Water noise rising around the hull could overwhelm a good contact above roughly 18 knots, and rolling or pitching in heavy weather caused similar problems. Operators swept an arc and paused at intervals so the relatively slow sound wave could return. Those pauses consumed time and left gaps in the underwater picture even under favourable conditions. An escort could not simply race at a submarine and expect its sensor to keep working perfectly.
Notable Point · 21:47-23:36
Why ASDIC struggled at high speed and in heavy weather
ASDIC contacts became difficult above about 18 knots or in bad weather, making the search pattern and operating environment critical.