Speed Determination Graphs

[buznee]

I made some look up graphs to calculate speed.









Here's a little guide to use them...

First of all you can't be turning and it is best if you are completely stopped to reduce error.

1. Findout what ship it is

2. Find its range

3. Open the Timer

4. Measure its bearing and hit the Timer, if its range is less than 1750 yds use the first graph and stop the timer in 10 seconds to measure the change in bearing. If its range is at least 1750 yds use the second graph and time the bearing change for 30 seconds.

5. Now that you have range and bearing change, go to the graph and read off knots. The ranges are represented by the different colored lines, bearing change is on the x-axis and you read off knots on the y-axis.

6. If the ship AOB is less than 70-80 degrees its a good idea to use the third graph to find a correction. Unfortunately with this graph you need to guestimate the AOB of the ship but this is better than nothing. I guess that comes from experience.