sub detection range of surface ships

[Yokes]

I have been really surprised by the poor range at with submarines detect surface contacts.

Here's a small example scenario where on old US diesel sub (Barbel class) has a convoy of 25 ships (with 10 noisy merchants) passing virtually overhead. The sub is creeping at shallow depth. Despite the 10 merchants travelling at 18 knots (cavitating) the sub does not hear them until they are within 1 NM. This does not seem right. I am not a sonar expert, but my best educated guess is that even a sub of this vintage should be able to hear 10 cavitating merchants at much longer range than 1 NM. (10 NM? 20 NM? 100 NM? I have no idea what the right answer is. I just feel confident that it's more than 1 NM.)

Another peculiar thing with this example is that the sub detects with its hull-mounted sonar (AN/BQH-2D) and not its towed sonar (AN/BLQ-2B). Is the towed sonar not working?

I plan on trying this with more submarines to see if it is just this sub.

Yokes

[Yokes]

Here's version 2 with a Victor III sub. This time it detects the first ship (a frigate) at about 8 NM.

I am surprised that it hears the frigate before the merchants. I would expect the merchants to be much noisier.

Also, the sub detects the ship using its hull-mounted sonar (Shark Gill) and not its towed sonar (Shark Tail). I'm starting to see a pattern...

Yokes

[Yokes]

Part 3: a Virginia class sub.

Detects immediately at about 14 miles.

However, it detects using its hull-mounted sonar (AN/BQQ-10) and not its towed sonar array.

Are towed sonar arrays working?

Yokes

[mikmykWS]

Ok TAS doesn't seem to be broke. I was able to get detections when the TAS was facing them although that geographic area is tough and shallow in many places. You've also got rain. If you move the engagement to deeper water I was able to get a TAS detection at 14nm with the old array.

I'll ping D on this to take a look though just in case.

Mike

[scouseern]

Hi,

As a Royal Navy Submariner of 17 years experience i can tell you that your ranges on hull sonars are roughly correct. However as Yokes states most noisy MV and Warships will be picked up by Towed array BB (Broadband) before this. However the resulting contacts will be ambigious, i.e. on both sides of the sub, due to the way a towed array works. resolving which side the contact is on involves manouvering the submarine.

Best detection on a towed array is achieved when the contact on the beam. so a sub pointing a contact will NOT gain it on the Towed Array as it will be outside the Arrays arcs of coverage.

Similarly a contact astern of the sub i.e in the after 60 degrees, will not be detected by a bow mounted sonar system. its in the 'Stern Arcs' Hence the stern arc clearance procedures practiced by submarines everywhere (Crazy Ivan etc)

If i can be of any help on sub issues feel free to message me, if i can help and its not classified, its no problem.

[Dimitris]

Hello,

Is this currently (v1.04) a problem?