Abstract: A submarine periscope system has a mast head 7 with a casing 10 from which protrudes a shaft 16 carrying observation instruments which are protected by a housing 8. A seal arrangement 30 is provided at the interface between the casing 10 and shaft 16 which imposes low friction torque at water pressures within the operational depth range of the periscope system and permits the shaft 16 to rotate for azimuthal movement of the observation instruments. A rotary drive 14 is connected to the shaft 16 for this purpose. The seal arrangement 30 imposes high friction torque at water pressures outside the operational depth range of the periscope system and a water depth pressure valve disables the shaft rotary drive to provide integrity of the seal arrangement outside the operational depth range. The mast head 7 is telescopically extendable by a hoist device 13 and does not penetrate the hull 2 of the submarine 3.

Abstract: A submarine periscope of the non-hull penetrating type has an extendable hoist (11) secured at one end to the submarine hull (2) and at its other end carries a sensor pod (8). Pod (8) is rotatable by a motor (13) carried by the hoist (11) and is electrically connected to sensory signal output devices (34,35) inside the hull (2) by a flexible cable (24) penetrating hull (2) at a gland (21) to which is fitted a rotatable signal transmission device (19). Cable (24) terminates at slip rings (32) secured to the transmission device (19) inside the hull (2). The transmission device (19) is rotatable by a motor (29) and motors (13,29) are both controlled by a controller (30) arranged to provide for synchronous rotation of pod (8) and device (19).