Lee bowing

[dom]

That's tactical considerations and "shooting". I'm talking about getting upwind as fast as possible in clear air and even tide. Angle the tide any way you like in relation to the boat, and you will always be fastest doing the best VMG for your boat, not pinching.
Tactically in close proximity to other boats you frequently do things other than sail your boat as efficiently as possible, but I'm talking about where you're just trying to get to the mark as fast as possible,

This discussion keeps spawning new subjective terms, "shooting" being the latest, described above as an action constrained to "a boat length or so". I would be happy to "shoot" for a lot longer than that if it so-constrained other competitors, or perhaps forced them into a "frustration maneuver".

Great, now have my own little subjective Joker to throw into the mix at will!

I remain convinced that a rigorous explanation of basic concepts such as Ground Wind, True Wind, Apparent Wind, tidal vectors, etc., coupled with a ban on subjective terms like "lee bowing, and "shooting", would put paid to these pointless nomenclature arguments

 

[flaming]

I remain convinced that a rigorous explanation of basic concepts such as Ground Wind, True Wind, Apparent Wind, tidal vectors, etc., coupled with a ban on subjective terms like "lee bowing, and "shooting", would put paid to these pointless nomenclature arguments

Quite agree. But there are numerous historical threads on these forums where angry posters maintain that True Wind is the wind over the land and will not adapt their thinking. Which makes it pretty hard to explain why the tide has an effect on the True wind....

And yes, I will occasionally pinch above best VMG for some time, but there is always a tactical, and normally boat on boat tactical, reason for it. When in clear air and constant tide and not trying to just edge round a mark without doing 2 quick tacks, then pinching just doesn't pay.

 

[NormanS]

I'm just so glad that I can sail my boat using wind, and sometimes tide, to best advantage, by some sort of common sense which seems to be in my head, without all the calculations and considerations that some obviously need.

 

[dom]

Quite agree. But there are numerous historical threads on these forums where angry posters maintain that True Wind is the wind over the land and will not adapt their thinking. Which makes it pretty hard to explain why the tide has an effect on the True wind....

And yes, I will occasionally pinch above best VMG for some time, but there is always a tactical, and normally boat on boat tactical, reason for it. When in clear air and constant tide and not trying to just edge round a mark without doing 2 quick tacks, then pinching just doesn't pay.

Indeed, and these DIY definitions in turn introduce unnecessary confusion, such as the notion that a boat somehow experiences a tide on its lee bow. It doesn't, the tide just alters the True Wind.

And yes, all else being equal, the best approach is to maximize speed towards an imaginary point some distance away from the turning-mark/cruising-destination and let tide do the rest. I hesitate to use VMG, because even there people tend to define it according to personal preference

 

[Buck Turgidson]

This discussion keeps spawning new subjective terms, "shooting" being the latest, described above as an action constrained to "a boat length or so". I would be happy to "shoot" for a lot longer than that if it so-constrained other competitors, or perhaps forced them into a "frustration maneuver".

Great, now have my own little subjective Joker to throw into the mix at will!

I remain convinced that a rigorous explanation of basic concepts such as Ground Wind, True Wind, Apparent Wind, tidal vectors, etc., coupled with a ban on subjective terms like "lee bowing, and "shooting", would put paid to these pointless nomenclature arguments

Which would be fine if true wind meant the same to all people. Unfortunately it doesn’t.
Ground wind and sailing wind are manufacturer specific terms. True wind used to be defined as wind observed at a fixed point and still is in everything except some sailing circles. So you’re basic concepts turn out to be not basic after all.

 

[dom]

Which would be fine if true wind meant the same to all people. Unfortunately it doesn’t.
Ground wind and sailing wind are manufacturer specific terms. True wind used to be defined as wind observed at a fixed point and still is in everything except some sailing circles. So you’re basic concepts turn out to be not basic after all.

It still is! ...a point stationary with the respect to the water around it. That may in turn be moving in relation to the land where we might measure the Ground Wind, which is in turn moving in relation to the sun, which is moving with respect to other stars....

One just needs a clear frame of reference.

 

[Buck Turgidson]

It still is! ...a point stationary with the respect to the water around it. That may in turn be moving in relation to the land where we might measure the Ground Wind, which is in turn moving in relation to the sun, which is moving with respect to other stars....

One just needs a clear frame of reference.

You see. That’s your definition.
It’s not the correct definition of true wind.
https://www.wmo.int/pages/prog/amp/...AR-99/Presentations/session_08/08.2_Smith.pdf

 

[dom]

You see. That’s your definition.
It’s not the correct definition of true wind.
https://www.wmo.int/pages/prog/amp/...AR-99/Presentations/session_08/08.2_Smith.pdf

Hardly my definition!

But I had to laugh at the first para of the conclusion :

"Principal problems include confusion related toinconsistencies in definitions for true wind used by meteorologists, oceanographers and the merchant marine, and the lack of standard reporting of both windand navigation measurements (or the convention used). The primary recommendation is to set a standard for reporting......."
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[Medway Matt]

As for tides having a negligible effect on true wind vectors; believe it or not they can exert a truly significant influence and a mistake here can see a boat swiftly buried even if his boat-speed is top notch.

Edit. Example:imagine a ground wind dead ahead of 10kts and a tidal flow of 3kts running perpendicular to it. Nothing special there. This will shift the true wind by over 16 degrees!

I stand corrected! :encouragement:

Though in mitigation the speeds of wind and current are getting fairly close, sort of.

Wow agreement reached on a forum, whatever next?

 

[flaming]

When you're talking about sailing yachts, I would think it makes sense to use the definitions that match the displays on your instruments. People may dislike it, but in essence the instrument manufacturers have defined the terms.

So Ground wind, True wind and Apparent wind.

 

[Buck Turgidson]

It still is! ...a point stationary with the respect to the water around it. That may in turn be moving in relation to the land where we might measure the Ground Wind, which is in turn moving in relation to the sun, which is moving with respect to other stars....

One just needs a clear frame of reference.

Hardly my definition!

But I had to laugh at the first para of the conclusion :

"Principal problems include confusion related toinconsistencies in definitions for true wind used by meteorologists, oceanographers and the merchant marine, and the lack of standard reporting of both windand navigation measurements (or the convention used). The primary recommendation is to set a standard for reporting......."
​

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But the reference frame is always the same!

 

[dom]

I stand corrected! :encouragement:

Though in mitigation the speeds of wind and current are getting fairly close, sort of.

Wow agreement reached on a forum, whatever next?

The Ground/True argument flares up again

 

[Medway Matt]

The best way to think of the true wind is that experienced by stopped vessel floating freely in the current. It follows that lee-bowing will have a zero influence on the difference between true and apparent wind, for everything takes place on that floating carpet.

The moored buoy on the other hand experiences the ground wind and we must consider its frame of reference to successfully round it. In practice, tidal flows bend, shift, and eddy, which can in turn influence the ground wind, adding an extra complication.

Surely the vessel floating freely is experiencing apparent wind? It may not be sailing but its wind is still effected by its movement in the same way; and the moored buoy is experiencing true wind as it's a fixed object (apart from the eddies, shifts, etc. causing localised variations). Ground wind just sounds like true wind to me.

That forum agreement thing didn't last long!

 

[Medway Matt]

The Ground/True argument flares up again

I was typing my apparent / true / ground wind post as you posted.

 

[dom]

Surely the vessel floating freely is experiencing apparent wind? It may not be sailing but its wind is still effected by its movement in the same way; and the moored buoy is experiencing true wind as it's a fixed object (apart from the eddies, shifts, etc. causing localised variations). Ground wind just sounds like true wind to me.

So, True Wind cannot be directly measured on a boat?

 

[lw395]

When you're talking about sailing yachts, I would think it makes sense to use the definitions that match the displays on your instruments. People may dislike it, but in essence the instrument manufacturers have defined the terms.

So Ground wind, True wind and Apparent wind.

But there's the true true wind and the comedy indicated instrument wind...

 

[Medway Matt]

So, True Wind cannot be directly measured on a boat?

It can if you moor to that handy buoy.

 

[RichardS]

It can if you moor to that handy buoy.

Or are tied up in the marina waiting for it (whatever it is) to drop.

Richard

 

[flaming]

Surely the vessel floating freely is experiencing apparent wind? It may not be sailing but its wind is still effected by its movement in the same way; and the moored buoy is experiencing true wind as it's a fixed object (apart from the eddies, shifts, etc. causing localised variations). Ground wind just sounds like true wind to me.

That forum agreement thing didn't last long!

The only problem with that argument is that it then doesn't have a term for the wind that is the measure in velocity difference between the water and air. Which is the measure of the power we have available to our boats, and the direction in which we are able to point them.

If you call the wind relative to the ground "true wind" then what do you call this wind?

 

[johnalison]

The only problem with that argument is that it then doesn't have a term for the wind that is the measure in velocity difference between the water and air. Which is the measure of the power we have available to our boats, and the direction in which we are able to point them.

If you call the wind relative to the ground "true wind" then what do you call this wind?

'Water wind' ? No, that would be silly. I'm with flaming on this. The terms have arisen for historical and technological reasons. When B&G or whoever it was managed to make an instrument combine wind and water transducer information to read boat apparent and 'true' wind, 'true' was the term naturally used. It was perhaps twenty years or more before GPS came along and allowed sailors to see where the ground was and how this could provide another frame of reference. Sailing instruments invariably give the simplified 'true wind', though this may not apply to some derivatives such as the wind readout on my Multi.

Ground wind is of almost no concern to a sailor under way, so people like me are going to continue to use the terms as they have mostly been for the last 40 years or so. Fortunately, much of my time is spent sailing in tides of less than 2kn, so the difference between ground and true wind is usually not great.