Quote:
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Originally Posted by XanderF
The easiest method I found was posted over in the 'hitting fast targets' thread.
Put your periscope just ahead of the ship crossing your FOV. As soon as the bow touches a vertical line, start the stopwatch. Stop it when the stern crosses the line. You already know how long the ship is in meters from your recognition manual, and you know have the time he took to cross that distance.
The EXACT speed is thus:
V (knots) = 1.9438444908 * Length (meters) / T (seconds)
...or you could replace the constant with 1.95, or 2x for a very quick estimate (and one you can likely do in your head. Double the ship's length, and divide by the time it took to cross bow-to-stern through your 'scopes line)
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*grins* Actually Herr Kaleun, that is the formula for the average velocity of an object travelling with a non-constant speed (speed is the rate at which position changes, velocity is the rate at which speed changes, and acceleration is the rate at which velocity changes). In reality, the formula is this:
V=D/T
when V=velocity, D=displacement (the change in position), and T=time.
Sorry, shouldn't be too picky...this Kaleun paid too much attention in physics class. LOL