I'm not a code guru like many of you guys; I'm just commenting on the gameplay here.
I was just detected by a fishing trawler while approaching submerged, at dusk, at a distance of
3.8 nautical miles!
Whatever one's justification, this seems patently ridiculous.
I'm not saying it's impossible to approach; as noted elsewhere in this forum, it's relatively easy to approach a ship and sink it while using the scope briefly and intermittently. I just find it a real immersion-killer to have to worry about supernatural lookouts when the only thing I'm exposing is my periscope and the target is still a miniscule speck on the horizon.