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Autopilot Drifting Off Course
This issue is typically a sign that the rudder gain is set too low. To improve, increase the Rudder Gain (depending on the boat speed at which the drift occurs). If using the GHC™ 20 autopilot controller, it must be put into Dealer Mode to access the Autopilot Gain Settings.
Dealer Mode
From the GHC™ 20 autopilot controller main page:
Select Menu
Select Setup
Select System
Select System information
Press and hold the center soft key for 5 seconds or until Dealer Mode appears
Select the Back button twice
The GHC™ 50 autopilot controller has Autopilot Setup and does not require extra steps to access Dealer Mode.
Autopilot Gain Settings - Rudder Gains
On a GHC™ autopilot controller
On the GHC™ 20 autopilot controller, select Menu > Setup > Dealer Autopilot Setup > Autopilot Tuning > Rudder Gains.
On the GHC™ 50 autopilot controller, from the autopilot screen, select 
> Response > Adjust the rudder response. If you want the rudder to be more responsive and move more quickly, increase the value. If the rudder is too responsive and moving too quickly, decrease the value.
Note the starting numbers in the gains and counter gains field. Adjust the Gains and or Counter Gains as needed. Make small increment changes, then test autopilot. Continue making changes until the desired results are achieved.
If performing this procedure outside of the Sea Trial Wizard, the Dealer Mode must be enabled (see above directions).
On a Chartplotter
Select Options > Settings > My Vessel > Autopilot Installation Setup > Autopilot Tuning > Rudder Gains.
Note the starting numbers in the gains and counter gains field. Adjust the Gains and or Counter Gains as needed. Make small increment changes, then test autopilot. Continue making changes until the desired results are achieved.