I agree. I would add length to the radio antenna such that it would break the surface at whatever depth you deem appropriate.
Why not make it match the periscope length. Then you can radio from PD.
__________________
there are only two things in the world: submarines and targets.
Fortis et stabilis et fidelis, semper
  
------------------------------------------------------------
Silent Hunter 4 1.5 Gold Edition on CDROM
LAA enabled
Dell XPS with 32 GB Ram running Win10
|