I saw a 6 x 42 collection ( owner now RIP ) which were similar to the handheld version, but which were heavier, no plastic, adapted for fixed, or semi- fixed mounted use on what I guessed were the Martin Mars and similar flying boats, for antisubmarine patrols in the Atlantic. The idea was to see U-Boot wakes at night, when they were running on the surface to charge their batteries. Maybe they were used on the PBY also. I once had a similar 6 x 42, fixed focus, made in Pasadena, for mounting in the nose of the P-61 Black Widow night fighter
A PBY was my first airplane ride, from Oakland, Calif. to Newport, Oregon, prior to employment as a summer job crewmember for in-port maintenance on two week duration shifts. One of the pilots let me ride in the right cockpit seat. Noisy. The boats were basically Gulf Coast shrimpers adapted for explosive seismic oil exploration by a Shell Oil subsidiary. I served one two week offshore stint when one of the regular crew was absent. There are many albatrosses off the Oregon and Washington coasts, if one watches from perhaps 20 or 30 miles offshore. I fed kitchen scraps to them. We saw a large sunfish one day, but never any whales or dolphins.
Once, the geologists set off a charge too close to the boat. I was in my bunk. It was as though someone was beating the hull with a sledgehammer. Similar to a U_Boot under depth charge attack, I suppose. The Norwegian captain was angry . " That was too close".
About the "over the hump" anecdote, above. A longtime family friend, a biologist colleague of my father, was at Myitkina in Burma as a radio controller for the flights to Kunming. He hitched a ride once, thru a pass below some peaks. I do not know if the C-47 - DC-3 were supercharged. His brother , a B-17 pilot, was killed in a raid upon a synthetic fuel plant,not far from Jena , IIRC , in late 1944.
My father was a Lt. JG. in malaria control at Samar, and later at Tsingtao.