True Wind - your definition.

[pyrojames]

"Glossary of Meteorological Terms" has this to say -

True wind direction
The direction, with respect to true north, from which the wind is blowing. Distinguish from magnetic wind direction. In all standard upper-air and surface weather observations, it is true wind direction that is reported.

I agree. The democratic opinion of YBW agree. I suspect that if you suggested to non-sailors that the true wind speed was zero, because you happened to be sitting a tide of the same speed and direction as the wind, they would think you were bonkers.

RayMarine et al, have just claimed it for their marketing. More fool those who believe the marketing is gospel. That will be their own downfall!

 

[RichardS]

GPS is nothing to do with it. Wind was around quite a bit before GPS was invented. (and indeed anemometers)

As far as I'm concerned, my previously stated view that the only important definition of wind is duck fart, trumps all this hot air ....... however, the non sequiter expressed above seems like a bit of a stinker, except it's silent but not deadly.

If someone suggests that a GPS/anemometer/feather is needed to measure a particular variety of wind on a boat, how does the observation quoted above address that suggestion?

Richard

 

[lw395]

I agree. The democratic opinion of YBW agree. I suspect that if you suggested to non-sailors that the true wind speed was zero, because you happened to be sitting a tide of the same speed and direction as the wind, they would think you were bonkers.

Actually that case is quite interesting.
I think a civilian might recognise that a boat drifting in zero apparent wind 'has no wind in its sails'. It has no motive power. It cannot sail.

 

[lw395]

As far as I'm concerned, my previously stated view that the only important definition of wind is duck fart, trumps all this hot air ....... however, the non sequiter expressed above seems like a bit of a stinker, except it's silent but not deadly.

If someone suggests that a GPS/anemometer/feather is needed to measure a particular variety of wind on a boat, how does the observation quoted above address that suggestion?

Richard

We need to sort this out. We can pioneer proper terms to describe the turbulence, variation, wetness and err, 'flavour' of the wind.

 

[noelex]

The sailing term "true wind" is very poorly named. Many people have pointed out it should be called "current wind" or "speed through water wind" or something similar. This would mean we could stop referring to "ground wind" as such and call this parameter true wind. This would be much more sensible.

However, I don't think this going to happen. We are stuck with the terminology.

The most important thing is not the name, but to understand what information your instruments are displaying.

The vast majority of yacht wind instruments that can display more than just apparent wind are set to display "current wind" or "speed through water wind". You can call this true wind, or any term you like but it is important to understand it is not ground referenced true wind. If you are sailing in current and look at the wind instruments the wind display will not coincide with what you experience if you dropped anchor, or tied to dock in the same location even if the instrument is 100% accurate.

On some instruments this can be changed and I think it is worth at least trying the alternative of switching to ground referenced true wind or ground wind or simply true wind if you feel this term is more appropriate. Once again it does not matter what you call it, it is important to understand what information the instrument is presenting.The main advantage of this switch is that it removes the errors that are commonly found in the paddlewheel output from the equation. On most cruising boats this results in a more accurate stable display, but the change will result in different information to the wind information on the vast majority of yachts.

The majority of YBW poll responders feel the change would result in the instrument displaying "true wind" as they define the term, but suprisingly very few boat instruments are set up this way.

 

[[163233]]

With no instruments, I only have the wind on my face and the wind on the sea, now it seems that neither is true.

Raymarine has brought us a philosophical apocalypse with the death of truth.

 

[lw395]

The sailing term "true wind" is very poorly named. Many people have pointed out it should be called "current wind" or "speed through water wind" or something similar.
This would mean we could stop referring to "ground wind" as such and call this parameter true wind. This would be much more sensible.

However, I don't think this going to happen. We are stuck with the terminology.

The most important thing is not the name, but to understand what information your instruments are displaying.

The vast majority of yacht wind instruments that can display more than just apparent wind are set to display "current wind" or "speed through water wind". You can call this true wind, or any term you like but it is important to understand it is not ground referenced true wind. If you are sailing in current and look at the wind instruments the wind display will not coincide with what you experience if you dropped anchor, or tied to dock in the same location even if the instrument is 100% accurate.

On some instruments this can be changed and I think it is worth at least trying the alternative of switching to ground referenced true wind or ground wind or simply true wind if you feel this term is more appropriate. Once again it does not matter what you call it, it is important to understand what information the instrument is presenting.The main advantage of this switch is that it removes the errors that are commonly found in the paddlewheel output from the equation. On most cruising boats this results in a more accurate stable display.

Personally, I don't have much time for all that plotter-jockey bollux.
What do you actually want to know?
How accurately do you want to know it?

In the short term, I want to know if I'm on the favoured tack.
I want to know if the wind is shifting.
Going downwind, in a cruiser I'd like a good enough number for the true wind, to know how much sail to have when I head up.

In the longer term, I want to know if the forecast is turning out accurate.
Do we have SW4? Is it veering as the day goes on as predicted?
Is what's changing good for my race strategy or passage plan?

I don't want false precision telling me the wind to 0.1 knots or 1 degree, it adds no value.
Mostly I prefer apparent wind speed, because the number is what it is, not munged by Raymarine.

 

[Yealm]

For sail trim I tend not to use instruments - rely on visual cues like telltales and feel of boat. Occasionally use apparent wind direction upwind and ground wind direction downwind.

For assessing atmospheric conditions/trends I use ground wind and direction.

For assessing tide strength/direction I use tidal arrrows on chart plotter.

The only thing I miss is not having a paddle wheel to calculate STW - to give an indication of how well I’m sailing. But I hate the fouling and inaccuracy of a paddle wheel so happy to not use one.




For everything else

Personally, I don't have much time for all that plotter-jockey bollux.
What do you actually want to know?
How accurately do you want to know it?

In the short term, I want to know if I'm on the favoured tack.
I want to know if the wind is shifting.
Going downwind, in a cruiser I'd like a good enough number for the true wind, to know how much sail to have when I head up.

In the longer term, I want to know if the forecast is turning out accurate.
Do we have SW4? Is it veering as the day goes on as predicted?
Is what's changing good for my race strategy or passage plan?

I don't want false precision telling me the wind to 0.1 knots or 1 degree, it adds no value.
Mostly I prefer apparent wind speed, because the number is what it is, not munged by Raymarine.

 

[Yealm]

I don’t think anything to do with marketing.

It’s just standard terminology. You need to have terms to distinguish wind speed calculated with a paddle wheel from wind sped calculated with GPS..

For the (wrong) majority who think True wind is defined relative to a fixed point in the earth, what do they call the wind speed on their instrument display using a paddle wheel (which the manufacturers call True Wind)?

I agree. The democratic opinion of YBW agree. I suspect that if you suggested to non-sailors that the true wind speed was zero, because you happened to be sitting a tide of the same speed and direction as the wind, they would think you were bonkers.

RayMarine et al, have just claimed it for their marketing. More fool those who believe the marketing is gospel. That will be their own downfall!

 

[prv]

For the (wrong) majority who think True wind is defined relative to a fixed point in the earth, what do they call the wind speed on their instrument display using a paddle wheel (which the manufacturers call True Wind)?

They call it "true wind" and think it's relative to the ground, even though it isn't

Pete

 

[lw395]

I don’t think anything to do with marketing.

It’s just standard terminology. You need to have terms to distinguish wind speed calculated with a paddle wheel from wind sped calculated with GPS..

For the (wrong) majority who think True wind is defined relative to a fixed point in the earth, what do they call the wind speed on their instrument display using a paddle wheel (which the manufacturers call True Wind)?

And how often do they work out the difference, and what benefit does it give them?
I spent quite a few hours this summer setting course for racing.
Getting 3 people to agree what the true wind was on an anchored committee boat was hard enough.
Then it was often 10 degrees different at the wing mark.

 

[TSB240]

I know of three winds.

The wind I can beat into at 30 degrees. This wind is really windy when I sail into it and rather disappointing when I sail downwind.

The wind I can beat into at 45 degrees. I like this wind as it stays the same whatever direction I sail in.

Bramblemet. This is used to decide whether I shall go sailing or not. I wouldn’t have much of a clue what angle to sail into it...

We are used to the three wind definition. Keeping it simple.... 1.too little to sail. 2 too much to sail. 3.from the wrong direction to sail. Our 4th category depends on the type of curry consumed and is measured by recording how much lead weighting was required on each corner of the duvet. I believe the Indian navy have their own nmea sentence. $WINDALOO.

 

[prv]

With no instruments, I only have the wind on my face and the wind on the sea, now it seems that neither is true.

Raymarine has brought us a philosophical apocalypse with the death of truth.

Don't blame Raymarine - what they call True Wind is your "wind on the sea". It's the OP and his friends who want to redefine it as a kind of "wind on the seabed" that you without instruments cannot feel or see while sailing.

Actually your "wind on the sea" is a useful addition to the debate. One time when the difference between true and apparent wind matters a lot is when we're motoring in light airs, and wondering whether there's enough wind to be worth sailing. On our faces we feel a breeze (on Ariam we often call it "Volvo wind") and it's very tempting to want to sail in it - but of course if we succumb to that temptation, stop the engine, and set sails, we'll find ourselves drifting. So all of us (I assume) have learned that we need to make that assessment by looking at the ripples on the water and not the feel of the wind on our face.

The wind that is kicking up those ripples is the True Wind that we have available to sail in, and that's the oldest and most intuitive definition for a sailor and nothing to do with any instrument manufacturer or land-based meteorologist.

Pete

 

[anoccasionalyachtsman]

I've asked this before, any chance of an answer from 'the majority'?

What do you call the wind experienced by a boat drifting with the tide?

Do you see any value in that information?

 

[Yealm]

OK. Imagine a day without wind. Nothing. Calm sea, flags drooping.

You motor out at 15 knots through the water (paddle wheel speed) with a tide of 5 knots in your favour. So speed over ground (GPS speed) is 20 knots.

On your instruments....

Apparent wind - 20 knots
True wind - 5 knots
Ground wind - 0 knots

The terminology is needed to distinguish the different things been measured.

A person can say he doesn’t care about the nuances or doesn’t understand them and all he needs is a rough idea of wind speed. That’s fine.

But I don’t think it’s ok to say the nuances/terminology are wrong or don’t exist. And in some racing situations they may be critical.

Don't blame Raymarine - what they call True Wind is your "wind on the sea". It's the OP and his friends who want to redefine it as a kind of "wind on the seabed" that you without instruments cannot feel or see while sailing.

Actually your "wind on the sea" is a useful addition to the debate. One time when the difference between true and apparent wind matters a lot is when we're motoring in light airs, and wondering whether there's enough wind to be worth sailing. On our faces we feel a breeze (on Ariam we often call it "Volvo wind") and it's very tempting to want to sail in it - but of course if we succumb to that temptation, stop the engine, and set sails, we'll find ourselves drifting. So all of us (I assume) have learned that we need to make that assessment by looking at the ripples on the water and not the feel of the wind on our face.

The wind that is kicking up those ripples is the True Wind that we have available to sail in, and that's the oldest and most intuitive definition for a sailor and nothing to do with any instrument manufacturer or land-based meteorologist.

Pete

 

[prv]

A person can say he doesn’t care about the nuances or doesn’t understand them and all he needs is a rough idea of wind speed. That’s fine.

But I don’t think it’s ok to say the nuances/terminology are wrong or don’t exist. And in some racing situations they may be critical.

Did you mean to reply to my post that you quoted? It seems mostly like a non-sequiteur, but to the extent that it's related it's in violent agreement.

Pete

 

[Yealm]

I’m not sure we are in agreement?!

You are rather dismissing ground wind ?

Did you mean to reply to my post that you quoted? It seems mostly like a non-sequiteur, but to the extent that it's related it's in violent agreement.

Pete

 

[lw395]

.....

What do you call the wind experienced by a boat drifting with the tide?

....

Feeble?
When do we ever sail in tides of more than a few knots?
Most of the time the current is smaller than the resolution or accuracy of the wind instrument.
If you're on the Solent, the tides can be significant, say up to 4 knots?
Have a look at this, and see how often the 'ground' wind varies between two adjacent stations, or from minute to minute, by far more than the tide:
https://weatherfile.com

Where the current changes from place to place, varying the true wind, 99% of the time you are close to land which varies it by a lot more.

 

[Richard10002]

I don’t think anything to do with marketing.

It’s just standard terminology. You need to have terms to distinguish wind speed calculated with a paddle wheel from wind sped calculated with GPS..

For the (wrong) majority who think True wind is defined relative to a fixed point in the earth, what do they call the wind speed on their instrument display using a paddle wheel (which the manufacturers call True Wind)?

I am one of your "wrong" majority. When you say paddle wheel, do you mean the wheel that measures speed through the water, (the log), or a wheel that measures wind speed directly over the deck, (relative to the boat?). I think you mean the former, but it would be good to be clear.

I call the wind blowing over the ground True Wind. I call any wind that is relative to the boat, the apparent wind, (there are obviously times when the apparent wind is the same as the true wind). If an instrument has a facility to differentiate between the wind caused by the movement of the water under the boat, and the movement of the boat through that moving water, I would probably be happy to have the info but, in my head, if the instrument called the wind caused by the movement of the water "True Wind", I would be mentally aware that it did not match my own meaning of the words.

It seems that there is some agreement that the industry has chosen to call something that isn't true wind, "true wind", and that the simplest thing would be to accept that this is now fact.

There is also some evidence that the industry standard has not been accepted by two thirds of sailors responding here, (a small poll, but possibly representative?), in which case, whatever is the case, the choice made by the industry, and seemingly imposed on us, has caused some confusion, and which should be the subject of explanation in a variety of areas.

 

[noelex]

If an instrument has a facility to differentiate between the wind caused by the movement of the water under the boat, and the movement of the boat through that moving water, I would probably be happy to have the info but, in my head, if the instrument called the wind caused by the movement of the water "True Wind", I would be mentally aware that it did not match my own meaning of the words.

If you have a standard yacht wind instrument, it will in all likelihood already be displaying true wind that is referenced to the water as this is the default option.

If you want your instrument to display true wind that matches your definition (and I too feel this is the more sensible display for a cruising boat) you may need to buy one of the newer instruments (unless you have an older advanced instrument) and make some software adjustments.