hey jim, torpedomen go into both front and rear torp positions(Tslots), keep developing 2nd torper level to the first one using R(gun) or Pilot Station or supp slots because you might need him later. if you use a gunner R slot(s) are on main deck or conning tower. each torp in tubes counts as one for ammo in ship info box at bottom, R slot load being last ammo slot usually.
keep torper 2-3 levels above BO to operate BO level sub tubes, and get tier 6 torps use in Premium subs at lvl 103, i think.
planesman and sonar in supp slots always, always full to the last recruit...or you suck air to fill tanks at start of each battle planesman is not full. sonar is your lifeline against other subs. the eleven button for max range to live
begin to develop 3-6 Engines early depending on nation. or use ^^level BB engines. work to get full vets and full experts. levels ranging 8-10 levels below(few sailors) to lvl 120 if they fit.
BO is just a driver...minimze his experts to 25-35, a few recruits, 0 to none vets. your sub aims your torps. F4 gives you optionsl firing as with guns. gradual saves torps. maximum aimed well sinks ships fast. the higher level the more torps.
levelling subs is a long hard process. i recomend doing the whole grind 1-120 at least once for the experience...you will learn a ton! most just level a nationed sailor to high tier 4, or even tier 5 level of sailor, then making him a sub BO. NATION BEFORE LVL 25...class anytime.
there's so much. any questions ask. in game usually in blitz still developing all pilot lines. this is what usually works best for me. opinions may vary.