Spawning distance?

[Shkval]

Well during my current patrol I run into modern tanker, I do have a habit of personally doing regular sound checks every 32-33 km during the night, and every hour during a day... and guess what? She was not there... and my perfectly rested WO and watch crew did not saw her until she was 4,5 km away... how this can happen... I'm not talking about some fishing boat... it's a bloody 150 m long TANKER? Of course weather is perfect... clear sky, lots of stars, sea calm as oil, no fog... shouldn't they be able to see her at 7.5 to 9 km?
So my question is what is the spawning distance in relation to my sub, i.e. does contacts always spawn beyond horizon? Or I can expect a guns-blazing destroyer at 2-3 km?
Something crossed my mind right now... could this be a bug in weather system...i.e. computer "thinks" that he had activated bad weather routine... little bit foggy... little bit rainy and reduces capabilities of my watch crew, but in fact weather is still fine?

[Soviet Creeper]

Sometimes stuff like that happens, I think the only way a ship can spawn close too you is if it is scripted, like a convoy. One time I was raiding a port, a convoy spawned outside of it and before I knew it I had 2 DDs depth charging me in shallows. It didnt end well.

[Gargamel]

Aside from the above me ruined spawns, I believe everything is already spawned upon your load. Hence the insane load times. So if you were close to a spawn point then it could have spawned. But most likely, it was already there and your crew just never saw it. Please correct me if I'm Aron on this though.

[Kptlt. Siegmann]

Ships will never "spawn" within 30-50km (I forgot the exact limit, it's somewhere in that range though) of your location, scripted event or random. Your crew simply just didn't see the ship for whatever reason. Bernard must've flipped the lenses on your watch crew's binoculars :har:

[runio]

She was not there... and my perfectly rested WO and watch crew did not saw her until she was 4,5 km away... how this can happen...
It happens when you use TC>128.

[Mittelwaechter]

All contacts "spawn" (start to exist in your game world, affecting your sensors and/or your video card) between the range of your "atmosphere" (stock 8 km/modded 16km radius) and the outer rim of your world (~ 30 km radius).
The game itself checks this "ring of existence" within a set parameter of intervals - but influenced by your TC settings. Slow contacts like ships (or stationary contacts like harbours) will never fail to spawn at or near the outer rim, because the check up routine is fast enough at any TC setting to catch the object within this "ring of existence". A problem are the flyboys. They are much faster at i.e. 250 knots and may "jump into your atmosphere" between the check up sequences at higher TC settings. They won't spawn because they would pop up out of nowhere above your U-Boot. No contacts spawn within your atmosphere but only "beyond horizon".
Some points to remember: there is only minor visual difference between the first two sight conditions of 100% and ~66% visibility - and they switch in a few seconds. Your "perfect"weather report may be outdated within a minute. The first hydrophone model has a second deaf zone at around 350° to 10°. You don't get a report of your hydro operator for contacts within visual range, if the periscope is up for a few centimeters and you should be able to identify them yourself. Not sure about this, but if you fail to detect a rather close contact, your scope is "a bit up" so your hydro operator denies to report too - and now you surface - your watch crew may start to report the contact only at the next visual range step at ~25%.
It's a few months I played the game and I can't remember right now: do we get a "Ship spotted" if we surface to attack an already observed contact?

[Shkval]

All contacts "spawn" (start to exist in your game world, affecting your sensors and/or your video card) between the range of your "atmosphere" (stock 8 km/modded 16km radius) and the outer rim of your world (~ 30 km radius).
The game itself checks this "ring of existence" within a set parameter of intervals - but influenced by your TC settings. Slow contacts like ships (or stationary contacts like harbours) will never fail to spawn at or near the outer rim, because the check up routine is fast enough at any TC setting to catch the object within this "ring of existence". A problem are the flyboys. They are much faster at i.e. 250 knots and may "jump into your atmosphere" between the check up sequences at higher TC settings. They won't spawn because they would pop up out of nowhere above your U-Boot. No contacts spawn within your atmosphere but only "beyond horizon".
Some points to remember: there is only minor visual difference between the first two sight conditions of 100% and ~66% visibility - and they switch in a few seconds. Your "perfect"weather report may be outdated within a minute. The first hydrophone model has a second deaf zone at around 350° to 10°. You don't get a report of your hydro operator for contacts within visual range, if the periscope is up for a few centimeters and you should be able to identify them yourself. Not sure about this, but if you fail to detect a rather close contact, your scope is "a bit up" so your hydro operator denies to report too - and now you surface - your watch crew may start to report the contact only at the next visual range step at ~25%.
It's a few months I played the game and I can't remember right now: do we get a "Ship spotted" if we surface to attack an already observed contact?
Well my TC was 256 but how a 5 knot fast tanker came so close? This theory about "stepping on" spawning point looks logical to me... because later everything else at the same TC "appeared" correctly at proper distances...I don't know...