For the snorkel is a alone 3D model with annimation ( idem with periscopes,torpedos doors etc ) :
C:\Ubisoft\Silent Hunter 5\data\Submarine\NSS_Uboat7c\Submarine Parts\Room_EXT - Snorkle + Anim.gr2
i think we need to add a Ext_object dial in sensors.sim ( idem as periscopes ? )