Almost all Japanese ships did not have sonar. With the engine noise vibrating the entire ship like a bell, there's no chance the crew would hear a submarine's sonar ping.
Even if they could hear the ping, what's the score? The ship would know there's a sub out there somewhere. The sub knows the location, speed and heading of the ship. That's a fair trade!
Sometimes when things aren't going your way, the thing to do is to introduce a little chaos to the mix and see what happens. Commander Enright of the Archerfish, stalking a bunch of DDs and the carrier Shinano, elected to run his radar in the face of certain knowledge that the Japanese could detect his radar.
Again, let's keep score here. It's Japanese 1, they know there's a sub out there somewhere, against Submarine 5++, they know the position, speed and heading of every Japanese ship. They know instantly when they change course and speed and what the new numbers are.
But most importantly, the chaos introduced with the clear radar signal was this: why would a submarine fully exposed to several DDs stay on the surface and run his radar for all to hear? Could it be because he was coordinating a wolfpack stalking their new carrier? That must be it! They're out there waiting. Time to stop the fast direct run to shelter and institute a slower zig-zag to foil all those subs.
Had they kept to their 30 knot blitz to shelter, Archerfish could never have fired a single torpedo. At best they could have radioed a position and heading, then left the area for other targets. Instead, the Japanese admiral slowed and zigged.....directly in front of Archerfish.
Boom, boom, boom, boom, glug, glug, glug. Draw your own conclusions!
