I got a self study sheet on NETPO this past summer. I find it good for self study. As was already mentioned, it looks intimidating/complicated in this sort of abstract, mathematical setting, but if you want, sit down, work it out so that it makes sense. Its fairly easy to figure out the patterns and what it means. If you're not up for that, you'll learn it during your training. I'm in a Contemporary Studies programme (its not math), and I'm doing fine at understanding these concepts. I haven't done MARS III and IV yet, so I'm not an authority on this stuff by any means, but I figure posting this might help you out. Enjoy!

Radian Rule - a change of course of x ° will, after y distance get you z distance from your position had you maintained original course.

x ° at y yards/Nm (nautical Mile) = z yards

1 ° at 300 yards = 5 yards

1 ° at 600 yards = 10 yards

1 ° at 900 yards = 15 yards

1 ° at 1Nm = 33 yards

3 ° at 1Nm = 100 yards

6 ° at 1Nm = 200 yards

6-3-1 Rule - In the time on the left, you will travel the distance on the right, at 10Kts (Knots, or Nautical Miles per Hour)

6 mins = 1Nm

3 mins = 1000 yards

1 min = 1000'

Regain Track with 3 ° - If you find that you're no longer on the course you plotted on the chart, but you've got the right heading, you can make a 3 ° course alteration port or starboard (wherever you're supposed to be).

10 Kts regain 100 yards in 6 minutes

13 Kts regain 130 yards in 6 minutes

15 Kts regain 150 yards in 6 minutes

Regain Track with 6 ° - Same as above, but with a 6 ° course alteration. Speed in Kts x 2, with a 0 on the end, and this is the distance that will be regained every 6 mins

10 Kts regain 200 yards in 6 minutes

13 Kts regain 260 yards in 6 minutes

15 Kts regain 300 yards in 6 minutes

Clock Rule (for CPA's) I think it stands for Closest Point of Approach, but it wasn't covered in NETPO. Perhaps another MARS person can help fill us in on what it means. However, I was able to figure out the pattern. Take the degree value of a contact off the bow, and imagine that that value was the minute hand on a clock. So if a contact is 45 ° off the bow, think 45 minutes, which is 3/4 the way around the clock.

45 ° off the bow = 3/4 dist

30 ° off the bow = 1/2 dist

20 ° off the bow = 1/3 dist

10 ° off the bow = 1/6 dist

15 ° off the bow = 1/4 dist