Raymarine Autohelm 100 - Gyroplus Offset and Drift Compensation; Procedure

80 TYPE 100/300 Operation and Installation Handbook
3.10 GyroPlus Offset and Drift Compensation
The GyroPlus uses the latest generation solid-state rate gyro to enhance
steering performance at response level 3 (see Calibration for details). Like
all rate gyro's the GyroPlus is subject to offset and drift. However, this is
automatically compensated for whenever the autopilot is in AUTO mode.
When the GyroPlus is initially installed, it is important that offset and drift
compensation ( a once-only operation) is carried out before selecting
response level 3 - failure to carry out this procedure will result in rapid
course changes when level 3 is selected.
Procedure
Compensation for offset and drift is achieved by simply using the autopilot
in response level 1 or 2 for at least 5 minutes before you select level 3.
Alternatively, if you want to use response level 3 as soon as you engage
AUTO, then the following procedure must be carried out.
1. Moor the vessel so that the heading remains constant.
2. Press AUTO and leave for at least 5 minutes.
3. After 5 minutes, press STANDBY to return to "standby" mode. The
autopilot will nor have stored the compensation value for future use.