#18 True wind angle calculation

improvement
open-accepted
nobody
5
2009-02-13
2008-07-15
No

I think this calculation is already done, but we should considere the drift of the boat.

The fact is to calculate a precise wind angle, at a buoy for example, by combination of the vessel course on the water, on the ground and anemometer sensor.

Information you need are:
- Vessel heading on the water
- Vessel heading and speed on the ground
- Apparent wind angle and speed

The anemometer sensor gives us the apparent wind angle from the bow and the speed.

With GPS tracking we have the ground heading (Course Made Good CMG) and the ground speed.

If we considere that the true heading of the boat (on the water) and CMG are the same, you could calculate the true wind. But most of the time, True Heading and CMG are different due to current, drift. This difference is called Crab-Angle.
So if you want a true wind angle you need to add or substract this crab-angle to your previous calculation.

The True Heading of the boat is given by compas or gyrocompas.

My request concerns 3 NMEA input messages:
- MWV from anemometer
- VTG from GPS
- HDT from gyrocompas

Discussion

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    Moreover we need the water speed in order to have the current vector.
    This data is given by the NMEA message VHW.

     
  • cyrille rosay
    cyrille rosay
    2008-07-22

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    The feature request has been accepted.

    ACTION FOR THE NEXT ASSIGNEE
    write or modify the requirement.
    The assignee must attach the new version of the requirement (doc)

     
  • cyrille rosay
    cyrille rosay
    2008-07-22

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    waiting for agreement from Yoda or DerSaint

     
  • cyrille rosay
    cyrille rosay
    2008-08-16

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    task created.
    under development

     
  • cyrille rosay
    cyrille rosay
    2009-02-13

    • status: open --> open-accepted