A substitute for the 3 minute, 15 second rule
Distance in Kmeters x 32.5 divided by minutes = knots
Or distance in meters x .0325 divided by minutes = knots
Plot target's first position and begin timer. Plot subsequent positions and plot target's general course. Measure distance traveled and note minutes on timer.
For example 2.6 Km x 32.5 divided by 12 minutes = 7.0416 knots
The more observations and calculations you make, the more accurate your estimation of speed.
This is really useful with a target on a zig-zag course.
|