Its good practice to submerge after sending messages especially when within aircraft patrol zones ( overlapping much worse ) crew spots them most of the time but often too late. Flak guns inoperable as you say with decks awash even on the conning tower its been discussed many times. The Binos /scopes/sensor guns etc are all linked to the same " mathematical waterline" unfortunately
All fair questions asked many times before in the past maybe addressed somehow in the future
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