wind speed indicator

[PhilipH]

from other posts it appears that some people work off apparent wind and others off true wind. The default position on our wind instrument is apparent, but I prefer to work off true and always adjust when we turn on the instruments - what do others do and why?

 

[Aja]

Working off true wind when beating means your wind angle is all wrong. Better to have apparent wind angle so you can tell how well you are pointing.

Donald

 

[bbg]

What? With integrated wind instruments you can see how you are pointing compared to the true wind. Personally I only like working with TWS, TWA and TWD. With well set-up boats/instruments you can see lifts/headers more easily. I also like using TWA downwind as it is really plain when you are getting into the danger (accidental gybe) zone.

BUT - I also think it is a matter of preference and a question of being comfortable with what you are used to using.

 

[Oldhand]

Apparent wind angle for sail trim and both apparent and true wind speed. The latter is required when broad reaching or running so you know what to expect if you have to harden up. Apparent wind gives you the pressure on the sails but can lull you into thinking the wind is lighter than it is, when aft of the beam. True wind direction (direction not angle) is very useful for assessing the sailing conditions after a turning mark or waypoint, assuming you know the heading of the next leg.

 

[Twister_Ken]

Apparent speed and angle

 

[Swagman]

Apparent also.
JOHN

 

[PhilipStapleton]

I teach with the wind instrument on true, but get the students to use the Windex and the sails for apparent angle. The instrument's on true for the wind speed - so they know what to expect when they harden up. I also point out that the indicated speed is wrong if there's any tidal set.

 

[DJE]

Apparent wind. No choice for me.
I fitted the Raymarine wind instrument myself but the old Stowe log refuses to break down so I can't justify replacing it with a Raymarine unit and the two don't talk to each other.

 

[KellysEye]

Apparent, because that's the wind we're sailing in. I've never really understood why anyone would want to use true but that's probably me being thick.

 

[boatmike]

Depends on how much I want to lie when telling how close winded catamarans are..... Seriously though, Apparent is to sail by and trim to as others have said but true wind will tell you how well you are actually making up to windward. NBG going like a bat out of hell close to the apparent wind and not making any speed to windward! Sailing a fast cat where the apparent wind can come close to the nose because of the higher speed teaches you that true can be sanity when apparent is vanity!

 

[PhilipH]

Yes, I should have said that having the electronic instrument on true I then actually sail using the windex. I like to know what is happening to true wind speed rather than having to calculate.

 

[Salty John]

Apparant - that's the wind you sail in.

 

[Stork_III]

With my DatalineX system, I prefer to have the WIND showing TRUE for analogue and digital read out , The TACK showing APPARENT for analogue and digital read out. Prefer to make my own allowance, as I don't trust the LOG reading.

 

[BlueSkyNick]

Agree only apparent is relevant. True is not really true because it is only a calculation based on apparent wind, direction and boat speed all of which have some error.

Also, apparent wind speed and direction are more erroneous when on a broad reach or run, for us anyway, because the anemometer is ahead of the mast and therefore not in clean air.

I tend to use the windex or tell tails more than rely on the instrument.

 

[SnaxMuppet]

I tend to work off apparent most of the time but shortly before going about I flick it to true. When the boat is actually turning I find that true is more stable and more accurate and is more useful to accurately judge the turn onto the next tack.

I also prefer to have it on true when running.

 

[BlueSkyNick]

[ QUOTE ]
When the boat is actually turning I find that true is more stable and more accurate .....

[/ QUOTE ] How does your system know what the true wind is, to be more accurate than apparent?

 

[SnaxMuppet]

[ QUOTE ]
[ QUOTE ]
When the boat is actually turning I find that true is more stable and more accurate .....

[/ QUOTE ] How does your system know what the true wind is, to be more accurate than apparent?

[/ QUOTE ]

Yup... I know... doesn't make sense does it!

AFAIK the true wind is calculated from the wind measured at the mast head (which is the apparent wind) and the log speed (which is speed through the water forwards). Clearly, it makes no sense that the calculated "true" wind is more accurate than the measured apparent wind. After all, the "true" wind is only a calculated approximation.

However, my point is this... the apparent wind direction will change as boat speed changes. If you are beating into wind then your apparent wind will be from more ahead than the true wind due to the forward movement of the boat. If you slow the boat down without changing heading (and assuming the real wind is constant) then you will see the apparent wind indication go more abeam as the boat slows. However, if you do the same thing while showing "true" wind then it should remain pretty much the same indication (or at least move less). That is why I use "true" when tacking as the boat speed is changing (slowing into the tack and then accelerating away) so the indications are more stable.

I do agree with you though... it isn't really any more accurate but the indicator is more stable and so I find it easier to use when tacking.