Hidrophone atack

[Mittelwaechter]

Hi Bojan,

let's sort it out as far as possible.

Your first and second bearing was identical and after 20 minutes they enclosed an angle of only two degrees.

=> as you realized the contact is coming towards you.

Wait until the difference of two bearings within a "short" time interval (maybe 6 minutes) changes for 'some' degrees. Make the last bearing the 'second one' and the one before the 'first bearing'. The new time constant is six minutes now and you can work with it.
Take the third bearing after six minutes and you have all the data for your auxillary drawing. The contact is quite close to your position, but it doesn't matter at all because you don't have to sail far to get in shooting distance.

The diameter of the initial auxillary circle (M) is irrelevant - all the following drawings, angles and circles are relative to your initial auxillary circle M.
You can zoom in and work with a radius of 250 meters or you zoom out and work with a radius of 150 km - it doesn't matter. Your map shows either only small markings or huge circles in "normal mode".

Draw your circle M before you start to hunt by hydrophone. (maybe somewhere in the Indian Ocean?)
Perpare the base angles too - as I did it in the tutorial.

Start to work on your auxillary drawing after the second bearing - well you have the first angle (A1) by then.

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Your first reading was 350°, your second reading 348°

=> A1 = 350° - 348° = 2° (too small to be good for SH3 map!)

The base angles at P1 - M are (180 -2A1) : 2 = 88°

Your third reading was 340°

=> A2 = 348° - 340° = 8°

The base angles at M - P2 are ... = 82°

Here is your auxillary drawing - starting with the green circle M,
adding the base angles in blue (88° and 82°),
the dotted golden circle lines C1 and C2 (they are too big for my Z.u.L program ),
the black U-Boot position
and the red AOB angle of 2°




Thinking about the wonky SH3 map tools you should be good with your 5° AOB.

The difference results (after 20 km!) in ~ +1000 meters real shooting distance. But you are quite perpendicular to the contacts course and the distance is irrelevant for this kind of attack.

You should definitivley hit the target with a "one degree fan shot" of two eels.
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A medium range contact can be reported short after you dive to PD.
It is important as you can conclude the time index for the bearing reports has to be short - or the contact will pass you.

A 20 km hydrophone circle is good enough for all your work.
Depending on equipment, weather and skill of your operator the real range may differ.

Keep up the good work!

Edit: the later confirmed AOB was 95°? Not sure what you are talking about in this passage, but if the AOB was 95° at the time you wanted to open fire (did you do a visual check?) you did a good job mate!