Summary Technical Report of Division 6, NDRC. Volume 6B. Methods of Submarine Buoyancy Control

The primary aim of this volume is to clarify the problems encountered in diving a submarine. In the early days of submarine operation, the ballast adjustments were made mainly by feel and accumulated experience. Gradually diving officers came to realize that relatively large changes in the density of the water with depth would sometimes be encountered. Lacking contact with oceanography, however, they did not suppose that such conditions were predictable or could in any way be charted. The possibility of encountering unexpectedly marked density changes made it advisable to be somewhat cautious in diving through a considerable depth range. Once it was realized that the distribution of temperature and salinity in the sea directly affected submarine diving operations, measurements of the effects and the charting of the available oceanographic data in a form convenient to the diving officer were undertaken. During the war period most of the studies of the performance of submerged submarines and of the compressibility of their hulls had to be carried out during the course of training activities. The precision and completeness of the data presented in this volume therefore, leave much to be desired. Diving officers have found, however, that even rough measurements and a general understanding of the factors influencing the distribution of density in the sea can be helpful.