Does anyone know what the most true to historic sonar range is?

[Noelly]

See I don't wanna cheat and looking to do the most realistic play through I can

Would that be

x1
x2
x3
or
x4 sonar range?

[Kraznova]

That is an entirely subjective answer depending on a user's skill level and how they use ASW assets. In general, start with x1, and then see if YOU feel like its appropriate.

[MizuYuuki]

The x1 setting for active sonar provides slightly over 1500 yds detection range under favorable conditions, and originally, if I'm remembering correctly, that was the only setting available in the game, although, there may have been an x2 setting. Historically, the range of some WW2 active sonar was up to 3000 yds or more. As I recall, the longer settings were added by an update after some players complained that it was too hard to find the enemy subs. However, the ambush distance for AI subs was reduced to 1500 yds sometime during the summer of 2021, and all AI initiated submarine encounters were made to be ambushes to help the AI score some torpedo hits. To my mind, if you increase the sonar range to more than 1x default value, it's going to be trivially easy to locate AI submarines that have attacked you unless the sea state is 5 or above. Also, the 1500 yd ambush distance has been relatively ineffective in giving the AI more torpedo hits because ships in the game are highly maneuverable.

So, what I've done is to use the 1x sonar setting, but adjust the ambush distance for AI subs to 3000 yds (which is the same as for the player) and disable "all sub encounters are ambushes" because otherwise it leads to a very non-historical frequency of sub attacks on fast moving task forces. To compensate the AI, I don't initiate evasive maneuvers by my ships until after the first torpedo hit. This matches how the AI plays when it is attacked by submarine launched torpedoes.

So, the resultant game play is that there are fewer sub attacks, but those attacks usually result in a hit for the AI, and the AI subs are harder to find because they are further away. To my mind, that's more historical than the way the game is currently set up.

[JAKeller]

The current default is x2 range. This is reasonable. Remember that this means that under perfect conditions (Sea State 1 and Clear Weather), the detection range is 3000 yds. All degradation percentages are based on that base number.

E.g. Detection Range (based on Sea State and Weather) = 64%

Detection Range = 1920 if you're being noisy (i.e. moving at full speed, turning hard, and presenting your side to the AI)

Layers (for subs): If above the layer depth, the duct strength acts as a multiplier (e.g. 1.5), in the case above, detection = 2880. Below the layer might be 74%, so detection = 1421.

A sub speed of 9kns yields full detection range to the AI. I've noticed detection seems linearly proportional to speed, so moving at 2kns means an additional 78% drop in detection range (assuming US subs). There is a minimum detection range of what looks like about 250-300 yds, so stopping completely will not make you invisible. Understanding detection ranges allows the player to make better submarine speed choices during an attack's evasion portion.

[MizuYuuki]

Excellent info JAKeller. I want add that passive sonar (hydrophone) will detect a sub which is in the acoustic duct at great distances (more than 10,000 yds and possibly much more than that) if the enemy is aware that a sub is in the area. The game plays as though passive sonar is not in use by the AI until a submarine has been detected by some other means such as torpedoing a ship, having the periscope spotted or surfacing. So, if a sub has torpedoed a ship, escaped the pursuing DDs by diving deep and waited until the DDs are far away, those DDs will immediately detect the sub and come after it if the sub returns to the duct depth or above.

[JAKeller]

Always make sure your surface radar is on for all ships capable fo using. I know it's a gamey thing, but subs with raised periscopes are more visible. Detection at 10k yds? Unlikely, unless you're in Sea State 1 or 2 under Clear skies with a strong (i.e. 2+) duct strength, AND the sub is going at full speed, and even then I'm not completely sure. I've never actually tested it, which is why I can't say it with 100% certainty. Frankly, without the ability to have a 2nd player in a scenario, I'm not really sure that scenario CAN be accurately tested.

I have noticed the newest version has given the AI subs a buff. They get to span in 1500 yds to the port or starboard (usually at 45º to the convoy's base course) and the torps seem to track a target right up to the moment they 'activate' (i.e. 500 yds from launch). It's like they're wire-guided for the first 500 yds. I used to accelerate my lead DD (the usual target) when I first began to see a torp launch i the distance. Given the closer spawn range and the apparent wire-guidance during the initial phase of a torp track by AI subs, this can make torpedo evasion a bit trickier. Use accordingly.

[MizuYuuki]

I just tested this in custom battle with an IJN type B sub and a USN Fletcher DD, sea state 2, layer at 166 ft, layer strength 0.66 and duct strength 2.2, and active sonar range of x1 (just to keep this from interfering with the test). After torpedoing a USN CA, the DD that was searching for my sub passed by the stern of it at 2,640 yds with the sub at -100 ft moving at 7 knots silent running and did not detect the sub. I then moved the sub out to a distance of 8,000 yds from the DD and brought the sub up to periscope depth (scope down), and the DD immediately detected my sub and set a course for it. I evaded by submerging, moved the sub out to a distance of 12,000 yds and slowed it to 2 knots. The DD was searching in a circle 12,000 yds away. When I brought the sub up to periscope depth the DD changed course toward my sub exactly when the sub reached periscope depth (scope down). The DD eventually caught up to the sub and sank it since I didn't try to get away.

So, I was wrong about the sub being detected by passive sonar (hydrophone) at great distance when in the Duct. It seems to be much more simplistic than that with periscope depth triggering detection. Although, I'll have to run this test in higher sea states to see if sea state is a factor. Subs do have something protruding above the surface when at periscope depth with the scope down. I don't know what that is.

[JAKeller]

Depending on the sea state, part of the conning tower though at sea state 2 probably not. Maybe as you say peri depth triggers possible detection via the duct strength. I'll have to start giving this some thought too. I'm in the middle of reverse engineering their land combat damage model, but that can wait a bit. (BTW, it's primarily a ratio based system. I've got the behavior mostly down; just need to work out all the modifiers)

[Noelly]

Thanks for all of the information guys It really helps! :3

[Skarwulf]

Another thing to remember is that your ships will negate their own sonar effectiveness if they're traveling too fast. I usually run my sonar-equipped boats at 16-18 knots to ensure high detection capability. Any faster and you will lose the track. Also, your ships will lose detection ability if the sub is in the baffles, meaning it's directly behind your ship. The noise of its own propellers will make a ship deaf to the rear.

[cswiger]

Originally posted by Skarwulf:

Another thing to remember is that your ships will negate their own sonar effectiveness if they're traveling too fast. I usually run my sonar-equipped boats at 16-18 knots to ensure high detection capability.

Sonar works best below 8 knots. Sonar is significantly impaired above 12 knots, and 16+ knots means you likely won't detect anything.

[JAKeller]

Originally posted by cswiger:

Originally posted by Skarwulf:

Another thing to remember is that your ships will negate their own sonar effectiveness if they're traveling too fast. I usually run my sonar-equipped boats at 16-18 knots to ensure high detection capability.

Sonar works best below 8 knots. Sonar is significantly impaired above 12 knots, and 16+ knots means you likely won't detect anything.

I never go above 10-12 kns when doing ASW. I'll backtrack the torpedos to their source (which is itself 500yds/m from the launch position of the submarine and rush there (typically at about 20kns) but slow to 10kns when I start searching.