Calibration

G'day all, new boat, first outings, 2 x 500-ish mile races north on the east coast of Aus to warmer places.

What I note is:

1. In areas of known south flowing current (Eastern Australian Current and all that), the B&G5000 are calculating Cur_Dir to be 20-30 degrees left of 180, i.e. more like 200-210;

2. When sailing downwind on port gybe at a HDG 000, COG will often be less, e.g. 355.

I'm pretty happy with the speedo calibration; generally when in current Cur_Rate value is about right. I'm not saying the two things are necessarily connected, but that would seem to be the case. It appears to be a difference between compass and GPS, but I'm not even sure how one would validate that theory.

Any guesses?