Submarine Cable. Telegraphic or telephonic cable laid on sea bed.
Submarine Escort. War vessel that remains in a sea area in which submarines are exercising in peacetime. Its duty is to see that passing ships keep clear of the area.
Submarine Sentry.*Wooden hydroplane, or 'kite', formerly used for indicating when a vessel entered water with less than a specified depth. While vessel was making way-at a specified speed-the kite kept to the specified depth. If vessel went into water less than the specified depth a projection below the kite struck the ground and caused the kite to surface. Change in lead of wire usually operated an alarm bell.