I have read somewhere of a couple of skippers mentioning being able to find convoys because the escorts were constantly pinging. Also, pinging was used to take soundings to find the bottom in potential shoals areas. No one at the time had all-inclusive, reliable charts of the Pacific. If I remember correctly, the type of sonar used is the determining factor for the pinging - if I'm not mistaken (the odds are against me
)... but the numbers escape...