Question about radar
 

Ok, i'm playing RSRDC with no other extra mods and it's 1942 July and HQ has finally given me the permission to purchase the Surface Radar. Sweet! Now I can track ships on surface without going to periscope depth for a sonar check. But can the japanese track me if I have it turned on all the time with some kind of radar detection system (I have no idea how the naval radar worked IRL)? Or should I just use it periodically and turn it off all the time?
Thanks in advance! :)

I think in the early and middle of war, it's safe to turn on the radar.
I'm not sure is there any anti-radar equipment for japs later, but after August 1943, you can buy the "Radar warning receiver" for you sub, so you won't be caught by Japanese radar easily. Don't worry too much. :)

Run the thing! It tells you the position, course and speed of everything out there and the only piece of information you give them is that you're out there somewhere. Granted, sometimes you won't want that known, but once detected, radar's advantages vastly outweigh the disadvantages.

Are you still running an S-18 class boat? That's the only one I know of that has to submerge before it's hydrophones start working.

If he's running RSRDC, there is a bug in it that only allows the hydrophones to work when a sub is submerged. They won't work when surfaced.

As for the OP's original question; sometime in 1944 the Japanese do get radar detection capabilities.

Remember, if the enemy can detect your radar, you don't appear as a blip on a screen somewhere saying "the party is here!"

They only know that they detect a radar signal from somewhere. In the war, this often prodded the enemy into making unwarranted assumptions and doing something stupid as a result.

In his encounter with the Shinano, Commander Enright ignored all the crap about being careful about running radar. He ran the thing continuously throughout his action. Admiral Abe of the Shinano detected the radar signal, decided that meant a whole wolfpack was after him and changed his battleplan entirely.

He changed his course from one that would completely eliminate Archerfish's chance to take a single shot, slowed down and altered course directly across Enright's sights. Boom! (repeat as necessary). Scratch the biggest single target of the war.

Why? The pressure of detecting a radar signal worked decisively in Enright's favor. He knew Shinano's exact course and speed. Shinano knew there was a freakin wolfpack out there or they wouldn't be running their radar conrinuously.

Radar detectors were no help to the Japanese navy.

That may have been the way things were in real life, but in the game, not so much. DDs would always head right for me when they detected my radar.

Really? That sucks.