As all speed measurements are arbitrary, it shouldn't matter. It is just something to get used to.
If you need an ingame measurement of knots vs time, draw out a 10km line from your current position and straight ahead. Experiment with speed settings, and you will see how long it will take you to get there. You could translate this to km/h, but it is rather pointless.
Just make a note that under say X knots you will reach intercept course Y in 10 hours, and under Z knots intercept course Q in ten hour (Do this during an egress from home base at constant speed of X or Z. Use the pencil, mark an X at original position when you've reached target speed of X or Z. Then trod along in a straight line for ten hours, and measure distance traveled). Keep it simple, 10 and 15 knots are perfectly good values for X and Z. Makes for a great guide when trying to intercept targets from some radio contact. Especially as contacts reported medium speed (as is most common) means 6-8 knots. Plot a course some 25% ahead of worst case scenario (that is a somewhat fast target) at your preferred or necessary speed based upon the calculations, and track down projected target course until contact is made.
Bingo should then be your name
