How does a passive sonar (WWII) estimate the distance to target

vimza · 06-09-16, 02:39 AM

Is it possible for a hydrophone operator (no active sonar) to judge the distance to a surface ship and if it is closing or going away?

I understand how he gets the bearing and the speed of the target but i'm not sure about the distance. How much detail can he get on a WWII U-boat.

ETR3(SS) · 06-09-16, 04:58 AM

If you can get bearing and a reliable speed, you can calculate range based on bearing rate. To get a reliable speed estimate you would have to know how many turns of the shaft per knot of speed for the contact.

As far as determining if a contact is opening or closing, that would be based off of noise of the contact. Quieter opening, louder closing.

All this only gives an estimation though and you would still need visual observations on the target to obtain a firing solution.

06-09-16, 02:39 AM	#1
vimza Seaman Join Date: Aug 2013 Posts: 32 Downloads: 0 Uploads: 0	How does a passive sonar (WWII) estimate the distance to target Is it possible for a hydrophone operator (no active sonar) to judge the distance to a surface ship and if it is closing or going away? I understand how he gets the bearing and the speed of the target but i'm not sure about the distance. How much detail can he get on a WWII U-boat.

06-09-16, 04:58 AM	#2
ETR3(SS) Ocean Warrior Join Date: Dec 2007 Location: Between test depth and periscope depth Posts: 3,021 Downloads: 175 Uploads: 16	If you can get bearing and a reliable speed, you can calculate range based on bearing rate. To get a reliable speed estimate you would have to know how many turns of the shaft per knot of speed for the contact. As far as determining if a contact is opening or closing, that would be based off of noise of the contact. Quieter opening, louder closing. All this only gives an estimation though and you would still need visual observations on the target to obtain a firing solution. __________________ USS Kentucky SSBN 737 (G) Comms Div 2003-2006 Qualified 19 November 03 Yes I was really on a submarine.