Active Sonar

[Nisgeis]

S-27 and S-28 had JK/QC Sonar, which was both passive supersonic and active supersonic sonar. QB (supersonic projector) was in production before the war started, but I think they were steered towards new contruction. I'm not sure about NM sonar (depth fiding) on the S-boats, but the S-boats were used as guniea pigs for testing new equipment, so you'd be surprised what some of them had. JP was passive and a late introduction, coming in after SJ radar.

[LukeFF]

Originally Posted by Nisgeis

S-27 and S-28 had JK/QC Sonar, which was both passive supersonic and active supersonic sonar. QB (supersonic projector) was in production before the war started, but I think they were steered towards new contruction. I'm not sure about NM sonar (depth fiding) on the S-boats, but the S-boats were used as guniea pigs for testing new equipment, so you'd be surprised what some of them had. JP was passive and a late introduction, coming in after SJ radar.

QB was known to be fitted to a number of S boats, depending on when they were modernized. S-18s started being refitted in late 1942, while S-42s started their refit process early in 1943.

As for TDCs, apparently S boats were fitted out with the older TDC Mk. 1s as they were taken off the fleet boats, so it's not entirely unreasonable to have a TDC on the S boats (though, early in the war, they shouldn't have any sort of TDC).

[LukeFF]

Originally Posted by Nisgeis

I'm not sure about NM sonar (depth fiding) on the S-boats, but the S-boats were used as guniea pigs for testing new equipment, so you'd be surprised what some of them had. JP was passive and a late introduction, coming in after SJ radar.

A number of S boat did receive fathometers, yes.