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TorpX · 09-04-12, 12:00 AM

I haven't used this method, so I decided to break out a pencil and paper and take a closer look at it. For some reason my brain learns better from graphite on paper, than illuminated pixels on a computer screen.

I must admit I like this method, now that I understand it. However, there is a simpler alternative that will suffice in many cases. This is the Normal Approach Course. I'm guessing some here already know what this is, but I thought I'd outline it for those who don't.

The Normal Approach Course gets it's name from the fact that you are taking a course normal (perpendicular) to the target. That is, if the target is on a closing track, the true bearing of the target is 25 deg., and it is drawing off to the South, you would steer 115 deg. true. You don't need to know the distance, exact course, or speed of the target. (This makes it ideal in situations where you have only a sound contact.) By the way the situation develops, you will know if a interception is possible:

Case 1- You are gaining bearing on the target.
That is the true bearing of the target goes from 25 to 24 to 23 deg., etc., etc. You can maintain your speed and reach the target's track ahead of it. You can reduce speed to intercept. Or, you can maintain speed and cut into the target's track to intercept sooner.

Case 2- True bearing of the target is constant.
If you and the target hold course and speed, an interception is assured. (You are on a collision course!)

Case 3- You are losing bearing on the target. That is, the target's bearing is going from 25 to 26 to 27 deg., etc. In this case an interception at this speed is impossible. You must either increase speed, or consider weather it is advisable to continue the approach (it is sometimes possible to get close enough for a torpedo attack even though an "interception" does not take place).

The key element of the Normal Approach Course is that it allows an intercept at a minimum of speed. Another critical element is that it is only relevant for targets on a closing track (moving closer to you). Following a Normal Approach Course on a target that is already moving away from you will avail you nothing. In this case you would be better off to follow the method already explained in this thread.

09-04-12, 12:00 AM	#27
TorpX Silent Hunter Join Date: Sep 2010 Posts: 3,975 Downloads: 153 Uploads: 11	I haven't used this method, so I decided to break out a pencil and paper and take a closer look at it. For some reason my brain learns better from graphite on paper, than illuminated pixels on a computer screen. I must admit I like this method, now that I understand it. However, there is a simpler alternative that will suffice in many cases. This is the Normal Approach Course. I'm guessing some here already know what this is, but I thought I'd outline it for those who don't. The Normal Approach Course gets it's name from the fact that you are taking a course normal (perpendicular) to the target. That is, if the target is on a closing track, the true bearing of the target is 25 deg., and it is drawing off to the South, you would steer 115 deg. true. You don't need to know the distance, exact course, or speed of the target. (This makes it ideal in situations where you have only a sound contact.) By the way the situation develops, you will know if a interception is possible: Case 1- You are gaining bearing on the target. That is the true bearing of the target goes from 25 to 24 to 23 deg., etc., etc. You can maintain your speed and reach the target's track ahead of it. You can reduce speed to intercept. Or, you can maintain speed and cut into the target's track to intercept sooner. Case 2- True bearing of the target is constant. If you and the target hold course and speed, an interception is assured. (You are on a collision course!) Case 3- You are losing bearing on the target. That is, the target's bearing is going from 25 to 26 to 27 deg., etc. In this case an interception at this speed is impossible. You must either increase speed, or consider weather it is advisable to continue the approach (it is sometimes possible to get close enough for a torpedo attack even though an "interception" does not take place). The key element of the Normal Approach Course is that it allows an intercept at a minimum of speed. Another critical element is that it is only relevant for targets on a closing track (moving closer to you). Following a Normal Approach Course on a target that is already moving away from you will avail you nothing. In this case you would be better off to follow the method already explained in this thread.