Yup. I cheat a little bit and pause to get a good mark on the map. Then at x seconds plot point 2. That gives speed and course. then i extend the plot and revise as time goes. Since I am a bit of a perfectionist I use my TI-83 for the speed check. I wrote a program to take the yards traveled and time (s) and find speed in knots.
Basically it just does (10800/6076)*(dist yards/seconds) which comes out to knots.
I also have an AOB program which does the following. I dont use it very often because I just set up a triangle and measure the angles by hand. But it comes in handy.
Ship: Length = L
Ship: Mast height = H
Ship: Ratio = L/H = R (R for ratio so i remember what it is)
Observed Aspect ratio (tick marks, this one you put in as a division ie (7.5/4.3)) = O (O for Observed)
Actual vs Observed Ratios = O/R = R (this replaces R in the memory with the new ratio)
arcsin(R) = A (A for Angle)
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Optional (i keep my calculator in radians)
A*(180/pi) = A
A now is the AOB in degrees!
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