Judging true wind direction

snowleopard

snowleopard

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Woodlouse said:
I've come across people with 70,000+ sea miles who still struggle to tell where the wind is coming from
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So if you don't have instruments to tell you the true wind direction, can you judge it and how do you do it?

NB I'm not talking about apparent wind so wet fingers, burgees, telltales etc don't count.

I too have been surprised at the number of experienced sailors who can't
 
As it is an arithmetical problem involving apparent wind speed and boat speed I am not well-qualified to answer, however, I think I have a good general feel for it. Mostly it doesn't matter much, as we just trim the sails to their best effect. The time when is seems to matter on my boat is when close-hauled in a seaway. If the boat is slowed by hitting a wave the apparent wind moves aft and a novice helmsman, who may have been told to steer at 30 degrees to the wind, will tend to head up to correct the apparent change, slowing the boat further and inevitably pinching to a near-stop.

I suppose that I mostly judge the true wind from looking at the water.
 
If you're taking a book on a programming language you're unfamiliar with to amuse yourself in the off watch hours of a transatlantic, the conversion between true and apparent given boat speed is a pretty good first practical exercise after "Hello World".

Now you're going to tell me a laptop counts as an "instrument"...
 
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It depends how well you know your boat but when close hauling I know that I can tack though 90-95 degrees, therefore true wind must be about 45 degree's off the windward bow. Other than that it's all external references as mentioned by cruiser2b.

I don't have wind instruments so my primary wind indicator is the mast head burgee. True wind direction doesn't often bother me unless I'm trying to figure out how it's going to funnel around islands and down narrow channels. Having just been sailing in Norway it would have been great if, with all their thousands of flag staffs they could have at least flown a few from the tops of hills, rather than all down by the waters edge. It would have made sailing through the skerries much more predictable (though I have since found out reading in another post that sailing in confined quarters is reckless and irresponsible:o).

To be honest I was referring to apparent wind in my quoted statement, but not to worry. This could be a topic with some interesting ideas.
 
Largely depends on what sort of waves we're cutting through, but if we're close to wind then COG will be about 50 degrees (sometimes slightly less) to wind including leeway, although by heading, the compass would generally look like a tack through 90 degrees not 100. We have confirmed that many times by GPS track. At other times, I'm not greatly bothered.

Also, depends on the circumstances but wave direction can be helpful, but needs to read properly.
 
snowleopard said:
So if you don't have instruments to tell you the true wind direction, can you judge it and how do you do it?
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We're close-hauled heading south on stdb tack, the true wind is therefore in the south-west, maybe a tad west of south-west given that we don't point that well.

We're on a beam-reach, judging by the ripples on the water being parallel to our fore-and-aft line, on port tack heading east, the true wind is therefore in the north.

We're on a broad-reach on port tack heading north north-west, the true wind is in the south, possibly south south-west depending on just how broad our reach is.

How much more accuracy do you need?
 
Babylon said:
How much more accuracy do you need?
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By God this really is a cruising forum! :D

I oftn don't sail with the windex on as it isn't calibrated.

Using my face and ears. Feel the wind on the cheek, turn head so both cheeks get cold, once cheeks are cold, it's time to turn to ears. Move head left ad right till both ears hear wind and feel cold. There is your apparent.

Close hauled, 90% of the time is spent watching the tell tales on the genoa. Maximum speed and it stops any boredom setting in.

True wind is relative, it's the apparent that I'm concerned with as that is what I am trimming to.
 
My thoughts on true wind are that it would always be more aft than apparent wind if close hauled or reaching.
The difference between boats heading and ground track, as seen on the plotter is a good indicator of true wind.
Previous question removed!
C_W
 
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Clyde_Wanderer said:
My thoughts on true wind are that it would always be more aft than apparent wind if close hauled or reaching.
The difference between boats heading and ground track, as seen on the plotter is a good indicator of true wind.
Or am I talking bolloc*s?
C_W
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A little bit, maybe, yes..... :)

So many different factors involved with Heading and COG. Tide, leeway and general rudder wiggling ability.
 
snowleopard said:
So if you don't have instruments to tell you the true wind direction, can you judge it and how do you do it?
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Starting point is apparent wind direction. Adjust for boat speed / direction. Confirm with (as per others) wavelets/ripples on the surface.
 
monkfish24 said:
A little bit, maybe, yes..... :)

So many different factors involved with Heading and COG. Tide, leeway and general rudder wiggling ability.
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Well as an example, a few wks ago sailing up Cumbrae pass towards Toward bank, compass heading N, windex says wind from N, NE, ground track on plotter showing progress in a N NW direction, the tide runs N to S and vice versa in this stretch of water so tide set & drift was not relevent in this case.
The only explanation was that the true wind was further aft than the windex indicated. (windex is not electronic, just one of those arrows on top of mast)
C_W
 
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Clyde_Wanderer said:
Well as an example, a few wks ago sailing up Cumbrae pass towards Toward bank, compass heading N, windex says wind from N, NE, ground track on plotter showing progress in a N NW direction, the tide runs N to S and vice versa in this stretch of water so drift was not relevent in this case.
The only explanation was that the true wind was further aft than the windex indicated. (windex is not electronic, just one of those arrows on top of mast)
C_W
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I see, so from that I'd expect to be seeing the true ENE direction?

Your right in saying that to find TW from AW you'd be looking further aft. the forward speed will draw the apparent forward unless running dead downwind where it will just drop in speed.
 
Clyde_Wanderer said:
Well as an example, a few wks ago sailing up Cumbrae pass towards Toward bank, compass heading N, windex says wind from N, NE, ground track on plotter showing progress in a N NW direction, the tide runs N to S and vice versa in this stretch of water so tide set & drift was not relevent in this case.
The only explanation was that the true wind was further aft than the windex indicated. (windex is not electronic, just one of those arrows on top of mast)
C_W
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True wind will always be further aft than indicated by a tell tale or mast windex. Just how far forward the apparent wind comes forward from the true depends on how fast your going.
 
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