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• Take the boat heading into wind and read the Awa angle.
If the Awa value is not zero, there is a calibration error. This method is not as
accurate as the next.
• Perform two or three tacks upwind in even wind strength, then compare the
average Awa tack-to-tack using RNS's DataTrak function.
Any calibration must be performed under even wind strength, as variances will result
in different Awa readings tack-to-tack. It is also important to calibrate Awa offset in
the absence of wind shear and wind gradient; however, calibration in light air (such as
a sea breeze filling in) is not recommended.
To achieve successful Awa offset calibration:
• Choose a day with no wind shear, minimal gradient and a steady true wind speed.
• Ensure that the DataTrak function is on-line and operational.
• Sail upwind at your optimum close-hauled angle.
• Complete four to six tacks in steady wind conditions.
• Use the 'wand method' of averaging the charts to ascertain the difference in Awa
on each tack.
Once you have determined the Awa offset, enter it into the Masthead unit offset
parameter within your instrument system. Use half the difference between the wind
angle on each tack. This keeps the Awa symmetrical tack-to -tack, because laylines are
predicted based on the Awa.
RayTech RNS V5.0 - User's Manual
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