Raymarine Marine GPS System manual Compass Calibration, Apparent Wind Angle Calibration

RayTech Navigator User’s Guide

Compass Calibration

Compass calibration involves two procedures: Deviation and Heading Error calibration. Calibrating Deviation corrects compass error around the different points of the compass. Keep in mind that some instru- mentation systems have the ability to swing (calibrate) the compass automatically.

Heading Error calibration ensures that the heading the compass indicates always reflects your true heading. Calibration of this kind is usually achieved by piloting the boat along a known line of transit. For best results, you should have your compass professionally swung.

Apparent Wind Angle Calibration

You must perform Apparent Wind Angle calibration after the mast head wand is initially installed on your boat. Since the wand may not lie exactly on the fore and aft line of the boat, Awa calibration is necessary to compensate for this. The Awa should read zero when the vane is on the centerline of the boat. If you don’t get a zero reading, you must enter an offset value into the instrumentation system.

The amount of Awa alignment error can be established in two ways:

∙Take the boat head-to-wind and read the Awa angle. If the Awa value is not zero, you have a calibration error. This method is less accurate than the following one.

∙Perform two or three tacks upwind in even wind strength, then compare the average Awa tack-to-tack by using Navigator’s DataTrak utility.

The calibration must be performed under even wind strength, as differing wind strengths 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.

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