[magic452]

With map contacts ON, it is very easy to get a good target speed.

Just mark the position of the target on the map, at the end of the sonar line or the radar position mark. Wait till the position mark jumps and then mark a X and start the stop watch. Wait 3 minutes (3.25 minutes for metric) and mark another X. Measure the distance between the marks and that will give you target speed. 100 yards/meters = 1 knot, 900 yards = 9 knots, etc.

Do this twice and you also will get a good target course by extending the line.

The speed calculator in the TDC isn't very good unless you get very good range/bearing and AoB data. I never use it but use the 3 minute rule instead.

@ Filson the TDC/PK will calculate a good firing solution even if your boat is moving, no need to be stopped.

Magic