Hans Uberman

I don't find it to be an entire waste of renown depending on the type of radar and where you do your patrols. Whenever it's night, and I'm patrolling near enough to land that Hawker Hurricanes, or similar non-radar equipped craft can get at me, I find it helpful. You can't detect their radar emissions, as they have none, and your crew can't always see them coming in time. The rotating radar types with enough range have helped somewhat with this problem. (Remember that radar is supposed to detect aircraft at much greater distances than surface objects.) Not that it comes up often, but if I don't have a snorkel and need recharging, it's there. Other than this, I rarely use the thing.