Edit: I checked your screenshots.
How comes A2 is smaller than A1?
Have a look at your 2.3 circle to add "s" - does it match the criterias? Does the second bearing cut the courseDIRECTION into two equal parts between first and third bearing? It should be a hint something is wrong.
Assuming A1 and A2 are correct - you made a mistake at the auxillary drawing.
The AOB is 11° - not 37°.
The 'side' you choose for the auxillary drawing is not important. I mentioned it in the Konrad story but it is not necessary to care for.
For an incoming contact the AOB must be smaller than 90° (in SH3 smaller than 60° !!)
Is your U-Boot at full stop for the first three bearings? Do you stop for the crossbearing? Try to mark the point of the crossbearing.
Draw the 20 km bearings from the outside/the circleline onto your boat and move them like I did it in the tutorial. Remeber the bearing is a "cone" of 350 meters width on the hydrophonecircle. Try to center the bearingline to minimize error.
Try to work as exact as possible to counter the inaccuracy of the SH3 maptools.
Let's call it a day!
Regards
Mittelwaechter