#2: Are you shooting from a position so the torp impacts at a 90 degree angle, +/- 5 degrees? Some ships have a shallower draft than others, SH3 set the depth of the torps at 4 meters. Maybe you were hitting the bottom of the ship and again not getting a 90 degree angle at impact.
#5: When they start zig-zaging, plot the course changes on the Nav map; you'll soon see the pattern and be able to position your boat to get a 90 degree angle shot.
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