True wind direction

In my ST60 set up I have the Graphic display.
One of the pages I have shows Wind as direction and force along with heading and course.
The gps feed into the system is from an old Garmin unit. Sometimes the course part of the graphic display goes blank for a few seconds. When this happens the wind info is erroneous. I imagine that the graphic is actually telling the true wind, but just a hunch.
 
Main reason for wanting it is race tactics, so planning subsequent legs of the course. Of course you can work it out, but it would be so much easier to have it on a display. My arithmetic always seems to let me down especially in the heat of the race course!
 
maby said:
All true, but I don't think that this definition of true wind is what the OP is looking for either - he wants a "true wind" reading of zero degrees to indicate that the wind is coming from the north rather than directly in over the bows. I don't think any boat instruments offer that - it is of very limited value to the helmsman or navigator.
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I can assure you it is widely available, and of considerable interest if you know how to use the information.
 
maby said:
All true, but I don't think that this definition of true wind is what the OP is looking for either - he wants a "true wind" reading of zero degrees to indicate that the wind is coming from the north rather than directly in over the bows. I don't think any boat instruments offer that - it is of very limited value to the helmsman or navigator.
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The better instruments will offer true (or ground) wind in degrees magnetic or true. It is not a difficult software calculation.
How the ground wind direction is changing direction is a useful, even for a crusing sailor, trying to pick a suitable anchorage for the night. For a top racing boat it is vital information.
 
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While it is true that True Wind Speed and direction are derived from the log and wind sensors, different systems can work in various ways. My 12 yr old Raytheon ST60s will usually only show the True wind as Beaufort if the GPS is switched on, though one would expect that the sensors, including compass, should be sufficient. This is not normally a problem, though it occasionally comes to light when we are in harbour.

Although the speed log is not wholly accurate, and mine is usually calibrated to read 0.1 knot fast, the effect of the error on the True Wind readout is not excessive in a normal sailing wind. I imagine it could be much greater at low wind and boat speeds, but I can't say that it bothers me much. I generally have mine set to read Apparent, but True is useful when motor-sailing, and sometimes when sailing downwind when I know it is time to panic when True is over 25 knots.
 
Just looked in the manual for the ST60 Graphic display.
It can indeed show the Ground wind..
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bbg said:
Most decent instruments can do it. And it has a lot of interest, even for cruising sailors, precisely so they can plan the next tack (or gybe). If you are anticipating a persistent shift, you might decide that you want to tack "early", in anticipation of the shift continuing. So you want to know, for example, when the wind goes from 260 TWD to 270 TWD.
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or to help you decide which side of the boat to call the spinnaker pole for on the next downwind leg....
 
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