Calibrating the autopilot

Hi Chuck!

I have a 32 footer sailboat with a wheel rudder.

I have a complete Evolution Autopilot system with ACU100 (wheel) and p70 control head, but without rudder reference trasducer.

I have done the autopilot calibration procedure correctly and the compass shows a 3° Deviation.

The vessel type is set to "Sail".

Nevertheless, when I am sailing on light winds at 4 to 5 knots of boat speed, with some side tide (1,5 knots), even setting the autopilot in "Performance" mode, it drives the boat in a "swinging" pattern of -let's say- 15° from port to starboard and back, as it have problems to steer the boat straight. This happens in all types of autosteering modes (Auto, Wind, GOTO a WP, Follow Route).

I also point that the sails are correctly set and there are very small waves (0,30 m).

Do you have any suggestions on how can I correct this "swinging" problem?

I suspect that at a low boat speeds with some side tide, the autopilot struggles to manage the combination of both factors (boat speed and tide).

Many thanks in advance for your help.