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Old 09-25-17, 12:52 PM   #9
Pisces
Silent Hunter
 
Join Date: Dec 2004
Location: AN9771
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Quote:
Originally Posted by Jonatron5 View Post
...
This is the method I have been using (Wich may or may not work)

The hydrophone on my sub has a 20km single ship resolution, so I manually get on the hydrophone (because my crewmen are idiots ) and find a bearing to a vessel. Say for example 035, so I go to my navigation menu and draw a 20km radius circle around my ship, and draw a straight line to the circle at a 035 degree bearing (relative to the bow) and delete the circle, that gives me a line that I know for certain their is a ship on, next I sail 10km(half the distance of the line) at a heading 90degrees perpendicular to the original line, in this case heading 125, then I drop to periscope depth again and get on the hydrophone and listen for a bearing and repeat the process, interestingly enough, the two lines that get drawn usually intercept, and I have been operating on the assumption that is the position of the target vessel.

You do this twice, and you have a path of travel for the target vessel.

Please explain to me if this is totally wrong, and what I should be doing instead of this.
Remember that at any time the target is moving. (if not damaged) It has cargo to deliver. It is extremely unlikely that it was at that intersection at that time. As being at that intersection implies it was there at both times, thus stationary. The target is moving away from the bearing, a bit along it but also away from it. If you can make an estimate of target speed (usually 12 knots maximum; the sonar operator give slow, medium, fast.. look in the game config files how fast each is) and consider the time interval between bearings then you know how far apart the 2 valid points on each bearing line can ultimately be. Use a circle with the right radius length and do some trial and error finding points that match. Move the center along a bearing line and locate places that have the circumference touch or cross the other bearing line. This results in areas where the target likely was inside. The better your speed estimate the smaller the area. But with enough areas plotted a path should develop over time.

Target motion analysis the way you did is how modern subs do this. But they have sensors that record bearings at better resolution and at regular time intervals. It is hard to do in the WW2 era. Longer time intervals are needed.

There are several threads and videos describing how to do hydrophone tracking. Search for 4-bearing method in both the Silent Hunter 3,4 and 5 section. It is predominantly a graphical map-drawing exercise.

By being patient and recording bearings, with this tool you can at least figure out where it is going to. (own course, AOB and target bearing is enough to figure target course) It does not give you speed or range. That needs other methods. http://www.subsim.com/radioroom/showthread.php?t=147719

But simply chasing a target by moving fast along the bearing (doing regular hydrophone checks) should also get you near. Close enough to start plotting positions on the map. However, you are using a type-2 though and that has limited speed-advantage over merchants. You can get most, but some might be lost. Especially in bad weather.
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