In this photo you see what I have tried to explain yesterday. The blue line with the small circle at the end is the direction Easy is heading (HDG) at. The black/green dashed line with the small black circle at the end is the actual course over ground (COG). The length of both lines is the track in 120 min. If you connect both endpoints (light green arrow), you have the vector of the current in 120 min. So, the current is running about 5 nm in 120 min, 2,5 nm in 60 h, equal to 2,5 kn. The direction of the current is 20°.