get to this point. Hat's off. Darren Bundocks comment, Oracle is getting prepared for the Final, and seeing the Kiwis races, I'm glad OR has a two boat test to keep pushing the limits, TNZ is fast, Oracle looks even quicker , but how much faster can you go? Will find out soon, but I'm sure beyond speed diff , if any, we will see some incredible Matches between them.
Have Fun
| | | Re: AC72 Oracle Team USA Spaceship has landed
[Re: northsea junkie]
#261650 07/24/13 07:17 AM 07/24/13 07:17 AM |
Joined: Sep 2004 Posts: 2,584 +31NL Tony_F18
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Posts: 2,584 +31NL | I think something is lost in the translation and/or the transmission of this remark.
Look, apparent wind is the resultant of the true wind in the sail and the boatspeed in opposite direction. The last is derived from the so-called groundspeed.
So, when the current is with you, your groundspeed will be higher then in the situation when the current is against you.
I think the foils add more complexity to the equation. The speed at which an AC72 starts foiling is determined by the speed through the water (23kts?). So to reach the same speed through the water you would need to sail quicker over ground than if you where sailing against the current right? (Maybe 3kts or so). | | | Re: AC72 Oracle Team USA Spaceship has landed
[Re: brucat]
#261652 07/24/13 07:35 AM 07/24/13 07:35 AM |
Joined: Jun 2001 Posts: 12,310 South Carolina Jake
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Posts: 12,310 South Carolina | The less windspeed comment does make sense. As the water moves at 3 knots in the same direction as the wind, it's just like having 3 knots less wind. Consider your car on a conveyor belt. If the wind was 10mph and you are driving into it at 10 mph, you would normally experience 20mph of apparent wind. If your car was now on a conveyor belt that was moving 10mph in the opposite direction (so your car is now not making any forward progress), the apparent wind would be only 10.
It doesn't matter foiling or not - the speed vector of the water current that is parallel to the wind directly subtracts (or adds!) to the wind speed.
Jake Kohl | | | Re: AC72 Oracle Team USA Spaceship has landed
[Re: P.M.]
#261653 07/24/13 07:57 AM 07/24/13 07:57 AM |
Joined: Jan 2005 Posts: 6,049 Sebring, Florida. Timbo
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Posts: 6,049 Sebring, Florida. | OR...perhaps TNZ was so far ahead, they were just 'testing the waters' i.e. they took the opportunity to do some on course speed testing, to see if one side of the course was heavily favored with that current/wind combination, so if they run into that same combo in the finals, they'll already know the answer to the age old question at the top mark;
"Right or Left?"
Blade F16 #777
| | | Re: AC72 Oracle Team USA Spaceship has landed
[Re: Timbo]
#261654 07/24/13 08:06 AM 07/24/13 08:06 AM |
Joined: Jun 2001 Posts: 3,906 Clermont, FL, USA David Ingram
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Posts: 3,906 Clermont, FL, USA | OR...perhaps TNZ was so far ahead, they were just 'testing the waters' i.e. they took the opportunity to do some on course speed testing, to see if one side of the course was heavily favored with that current/wind combination, so if they run into that same combo in the finals, they'll already know the answer to the age old question at the top mark;
"Right or Left?" I'm quite confident these guys knew exactly where they were going and why. The effect of current on VMG is something they got sorted out long ago.
David Ingram F18 USA 242 http://www.solarwind.solar"Do or do not. There is no try." - Yoda "Excuses are the tools of the weak and incompetent" - Two sista's I overheard in the hall "You don't have to be a brain surgeon to be a complete idiot, but it helps"
| | | Re: AC72 Oracle Team USA Spaceship has landed
[Re: Jake]
#261656 07/24/13 09:17 AM 07/24/13 09:17 AM |
Joined: Sep 2002 Posts: 3,224 Roanoke Island ,N.C. Team_Cat_Fever
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Posts: 3,224 Roanoke Island ,N.C. | The less windspeed comment does make sense. As the water moves at 3 knots in the same direction as the wind, it's just like having 3 knots less wind. Consider your car on a conveyor belt. If the wind was 10mph and you are driving into it at 10 mph, you would normally experience 20mph of apparent wind. If your car was now on a conveyor belt that was moving 10mph in the opposite direction (so your car is now not making any forward progress), the apparent wind would be only 10.
It doesn't matter foiling or not - the speed vector of the water current that is parallel to the wind directly subtracts (or adds!) to the wind speed. The foiling side of it is to get the lift, to free up hull drag. Which creates less effort on the sails/wing to move the boat faster.More flow over the foils increases lift ,but would also increase drag. The light air basis of the original statement may have some merit, but since SF is not known for light air (to the contrary) I don't think it pertains here. As your speed increases ( due to wind or current)so does your apparent wind. Don't let these non-multihull sailing commentators scramble your brain with their babble. All of you guys know better.
"I said, now, I said ,pay attention boy!"
The cure for anything is salt water - sweat, tears, or the sea Isak Dinesen If a man is to be obsessed by something.... I suppose a boat is as good as anything... perhaps a bit better than most. E. B. White
| | | Re: AC72 Oracle Team USA Spaceship has landed
[Re: Team_Cat_Fever]
#261657 07/24/13 09:33 AM 07/24/13 09:33 AM |
Joined: Jun 2001 Posts: 12,310 South Carolina Jake
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Posts: 12,310 South Carolina | The less windspeed comment does make sense. As the water moves at 3 knots in the same direction as the wind, it's just like having 3 knots less wind. Consider your car on a conveyor belt. If the wind was 10mph and you are driving into it at 10 mph, you would normally experience 20mph of apparent wind. If your car was now on a conveyor belt that was moving 10mph in the opposite direction (so your car is now not making any forward progress), the apparent wind would be only 10.
It doesn't matter foiling or not - the speed vector of the water current that is parallel to the wind directly subtracts (or adds!) to the wind speed. The foiling side of it is to get the lift, to free up hull drag. Which creates less effort on the sails/wing to move the boat faster.More flow over the foils increases lift ,but would also increase drag. The light air basis of the original statement may have some merit, but since SF is not known for light air (to the contrary) I don't think it pertains here. As your speed increases ( due to wind or current)so does your apparent wind. Don't let these non-multihull sailing commentators scramble your brain with their babble. All of you guys know better. Hmmm...I'm not sure that the water still isn't the largest resistance to the boat speed even on foils...but I'll have to ponder that.
Jake Kohl | | | Re: AC72 Oracle Team USA Spaceship has landed
[Re: P.M.]
#261663 07/24/13 10:48 AM 07/24/13 10:48 AM |
Joined: Sep 2002 Posts: 3,224 Roanoke Island ,N.C. Team_Cat_Fever
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Posts: 3,224 Roanoke Island ,N.C. | I'd have to guess aero drag is bigger once on foils.
"I said, now, I said ,pay attention boy!"
The cure for anything is salt water - sweat, tears, or the sea Isak Dinesen If a man is to be obsessed by something.... I suppose a boat is as good as anything... perhaps a bit better than most. E. B. White
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