Contact Intercept

[Pisces]

Originally Posted by Captain Nemo

I find the easiest and fastest way to intercept a contacts course is by doing the following:

1. Draw a line from the contact in the direction that it is heading.
2. Ask the navigator to plot a waypoint that intersects somewhere along the line (track) that you have drawn showing the contacts course.
3. See how long it will take your u-boat to reach that waypoint (intersection) and from this work out how far the contact would have travelled in this time. From this ajust your course (waypoint) accordingly.

Example: Contact is travelling east at 6 knots. At full speed my u-boat will take 2 hours to reach the contacts track. In this time the contact will have travelled just over 22 kilometres. From this decide if you need to move your waypoint along the contacts track closer to the original contacts position or further away to make the intercept.

Hope all that makes sense.

Nemo

Ok, lets say the initial AOB is 90 degrees port. (target goes from your right to left. And your fastest speed is 16 kts. ( so the initial distance to the track is 59 km in 2 hours)

After 2 hours the contact moved 22 kilometers along it's track.
This makes your distance to the new projected meeting point 63 km. (it's 22 degrees to the left)
But this will take longer: 2 hours 8 minutes.
And so, in that time the target moves 23.7 km.
This again moves the projected meeting point even further to the left (23.6 degrees)
And so your distance to this new meeting point grows slightly to 63.6 km
It would take you now a minute more to reach that.
And so on,
and so on. But let's consider this minute close enough for now

In other situations you might have to do more repeated calculations, as your distance to the projected meeting point creeps further away.

So, how do you consider repeatedly calculating the distance that the target moves in the same time it takes you to do it "the easiest and fastest"?

To each his own method, of course. But I think those words better apply to the graphical method as described. Where no calculation is needed.