Interesting variation on the theme, measuring the target track by distance rather than time. I'm not sure under what circumstances it's easier to measure distance rather than time though - how do you tell (easily) when the target has gone 1 nautical mile? Is that something that only works well if you have map updates on? Without the map updates, I don't know how you would ever really be able to determine when the target had gone 1 mile with any reliability, which I suspect is why it seems a lot easier to track and estimate speed based on elapsed time and then measure the distance later using the ruler tool.
One minor point - your wheel has a label "KNOTS per HOUR" - Knots already means nautical miles per hour (i.e., 1 Knot means 1 nautical mile per hour), so you don't really say "knots per hour" - that would be like saying MPH/hour.
Just a small point, but since you've got your name on the wheel I thought you might want to fix it. Thanks for offering this up, as I suspect some of our metric friends playing with map updates on might find it useful
