Stationary targets showing up on passive sonar

nomad_delta · 06-12-07, 03:32 AM

How is it possible that my sonar man gives me contacts like this:

"14:42 SO Sound contact, sir! Merchant Stationary Closing! Bearing 356! Long range!"

If the merchant is stationary, how can it be "closing" (I was moving 0 knots at the time), and more importantly -- how can the sonar man hear it if it's not moving at all? I went to the hydrophones myself and listened in that direction, and sure enough a bunch of 'Unknown' targets appear when I point the hydrophones in that direction -- but no sound, of course!

Is this yet another bug or is there something obvious that I'm missing?

nomad_delta

DeerHunter UK · 06-12-07, 04:26 AM

The merchant could be drifting on the current and therefore moving. As to hearing the merchant through the hydrophones, I can only imagine that although "stationary" the engines may be running. But of course if that were true and your AI sonar could hear that then you should be able to aswell.

greyrider · 06-12-07, 06:49 AM

deerhunter is right, it will drift with the current and move very slowly, but what your sonarman hears more than anything with
a stationary target is the water slapping against the hull, the waves.

also auxcillary motor equipment like pumps and draining, maybe toilets flushing too,
all i know is that we cant hear it. thats what writes the name of the target in the sonar notepad as unknown,merchant, or warship.

Quillan · 06-12-07, 09:55 AM

"Stationary" in the game does not mean non-moving. It actually means "speed is less than 0.5 knots" or some such amount. "Closing" just means the ship's bow is closer to you than its stern. And if the ship is truly stationary due to damage they still can make noise. Listen in on the hydrophones sometimes, there's rattling and flooding sounds that can be picked up. It should say "constant distance" instead of closing, though. ~

SteamWake · 06-12-07, 10:06 AM

Theres alot more sounds comming from a ship than the screw churning in the water.

Bilge pumps, generators, even ventilation equipment. A ship doesent have to be moving to make noise.

Closing is a relative since this is a simulation if you are drifting and 1/4th of a knot towards your target it will be considered closing.

What I really wonder about is why do life rafts show up on sonar ? You cant 'hear' them.... Ive tried yet they will show up on the map.

Also whats with the "ship spotted" when a sinking ship or for that matter crashing airplane pops a 'survivor'.

06-12-07, 03:32 AM	#1
nomad_delta Planesman Join Date: May 2007 Location: San Francisco, California Posts: 185 Downloads: 1 Uploads: 0	Stationary targets showing up on passive sonar How is it possible that my sonar man gives me contacts like this: "14:42 SO Sound contact, sir! Merchant Stationary Closing! Bearing 356! Long range!" If the merchant is stationary, how can it be "closing" (I was moving 0 knots at the time), and more importantly -- how can the sonar man hear it if it's not moving at all? I went to the hydrophones myself and listened in that direction, and sure enough a bunch of 'Unknown' targets appear when I point the hydrophones in that direction -- but no sound, of course! Is this yet another bug or is there something obvious that I'm missing? nomad_delta

06-12-07, 09:55 AM	#4
Quillan Samurai Navy Join Date: Apr 2005 Posts: 579 Downloads: 2 Uploads: 0	"Stationary" in the game does not mean non-moving. It actually means "speed is less than 0.5 knots" or some such amount. "Closing" just means the ship's bow is closer to you than its stern. And if the ship is truly stationary due to damage they still can make noise. Listen in on the hydrophones sometimes, there's rattling and flooding sounds that can be picked up. It should say "constant distance" instead of closing, though. ~ __________________ We, the unwilling, led by the unknowing, are doing the impossible for the ungrateful. We have done so much, for so long, with so little, that we are now qualified to do anything with nothing.

06-12-07, 04:26 AM	#2
DeerHunter UK Machinist's Mate Join Date: Mar 2000 Posts: 124 Downloads: 56 Uploads: 0	The merchant could be drifting on the current and therefore moving. As to hearing the merchant through the hydrophones, I can only imagine that although "stationary" the engines may be running. But of course if that were true and your AI sonar could hear that then you should be able to aswell.

06-12-07, 06:49 AM	#3
greyrider Watch Officer Join Date: Apr 2005 Location: massachusetts Posts: 334 Downloads: 237 Uploads: 0	deerhunter is right, it will drift with the current and move very slowly, but what your sonarman hears more than anything with a stationary target is the water slapping against the hull, the waves. also auxcillary motor equipment like pumps and draining, maybe toilets flushing too, all i know is that we cant hear it. thats what writes the name of the target in the sonar notepad as unknown,merchant, or warship.

06-12-07, 10:06 AM	#5
SteamWake Rear Admiral Join Date: Mar 2005 Posts: 13,224 Downloads: 5 Uploads: 0	Theres alot more sounds comming from a ship than the screw churning in the water. Bilge pumps, generators, even ventilation equipment. A ship doesent have to be moving to make noise. Closing is a relative since this is a simulation if you are drifting and 1/4th of a knot towards your target it will be considered closing. What I really wonder about is why do life rafts show up on sonar ? You cant 'hear' them.... Ive tried yet they will show up on the map. Also whats with the "ship spotted" when a sinking ship or for that matter crashing airplane pops a 'survivor'.