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Old 14-11-2013, 09:04   #241
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

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If you are pinching to make the mark then that means you tacked short on the lay line, knowing in advance that there is a consistent geographically induced veer that left you pinching to reach the mark previously should tell you that the next time you are tacking on the lay line for the mark that you should extend further to allow you to lay the mark under optimal VMG.

There is never a time that pinching is a viable strategy for speed.

Pinching can be and is used frequently tactically however. Usually to recover from a bad tactical decision made earlier though. For example if you end up inside boat approaching the windward mark but are below the lay line and have overlap with the boats to windward and can't tack if you are close enough you can call for room and pinch up to clear the mark.

The situation you describe still has nothing to do with Lee Bow Effect it is just about current and wind - you are not gaining an advantage on other boats because of the orientation of your bow to the current - you are gaining advantage because you are entering a wind veer on optimal tack.

edit: Also Veer is when the wind moves clockwise and Back is counterclockwise so if you are approaching a mark on starboard tack for a port rounding a veering wind would lift you above the mark meaning you would have to foot to make it versus pinch and the opposite for a port tack starboard rounding. Starboard roundings are less common for anything other than gybing marks, gates or non-windward or leeward marks that dont involve major course changes to the fleet as they present dangerous crossing situations due to Port-Starboard rules
you are correct ... the wind backed (i used veer as an incorrect term to discribe a change in wind direction)

the only thing I would point out is that this is in a narrow tidal harbour where the tidal affect was king, pop your nose round the point and you where swept back very quickly, pinching won the day very often because a tack would be suicidal. we also sailed in a handicapped fleet with very different classes so strategy of the competitor was rarely the same for us.
unfortunately the course was often set on our 10 minute gun and being in a planning dinghy the chart table didn't fit !! so was abandoned
this was use "your gut feeling" sailing

mistakes where made on every leg, those who made the least won. the variables of tidal eddies of current and whether the veer or back would occur was often chance. probably why I have a try it and wing it approach rather than spending the time I should finding out or even being able to except constants
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Old 14-11-2013, 09:21   #242
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

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pauls quote:
Now place your boat, sailing the same speed but in a current. Your entire boat will be swept by the current, but your movement through the water will be identical. The flow diagram will be the same. Your movement over the ground will be affected by the current, but not your movement through the water.
fine if you are going to a point on the table cloth not to the chair with the table cloth moving in a stable direct .
I am either not making my point, or I am completely wrong about this. I think I'm not making my point.
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try putting your hand under a tap..... change the angle of you hand ... it creates side ways movement. if the tap moved but you kept you hand in the stream ... you would still have sideways movement ! ok maybe not the best explanation but if you stay still on the table cloth but the table cloth moves you are drifting, now... we are not in a bowl we are in a hull with dynamic design , other wise we would be sailing in tuperware bowls( no comments from the wooden boat gang lol )
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do the same workings as a cts wind vector . wind on the sail has the same affect as current on the keel ... just I have to explain it
In your hand under the tap example, your hand is ultimately attached to the ground, not the water. This is a crucial difference. Our reference points matter. When sailing on the tablecloth, we are not necessarily drifting. We have our sails up, and they harness the True Wind (water-referenced). We are sailing across the tablecloth, and at the same time the tablecloth is moving (current).

For the moment, say there is no land, no GPS, no stars in the sky. There is only water and wind. We can't even tell if there is a current or not, as we have no point of reference other than the water. Now go sailing. Whatever point of sail you choose, you move through the water as if there is no current. The angle of the water flow across your keel will depend on the wind, your point of sail, and your boat speed. This is leeway. It doesn't matter if there is current or not. This is the essence of the tablecloth analogy.

Now throw in some land, and a harbor you are trying to reach. Yes, you need to pick a course that factors in wind and current, but your boat sails exactly the same way as it did before.
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Old 14-11-2013, 10:28   #243
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

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Hi Evans
Yes, I fully agree. But none of this has anything to do with the keeping the current on your lee side either.
You and I are agreeing, but you don't seem to realize it (my bad writing perhaps). We agree it is all about being on the right side of shifts.

Sometimes (something more than 50% because of the preponderance of courses with W/L legs) that has the current on the lee side, so some people think they are benefiting from "the lee bow effect". But they are not, they are benefiting from being on the lifted tack.

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In fact I would venture to say those that do believe in it and claimed to have won races with it are actually merely benefiting by placing themselves in the right place at the right time benefiting from the right combination of vectors of force.
We agree completely!
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Old 14-11-2013, 10:37   #244
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

paul and Foolishsailer ..... thanks for you patience

I understand the principle of how to view the tide as a table cloth, I just found it hard to understand the logic of it, but can see from a paper exercise the principle must be excepted, with tidal stream being added as a vector. Daftly ....I except it completely in passage planning

the fact that most of my racing strategy has come from experience in basically a river, does not help when it comes to reference points, tacking angles and laylines where done from experience of what worked in strong variable currents.

Also sailing to a visual static point changes the perception of what your hull is doing, although in reality it has given me an advantage in handling a cruiser in shallow and tight tidal dockings.

interestingly for me, my exmaniner told me I had past by winging it through experience instead of using tried and tested techniques ( you will be glad to know that lee bowing the tide was not one of them )

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Old 14-11-2013, 11:38   #245
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Hoofsmit, I sail in the San Francisco and Pacific Northwest areas, where strong currents are pretty common (the pass near my house sometimes sees 12+ knot currents). I remember the first time I steered a boat in San Francisco bay. I was aiming for a point on shore, and I ended up sailing through almost 45 degrees trying to keep the bow pointed at that mark.

That was my first experience in big current, and I had a lot to learn. These effects are so pronounced that it is sometime hard to ignore the land-related factors when analyzing how our boats sail.
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Old 14-11-2013, 15:33   #246
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

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Excellent stuff.

You are the first person I have ever talked to who actually seems to understand all this. You have an advantage over Seaworthy and me in that we started this discussion in a state of utter cluelessness.

The subtle points are not unimportant, because they illustrate the limits of the phenomenon and therefore give clues about its nature. Very good stuff.

Why don't you have a look at these posts:

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

and tell us if you think we're on the right track?


And next question -- do you have any opinion on whether it is ever possible to gain miles by actually pinching, in order to stay on the best tack for a while longer? If so, how can it work if you're giving up VMG to windward?

One of the puzzles is that your polars give you max VMG to windward, but that is to the True Wind, not to the Ground Wind. Maybe that makes no difference, but I haven't figured it out yet.
OK, I've had a think. Once again, I may have lost track of who is arguing which point. I'll do my best to put my thoughts in to words.

I think the 'pinching' point is unrelated. The LBE will alter the apparent wind regardless of where you are pointing. In my mind, the only use of 'pinching' is to point slightly higher than you normally would, at the expense of boat speed, if you aren't quite laying a mark and making two rapid tacks is undesirable. What I call 'luffing a mark' is a similar ploy, a last-few-seconds attempt to round a mark that is sitting on the bow by using your speed to turn up head to wind, and hoping you can bear away again before you run out of speed. Both of these are short-term 'tactical' manoeuvres, rather than 'strategic' ones such as exploiting the LBE.

I think I can see why the 'favoured tack' thing popped up in relation to LBE. In the constant-current situation, there is no distinction between the effect of LBE on the true wind (creating an 'advantageous tack' in the parlance of this thread), and a wind offset to one side of the destination (creating a 'favoured tack'). In both cases, it is prudent to make the tack which gives the greatest SOG towards the destination first, to insure against any future wind shifts. There is no real distinction between 'favoured' and 'advantageous' tack in this situation, which is what I think the instrument maker linked a few pages back was thinking about when they tried to dispute the existence of the LBE. They may only have been concerning themselves with very short races.

The true LBE comes about when the tide changes during the course of the voyage. The effect of this is a 100% predictable shift in apparent wind, much like having a totally accurate forecast of a true wind shift. If you knew from a forecast that the true wind was going to shift to swap the favoured tack from one side to the other half way through a voyage, you would start your voyage on the favoured tack, then tack over when the wind shifted to remain on the favoured tack. A boat which started the voyage on the unfavoured tack would not lose anything if the wind did not shift (the equivalent of the constant-current scenario for LBE), but would find itself well downwind of the other boat if the forecasted wind shift did happen. Even without a forecast, you assume this may happen and make the favoured tack first - you have nothing to lose and potentially a lot to gain. This is a much better understood concept than LBE, so I hope explaining it in these terms is helpful.

In the LBE scenario, if the current is constant then there is nothing to be lost by starting on the unfavoured tack first. However, the strategic decision relating to the LBE is when we know that the current will shift, and therefore bring with it a shift in apparent wind. Because of this, we start on the favoured tack (or 'advantageous tack' if that is what we have decided to call the creation of a favoured tack by the LBE), and then tack over when the current changes. This is how to exploit the LBE. A boat that does not do this will, like the boat starting on the unfavoured tack with the forecasted wind shift, find itself well downwind of the lee-bow vessel when the current changes.

As for the wind names debate, I don't really know about the names that modern instrument makers use. I think people are trying to make a distinction between the wind direction over the ground at slack water, and the minute change that friction between the air mass and a moving current will make. This is not, in my mind, a distinction important to sailing. I see only two wind names relevant here - the true wind which is what is blowing over the ground or seabed, and the apparent wind which is the true wind with the vectors added to it of the wind created by the boats motion ('headwind'?) and the motion of the current ('current induced wind' in my diagram - a more elegant name might be 'tide wind'?).

An alternative (if a little wordy) definition of the LBE might then be:

The changes in favoured tack brought about by the influence on the apparent wind of changes in the tidal stream.

and the strategic decision to use the LBE is then...

...the exploitation of these shifts by tacking at slack water to remain on the favoured tack.

A subtle point that there has been some debate on is whether a current from the lee side will always be favourable. The 'switchover points' are in fact in relation to wind direction rather than boat direction, but the 'current coming from the same side of the wind that you are pointing on effect' isn't really a viable name. Also,the wind shift created by boatspeed puts the 'switchover points' just slightly to one side of the true windward and leeward as I have said before - a bit to port when on starboard tack, and vice versa. I think this may well be on 'apparent windward and leeward' but I might have to do some drawings to be certain. Make some sketches with wind vectors and you will see what I mean. If the boat is dead in the water though, the switch will occur when the direction of the tide passes exactly through the windward and leeward directions, as 'apparent' and 'true' are the same when the tide lines up with the wind with zero boat speed.

This discussion complicates the issue, and as some people still dispute more basic points we should steer clear of this... for now.

The most common scenario (both in discussion of the LBE and, I think, in real life) is when true wind is at 90 degrees to the current, in which case lee-bow effect is a perfectly acceptable name. This is also when the effect is strongest, so discussion of these extremely fine points really does have little or no relevance in the real world.

Sorry about the long post, but I have been mulling this over for a few days!
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Old 14-11-2013, 16:12   #247
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OK, I've had a think. Once again, I may have lost track of who is arguing which point. I'll do my best to put my thoughts in to words. I think the 'pinching' point is unrelated. The LBE will alter the apparent wind regardless of where you are pointing. In my mind, the only use of 'pinching' is to point slightly higher than you normally would, at the expense of boat speed, if you aren't quite laying a mark and making two rapid tacks is undesirable. What I call 'luffing a mark' is a similar ploy, a last-few-seconds attempt to round a mark that is sitting on the bow by using your speed to turn up head to wind, and hoping you can bear away again before you run out of speed. Both of these are short-term 'tactical' manoeuvres, rather than 'strategic' ones such as exploiting the LBE. I think I can see why the 'favoured tack' thing popped up in relation to LBE. In the constant-current situation, there is no distinction between the effect of LBE on the true wind (creating an 'advantageous tack' in the parlance of this thread), and a wind offset to one side of the destination (creating a 'favoured tack'). In both cases, it is prudent to make the tack which gives the greatest SOG towards the destination first, to insure against any future wind shifts. There is no real distinction between 'favoured' and 'advantageous' tack in this situation, which is what I think the instrument maker linked a few pages back was thinking about when they tried to dispute the existence of the LBE. They may only have been concerning themselves with very short races. The true LBE comes about when the tide changes during the course of the voyage. The effect of this is a 100% predictable shift in apparent wind, much like having a totally accurate forecast of a true wind shift. If you knew from a forecast that the true wind was going to shift to swap the favoured tack from one side to the other half way through a voyage, you would start your voyage on the favoured tack, then tack over when the wind shifted to remain on the favoured tack. A boat which started the voyage on the unfavoured tack would not lose anything if the wind did not shift (the equivalent of the constant-current scenario for LBE), but would find itself well downwind of the other boat if the forecasted wind shift did happen. Even without a forecast, you assume this may happen and make the favoured tack first - you have nothing to lose and potentially a lot to gain. This is a much better understood concept than LBE, so I hope explaining it in these terms is helpful. In the LBE scenario, if the current is constant then there is nothing to be lost by starting on the unfavoured tack first. However, the strategic decision relating to the LBE is when we know that the current will shift, and therefore bring with it a shift in apparent wind. Because of this, we start on the favoured tack (or 'advantageous tack' if that is what we have decided to call the creation of a favoured tack by the LBE), and then tack over when the current changes. This is how to exploit the LBE. A boat that does not do this will, like the boat starting on the unfavoured tack with the forecasted wind shift, find itself well downwind of the lee-bow vessel when the current changes. As for the wind names debate, I don't really know about the names that modern instrument makers use. I think people are trying to make a distinction between the wind direction over the ground at slack water, and the minute change that friction between the air mass and a moving current will make. This is not, in my mind, a distinction important to sailing. I see only two wind names relevant here - the true wind which is what is blowing over the ground or seabed, and the apparent wind which is the true wind with the vectors added to it of the wind created by the boats motion ('headwind'?) and the motion of the current ('current induced wind' in my diagram - a more elegant name might be 'tide wind'?). An alternative (if a little wordy) definition of the LBE might then be: The changes in favoured tack brought about by the influence on the apparent wind of changes in the tidal stream. and the strategic decision to use the LBE is then... ...the exploitation of these shifts by tacking at slack water to remain on the favoured tack. A subtle point that there has been some debate on is whether a current from the lee side will always be favourable. The 'switchover points' are in fact in relation to wind direction rather than boat direction, but the 'current coming from the same side of the wind that you are pointing on effect' isn't really a viable name. Also,the wind shift created by boatspeed puts the 'switchover points' just slightly to one side of the true windward and leeward as I have said before - a bit to port when on starboard tack, and vice versa. I think this may well be on 'apparent windward and leeward' but I might have to do some drawings to be certain. Make some sketches with wind vectors and you will see what I mean. If the boat is dead in the water though, the switch will occur when the direction of the tide passes exactly through the windward and leeward directions, as 'apparent' and 'true' are the same when the tide lines up with the wind with zero boat speed. This discussion complicates the issue, and as some people still dispute more basic points we should steer clear of this... for now. The most common scenario (both in discussion of the LBE and, I think, in real life) is when true wind is at 90 degrees to the current, in which case lee-bow effect is a perfectly acceptable name. This is also when the effect is strongest, so discussion of these extremely fine points really does have little or no relevance in the real world. Sorry about the long post, but I have been mulling this over for a few days!
Yippee do dar day............. Thank you very very much
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Old 14-11-2013, 16:25   #248
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

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In my mind it works for any angle of current, other than two points (roughly, to windward and to leeward) where it makes no difference to the direction of the apparent wind vector. At these points, it switches from helping to on one tack (coming from your leeward side) to hindering you (coming from windward).
Hi Europaflyer
Did you have a chance to read my post #223? After stumbling along for a while things have really crystallised for me (partly thanks to you as your earlier comment above made me think).

There is no lee bow effect. The diagram I have drawn very clearly demonstrates this. The tack which is lifted by current is the one that results in the current being closer to your bow. For some angles of current this means it is your lee bow, but this is not universal. And it certainly doesn't work over 180 degrees of the current being on your lee bow.

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While the lee-bow effect is not relevant to tactical decision making if no current change is observed during racing (which is perhaps what they are thinking of), that does not mean it does not exist. In, say, a cross Channel race where the tide may change several times during the race, the boats which tack to exploit lee bow effect will win, because of the points I have made earlier..
The best technique is to sail the favourable tack first, NOT specifically the tack lifted by the current. If the mark is not directly along your CTS, the lifted tack is not necessarily the favourable one (ie the one closest to the CTS).

For the channel crossing the current is roughly perpendicular to the CTS, so if Cherbourg is dead upwind, then it just happens that having the current on your lee side is beneficial. This is just one set of circumstances, not some general rule. If the current was at a different angle then it may be better being on the tack with the current on the windward bow. There is truly nothing that warrants being called the 'Lee Bow Effect'.

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OK, I've had a think. Once again, I may have lost track of who is arguing which point. I'll do my best to put my thoughts in to words.
Well FoolishSailor and I are arguing that there is no LBE. Dockhead must be busy, he hasn't replied for a while.

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I think the 'pinching' point is unrelated. The LBE will alter the apparent wind regardless of where you are pointing. In my mind, the only use of 'pinching' is to point slightly higher than you normally would, at the expense of boat speed, if you aren't quite laying a mark and making two rapid tacks is undesirable. What I call 'luffing a mark' is a similar ploy, a last-few-seconds attempt to round a mark that is sitting on the bow by using your speed to turn up head to wind, and hoping you can bear away again before you run out of speed. Both of these are short-term 'tactical' manoeuvres, rather than 'strategic' ones such as exploiting the LBE.
Agreed, except with the last bit . There is as much a 'Windward Bow Effect' to exploit as there is a 'Lee Bow Effect' to exploit, but only in a limited set of conditions when the mark is upwind of the CTS or close to it and it makes this tack closer to the CTS (ie the favourable tack).

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I think I can see why the 'favoured tack' thing popped up in relation to LBE. In the constant-current situation, there is no distinction between the effect of LBE on the true wind (creating an 'advantageous tack' in the parlance of this thread), and a wind offset to one side of the destination (creating a 'favoured tack').
Calling it the LBE is misleading. The tack with the current more on the bow is lifted more. It is not necessarily the lee bow.

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In both cases, it is prudent to make the tack which gives the greatest SOG towards the destination first, to insure against any future wind shifts.
Agreed 100%. This does not necessarily have anything to do with having the current on the lee bow though.

Will reply to the rest later. Lots more to comment on. It is getting late here .
Thanks for thinking about the issues and replying. Long post is wonderful!
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Old 14-11-2013, 16:27   #249
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

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Yippee do dar day............. Thank you very very much
You're welcome!

After brief thought, I have decided that the points where the current switches from being favourable to unfavourable are exactly to windward and leeward of the apparent wind, ie. at 360 and 180 degrees apparent. The effect is maximal at 90 and 270 degrees apparent - helping you at one side (the now somewhat inaccurately named 'lee bow' side) and hindering you at the other. It varies sinusoidally between these points.

As I say, discussing this only complicates things really, but I felt I had to clear up things from my previous post. Perhaps, as Dockhead says, understanding these fine points is key for some people to understanding the whole thing. I think it helped me.
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Old 14-11-2013, 16:32   #250
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

I hate to be the bearer of bad news, but almost none of this discussion has been about the “Lee Bow Effect,” but rather simply about sailing in current (which as previously mentioned, simply produces a change in the direction and velocity of the true (or sailing) wind from the ground wind).

The “Lee Bow Effect” was described in an early post (but not the first) and repeated a page or two back, but let me try to paraphrase. It refers to a very narrow set of circumstances where you are close hauled (beating) and the current is coming from directly in front of you or slightly to weather, and the “Effect” then (incorrectly) posits that by pinching up a little above your normal (i.e. max VMG) heading and putting the current onto your lee bow (and lee side of keel) that it will give you a “push” to weather that more than offsets the reduction in speed due to the pinching. (That is where the “pinching” aspect of the theory comes in – to “shift” the current from the windward to leeward side.) The “Lee Bow Effect” is a myth for reasons previously outlined in this thread.

At any given time, these conditions can apply to only one tack / heading, as the other tack puts the current roughly on the beam (until the “wind” and/or current change), and that is again simply sailing in current.

It may help some to visualize this by putting numbers on this, so for instance: current is out of the NE (from 45 deg running to 225 deg); “wind” out of the north (0 deg); “best” heading is NE (45 deg) and leeway is 3 deg, therefore COG is 48 deg. The “Lee Bow Effect” says that by pinching up say 5 deg (to a heading of 40 deg and COG of 43 deg), the current will hit the lee side by 2 deg rather than the windward side at 3 deg resulting in a “push” and net gain to weather. But this is not the case.

Note again that other current-to-boat angles (other than just off the bow) are not consistent with the “Lee Bow Effect” (although there is an equivalent downwind scenario where the “Lee Bow Effect” would suggest that you soak lower than your optimum downwind angle to “shift” the current from the leeward to windward side to help “push” you downwind, but that is equally wrong and only further complicates the issue).

Cheers,
LJ
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Old 14-11-2013, 16:41   #251
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Hi Seaworthy!

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There is no lee bow effect. The diagram I have drawn very clearly demonstrates this. The tack which is lifted by current is the one that results in the current being closer to your bow. For some angles of current this means it is your lee bow, but this is not universal. And it certainly doesn't work over 180 degrees of the current being on your lee bow.
Hmm. As in my last post #249, I don't think the angle of the current relative to your boat is what matters, bur rather the angle of the current relative to apparent wind. Calling it 'lee bow effect' is more because people have applied this as a rule of thumb. The alternative names (apparent wind current angle favourable hemisphere effect?!) don't really bear thinking about. I'm happy with LBE in the same way that I'm happy calling a halliard a halliard even when it doesn't haul a yard.

I think I'm right in saying that your claim that 'there is no LBE' relates to the exact definition, rather than your thinking that the effect as I defined does not exist?

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Agreed, except with the last bit . There is as much a 'Windward Bow Effect' to exploit as there is a 'Lee Bow Effect' to exploit, but only in a limited set of conditions when the mark is upwind of the CTS or close to it and it makes this tack closer to the CTS (ie the favourable tack).

Calling it the LBE is misleading. The tack with the current more on the bow is lifted more. It is not necessarily the lee bow.
Not sure I agree about the current on the bow thing. What do you think about my apparent wind angle theory?

It's great to have these discussions. I think we might actually be contributing something useful to sailing theory here! On the strength of that, I think I'll summon up the courage to read the 'course to steer' thread. Apparently you came up with an original method for calculating the CTS in that, and I look forward to finding out what it is. Tomorrow.
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Old 14-11-2013, 16:47   #252
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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 Lee Jerry View Post
I hate to be the bearer of bad news, but almost none of this discussion has been about the “Lee Bow Effect,” but rather simply about sailing in current (which as previously mentioned, simply produces a change in the direction and velocity of the true (or sailing) wind from the ground wind).

The “Lee Bow Effect” was described in an early post (but not the first) and repeated a page or two back, but let me try to paraphrase. It refers to a very narrow set of circumstances where you are close hauled (beating) and the current is coming from directly in front of you or slightly to weather, and the “Effect” then (incorrectly) posits that by pinching up a little above your normal (i.e. max VMG) heading and putting the current onto your lee bow (and lee side of keel) that it will give you a “push” to weather that more than offsets the reduction in speed due to the pinching. (That is where the “pinching” aspect of the theory comes in – to “shift” the current from the windward to leeward side.) The “Lee Bow Effect” is a myth for reasons previously outlined in this thread.
That's not the LBE as I have ever understood it, read it or been taught about it. That's more a sort of funny ferry-gliding pinching effect, made by someone who does not understand that the motion of the current is not what affects boat performance, but rather the movement of the boat relative to the current.

I think much of the disagreement about the LBE comes from people who understand it to relate to something other than what I am talking about.
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Old 14-11-2013, 16:54   #253
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Yippee do dar day............. Thank you very very much
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I Have really enjoyed this thread , thanks to all for your posts...

I have made my mind up to wait is ment by lee bowing the tide

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Old 14-11-2013, 16:57   #254
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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 Lee Jerry View Post
I hate to be the bearer of bad news, but almost none of this discussion has been about the “Lee Bow Effect,” but rather simply about sailing in current (which as previously mentioned, simply produces a change in the direction and velocity of the true (or sailing) wind from the ground wind).
Lots of sailors, including Europaflyer consider that there is some benefit to being on the tack that results in the current being on your lee bow. This is considered by many to be the Lee Bow Effect (whether or not they also believe that pinching to put the current on your lee bow is beneficial).

It is good to hear that this is not correct. It agrees with what I have found if you look at post #223, and also agrees with what Paul Elliot and Foolish Sailor have posted. Very few people have actually said this though.

Quote:
Originally Posted by Lee Jerry View Post
The “Lee Bow Effect” was described in an early post (but not the first) and repeated a page or two back, but let me try to paraphrase. It refers to a very narrow set of circumstances where you are close hauled (beating) and the current is coming from directly in front of you or slightly to weather, and the “Effect” then (incorrectly) posits that by pinching up a little above your normal (i.e. max VMG) heading and putting the current onto your lee bow (and lee side of keel) that it will give you a “push” to weather that more than offsets the reduction in speed due to the pinching. (That is where the “pinching” aspect of the theory comes in – to “shift” the current from the windward to leeward side.) The “Lee Bow Effect” is a myth for reasons previously outlined in this thread.
Yes, despite the rubbish I embarrassingly wrote very early in the thread (my excuse was I hadn't thought about planes of reference in 8 months and it took a while to get my head in gear again LOL), this concept is nonsense. I do remember laughing out aloud the first time I heard this proposal.

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At any given time, these conditions can apply to only one tack / heading, as the other tack puts the current roughly on the beam (until the “wind” and/or current change), and that is again simply sailing in current.
Yep

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Note again that other current-to-boat angles (other than just off the bow) are not consistent with the “Lee Bow Effect” (although there is an equivalent downwind scenario where the “Lee Bow Effect” would suggest that you soak lower than your optimum downwind angle to “shift” the current from the leeward to windward side to help “push” you downwind, but that is equally wrong and only further complicates the issue).
Yes, agreed also. This is just as silly a concept.
Great to have you chime in. I felt I was posting in a vacuum for a while there when insisting there was no LBE .
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Old 14-11-2013, 17:00   #255
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Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

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Did you have a chance to read my post #223?
Have now! Your (very good!) diagram seems to me to support my point about it being relative to apparent wind rather than to any part of the boat. The biggest shifts in apparent wind from true wind (and so biggest benefit or hindrance to closehauled boats, depending on their tack) are when the current is at 90 degrees to it - the two points just above '3 and 9 o'clock'. Nil effect when the current lines up with the wind at 360 and 180 degrees.

Apparent wind current angle effect it is. To hell with the bow. In other words, if the current is coming from between 0 and 180 degrees from the apparent wind, you need to be on port tack, and when it is from 180-360 you need to be on starboard.
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