Author Topic: wind vs current  (Read 1445 times)

SimonP

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Re: wind vs current
« Reply #15 on: October 07, 2020, 03:52:57 PM »
Wind against current increases lift regardless whether you are on a foil or a displacement craft. You can point higher upwind and point lower downwind without stalling.
I got stuck in a gybe the other day perfectly balanced for several seconds in a current pointing directly downward but going nowhere. It's a very odd but cool feeling.

foiled again

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Re: wind vs current
« Reply #16 on: October 07, 2020, 08:12:10 PM »
"Water current can only influence drive through the apparent wind it produces."
 
This is definitely true. If you only have a foil board and no hand wing and you point it into the current, you are not going to get any lift, you are just going to get sent down stream because there is no hand wing to utilize the apparent wind that is produced. 

If you want to understand this from the layman's perspective, read the holy grail for all airplane pilots called "Stick and Rudder: An Explanation of the Art of Flying" by Wolfgang Langewiesche first published in 1944 and still available in bookstores everywhere.

LaPerouseBay

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Re: wind vs current
« Reply #17 on: October 07, 2020, 09:35:44 PM »
Bill, to be more precise, we are all moving through Space and Time at the speed of light.

Yup. Even more correctly, through spacetime.

Hmmm...  That spacetime taradiddle refers to a sum total in 4 dimensions.  I'm aging, so I'll stick to 3.   

Michael puts a number on how we all move thru space, in kph. 

https://youtu.be/IJhgZBn-LHg
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Admin

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Re: wind vs current
« Reply #18 on: October 08, 2020, 02:16:12 AM »
The Gorge is a perfect place to feel this firsthand because we get Easterlies (wind and water same direction) and Westerlies (wind and water opposite directions). 

On a foil you can get foiling a bit quicker in an opposing current when the current is strong (but it is very subtle, not enough to choose a different wing size).  When the current is light the difference becomes pretty negligible.  It does feel very cool though when you hit a pocket of strong opposing current going downwind at low speed and get suspended. 

The Event site in the springtime is a perfect test spot for this because you have a sandbar protected area inside of no current, then an opposing current in the channel, then a large eddy with matched current.  Aside from crossing the eddy lines which will make your foil jump every time you can feel the difference as you pass from matched flow to counterflow or no flow to counterflow.  Pretty cool.
« Last Edit: October 08, 2020, 02:18:09 AM by Admin »

foiled again

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Re: wind vs current
« Reply #19 on: October 08, 2020, 09:25:33 AM »
We have kind of the same thing, as that described by Admin,  in San Francisco Bay by the Golden Gate towards the north side, especially within about an hour each side of slack. We call it "Voodoo Chop". It helps to make the whole experience unique and fun.

PonoBill

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Re: wind vs current
« Reply #20 on: October 09, 2020, 05:54:28 PM »
Hmm...  That spacetime taradiddle refers to a sum total in 4 dimensions.  I'm aging, so I'll stick to 3.   

Michael puts a number on how we all move thru space, in kph. 

https://youtu.be/IJhgZBn-LHg

Cool video, thanks for that. I never heard of this guy but I subscribed.

Spacetime is easy to experience even for geezers. Toss a ball--it's a three dimensional object moving through time. The complexities start when you realize that time is different for every object. It varies with relative velocity and position in a gravitational field. It really is just a dimension, not a static thing. In fact at the quantum level it winds up dropping out of virtually every equation. It's reasonably accurate to say it doesn't exist at all, and if it doesn't exist in the waves (or particles if you insist on being classical) then how could it exist on the macro scale which simply consists of a LOT of quantum stuff. It's an emergent phenomenon.

For those interested in having their view of reality permently bent, twisted, stapled and mutilated I recommend Carlo Rovelli's "The order of Time" -- or for that matter anything else Carlo has written.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

LaPerouseBay

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Re: wind vs current
« Reply #21 on: October 09, 2020, 09:28:07 PM »
Hmm, I usually sidestep the quantum stuff.  Has any of that been proven yet?  Or is it all theoretical?  A quick search and all I found was 'reality is what you make of it.'  K. 

Anyhow, I had recently watched parts of the below linked video.  Also, years ago, Michael's zooming earth...

When you guys were claiming that "we all move at the speed of light" thru spacetime, something didn't seem right.  So, I had to google it.

In the words of Lewis Carroll Epstein:
“You can’t go faster than the speed of light, because you can’t go slower than the speed of light. You are always going the speed of light through spacetime. If you use some of your speed to go through space then there is less speed through time.” 

So, I used Epstein and Professor Green's intuitive explanation for time dilation to conclude that: your claim that we are all moving the speed of light thru spacetime is incorrect.

Because: According to Dr. Greene, motion affects time (and vice versa).   

Since I'm aging, I must be traveling slower than the speed of light, thru spacetime.  It sounds like a zero sum game in 4 dimensions to me.  Change one, the others adjust...

That said, living in 2 dimensions, as a 'flatlander' never made no damn sense to me neither. 

https://youtu.be/XFV2feKDK9E?t=9241
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Phils

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Re: wind vs current
« Reply #22 on: October 10, 2020, 12:50:33 AM »


Because: According to Dr. Greene, motion affects time (and vice versa).   

Since I'm aging, I must be traveling slower than the speed of light, thru spacetime.  It sounds like a zero sum game in 4 dimensions to me.  Change one, the others adjust...



You are correct in that motion does affect time but that does not invalidate the statement that we exist in spacetime at the speed of light.

Motion affects time in that as you move faster, time slows down for you.  (this is correct mathematically and has been proven with atomic clocks on airplanes)  My conclusion is get a faster foil and live longer.

PonoBill

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Re: wind vs current
« Reply #23 on: October 10, 2020, 07:12:20 AM »
Hmm, I usually sidestep the quantum stuff.  Has any of that been proven yet?  Or is it all theoretical?  A quick search and all I found was 'reality is what you make of it.'  K. 

You are typing on a device that could not work unless quantum stuff was real. Enjoying the heat from a sun that would not ignite and continue it's thermonuclear burn unless quantum tunnelling was real.  If it wasn't true then electrons would spin down into the nucleus of the atoms that form you and turn all the protons to neutrons. Atoms would have a tiny volume and you would be part of a small black hole that used to be our solar system. So yup, it's way more than just theoretical. Even though it's been central to science since the turn of the last century no one REALLY understands the why of it--that's at least partly why it's called quantum mechanics. We've got the operating manual, but no explanation of why it works this way. But all the resultant equations work with a level of effectiveness beyond classical physics, which is always inaccurate or totally incorrect at small or large scales. Even really weird stuff like quantum entanglement has ben demonstrated at our scale, with experiments that work shockingly well.

« Last Edit: October 10, 2020, 07:24:51 AM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

 


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