[perisher]

Without effective radar subs would remain submerged during daylight if the skipper thought that there was a probable threat from enemy aircraft. This would depend on the tactical situation and the proximity of enemy bases. Once reliable radar was installed subs would run on the surface in daylight and dive on a radar contact being made.

The sonar only attack was employed because the Americans, at first, over estimated the Japanese ASW capability. They thought that a periscope would almost always be spotted and that once the scope was sighted a D/C attack would be inevitable and probably fatal.