I would say the real difference in SH3 (SH2 and AoD) tonnage wise, is those who routinely use their hydrophones to find targets, versus those who don't.
If you routinely use your hydrophones, you will score almost 300% more over the course of an average career, than someone using the hydrophone guidelines from the U.Kdt.Hdb.
Should there be a -%300 penalty, for those who overuse hydrophones. Therefore you could at best play a -%200 realism.
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U.Kdt.Hdb B. I. 28) This possibility of using the hydrophone to help in detecting surface ships should, however, be restricted to those cases where the submarine is unavoidably compelled to stay below the surface.
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