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Lee-Bow..... Windsurfers...etc (Dons tin hat)

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iGRF View Drop Down
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Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post 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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Post Options Post Options   Quote 423zero Quote  Post ReplyReply Direct Link To This Post Posted: 16 Sep 19 at 7:58pm
Correct me if I am wrong  Smile 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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Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post 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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Post Options Post Options   Quote 423zero Quote  Post ReplyReply Direct Link To This Post 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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CT249 View Drop Down
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Post Options Post Options   Quote CT249 Quote  Post ReplyReply Direct Link To This Post Posted: 16 Sep 19 at 10:29pm
Originally posted by Oatsandbeans

This is interesting. At one end we have the die hard “lee bow” fraternity that from their “gut feeling “ and experience says that this is real, and the other camp that have worked out the vectors and other such maths and conclude that it all is b***ocks.
What if they are both right (sort of!)
I admit I am in the latter group, but I ask why do the other lot swear that it is real?
So maybe they are seeing something a putting it down to the LBE.
So 2 boats are beating into a strong tide on the same tack.
It will take a long time as they are hardly making any ground. If one is able to outpoint the other it will appear to make a lot of ground to windward as the leg is so slow. Think of it magnifying the effects of the small differences in height (pointing)that the two boats have. So by the end of the leg the boat that has pointed higher will have a good advantage over the other boat and he could easily put that down to the old LBE, and his ability to squeeze that last 5deg to lee how the tide.

What do you think?

I think you're right. 
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Post Options Post Options   Quote CT249 Quote  Post ReplyReply Direct Link To This Post Posted: 16 Sep 19 at 10:34pm
Originally posted by iGRF

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.

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 Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post 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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Post Options Post Options   Quote PeterG Quote  Post ReplyReply Direct Link To This Post Posted: 17 Sep 19 at 8:56am
Originally posted by GarethT

Yup. Watching from behind. He started behind and to leeward (in fouler tide), and ended up ahead and to windward. It was very obvious watching that something was going on. Even my non sailing wife noticed!

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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Post Options Post Options   Quote GarethT Quote  Post ReplyReply Direct Link To This Post 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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Post Options Post Options   Quote Oatsandbeans Quote  Post ReplyReply Direct Link To This Post 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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