Sonar is not a one-way observation.
Sonar helps you find the opponent’s direction and distance band, but it also tells them which sector you transmitted from. From their perspective, your search is new evidence that you were in that sector.
If only a few possible enemy positions remain and lining up a shot is your priority, moving may make more sense than scanning again. Conversely, a new sonar reading becomes more valuable when your information is old and you do not know which way to go.
A record describes the past, not the present.
Suppose a reading shows a contact to the northeast. It describes the moment of observation. If your opponent has had a chance to move since then, they may no longer be in the same place.
Instead of settling on a single cell, consider the places the enemy could have reached from the previous possibilities. They cannot move into an island, so use the map to refine those possibilities. Update your candidates when new records arrive rather than clinging to an old hypothesis.
Islands offer cover and impose limits.
Islands stop torpedoes, but sonar can detect enemies beyond them. A contact on the other side of an island does not necessarily give you an immediate shot. You may need to move around it to open a line of fire or predict where the opponent will emerge.
When using an island as cover, remember that it also limits your routes. A position that is hard to hit is not always one that is easy to move out of later.
A decision note for uncertain moments
Unknown: whether the opponent moved afterward.
Next question: are they in a position with a clear line of fire?
Separating facts from guesses can help reduce shots with little evidence behind them. Whether you scan, move, or attack, think about which uncertainty you want that action to address.