RE: Fundamental ASW Lessons from Basic Training: Warshi... - 2/20/2018 4:18:19 PM Primarchx





Posts: 3083

Joined: 1/20/2013

Status: offline quote:





"Checking Stockdale, I see that the change in Passive Sonar signatures is just +0.5-1dB by changing the aspect"



Where do we find this info? (the change in Passive signatures)



Does it update vs whatever contact we have selected, as we maneuver the ship? or is it in the ship database as various dB statistics per database listing?



It's in the signatures section of the platform's Data Base entry, spread out between Front, Side and Rear. I see these as baseline figures that are adjusted by environmental and performance changes. As far as I can tell they are static figures in the DB.



quote:



Also, is there any way to tell how loud the ship that you’re currently maneuvering in dB's is, helping to determine if you’ve been detected by the sub? or if you’re in a sub, if you’ve been detected by enemy combatants?



I wish! It's been something I've asked for in the past, as well as rating how 'strong' the incoming passive datum is. Without that info you really just have to make educated guesses and stick to SOPs when it comes to this ... see my Sub Ops - The Thin Blue Line post about those (http://www.matrixgames.com/forums/tm.asp?m=3876405.



If you're driving a sub and make a passive contact to another sub you really have few cues as to whether or where they might also see you. So in most cases the first thing you do is slow to Creep speed to reduce your noise and hopefully sharpen your passive sensors. Then you want to stay as far away and at as low a speed as you can but also work in a way that you can improve your contact info.



A few tricks here are that you can usually determine a CZ contact from a closer, direct-path contact since a CZ contact usually originates at the inner edge of a CZ and radiates away from there. You will probably NOT get a very localized position from a CZ contact except that it originates in one of CZ rings, though it's significantly more likely to be in the first CZ than subsequent ones. I'll often drop a pair of RPs as a guide along the bearing line beginning at the edge of the first CZ and ending at the outer edge.



Next discover what sensors are holding the contact. Recognize that a VDS or towed array is always deployed BELOW the Layer. Flank and bow arrays are of course in the same depth location as your sub. As you hold the contact move slowly between the various depths and see if the contact is improved or lost/gained by your passive sensors (and if so, which ones are doing what). In my experience this includes moving from Above the Layer to Shallow depth (if they are significantly different) as I've found contact on Shallow targets has improved even when my sub is Above the Layer. Making these depth changes may assist you in determining what depth your target is lurking with an educated guess.



So now let's assume an unidentified sub with no other available info than it's bearing and contacting sensor (TASS) has been spotted, with an uncertainty area that begins at the edge of your first CZ and spiking out from there. You can make two basic initial assumptions - it's somewhere in the first CZ and it's below the layer. You reduce speed, lay initial RPs to show the initial contact bearing and alter course in the contact's direction and begin to alter depth, but only maintain contact with the TASS. You notice aspect changes as you move towards it, indicating movement across your bow in one direction or another. Your data on the contact may improve (type, class, speed, bearing, depth), if you're lucky.



If it's truly a CZ contact your sensors will very likely lose the contact once it falls out of the CZ. This is probably a time for a dash to close distance, since CZs are usually the same distance and width for all passive sensors that can utilize them. This can be complex but I typically dash at the shallowest depth I can to avoid cavitation. This is because hull sensors have less range than towed arrays (which we know lurk below the Layer). Estimate a location you think you would reacquire the target and then move as fast as you prudently can to get there. Be sure to do a quick ESM sweep before dashing, just make sure no MPA are around dropping sonobuoys.



Let's say you make it to your dash destination with no incident. Slow back down to Creep, check the surface for ESM and then slowly move between the depths, to see if you can reestablish contact. It may take a little while, or not happen at all, depending on the target's course and speed. But let's assume you soon do pick up the contact. This time it's your bow sonar while above the Layer and the spike ends before the first CZ. You're close! But are you too close?



Now it's time to refine your data, maintaining the contact but keeping your distance. Dip into the Layer a bit and see where/if you lose the contact. This will help you determine how strong the contact is. If you lose it as soon as you go into the layer, odds are good it's not very close and if you maintain the contact with the bow sonar even on the other side of the Layer, it's gonna be close. Using Command's TMA and doing a bit of your own you can try to slip behind the target and get out of their bow sensor arc. Be aware that if you let a faster target do this you may have to dash to get into weapon parameters which could expose you to another enemy.



Once you've formed up the target's info you're ready to begin engagement. But that's another story!



< Message edited by Primarchx -- 2/20/2018 4:22:43 PM >

(in reply to BrianinMinnie Post #: 7