A lot of Navy binoculars were model B&L 7 x 50. But there were also smaller 6 x 30 B&L model bino's for the Navy, most of them without reticle, like this MK XXIX mod. 0 (only built in 1942 ). I don't think it was waterproof. There are only 2 screws in the cover plates. To make it waterproof, one should redesign the cover plates to provide for the use of a synthetic rubber gasket and a greater number of fastening screws. Also a good wax for sealing the objective lens and objective assembly is necessary.