Albrecht Von Hesse
01-22-07, 12:27 AM
I don't consider myself the definitive expert of convoy interceptions, but I thought I'd show how I calculate mine. This is the second of four tutorials which are divided into the following:
radio contact plotted with you ahead of the contact,
radio contact plotted with you behind the contact,
visual spotted with you ahead of the contact, and,
visual spotted with you behind the contact.At the moment I've only the first two done. Assuming there is interest in the second set of two I'll do those as well.
This tutorial covers instances where you receive a radio contact report of a convoy and you find yourself positioned behind them, or so close that reaching an intercept position has you in their visual range before you reach your interception point.
Your basic radio contact plotted with you behind the contact will look like the following:
http://i96.photobucket.com/albums/l192/Albrecht_von_Hesse/convoy%20interception%20radio%20contact/1a.jpg
Of course, whenever you can, ultimately your desire is to successfully intercept enemy convoys. This isn't always easy, especially if they already have a significant head start on you and heading away. A stern chase is long, long, long, and runs the risk of having you spotted if you grow to close. But there are ways to maximize your success at that.
One thing I recommend is to review several things before anything else: the time of the contact report, the time you're performing your interception calculations, the weather conditions and the convoy speed:
http://i96.photobucket.com/albums/l192/Albrecht_von_Hesse/convoy%20interception%20radio%20contact/2a.jpg
If you're running at high TC there may be a significant amount of elapsed time between the reported contact and when you start calculating, which is going to an effect on things. In the above example only 11 minutes has elapsed, which should have little effect on calculations. Several hours, on the other hand, would make it more 'interesting' for you.
Another reason to consider times is to estimate when you'll be passing by the convoy and when you'll be in position. Will it still be dark? Sun just coming up or setting? Broad daylight? This will effect the enemy's ability to visually detect you, as will weather conditions, too. As you get better at this, you might even want to try things like arranging for the interception to take place just as the sun is setting, with the convoy being backlit by the setting sun.
The method I use for plotting convoy course is to place the tip of the compass tool at the far end of the convoy heading 'tail' then draw the circle radius straight through the center marking of the convoy plot. Zoom in if you wish and tweak the exact position of the circle for more precision. Next I use the ruler tool and set one end at the convoy center, drawing outwards along the convoy path the compass tool marked out. The exact distance to mark often needs to be tweaked, as you'll see in a moment. To start I used a distance for the convoy as 140km. Also, as this is a stern chase, I also mark line-of-sight areas as well. In this example it is night, but also clear weather, so I've marked the line-of-sight areas as 16km diameter, centered on the start and 'finish' marks of the convoy.
http://i96.photobucket.com/albums/l192/Albrecht_von_Hesse/convoy%20interception%20radio%20contact/3a.jpg
Next I set my course to tangent of the 'finish' line-of-sight diameter. In this example you see that I have to travel 232km to match their 140km distance.
http://i96.photobucket.com/albums/l192/Albrecht_von_Hesse/convoy%20interception%20radio%20contact/4a.jpg
There are several ways of computing speeds/distances/times. I find it convenient to use the nomograph mod I have. Utilize whatever works best for you. In this next image I've compared arrival times for the convoy and myself:
http://i96.photobucket.com/albums/l192/Albrecht_von_Hesse/convoy%20interception%20radio%20contact/5a.jpg
I'll arrive ahead of them, but I'll do so with a lot of extra time. So I make adjustments to our distances (I wish I had a way to do this other than trial-and-error but I don't; all I can say is that estimating things gets easier with practice).
http://i96.photobucket.com/albums/l192/Albrecht_von_Hesse/convoy%20interception%20radio%20contact/6a.jpg
That's not gonna work, unless I want to wave bye-bye to their hind ends in the distance. So I tweak things again:
http://i96.photobucket.com/albums/l192/Albrecht_von_Hesse/convoy%20interception%20radio%20contact/7a.jpg
http://i96.photobucket.com/albums/l192/Albrecht_von_Hesse/convoy%20interception%20radio%20contact/8a.jpg
Here the convoy will travel 120 km with me traveling 218km to reach the line-of-sight circle. Add the 16km for that and I'll travel 234 to reach the same spot the convoy will in 120km. That's pretty close to the 2-1 rule (14knots to their 7knots). And as you can see in the final image, I will be in position shortly before they will. Also in that final image I've marked a diameter deliniating how far I want to be positioned from the convoy route/center of convoy. In this instance I selected 2km, and have positioned myself to be approximately 30 degrees off their beam.
You can't, of course, use a straight 2-for-1 meterstick for convoys or task forces that aren't traveling 7 knots. But the principle remains the same.
I hope this helps!
radio contact plotted with you ahead of the contact,
radio contact plotted with you behind the contact,
visual spotted with you ahead of the contact, and,
visual spotted with you behind the contact.At the moment I've only the first two done. Assuming there is interest in the second set of two I'll do those as well.
This tutorial covers instances where you receive a radio contact report of a convoy and you find yourself positioned behind them, or so close that reaching an intercept position has you in their visual range before you reach your interception point.
Your basic radio contact plotted with you behind the contact will look like the following:
http://i96.photobucket.com/albums/l192/Albrecht_von_Hesse/convoy%20interception%20radio%20contact/1a.jpg
Of course, whenever you can, ultimately your desire is to successfully intercept enemy convoys. This isn't always easy, especially if they already have a significant head start on you and heading away. A stern chase is long, long, long, and runs the risk of having you spotted if you grow to close. But there are ways to maximize your success at that.
One thing I recommend is to review several things before anything else: the time of the contact report, the time you're performing your interception calculations, the weather conditions and the convoy speed:
http://i96.photobucket.com/albums/l192/Albrecht_von_Hesse/convoy%20interception%20radio%20contact/2a.jpg
If you're running at high TC there may be a significant amount of elapsed time between the reported contact and when you start calculating, which is going to an effect on things. In the above example only 11 minutes has elapsed, which should have little effect on calculations. Several hours, on the other hand, would make it more 'interesting' for you.
Another reason to consider times is to estimate when you'll be passing by the convoy and when you'll be in position. Will it still be dark? Sun just coming up or setting? Broad daylight? This will effect the enemy's ability to visually detect you, as will weather conditions, too. As you get better at this, you might even want to try things like arranging for the interception to take place just as the sun is setting, with the convoy being backlit by the setting sun.
The method I use for plotting convoy course is to place the tip of the compass tool at the far end of the convoy heading 'tail' then draw the circle radius straight through the center marking of the convoy plot. Zoom in if you wish and tweak the exact position of the circle for more precision. Next I use the ruler tool and set one end at the convoy center, drawing outwards along the convoy path the compass tool marked out. The exact distance to mark often needs to be tweaked, as you'll see in a moment. To start I used a distance for the convoy as 140km. Also, as this is a stern chase, I also mark line-of-sight areas as well. In this example it is night, but also clear weather, so I've marked the line-of-sight areas as 16km diameter, centered on the start and 'finish' marks of the convoy.
http://i96.photobucket.com/albums/l192/Albrecht_von_Hesse/convoy%20interception%20radio%20contact/3a.jpg
Next I set my course to tangent of the 'finish' line-of-sight diameter. In this example you see that I have to travel 232km to match their 140km distance.
http://i96.photobucket.com/albums/l192/Albrecht_von_Hesse/convoy%20interception%20radio%20contact/4a.jpg
There are several ways of computing speeds/distances/times. I find it convenient to use the nomograph mod I have. Utilize whatever works best for you. In this next image I've compared arrival times for the convoy and myself:
http://i96.photobucket.com/albums/l192/Albrecht_von_Hesse/convoy%20interception%20radio%20contact/5a.jpg
I'll arrive ahead of them, but I'll do so with a lot of extra time. So I make adjustments to our distances (I wish I had a way to do this other than trial-and-error but I don't; all I can say is that estimating things gets easier with practice).
http://i96.photobucket.com/albums/l192/Albrecht_von_Hesse/convoy%20interception%20radio%20contact/6a.jpg
That's not gonna work, unless I want to wave bye-bye to their hind ends in the distance. So I tweak things again:
http://i96.photobucket.com/albums/l192/Albrecht_von_Hesse/convoy%20interception%20radio%20contact/7a.jpg
http://i96.photobucket.com/albums/l192/Albrecht_von_Hesse/convoy%20interception%20radio%20contact/8a.jpg
Here the convoy will travel 120 km with me traveling 218km to reach the line-of-sight circle. Add the 16km for that and I'll travel 234 to reach the same spot the convoy will in 120km. That's pretty close to the 2-1 rule (14knots to their 7knots). And as you can see in the final image, I will be in position shortly before they will. Also in that final image I've marked a diameter deliniating how far I want to be positioned from the convoy route/center of convoy. In this instance I selected 2km, and have positioned myself to be approximately 30 degrees off their beam.
You can't, of course, use a straight 2-for-1 meterstick for convoys or task forces that aren't traveling 7 knots. But the principle remains the same.
I hope this helps!