What is somewhat typical of the USN DeutscheQuality, especially in light of the pre-war training they had, was there was a directive issued that the boats were to stay submerged during daylight hours whenever within 500nm of known enemy airfields, yet when they came back in from patrol were reprimanded for having spent too much time submerged... lol - I have not seen any "directive" or orders in the several books I have read that countermands that "stay submerged" directive, but there almost has to have been, since especially after Mush Morton and several others earlier in the war were able to roam farther, find more targets, and attack more often, that being mostly on the surface was encouraged. Similar happens later in the war when the boats were used in lifeguard duty and basically had to stay on the surface to receive reports of downed fliers. Getting a proper ID on a distant plane, especially at certain angles, or when they are flying out of the sun (a preferred aviator tactic) is quite difficult, and getting a FOF comm is not reliable, so the general course of action was to Crash Dive and ask questions later... but there was SCAP (Submarine Combat Air Patrol) provided quite frequently at times, which once established, would help in that regard, but throughout the war, being topside for a submarine was indeed hazardous. If you look at some of the radio messages your boat receives, there are some other "reality fillers" you will find. You could also follow SOP and do a daily Trim Dive (simulated, of course) and other Standard Operating Procedures the boats did.
