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

[goboatingnow]

SL, to answer you yes and no. Lets just confine ourselves to the situation where the current is fine on the bow, and leave the other angles for a moment.

Your own diagram above shows the effect, moving the current from fine on the windward bow, to fine on the leeward bow, produces a greater wind angle, i.e. the boat is freed ( the opposite to header is not knocked its " freed"

Yes I agree at other angles of current there are other effects including windward current benefits. but the lee bow effect as understand in racing is purely where you are dealing with currents fine on the bow.

run your cone diagram, with one boat and two currents, one fine on the windward side and one on the lee side , both "fine" to the bow.


Lee bowing is very specific , it does not say that all leewards currents are beneficial or that all inwards currents are detrimental.

for example take the right hand boat and currents from say 11am around to 3/3:30pm only , lets focus on the one at 1pm and 3:30

Dave

[foolishsailor]

[QUOTE="Seaworthy Lass;1392383"]The tack with the current broader on the bow of the two will be KNOCKED more not lifted more. /QUOTE]

I wonder how many more drawings we will have to create to prove this?

Keep banging that drum Angela!

Maybe we can think of more examples to draw?

...that will likely be ignored? ;!

[europaflyer]

Originally Posted by Seaworthy Lass

This effect is entirely a myth. This thread has clearly shown that.
Truly Dave. It does not exist. Please don't make the same mistake I made early in this thread. There is no specific advantage to having the current on the lee side of the boat.

Come on Seaworthy, let's stop quibbling over the name. You've made your point that it isn't true for all current angles on the lee side. Extending that to saying that a generally understood effect doesn't exist is a little silly.

I think we all agree that current can alter true wind. Current can therefore, in some circumstances not necessarily involving the lee bow, create a favoured tack which swaps over when the current changes. We all agree that sailing on the favoured tack is good, therefore you need to tack when the current changes. Simple stuff, and a part I think of the RYA Yachtmaster syllabus. No myth, except to people who can't understand it.

The classic case of the LBE where its effect is greatest requires keeping the current in the lee bow, as per my original diagram on post #159 which I copy below. You can't seriously deny that the effect here doesn't exist, and that the requirement in this case is to tack to keep the current on the lee bow. OK, there are cases where this doesn't hold but the effect won't be nearly as potent in these cases. The name does just describe the rule of thumb for this most important case.

[goboatingnow]

Originally Posted by Hoofsmit

here we go again...... I will pop back in when you lot stop discusing wind

just a quick one for the table clothers

if the table cloth is split into 50 non parallel sections and each section is moves at a different rate , how does your cts allow for this real illustration of a area like the Fowey in cornwall uk

The lee bow effect is ONLY about a freeing wind, nothing else.

[foolishsailor]

Originally Posted by goboatingnow

SL, to answer you yes and no. Lets just confine ourselves to the situation where the current is fine on the bow, and leave the other angles for a moment. Your own diagram above shows the effect, moving the current from fine on the windward bow, to fine on the leeward bow, produces a greater wind angle, i.e. the boat is freed ( the opposite to header is not knocked its " freed" Yes I agree at other angles of current there are other effects including windward current benefits. but the lee bow effect as understand in racing is purely where you are dealing with currents fine on the bow. run your cone diagram, with one boat and two currents, one fine on the windward side and one on the lee side , both "fine" to the bow. Lee bowing is very specific , it does not say that all leewards currents are beneficial or that all inwards currents are detrimental. Dave

Non existent effect. You are looking at instantaenous effect only.

If you think this works then prove it by drawing a diagram either using the images I uploaded or making one tourself.

If you cant demonstrate its benefit from origin to destination - then it desont exist.

The problem with alot of what we are talking about is that in an instentaneous moment there is a benefical effect - but in the sum of the process of making a course or over time these instentaneous effects are nullified.

So i say - if you cant illustrate it, it doesnt exist!

[goboatingnow]

Originally Posted by europaflyer

Come on Seaworthy, let's stop quibbling over the name. You've made your point that it isn't true for all current angles on the lee side. Extending that to saying that a generally understood effect doesn't exist is a little silly.

I think we all agree that current can alter true wind. Current can therefore, in some circumstances not necessarily involving the lee bow, create a favoured tack which swaps over when the current changes. We all agree that sailing on the favoured tack is good, therefore you need to tack when the current changes. Simple stuff, and a part I think of the RYA Yachtmaster syllabus. No myth, except to people who can't understand it.

The classic case of the LBE where its effect is greatest requires keeping the current in the lee bow, as per my original diagram on post #159 which I copy below. You can't seriously deny that the effect here doesn't exist, and that the requirement in this case is to tack to keep the current on the lee bow. OK, there are cases where this doesn't hold but the effect won't be nearly as potent in these cases. The name does just describe the rule of thumb for this most important case.

Here we go again , a valuable but different argument,

In lee bowing there is no tack, SL diagrams show the phenonium clearly, simply bringing the current to the lee bow ( no tack occurred ) , results in a freer apparent wind, as the ground wind , itself frees, The lee bow effect DOES NOT MEAN that all lee side currents produce this or that ALL WIND side currents causes headers. we are just dealing with freeing wind , as a result of currents on the bow.

Nothing to do with tacking, CTS, progress to anything.

[europaflyer]

Originally Posted by Hoofsmit

if the table cloth is split into 50 non parallel sections and each section is moves at a different rate , how does your cts allow for this real illustration of a area like the Fowey in cornwall uk

Come on, hasn't your tablecloth been through enough already?

[foolishsailor]

Originally Posted by europaflyer

Come on Seaworthy, let's stop quibbling over the name. You've made your point that it isn't true for all current angles on the lee side. Extending that to saying that a generally understood effect doesn't exist is a little silly. I think we all agree that current can alter true wind. Current can therefore, in some circumstances not necessarily involving the lee bow, create a favoured tack which swaps over when the current changes. We all agree that sailing on the favoured tack is good, therefore you need to tack when the current changes. Simple stuff, and a part I think of the RYA Yachtmaster syllabus. No myth, except to people who can't understand it. The classic case of the LBE where its effect is greatest requires keeping the current in the lee bow, as per my original diagram on post #159 which I copy below. You can't seriously deny that the effect here doesn't exist, and that the requirement in this case is to tack to keep the current on the lee bow. OK, there are cases where this doesn't hold but the effect won't be nearly as potent in these cases. The name does just describe the rule of thumb for this most important case.

Again you have illustrated a gain in a single moment.

Take this and show a gain from origin to destination.

If you cant do this then the gain doesnt exist.

[europaflyer]

Originally Posted by goboatingnow

Here we go again , a valuable but different argument,

In lee bowing there is no tack, SL diagrams show the phenonium clearly, simply bringing the current to the lee bow ( no tack occurred ) , results in a freer apparent wind, as the ground wind , itself frees, The lee bow effect DOES NOT MEAN that all lee side currents produce this or that ALL WIND side currents causes headers. we are just dealing with freeing wind , as a result of currents on the bow.

Nothing to do with tacking, CTS, progress to anything.

Bringing the current to the lee bow results in a freer apparent wind. Agree totally. Extend that to past slack water when the current is coming from the other direction, you have to tack to keep it on the lee bow.

[goboatingnow]

Originally Posted by foolishsailor

Non existent effect. You are looking at instantaenous effect only.

If you think this works then prove it by drawing a diagram either using the images I uploaded or making one tourself.

If you cant demonstrate its benefit from origin to destination - then it desont exist.

The problem with alot of what we are talking about is that in an instentaneous moment there is a benefical effect - but in the sum of the process of making a course or over time these instentaneous effects are nullified.

So i say - if you cant illustrate it, it doesnt exist!

You are mixing up effects with benefits.


SeaWorthies cone, clearly shows that certain currents fine on the windward bow when switched to currents fine on the leeward bow, causing a freeing of the ground wind, and hence a freeing of the apparent wind. hence The boat can point higher…. Thats the end of the lee bow effect.

Whether the "advantage" can be utilised to achieve anything is purely based on the course and what is desired.

Clearly if one is attempting to make a mark to windward and finds that it is just going to be missed, then realising there is a current fine ( and thats important), then by pinching up to place the current on the lee bow, then the boat is freed ( and no longer pinches) and lays the mark in the same tack.

Discussions about tacking onto the other tack miss the point entirely

I don't need a diagram . SLs has drawn a fine one.

Dave

[Hoofsmit]

Originally Posted by goboatingnow

The lee bow effect is ONLY about a freeing wind, nothing else.

is that your perception

another in the box thinker

[goboatingnow]

Originally Posted by europaflyer

Bringing the current to the lee bow results in a freer apparent wind. Agree totally. Extend that to past slack water when the current is coming from the other direction, you have to tack to keep it on the lee bow.

forget tacking, forget slack water , the lee bow effect is just what it says, i.e. switching the current from fine on the windward bow to fine on the lee bow ( no tack involved) cause a freeing of the apparent wind.

Whether that freeing is useful, is another thing entirely


dave

[Seaworthy Lass]

Originally Posted by goboatingnow

SL, to answer you yes and no. Lets just confine ourselves to the situation where the current is fine on the bow, and leave the other angles for a moment.

Your own diagram above shows the effect, moving the current from fine on the windward bow, to fine on the leeward bow, produces a greater wind angle, i.e. the boat is freed ( the opposite to header is not knocked its " freed"

Yes I agree at other angles of current there are other effects including windward current benefits. but the lee bow effect as understand in racing is purely where you are dealing with currents fine on the bow.

Dave

No, my diagram does not show that at all. Where does it show it?

My diagram shows that for any particular current (just pick any current and look at the red line attached to the tip of the current's wind effect to see what the true wind is like and compare it to the two headings shown at the bottom) the lifted tack is the one with the wind closer to being on the bow. Nothing at all to do with it is on the windward or leeward side.

If the current is close to the bow then this is already the lifted tack regardless of what side of the bow the current falls on. this is a critical concept. If you then pinch to put the current from one side of the bow to the other, yes you will be lifted, but only because you have headed up and this will be at the great expense of speed.

See FoolishSailor's posts # 266 and 267 and read the links.

The 'Lee Bow effect' is truly a myth. There is nothing to it at all .

[europaflyer]

Originally Posted by foolishsailor

Again you have illustrated a gain in a single moment.

Take this and show a gain from origin to destination.

If you cant do this then the gain doesnt exist.

Oh come on, really? It's not a 'single moment', it's true for as long as the conditions on the diagram exist.

The diagram shows the lee bow boat making far more ground to windward than the lee bow one, because it is poingting far closer to the ground wind (incorrectly called true wind in my diagram ). Even in a constant-current scenario it will get to the other side of the channel faster, and that is all the effect is. We call it an 'effect' because it is a little counter-intuitive - you wouldn't think that a current at 90 degrees to where you want to be could possibly help you get there, but it does do by altering the true wind and allowing you to sail there more directly. A little logical leap but really nothing more complex than that. As I say, taught as part of RYA shorebased courses and really pretty trivial stuff once you look at wind vectors. If you don't get it then that's fine, just get someone else to work as your tactician.

[europaflyer]

Originally Posted by Seaworthy Lass

the lifted tack is the one with the wind closer to being on the bow.

Oh dear, oh dear.