I did a little test myself lastnight. Heres what i did. Left port in S-39,
(at Java) sailed out the channel and plotted a course dew south for five knotical miles and let her go ahead standard. We pushed 9knots as i waited. The sea was very calm and a 5knot wind from 260. My rudder was at 4 degrees port. (I am using FOTRS btw)
that was to make strait south... now I turned round and went back and had 5* to starboard.
turned to 180 again manually and dive to PD and ran at 5 knots i noticed myself drift to a heading of 178 in 5 knotical miles.
Tell me theres no current.
