TMA, no DEMON, no LOS switch

[NFunky]

No, the intersection I'm talking about is when a target changes from a lead to lag or vice versa his speed across the LOS is temporarily 0 so the next bearing line I get after the maneuver will cross the last one at close to the range of the target. I'm not describing it very well, but I can't remember the title of the old thread that details it. I'll try to dig it up.

I guess this is a little more scenario specific than I thought. So for the record, the scenario I've been playing with is in deep water with no fishing traffic, only long transit cargo and oil and maybe a yacht or something now and then. I'm driving an LA and my enemy could be an Akula II, Han, Xia or Delta IV.

I'm pretty sure the fishing boat and power boat are the only neutrals with the 50, 125 hz lines so I can classify my enemy as hostile sub as soon as I can see two tonals. My targets are usually either pretty far away or pretty quiet so I generally don't get broadband until way after PROBSUB classification. The scenario is easy when up agaist the Han or Xia and still not that hard against the Delta, but I start having a real hard time when its the Akula. I'm pretty sure the Akula is quiet enough that he'll have me on sonar at about the same time I have him and that's why I've started thinking about not giving him a solution by changing LOS.

I feel a bit foolish for forgetting about speed changes as neither of us has DEMON, it would be impossible for him to tell whether it was speed or course that changed. My biggest problem has when I start off tracking him in a lead LOS. Everyone knows you should track and fire from a lag LOS, but the moment I switch, I'll be giving my range away. I have had some luck just staying in a closing lead until he changes LOS, but the AI doesn't seem to care that much about lead vs. lag and often he doesn't change LOS for the entire dive. I know I probably don't have to worry about the the AI using the bearing-lines-crossing-at-range trick, but I'd like to play as if I was fighting a human player so I'll be more prepared for when I finally feel ready to play online.

BTW, are there any other TMA tricks that I should know about? This one has been such an education and has forced me to rethink sub combat tactics quite a bit.

[Dr.Sid]

That is neat trick you can apply on newbies. I explain it like this:

You have crossed LOBs .. target can either be moving in same or opposite direction. If it is moving in same direction, LOB intersection is its maximal possible range. If it is going in opposite direction, intersection is its minimal possible range. If the target is not going either way (like when making a zig), the intersection is exact range.

Still it needs good name .. what about zig trap ? Gee .. I hope bubbleheads will come with something better

[Molon Labe]

Originally Posted by NFunky

No, the intersection I'm talking about is when a target changes from a lead to lag or vice versa his speed across the LOS is temporarily 0 so the next bearing line I get after the maneuver will cross the last one at close to the range of the target .......... Everyone knows you should track and fire from a lag LOS, but the moment I switch, I'll be giving my range away.

Okay, that makes a lot more sense. I've actually never considered this before, so this is very interesting!

My take on what's going on is still a little different. It's not always the last bearing line before the switch that creates an intersection, when you've switched from lag to lead. Suppose during that time interval you stayed stationary in the LOS in the lead condition, producing parallel lines--no intersection. But if you go a few lines back to a position on your previous course, your net movement across the LOS will approach 0 or go negative for that interval and an intersection will be created somewhere beyond ownship. That's an overlead intersection--a maximum range.

So, I still see this in terms of the LOS switch creating a minimum and maximum possible range, it's just that the switch is being caused by a manuever in the other ship, but with the same result. The manuevering ship is putting itself at a bit of a disadvantage because it has less speed across the LOS over some interval, which tightens up the adversary's solution range.

I can think of two ways to try to mitigate this. First, if it's tactically feasible, approach the target from in front of or behind its course. This minimizes its speed across the LOS, so when yours drops off he doesn't have the speed to capitalize on it. The other way is to game the intervals. The closer you are in any interval to having no speed across the LOS, the tighter the solution range gets. So, try to be as far away from 0 during any 2-minute interval. That's not as complicated as it sounds, because it basically means driving your boat so that it's between your bearing lines on the even-numbered minutes.

Thanks for bringing this question up. TMA tactics just got a bit deeper and more interesting for me.

[goldorak]

In a contact dense environment use all the sensors, including periscope and esm. Try to do tma on surface contacts when you already have to care about possibile enemy subs is just overwhelming. Go to periscope depth and identifiy, classify and do tma on all visibile surface targets. For tma with periscope you only need 2 bearing lines + stadimenter information. It will be good enough. If there are esm signals merge them with the tma info. Idem for active sonar signals (although that could be bad news !!! ).

For sub contacts, if you're using the waterfall display then know this : if the trace of the contact is going away from your course : the contact is on a lag course (this is important because you don't have to do a course change just to find out). Viceversa if the trace of the contact is apporaching your course the contact is on a lead/overlead course (in this case you can't distinguish between the 2 and you must look at the bearing lines in the tma screen).

If the contact changes course you can see it on the waterfall display.
You will see what amounts to half an S, so if the contact was approaching your course before (lead/overlead) you'll see the trace go outwards (so lag), and viceversa. Comon wisedom has it that you can look at the bearing lines just before and just after the course change and have an estimate for the distance. Yes it will work, but without the other information (course) that won't do you any good. And sure as hell you'll get less information than what a previous tma could tell you.

Also if possibile always try tracking a contact on 2 sensors. Merge and triangulate 2 positions -> get precise tma without needing speed estimate and course change maneouvers.

Last but not least :

• in a lag course the point of intersection of the bearing lines will always be the MINIMUM possibile distance of the target.
• in an overlead (your going faster than him across the los) course the point of intersection of the bearing lines will always be MAXIMUM possibile distance of the target.

Depending on the situation you could always use active sonar.
Not as a primary ASW sensor, but from time to time it comes in handy.

[goldorak]

No, the intersection I'm talking about is when a target changes from a lead to lag or vice versa his speed across the LOS is temporarily 0 so the next bearing line I get after the maneuver will cross the last one at close to the range of the target. I'm not describing it very well, but I can't remember the title of the old thread that details it. I'll try to dig it up.


[cut]


I'm pretty sure the Akula is quiet enough that he'll have me on sonar at about the same time I have him and that's why I've started thinking about not giving him a solution by changing LOS.

You have to realise one thing : that a tma solution that is not updated is worthless. So if you change los because you must to get a fix on your enemy or to set a number of parameters (max distance, speed, course etc...) then not only you have to update your tma solution on him, but he has to update his solution on you as well. If he doesn't then his tma solution is going from good (if it was good to begin with) to bad to worse to worthless.

The golden egg so to speak is to learn how to keep the initiative.
That is to change frequently course and speed (at 2 minutes interval between the arrival of the bearing lines) so that your enemy has a hell of a time just trying to update his tma solution on you all the while you update easily your solution on him. And this is the real holy grail of manual tma. And it takes a lot of pratice. Because ultimately you will always have the initiative on your opponent, and his course changes and speed changes won't limit your ability to track him and constantly update your solution.

I don't know if the pdf is available on subguru, but its available on CADC website. Its called the red book and it contains a whole section that explains how not to lose (and update !!!) that precious manual tma you did while your quarry is changing course and speed. ^_^

[NFunky]

Looking at this situation further, it appears to be a 'whoever blinks first' kind of deal. I'd hazard to say that if both are tracking one another, but neither has a firm solution yet, the sub that takes the initiative by changing LOS will actually be at a disadvantage. His opponent will be able to get an immediate rough range while he will have to wait for his TA to stabilize and get another line or two before he gets one.

I wonder about changing course every two minutes. It would definately throw off an opponent's TMA, but would your own TA have time to stabilize and give you an accurate bearing line between turns?

[Molon Labe]

Originally Posted by NFunky

Looking at this situation further, it appears to be a 'whoever blinks first' kind of deal. I'd hazard to say that if both are tracking one another, but neither has a firm solution yet, the sub that takes the initiative by changing LOS will actually be at a disadvantage. His opponent will be able to get an immediate rough range while he will have to wait for his TA to stabilize and get another line or two before he gets one.

That's only going to be the case if he's beaming you. If he's headed toward or away from you an LOS switch is safe. But yeah, if he's beaming, it makes sense to make course changes without switching the LOS.

[Dr.Sid]

You can also change speed. That works same way. Doing very slow turns, like moving on circles, never straight is also good method for 1) improving your solution 2) worsening his solution, as all solutions expect the target to be moving straight. Leg can be spotted .. but slow gradual change in bearing rate can really puzzle the other guy.