The key words must be "all but." Unlike our game, they had selective listening abilities, from the lower end of the listening range to the supersonic. Therefore, contacts could be developed on the surface and they were expected to be so. The Sonar Operator's Manual makes it clear that the sonar operator is expected to stay on duty while surfaced until ordered to stand down.
In addition, the range of filters, not available in the game, made this possible. Own ship sounds were lower frequencies, listened to by selecting the bass boost filter. To filter out own ship sounds, filters above 500 cps were used. (no Hertz back then, it was cycles per second). There were two filters available for frequencies above that, even, so it is clear that sonic sonar was useful when surfaced. Supersonic sonar would not have cared much about ownship noises at all.
Here's the illustration in the sonar manual about using filters with normal sonic passive sonar.
From the manual:
Quote:
Filters can define and narrow the target
Propeller noise is made up of all frequencies. But background noise, from the water and the submarine, is mostly low-frequency sounds. Therefore, by operating with a high-frequency filter you can get rid of the background noise, yet still hear the screws.
|
BUT, in my search of all reported surface contacts developed by all submarines during the war, I did not find a single instance where the FIRST contact was made through sonar. Obviously visual and radar was superior there, but after contact was made, oftentimes sonar was put to use, even on the surface.
Sonar is one of Silent Hunter's weaknesses, with plenty of room for more realism and detail. There were three main sonar arrays, with filters and amplifiers for each, none of which is modeled. This could be a fascinating addition to future sub sims. Unfortunately, it looks like SH5 ain't it.