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

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Old Timer View Drop Down
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Post Options Post Options   Quote Old Timer Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 19 at 2:23pm
Originally posted by iGRF



Finally because it's relevant, forty years ago this month just gone, a windsurfer called Mike Todd and I crossed the Channel on a Tandem windsurfer, 1979 same year as that earlier picture. We set off in slack water, but on the French side of the Varne bank, the tide engaged our, you've guessed it, lee bow and our speed over the water increased and we were able not to fully plane but to at least hook into our harnesses.

So what do you think happened there, the tide gave additional flow over your foils giving you more pace or that the tide wind combined with the ground wind to give you a stronger sailing wind?
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Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 19 at 4:23pm
Originally posted by Old Timer


Originally posted by iGRF


Finally because it's relevant, forty years ago this month just gone, a windsurfer called Mike Todd and I crossed the Channel on a Tandem windsurfer, 1979 same year as that earlier picture. We set off in slack water, but on the French side of the Varne bank, the tide engaged our, you've guessed it, lee bow and our speed over the water increased and we were able not to fully plane but to at least hook into our harnesses.

So what do you think happened there, the tide gave additional flow over your foils giving you more pace or that the tide wind combined with the ground wind to give you a stronger sailing wind?


Well Old timer, we didn't really know anything other than the tide makes the wind feel stronger and being ignorant windsurfers didn't really call it anything, although logic would suggest it better to have two distinct reasons rather than one or you wouldn't know how to separate them or how to increase or decrease the combination if you don't know which bit is doing it, so calling it one thing is counter intuitive.

However some wise old dinghy sailing sage came along annd explained we had experienced 'lee bow effect' not that we even knew we had a lee or a bow, so as I said many many pages back your term not mine, so now, like a woman you've changed your mind and called it something else, no wonder all boats are female...

But it doesn't really matter what its called as long as you accept that angling the lower foil works better when the flow is on one side than it does on the other.

Edited by iGRF - 05 Oct 19 at 4:25pm
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Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 19 at 4:41pm
Haha, I've just thought of another conundrum..

When we reach a certain threshold, (used to be called the force four barrier), lets call it 10 knots for arguments sake, we kick the plate away, not just back, all the way, gone into the board thanks to that genius pair, back then in 1979. (I asked for it Mike Todd built it). The board breaks onto the plane and all that tide feel goes away.

Because the tide force gets replaced and exceeded by created wind force which gets stronger and stronger to the point it becomes possible to bear off full on into the tide and stay planing.

Just anecdotal nonesense meaning not a lot, but it's part of the phenomena of being able to exceed wind force, and in this case wind and tide force, where in some places like the famous windsurfing spot on the Columbia river, Oregon, where the walk of shame is more likely to be back down wind rather than up during the spring melt and places like Portishead in England where they have a very strong tide at their club we had some interesting races at back in the day.

So I prefer to know which of the three components I should go for in my 'sailing' wind and I think so should everyone else.

Edited by iGRF - 05 Oct 19 at 4:42pm
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Post Options Post Options   Quote Old Timer Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 19 at 4:56pm


Originally posted by iGRF

Originally posted by Old Timer


Originally posted by iGRF


Finally because it's relevant, forty years ago this month just gone, a windsurfer called Mike Todd and I crossed the Channel on a Tandem windsurfer, 1979 same year as that earlier picture. We set off in slack water, but on the French side of the Varne bank, the tide engaged our, you've guessed it, lee bow and our speed over the water increased and we were able not to fully plane but to at least hook into our harnesses.

So what do you think happened there, the tide gave additional flow over your foils giving you more pace or that the tide wind combined with the ground wind to give you a stronger sailing wind?


Well Old timer, we didn't really know anything other than the tide makes the wind feel stronger and being ignorant windsurfers didn't really call it anything, although logic would suggest it better to have two distinct reasons rather than one or you wouldn't know how to separate them or how to increase or decrease the combination if you don't know which bit is doing it, so calling it one thing is counter intuitive.

However some wise old dinghy sailing sage came along annd explained we had experienced 'lee bow effect' not that we even knew we had a lee or a bow, so as I said many many pages back your term not mine, so now, like a woman you've changed your mind and called it something else, no wonder all boats are female...

But it doesn't really matter what its called as long as you accept that angling the lower foil works better when the flow is on one side than it does on the other.

You should enter politics, you manage to not answer the question and give two contradictory points and redefine / misuse a definition in a couple of paragraphs and do it all 100% self belief and not a whiff of embarrassment. You really have missed your calling. 

At least I can now conclude what you call the lee bow effect isnít the much discussed myth. 
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Post Options Post Options   Quote ian.r.mcdonald Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 19 at 5:11pm
Page 36 and gybing centreboards havent been mentioned yet? Come on guys! Let's maintain tradition

Edited by ian.r.mcdonald - 05 Oct 19 at 5:12pm
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Post Options Post Options   Quote sargesail Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 19 at 6:10pm
Originally posted by sargesail

Originally posted by iGRF

As to those who would decry the 'Ferry Gliding' example simply because it doesn't correspond with their lee bow debunkingposition. I would suggest the following.

If you have say a 4knot current one way with your craft headed the other directly into the flow balanced exactly by a four knot wind on a dead run. Brought effectively to a standstill over the ground.

What would happen if the plate gybed to the left (or right) even just one degree (rudder still centred)?

If the others are to be believed nothing would happen. But the fact is the craft would shift right or left even though the water it is sailing in doesn't 'know' anything has happened.

Sorry whatever they're reading it's been misleading them.


Ok which of these 2? It may not be relevant but Iíd like to know what assumption we are making about impossible performance envelopes!



Gybing boards are in there!
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Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 19 at 7:17pm
Originally posted by ian.r.mcdonald

Page 36 and gybing centreboards havent been mentioned yet? Come on guys! Let's maintain tradition


Yep, we did discuss them as an illustration of the ferry glide thing and then the resident forum Banksy (sargesail)committed to sketch.
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Post Options Post Options   Quote sargesail Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 19 at 7:32pm
By the way the boat goes backwards as well as sideways cos you canít have lift without drag. The sail might flap because the sideways movement will cause the wind to come forward.
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