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Old 15-11-2013, 11:11   #316
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

europaflyer, we are in full agreement. I have been using the "water-referenced" and "ground-referenced" terms because some people have strongly objected to the term Ground Wind and I need to call them *something*.

What I want is are unambiguous TLAs (Three Letter Acronyms) for ground and water winds. AWA/AWS are good. As far as I know, TWD always refers to ground wind. TWS/TWA are ambiguous.
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Old 15-11-2013, 11:11   #317
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Euro.... if you want a really good laugh, go read #60
we have marks that move with us then suddenly disappear on that one !
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Old 15-11-2013, 11:17   #318
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

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europaflyer, we are in full agreement. I have been using the "water-referenced" and "ground-referenced" terms because some people have strongly objected to the term Ground Wind and I need to call them *something*.

What I want is are unambiguous TLAs (Three Letter Acronyms) for ground and water winds. AWA/AWS are good. As far as I know, TWD always refers to ground wind. TWS/TWA are ambiguous.
its simple

you use common sense and common English language

we either all go to the terminology thread and beat this out .... then come back here or we spend another #200 post trying to point out what has been pointed out in previous posts
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Old 15-11-2013, 11:19   #319
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

the other option is to give up and have a cup of tea
which I think I have reached
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Old 15-11-2013, 11:24   #320
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

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Euro.... if you want a really good laugh, go read #60
we have marks that move with us then suddenly disappear on that one !
I thought Post #60 was an excellent discussion of the reference problem, and the CTS technique.

Remember Algebra? The goal is to find an answer, and the technique usually involves reducing the equation to the simplest form, or a different form that can be solved. This is what Post #60 did.

This whole frame of reference thing is important. Not just in our ongoing lee-bow effect discussion, but in any kind of analysis. We can often become trapped by our chosen frames of reference, too. When I used to teach people how to troubleshoot electrical systems, sometimes I would turn the schematic upside-down. They were so locked into the "(electrical) ground is sacrosanct" concept that they couldn't make themselves treat is as just another distributed set of connections. Flipping the schematic broke them free of their reference bias and let them see the circuit with a new perspective.

OK, enough philosophy from me.
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Old 15-11-2013, 11:36   #321
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

I am back with lubrication
just as a heads up ... I am satisfied that whatever terminology you wish to use. that the tidal/current wind affect is the only relievent to a lee bow scenario and can be proved on paper with some trig and a bit of simply maths and a little bit of common.

What has not been fully explored are the dynamics effects it has on our boat.
So if anyone wants to join me, I will be looking at current affect on whatis in the water ( thinking outside of the box of a tablecloth-- this is really only relative to paper drawings trig with regard to wind) especially resistance of keel size and wetted area.

I will be back sometime even if I prove my self a fool ..... again
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Old 15-11-2013, 11:40   #322
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

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europaflyer, we are in full agreement.
Music.

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Originally Posted by Paul Elliott View Post
What I want is are unambiguous TLAs (Three Letter Acronyms) for ground and water winds. AWA/AWS are good. As far as I know, TWD always refers to ground wind. TWS/TWA are ambiguous.
Aaaand the music died.

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Euro.... if you want a really good laugh, go read #60
we have marks that move with us then suddenly disappear on that one !
Done. An interesting post, a long essay really and exactly the sort of thing I end up writing. Unfortunately, Dockhead is trying to dispute that current alters sailing dynamics by somehow pushing the keel around. The point he refuted is not one that anyone who understands the LBE for what it is - alteration of apparent wind by current - would have made in the first place. It is (with respect) the product of his own misunderstanding.

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We simply cannot understand the sailing part if we conceptualize both water and wind moving at the same time -- we get an idiotic confusion.
I don't - it's just a simple sum of vectors problem. As for idiotic confusion, well...
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Old 15-11-2013, 11:45   #323
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

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Music.



Aaaand the music died.



Done. An interesting post, a long essay really and exactly the sort of thing I end up writing. Unfortunately, Dockhead is trying to dispute that current alters sailing dynamics by somehow pushing the keel around. The point he refuted is not one that anyone who understands the LBE for what it is - alteration of apparent wind by current - would have made in the first place. It is (with respect) the product of his own misunderstanding.





I don't - it's just a simple sum of vectors problem. As for idiotic confusion, well...
music to mine as well

I am not always right but I am never wrong
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Old 15-11-2013, 11:58   #324
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

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Originally Posted by europaflyer View Post
Quote:
Originally Posted by Paul Elliott What I want is are unambiguous TLAs (Three Letter Acronyms) for ground and water winds. AWA/AWS are good. As far as I know, TWD always refers to ground wind. TWS/TWA are ambiguous.
Aaaand the music died.
Care to explain?

Quote:
(re. post #60)

Done. An interesting post, a long essay really and exactly the sort of thing I end up writing. Unfortunately, Dockhead is trying to dispute that current alters sailing dynamics by somehow pushing the keel around. The point he refuted is not one that anyone who understands the LBE for what it is - alteration of apparent wind by current - would have made in the first place. It is (with respect) the product of his own misunderstanding.
Why don't you read the First Post In This Thread? You know, the one where Dockhead links to several discussions of the Lee Bow Effect that you claim nobody "who understands the LBE for what it is" would even consider? That was the whole point of this thread at first.

Now, we have people explaining some other Lee Bow Effect, and most of us have agreed on those principles once we understood each others terminology.


Quote:
I don't - it's just a simple sum of vectors problem. As for idiotic confusion, well...
You are not being fair. There was confusion, in some cases because people believed in the bogus, originally defined Lee-Bow Effect, and in other cases because we were using the same terms for different things.

And Hoofsmit, saying:
Quote:
its simple

you use common sense and common English language
is being deliberately obtuse to the different historical usages of the True Wind terminololgy. There are plenty of people with common sense who are using these terms differently. I don't personally care what terms we use, as long as we understand each other.

And just when things were going so well... I think we all need a beer -- I'll buy!
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Old 15-11-2013, 12:07   #325
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

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Care to explain?
Just that I didn't really follow your acronyms, and think that it has the potential to confuse things a bit.

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You are not being fair.
No, I wasn't really. Sorry. I realise there was initially confusion as to what people were meaning by 'lee bow effect'.


How many people, then, agree or disagree with the LBE as I understand it in its simplest terms:

The creation of alternating favoured tacks by a tidal stream, through its influence on apparent (or water referenced true) wind direction.
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Old 15-11-2013, 12:38   #326
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

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Just that I didn't really follow your acronyms, and think that it has the potential to confuse things a bit.
OK, I had thought that the AWA/AWS (etc) acronyms were commonly accepted. I will follow up in that other thread.

Quote:
No, I wasn't really. Sorry. I realise there was initially confusion as to what people were meaning by 'lee bow effect'.


How many people, then, agree or disagree with the LBE as I understand it in its simplest terms:

The creation of alternating favoured tacks by a tidal stream, through its influence on apparent (or water referenced true) wind direction.
You will get no disagreement from me on these principles, and if people want to call it the LBE, I suppose we merely need to ignore (or better yet stamp out) the bogus LBE definition. As you may have noticed I get a bit prickly when it comes to competing terminology.
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Old 15-11-2013, 13:27   #327
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Paul
And Hoofsmit, saying:
Quote:
its simple

you use common sense and common English language
is being deliberately obtuse to the different historical usages of the True Wind terminology. There are plenty of people with common sense who are using these terms differently. I don't personally care what terms we use, as long as we understand each other.

you are totally correct and I apologise..... I was trying to be funny, but its not the first time my dry humour has been miss read... I am sorry

If I could add that the phrase of lee bow effect has been already been taken out of context from lee bowing the tide, most of the discussion in this thread would be settled, it won't help to cause more confusion by abbreviation ... but that is my view..... I just found somebody who agreed
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Old 15-11-2013, 13:58   #328
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

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you are totally correct and I apologise..... I was trying to be funny, but its not the first time my dry humour has been miss read... I am sorry
I wasn't offended, and I have been quite enjoying the debate and discussion with all of you. Like I said, it's time for a beer!
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Old 15-11-2013, 14:29   #329
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

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Angela,

See attached drawing. The dotted red lines are your laylines and your tacking angles. I am assuming a tacking angle of 90degrees.

If you calculated a CTS and short tacked the CTS line you would not be sailing an optimal course by a long shot as once you started entering the middle of the channel every port tack would be dead into the peak current.

A much faster route would be to sail on starboard tack the whole way across the channel until you reached near your layline and then tack so that now you are in lesser current for the entirety of your port tack .
Edited to add:
Scrap all the comments below. Incredibly stupid of me. Penny dropped, in fact it was more a cannon ball that dropped LOL.

CTS only applies for variable current over time, not variable current in different spots on the course. Of course you would head straight over to spend min time in adverse current . Red faced here.


Hi FS
Well, I would fail miserably as a tactician LOL. I am at the stage where my head is spinning looking at this problem, but I think I would do the exact opposite to what you suggest and I know you are an experienced racer. Doubt a sticky is ever going to be on that trophy if you follow my strategies given we are poles apart (I am at least getting the hang of the lingo, so there is some hope).

Let me preface this by saying it is the first time I have done any planning for a journey tacking with variable current.
My plans are sketchy without the profile of the current (eg is it 3.8 exactly in the centre and over a widish area, decreasing rapidly on the two sides as the depth varied, or does each segment take up about 1/3 of the width?) or without knowing the expected speed close hauled with a 15 knot wind wind in flatish water (flatish as wind is roughly with current), or without knowing if the wind is different near shore etc etc. But at least I can give you a general plan.

A few conclusions based on the data given:
The destination is directly into the ground wind.
The current is roughly divided in thirds (no specific info given).
The strongest current is in the first 2/3 of the journey.
The average current is about 1/3 of the likely boat speed (8 knots??) and is 4O odd degrees clockwise of the ground wind.
The CTS is therefore displaced clockwise of the ground wind.
Longest on port tack (a bit less than 2/3 of the time?) following the shortest track through water.

Here is my rough strategy based on the info given:

You would want the port tack (the one lifted by the current) to be in the portion of the strongest current to gain the most lift, so it needs to occur roughly for a bit less than the first 2/3 of the journey. So start on starboard tack briefly (better tactically anyway), tack to port and continue on for a bit less than 2/3 of the time. Tack back onto starboard tack for the rest of the trip. I know I am very hazy about the details, but that is the rough plan.

Why I don't like your strategy:
You nip over the channel on starboard tack in fact being knocked by the current the whole way so your sailing angle is worse and on top of this you end up a long way down stream and very likely will end up not sailing the last leg close hauled, as it would be EXTREMELY difficult to judge when to turn onto this last tack and lay the mark. You leave yourself no margin to take advantage of good shifts in ground wind. You may end up sailing a very long leg with a lot less wind if it is close to shore.

I really don't get sailing in conditions where you are knocked badly initially, to then have the least lift from the current that whole long final leg, which by the way is dead into current. At least the current is lifting me for 2/3 of the trip.

How much faster is it actually doing what you suggest? I am still puzzling how your technique works.

Edited to add: See my post #353 for the rest of my comments.
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Old 15-11-2013, 14:46   #330
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

FS:::: OR ANYBODY ELSE !

Could I ask for your opinions

We have suggested that the current/tide creates a wind by 'pushing' the boat.
This has then been worked in as a angle and speed to come to an answer to show the affect of the wind that hits our sails ( in simple terminology)

Why is the full current rate applied ? we have resistance from the water do we not?

We seem happy to add leeway knowing that it differs dependant on sailing angle

If we look at being on a table cloth the dynamics of resistance the affect of hull shape, keel shape and wetted area are completely ignored.

is this correct ?
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