I suspect that you're being a bit harsh on SwissSubCommander.
Passive hydrophones on escorts were rare until very late in the War and the problems of self-noise and signal interpretation were both works in progress and nowhere near to being even vestigially solved. The British had worked ahead on the problem because thanks to the fixed array of hydrophones that were placed in the Channel near Dover in 1917 but they generally only managed to detect surfaced U-Boats running the Dover Patrol's gauntlet.
ASDIC would not appear for trials before 1919 and it was into the 1920's before the first destroyer was so equipped. Then it took several years of trial and error to develop the skills and the tactics and to train instructors to run the operator training courses.
Most WW1 submarines were sunk by gunfire and or ramming but the biggest killer was mines. Depth charges were large and few in number, at least at first, during the summer of 1917. However, submarines were quite fragile, had poor underwater endurance and limited battery power. With few exceptions, the obvious one being the Royal Navy's
R-Class boats, subs and U-Boats lacked hydrophones so unless the captain risked raising the periscope, he was as blind as the hunters.
Most submarine and U-Boat classes were slow to dive, which made them vulnerable to being surprised, particularly at night and in bad weather. Because antenna theory was still in its infancy, virtually all installations had a transmitting and separate receiving antenna, which required stowing before the boat could dive and this took time. Failure to do so would usually render the wireless useless and that usually aborted the patrol.
Being a submariner in any navy during WW1 was a dangerous business.
The Battle of May Island
-C