cultural warship question.... ?

[Dread Knot]

Originally Posted by LCQ_SH

So I was thinking, why IJN didn't install sonar stations on big warships? Several times if have founded lonely warships and without an escort they would not possible know that I am there.....what's the catch in here?

Strange as it may seem, the Japanese carriers Shokaku and Zuikaku both had sonar equipment installed during their construction. Two types were installed, the Type 91 Mod Passive and the Type 97 hydrophones. However, I can't find any evidence that they were every used to detect or hunt a submarine.

That being said it comes down to an issue of speed. Sonar was generally ineffective at speeds over about 10 knots, requiring "sprint and drift" tactics in which the antisubmarine warship had to periodically slow almost to a stop to make best use of its sonar. A battleship, carrier, or cruiser creeping along at such slow speeds might be able to pick up a submarine, but by extension it's making itself the most beautiful target in the world. At those speeds and given their large size and draft, even the greenest sub skipper could quickly make the necessary torpedo solution and slam a couple of fish into it. An escort like a destroyer on the other hand could rely on it's shallow draft, and ability to accelerate quickly to get out of danger. For heavy warships the most effective ASW weapon they possessed, was an average speed of 20 to 30 knots. Historically, a sub had to be lucky and already in position ahead to even get a crack at them.

The reason that destroyers, destroyer escorts, frigates, corvettes and sub chasers made such ideal ASW craft was their large numbers, enabling them to work in groups. Shallow draft, maneuverability and high speed, making them difficult to hit, and expendability, they were relatively cheap and easy to produce compared to the heavier types.