Originally printed in 1946, The Fleet Type Submarine series of technical manuals remains
unparalleled. Contained in its pages and those of the companion texts are descriptions of every
operating component aboard a fleet boat. Underwater Log Systems Navpers 16168, acquainted crewmen with the subÕs positioning and tracking systems. Since subs operate below the surface, the normal means of establishing position at sea -- such as sighting the sun in the day or the stars at night -- are impossible. Yet, knowing the subÕs position and speed is vital both for navigation and combat. In an era before GPS, the log system allowed an accurate track to be made of the boatÕs position, and enabled calculation of the speed of target vessels. This book explains in detail the theory, operation, calibration and maintenance of various log systems. Originally ÒRestrictedÓ, this book was recently declassified and is here reprinted in book form. Care has been taken to preserve the integrity of the text.