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Lee-Bow..... Windsurfers...etc (Dons tin hat) |
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iGRF
Really should get out more Joined: 07 Mar 11 Location: Hythe Online Status: Offline Posts: 6496 |
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Topic: Lee-Bow..... Windsurfers...etc (Dons tin hat) Posted: 16 Sep 19 at 7:33pm |
Personally I'd like to see the so called hard evidence that something I not only experience every week of my life, but have used to devastating race winning effect on numerous occasions too many to even contemplate, is wrong. I bet it comes from lead mining where the rules are totally different.
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423zero
Really should get out more Joined: 08 Jan 15 Location: United Kingdom Online Status: Offline Posts: 3406 |
Post Options Quote Reply Posted: 16 Sep 19 at 7:58pm |
Correct me if I am wrong beating against the tide, which is travelling at roughly 45 degrees to hull direction, in effect pushing the sail sideways into the wind, therefore increasing airflow across the sail increasing drive ? Similar effect to pumping, is that what you mean iGRF ?
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Robert
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iGRF
Really should get out more Joined: 07 Mar 11 Location: Hythe Online Status: Offline Posts: 6496 |
Post Options Quote Reply Posted: 16 Sep 19 at 8:18pm |
Found this old picture to illustrate.
This was taken at Hayling Island in 1979 the windsurfer in the foreground is out pointing the windsurfers in the back ground, the tide was running right to left most of the rest of the fleet are simply sailing into it. Back then we'd never heard of the term 'lee bow' but we thought of the foil under the board being 'tacked'if you like contrary to the flow.(Like the gybing centreboards we came across much later). Over sheeting to extreme there in fact, to achieve the disired angle to increase the pressure and as you continue parallel to the others the windsurfer would come closer to the camera, moving more upwind than the others. Pointing higher, sailing faster it's called, but the tidal flow if there is any helps, something that comes naturally as it probably did for Gareths Number One son. Edited by iGRF - 16 Sep 19 at 8:36pm |
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423zero
Really should get out more Joined: 08 Jan 15 Location: United Kingdom Online Status: Offline Posts: 3406 |
Post Options Quote Reply Posted: 16 Sep 19 at 9:13pm |
He is hiking harder and it looks like he has more pressure in his sail, but he is in clear air and would also catch first gust ?
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Robert
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CT249
Far too distracted from work Joined: 08 Jul 06 Online Status: Offline Posts: 399 |
Post Options Quote Reply Posted: 16 Sep 19 at 10:29pm |
I think you're right.
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CT249
Far too distracted from work Joined: 08 Jul 06 Online Status: Offline Posts: 399 |
Post Options Quote Reply Posted: 16 Sep 19 at 10:34pm |
I can see the same thing happening every week at my club - which is located 120km inland from the sea on a reservoir and has NO tidal flow. The same thing repeatedly happened the other month with the Windsurfers in Garda, which has no tide. The windward board just looks to have a gust and be better sailed at the instant the pic was taken. The basic rules aren't different in lead mining, although they are often used in different ways.
Edited by CT249 - 16 Sep 19 at 10:36pm |
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Post Options Quote Reply Posted: 17 Sep 19 at 8:23am |
If you're going to make a gain by pointing your boat in a different direction to others (by tacking, gybing, footing or pinching), then something has to change. Wind direction, wind speed, tidal flow or direction. These changes can be temporal, or spatial. But, something has to change to for a gain to be made by sailing a different heading to your competitors.
If you do make a gain by footing off, or pinching up, and yet there is no apparent change, then you either failed to perceive the change, or you weren't sailing your optimum VMG to begin with.
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PeterG
Really should get out more Joined: 12 Jan 08 Location: United Kingdom Online Status: Offline Posts: 818 |
Post Options Quote Reply Posted: 17 Sep 19 at 8:56am |
But you said earlier "he did something with his feet" and you didn't know what. Is there any reason to think that his improved pointing had anything to do with the tide, and not simply that whatever he did with his feet meant he could point higher?
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Peter
Ex Cont 707 Ex Laser 189635 DY 59 |
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GarethT
Really should get out more Joined: 21 Apr 07 Online Status: Offline Posts: 714 |
Post Options Quote Reply Posted: 17 Sep 19 at 9:07am |
It wasn’t just the pointing higher. He was tracking higher too. A perceptible climbing sideways if you like. Like when you see people going sideways to leeward in an unhelpful tide (in fact like the people around him in a low mode).
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Oatsandbeans
Far too distracted from work Joined: 19 Sep 05 Location: United Kingdom Online Status: Offline Posts: 382 |
Post Options Quote Reply Posted: 17 Sep 19 at 9:40am |
A windsurfer allows you to have a amazing control over the angle of attack of both the sail ( in 3 axis) and foil (in 2 axis) .
In the pic the board to windward has the rig oversheeted past the centreline. If you think what the foil is doing it will be at a high angle of attack to the waterflow, generating a lot of lift ( and drag). This sounds as if it would give a high pointing low leeway mode. So I would not be surprised if this gave separation to the boards below that are in a more fast and free mode. |
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