detection distance

[jgf]

I realize many things factor into this, but as a rule of thumb how close does a destroyer have to be to hear my sub? And at what depth is the sub visible from the air?

(FWIW I spent ages with SH1 and loved it. Found SH4 visually impressive but ultimately irritating and monotonous. Now trying SH3.)

[RConch]

For question 1-it depends on how quiet are you and how experienced is the destroyer(s). Early war, you have a better chance of not being detected if you are deep and silent running and changing course. Later in the war it is easier for them to find you with better equipment. At that point, evasion and depth may protect you. More destroyers and less chance you will have without "Bolds". Sometimes it just comes down to luck.

Question 2- depends on where you are-Atlantic or the Med. The water clarity in the Med was much clearer, cleaner that the Atlantic. Also depends on the skill of the aircrew and how fast and how deep you crash dive. Personally I don't cruise underwater at periscope depth unless I am hunting a known target.

I am sure others have their own theories, and look forward to their comments.

[UKönig]

In answer to your 2nd question, being detected visually from the air while you are at depth does vary with water clarity and weather, but can go down to about 200 feet, and would look like a shadow in the water. Once you get past 500 feet, light doesn't get down anymore and it's pretty dark all the way around.