in OM you can calculate speed using the Kiub interface, but you still have time the target as it passes the perpendicular line on the scope. Using donreed1's method if you are stopped skips the step with the interface. Also, in OM, the U-Boat's don't pick up the target map contact at great distance. If the target is close, saving time in the Kiub set up for manual targeting can be invaluable, especially if the target is moving at a high rate of speed.
