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LEE BOW EFFECT
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Rupert View Drop Down
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    Posted: 20 Oct 11 at 7:35pm

I can see you'd get a curve if the tidal strengh changed over the course.
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 20 Oct 11 at 8:46pm
It's the Coriolis effect
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Posts: 4028 		Post Options Post Options   Quote G.R.F. Quote  Post ReplyReply Direct Link To This Post Posted: 20 Oct 11 at 9:19pm
The illustration assumes the tide coming on during an existing course as an extreme example to make the point.

If it was already there, then maybe a race officer might move the mark, or
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rogue View Drop Down
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graeme- seamonkey is not my sockpuppet, look closer to home.
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Posts: 170 		Post Options Post Options   Quote gbrspratt Quote  Post ReplyReply Direct Link To This Post Posted: 21 Oct 11 at 7:04am
It wouldn't curve. A curve indicates a variation. Either an increase or decrease on tide or speed. As everything is constant it would be straight. I can write that slower for you GRF if that helps?
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Posts: 1151 		Post Options Post Options   Quote 2547 Quote  Post ReplyReply Direct Link To This Post Posted: 21 Oct 11 at 8:32am
Originally posted by G.R.F.


I've seen it so often, lots and lots of times, by the time the boats (boards) who haven't clocked it have sailed left, by the time they come right they're having to bear away to get to the mark ..

You seem to have moved this topic on to a totally new situation; perhaps you have now given up the deluded perpetual motion concepts of your youth ...

awww ... man!!! we are so lucky to have you to point out these tactical hidden nuggets ....

What you have sketched is basically saying if you sail upwind to the mark whilst your competitors overstand so wildly they end up beam reaching into the mark you will win ... no f****** s**t ... I'd have never have guessed.

The standard of beach toy rallys in the 70s must have been pretty red hot for you to have seen this many times as I wouldn't expect even the most novice dinghy racer (or pondmonkey) to make such a basic error ...

BTW if the current was constant you'd sail in straight lines ...


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Posts: 241 		Post Options Post Options   Quote fudheid Quote  Post ReplyReply Direct Link To This Post Posted: 21 Oct 11 at 9:11am

Originally posted by JimC


The theory goes that if you point up so that the tide is one degree on the lee bow instead of 1 degree on the windward bow then you'll magically go much better. Of course if you sail your [expurgated] off so that you point two degrees higher *without slowing down* then you don't need any complicated theories about tide to explain why you're suddenly going better up the beat...

Yes, the tide pushes you across the track, but the apparent wind clocks back the other way as a result. Nothing special happens when the tide goes from 0.1 degrees one side to 0.1 degrees the other. It takes ages and a lot of drawing of force triangles to explain why, but that's what happens.

Remember all that counts is what the wind is doing relative to the sails and the water is doing relative to the foils. The boat hasn't got a clue what the sand on the bottom of the river is doing... In tide the effective wind direction and speed is not what you get in a moored boat, but what you get in a boat drifting in the current.

Of course if the tide is not constant in speed and direction across the race track there are enormous gains to be made by exploiting the differences, but that's something else again: not what was traditionally called the lee bow effect.
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I've just read the first page again and would like to thank JimC for answering quite succintley the original OPs question on the first page!
quoting that other great thinker axl rose " what we've got here is a failure to communicate"
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2547 View Drop Down
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Posts: 1151 		Post Options Post Options   Quote 2547 Quote  Post ReplyReply Direct Link To This Post Posted: 21 Oct 11 at 9:15am
Originally posted by fudheid

...
quoting that other great thinker axl rose " what we've got here is a failure to communicate"


Not really ... more like failure of one empty vessle to accept the facts ...
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Posts: 2753 		Post Options Post Options   Quote Isis Quote  Post ReplyReply Direct Link To This Post Posted: 21 Oct 11 at 11:25am
Seriously - Curves? this is just getting sillier...

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rogue View Drop Down
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Posts: 978 		Post Options Post Options   Quote rogue Quote  Post ReplyReply Direct Link To This Post Posted: 21 Oct 11 at 11:38am
Originally posted by seamonkey


Originally posted by fudheid


...
quoting that other great thinker axl rose " what we've got here is a failure to communicate"
Not really ... more like failure of one empty vessle to accept the facts ...


actually fudheid, Civil War, great EP though it was (I have the limited edition embossed CD case somewhere in the loft) the opening lines are not a Rose original unfortunately- it's a sample ripped from Cool Hand Luke starring Paul Newman... the next line is 'some men you just can't reach'

which is quite appropriate given a) grumpfy's short stature and b) his seemingly irreverent tactical wit you lot fail to appreciate....

So you get what we had here last week, which is the way he wants it... well, he gets it. I don't like it any more than you.



Edited by rogue - 21 Oct 11 at 11:39am
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