finding, intercepting, and engaging targets without automap, radar, or active sonar

[AdamMil]

Hey, long time no post. I'm trying SH4 with the GFO (game fixes only) mod. I wanted to try playing without map contact updates, but it was hard because it even removed the sonar bearing lines. I tried finding some tutorials for playing without map contact updates, but I couldn't find any good ones. They all seem to be overly simplified. Either the target is plainly visible from the start or else radar or active sonar is used to get an absolute position or they ask the omniscient WO. But what about the case when you're too far away to see or ping it, and you don't have radar?

I played with it for the past 8 hours or so and found a couple of workable approaches. My first approach was to use the information from passive sonar to do a TMA (target motion analysis). I wrote a program to automate the TMA and spit out an intercept vector that would put me in a firing position 1000 yards off the target's side, and on the whole it works fairly well. The main benefit of this approach is that it gives you the target's absolute position, course, speed, AoB, etc. just from passive sonar readings, but it's a bit of a pain to write down the bearings on paper and alt-tab out of the game for a couple minutes to input the data. I also had trouble with my incompetent crew failing to report and track sound contacts despite them being clearly audible, and when that happened the approach degraded because it's hard to be a good sonarman and get accurate readings in addition to plotting on the map and everything else I have to do. Precision is important with this approach.

So my second approach was based on just using the rate of bearing change to find a lead pursuit course with the target. If you're on a lead pursuit vector (i.e. a straight-line course and speed on which you will intercept the target), then the target should remain at a constant bearing. (This is in contrast to a lag pursuit course where you simply keep your bow pointed at the target. Subs are too slow for that to be viable most of the time.) So what I did was: Set my speed to the maximum that I feel is safe/stealthy and turn towards the target bearing.
Wait a little while and see how rapidly the bearing is changing.
If it's changing, turn in the direction it's changing in such a way as to "overshoot" and hopefully end up on a lead pursuit course, and repeat from step 2. Don't overshoot by more than 30 degrees or so.
Otherwise, if it's not changing, I'm on a lead pursuit course.
Sail until the target is in visual range (or range of other sensors). If you want, you can slow down as you get closer, for stealth. Just remember to find the intercept course for the new speed.
It's basically a rough version of Newton's method. Example: I'm traveling in some direction and hear a target far away on (relative) bearing 120.
I order ahead standard and turn 120 degrees to starboard. (The target is now at bearing zero.)
I wait for a little while. As I wait, the target bearing drifts from 0 to 354 (i.e. 0 to -6).
I "overshoot" by turning 20 degrees to port (to bearing 340). (The target is now at bearing 14.)
I wait some more. As I wait, the target bearing drifts from 14 to 11.
It's still drifting towards port so I "overshoot" by turning ten more degrees to port. (The target is now at bearing 21.)
I wait. The target bearing drifts from 21 to 22.
Now it's drifting to starboard, so I turn 3 degrees to starboard. (The target is now at bearing 19.)
I wait. The target stays on bearing 19. That means I'm on a lead pursuit intercept course.After doing this, the target bearing may still drift very slowly, like one degree every five minutes, because you can't set an exact course in the game. In that case just adjust course again by two degrees maybe. But if the bearing keeps drifting substantially or if the range keeps increasing even though you're on an intercept course, then you're too slow to intercept the target. (You can either speed up or give up.)

The upside of this approach is that it's simpler than using TMA and doesn't require alt-tabbing out of the game. And you don't have to be very precise to get good results. The downside is that it doesn't give you the target's position, course, speed, or AoB, so you still have to figure that stuff out using other sensors and you can't directly sail to a firing position. But it's good to know how to do that anyway. Being on a lead pursuit course takes most of the guesswork out of interception, and when the target gets within 4-8 km or so you can begin roughly estimating its position and plotting its track using the following technique: Identify the target as soon as you can, but before then just pick a ship of its class (cargo, warship) with an average mast height.
Every few minutes, take a stadimeter reading and note the target's bearing. It doesn't need to be perfect, but do the best you can. (In SH3 in rough seas it helps to pause the game when you're centered on the water line.) Radar or active sonar can also give you a position estimate, but may reveal your presence.
Take the range and bearing and plot a line of that length along the target's bearing on the map, put a mark at the end of the line, and delete the line. (If you're moving or turning it's best to do this while paused, or else quickly mark the position/course of your boat.)
When you have a few marks, draw a "best fit" line through the marks to estimate the target's track. Position yourself 90 degrees from the track at a good firing distance (say 500m).
Repeat these steps and keep adjusting the track and your position relative to it. As the target gets closer and you take more readings, the estimated track will get progressively more accurate.
If you want, you can start the stopwatch when the target is 2-3km away and measure the distance between marks to estimate speed. But if you're really close to the target track you can usually just guesstimate the torpedo lead angle. :-) 4-5 degrees works well for most cargo ships at 600m.
If the target detects you, is unarmed/unescorted, and starts zigzagging you can just surface and sail towards it at speed. If you get within 700 meters, it's relatively easy to score a hit - shoot just as the target starts to turn one way or the other and lead a little bit. Use the magnetic trigger if possible to avoid glancing impacts.

I use this overall approach with success in SH3 + GWX. (I went back to it because SH4 crashed and corrupted my saved games on 2 out of 3 patrols. :-|)

[TorpX]

I like that you worked this out and all, but there is a way that achieves the same essential result with less maneuvering.

The last time I was in such a situation I used the Normal Approach Course. This means setting a course normal to the bearing of the target.

Using your example:

I am running submerged at 2 kt. and detect screws bearing 120 deg. relative. I wait a little while and the bearing moves to 119 deg.

Now I order 4 knots and turn 90 deg. to port from his bearing. He will then be at 90 deg. relative.

This is a Normal Approach Course. It allows an intercept [I]with a minimum of speed, provided an interception is possible. If the target is too fast, the target track is too far away, or it has already passed, you cannot intercept it this way.

I continue to monitor the sound. If I am gaining bearing, I can reduce speed. If I am loosing bearing, I can increase speed to 6 knots, but going higher isn't really an option, unless the target is already close. If I am still loosing bearing at 6 kt., I must either consider surface pursuit options, or let it go.

Like your method, this isn't intended to provide detailed target data (nor is it necessary), but rather to get you within attack range. You then have the standard problem of a submerged periscope approach.

The NAC lacks the fancy geometry of sophisticated sonar-only methods, but in practical terms works just as well (at least imo).

[AdamMil]

I ... detect screws bearing 120 deg. relative... Now I order 4 knots and turn 90 deg. to port from his bearing. He will then be at 90 deg. relative... It allows an intercept with a minimum of speed, provided an interception is possible.Thanks for the example, but are you sure this works reliably? Let's say that after putting him on your starboard beam (90 deg. relative), you and him are now on similar courses. When you adjust your speed to maintain bearing, you'd end up adjusting your speed to be nearly the same as his. Thus you'd be traveling nearly parallel, which seems to me like the longest way to intercept.

[TorpX]

I'm sure it will work within the constraints I mentioned. It was taught in the US Navy, and Dick O'Kane describes it in his book, CLEAR THE BRIDGE.

As far as being "longest way to intercept", that could be, but consider, intercepting at max. speed, intercepting at min. speed, and intercepting at X speed, are different options.


Let's say that after putting him on your starboard beam (90 deg. relative), you and him are now on similar courses.

This isn't really the case. The NAC is 90 deg. off the bearing, the target's course could be almost anything, nor do we need to know what it is.

This diagram shows what the NAC is:

http://i1130.photobucket.com/albums/m526/TorpX/Misc/NAC_zps911eb74a.png


The target track(s) is red, the sub is blue, the bearing line is green.

The bearing line is moving in the direction of the green arrow, so we set the course indicated by the blue line. Let's say the target track is the red line A. The NAC allows an intercept with a minimum speed. Another course with a shorter path may allow an intercept, but would require a greater speed.

If the target is on course B, we are farther off the target track, and must move faster to intercept. If the target is on course C, it is the opposite. We are closer to the track, and can intercept with less speed. In every case, the NAC gives us the best chance for an interception (that is with the least speed).

Note, that it is possible that we start on a NAC, at our best speed, and still loose bearing. This means an interception is not possible.

By monitoring the bearing of the target as time progresses, we will know if we can intercept or not. Gaining bearing means we would reach the point, where our tracks cross, ahead of the target. Loosing bearing means we would reach that point behind the target.

If you knew the target's course and speed, it would make sense to calculate a specific intercept course, but lacking such data, a NAC gives you the best chance to prevent the target getting by.

[Aktungbby]

AdamMil! :Kaleun_Salute:after two+ years of silent running and a first rate diagrammed lesson from TorpX...you're well up on the DAY!:up:

[AdamMil]

Perhaps I'm dense, but I just don't see it. If they taught it, then I imagine it must have worked, so I'm probably misunderstanding you. But what about these cases?

http://i61.tinypic.com/t0l069.png http://i62.tinypic.com/124vaeo.png

In both cases, the sub turns to put the target on its beam, and in both cases it can adjust its speed to keep the target there, but in neither case will it ever intercept, no matter how slow the target is going.

Anyway, these examples call into question my own approach as well, since they show that it's possible to keep the target on a constant bearing without being on a lead pursuit course, even if one exists. If you overshoot by too much you might wind up on homing in on one of the constant-bearing courses that isn't an intercept course. (But I think it's less likely to occur with my 'algorithm' since you start out pointing yourself at the target.)

@Aktungbby: Thanks for the welcome. :-)

[Warren Peace]

Perhaps I'm dense, but I just don't see it. If they taught it, then I imagine it must have worked, so I'm probably misunderstanding you. But what about these cases?

http://i61.tinypic.com/t0l069.png http://i62.tinypic.com/124vaeo.png

In both cases, the sub turns to put the target on its beam, and in both cases it can adjust its speed to keep the target there, but in neither case will it ever intercept, no matter how slow the target is going.

Anyway, these examples call into question my own approach as well, since they show that it's possible to keep the target on a constant bearing without being on a lead pursuit course, even if one exists. If you overshoot by too much you might wind up on homing in on one of the constant-bearing courses that isn't an intercept course. (But I think it's less likely to occur with my 'algorithm' since you start out pointing yourself at the target and adjust course rather than speed.)

@Aktungbby: Thanks for the welcome. :-)

In either of those situations, hydrophone checks will give you all the information you need. In the case of your first example, checking for his screw noise will reveal one of two things; a) no change, meaning you are on the same course at the same speed, or b) his contact will begin gaining bearing and becoming quieter, indicating he is pulling away.

In regards to example 2; you'll hear his screws become quieter as you open the range, indicating you are moving away from him and need to readjust your course if you wish to still intercept (which would turn into a tail-chase, not something I typically recommend).

[AdamMil]

In either of those situations, hydrophone checks will give you all the information you need.Of course, but my point regards an easy procedure to establish a good intercept course. I'm trying to understand this Normal Approach Course technique, which given my (mis)understanding of it seems to produce weird results in these cases.

[TorpX]

Perhaps I'm dense, but I just don't see it. If they taught it, then I imagine it must have worked, so I'm probably misunderstanding you. But what about these cases?

http://i61.tinypic.com/t0l069.png http://i62.tinypic.com/124vaeo.png

In both cases, the sub turns to put the target on its beam, and in both cases it can adjust its speed to keep the target there, but in neither case will it ever intercept, no matter how slow the target is going.



You are right about the cases you illustrated. Neither of these would permit an interception with the Normal Approach Course. If the target had been detected earlier, the situation would be very different.

Here, I took your first case and extended the target track backwards to show how the Normal Approach Course could be used:

http://i1130.photobucket.com/albums/m526/TorpX/Misc/NAC1_zpsd08f7195.png


Your second case is just like the first, except the target is even farther past.

Here is a diagram which illustrates the problem. The target is shown at an early position, A, and later positions, B, C, D, and E are marked. The gray line is the normal course, and is the shortest distance to the target track. If the sub is close to the target track and detects the target early, the NAC is nearly the same (as in case A).

http://i1130.photobucket.com/albums/m526/TorpX/Misc/NAC2_zps3be631d4.png



The target can be easily intercepted if detected at A, with just a fraction of the targets speed (assuming the diagram is drawn to scale). It can be intercepted at B, with a little more speed, or even at C. The farther along towards D the target reaches, the harder it is to intercept (that is, it requires more speed).

If the target reaches D before detection, the NAC will not accomplish anything, as you stated. Once the target has reached D, or E (or any point to the right of D), no course will permit an interception without having a greater speed than the target. For submerged submarines in WWII, this was generally an impossibility.

That would be in the nature of chasing after and overtaking a passed target, and was considered a different problem.

The geometry here shows why, in submerged operations, it was considered important to detect potential targets as early as possible. It also shows why many targets were detected, but still 'got by'.

[AdamMil]

Ahh, I guess that's what you meant when you originally said "if ... it has already passed". Of course, without knowing the target's course, there's no way to know whether the target has passed or not, but as Warren Peace said, I can just try it out and see if the target is getting closer. (Thankfully SH3 sonarmen can discern that instantly. :-)

So it does seem like a good approach to know, since it's simple and when it works it does give the slowest possible interception as you said, and slower means stealthier. In some cases (e.g. when the target is close to point D) it could take 'forever' but I believe you when you say it works pretty well in practice.

In fact, our two approaches seem quite similar in that they both attempt to find a lead pursuit course based on zeroing the rate of bearing change. Yours (NAC) fixes course and adjusts speed to find the minimum speed required, but fails if the target isn't 'behind' you. Mine fixes speed and adjusts course to find the minimum time required, but fails if the chosen speed is too low. Since I'm early in the war I can afford to zip around on the surface and just want the fastest intercept. Later, when I have to be stealthier, I might switch to NAC to find the stealthiest intercept. :-) I appreciate the explanation, in any case! I learned something.

[TG626]

I'll add my thanks as well. A good read. One item I notice isn't being expressly remarked on it fuel conservation, which would have been a very real consideration. Along with everything else, making your intercept in the most fuel efficient manner would have been important I would think.

[AdamMil]

One item I notice isn't being expressly remarked on it fuel conservation, which would have been a very real consideration.Especially if you're submerged and your "fuel" is battery charge. :-) I was thinking about it, but it's hard to say anything concrete. Fuel usage increases proportionately more rapidly than speed, which implies that you'd want to go as slow as possible. However, going as slow as possible (e.g. with NAC) can lead to you sailing a much longer distance than necessary, which may result in a much greater overall fuel usage than taking a shorter path at a higher speed. Battery charge also affects speed, which adds another complication. And it probably all depends on the specific parameters of the batteries, engines, and submarine. A mathematical analysis to arrive at a general rule is surely possible, but too time-consuming for me. :-P

What I personally do, though, is cruise around at "ahead slow" speed, giving me about double the range of "ahead standard" while only reducing speed by about 25-35%, so I don't have to worry about fuel usage in combat. I try to intercept on the surface at standard or full and only submerge once I get within 3-4 km or so. But I'm still early in the war...

[TorpX]

Especially if you're submerged and your "fuel" is battery charge.
Yes. The Normal Approach Course was mainly something applied to submerged approaches.

Here is a quote from the 1950 Submarine Fire Control Manual, which speaks for itself:

310. FLEET TYPE SUBMARINE:

(a) The Fleet Type Submarine will make the following speeds submerged for the length of time indicated, if it starts with a full battery charge:

Knots Time
3.0 48 hours
6.0 3 hours
8.0 1 hour
9.0 1/2 hour

(b) Thus it can readily be seen that a major consideration when making an approach is conservation of the battery capacity.

If you have liberty to maneuver on the surface, you have much better speed, and many more options, to make an approach.

If the people who own the convoy, have aircraft out flying ahead (as they often did), then surface maneuvers become problematic. It occurs to me, that aircraft make a convoy much more secure. They don't need to even make attacks; their mere presence would hold down submarines and frustrate attacks.



Also, I didn't mean to imply the NAC is some kind of rigid method. You don't need to adjust speed to the minimum, or follow any specific plan. You could increase speed for a short time to gain bearing (and a better position), then reduce speed when you know you are close enough to the target track to be assured of getting an attack opportunity.

Often, a NAC would be taken when a target was first spotted, and later when they were within several thousand yards, change course and speed to meet tactical requirements.

I like the Normal Approach Course, because it has that elegant combination of simplicity and effectiveness. However, the Navy also had what they called the Optimum Approach Course:

http://i1130.photobucket.com/albums/m526/TorpX/Misc/OAC_zpsbd73a686.png
I've never really used the OAC, but I've certainly used the NAC many times.

[AdamMil]

(paraphrasing) 3 knots = 48 hours, 6 knots = 3 hoursI don't know how accurate Silent Hunter is in this regard, but that's a huge difference in endurance: 144 nm @ 3 kn versus 18 nm @ 6 kn. I expected a large difference, but not that large, so if you're submerged, choosing the intercept that lets you go as slow as possible (i.e. NAC) seems like it would outweigh other considerations much of the time.

The OAC seems to require knowing the target's course, so I imagine it's one of those things you'd use after you get close enough to see which way the target's headed.

I didn't get the impression that you were presenting an overly rigid method, by the way. :-) These are all good tools to have in one's toolkit, to use and adapt as best fits the situation...

[banryu79]

First of all many thanks for this most interesting and educational thread. I really appreciate it.


The OAC seems to require knowing the target's course, so I imagine it's one of those things you'd use after you get close enough to see which way the target's headed.

Actually you could work out a very good estimation of target course/speed/range while conducting a passive sonar only approach.

Maybe I'm not telling you anything newer, but worth mentioning.
Once you have found and set your boat on the NAC, you have at least two methods that I'm aware of.

1) First ther is the "four bearing method". It involves sampling the bearing to tgt in temporal steps and plotting. TMA done by hand, requires times and patience, but gives out good results. I rarely use this.

2) Then there is the "Using the [Is-Was disk] [Mk13 submarine attack course finder] to conduct a passive sonar only approach" method. This requires time and practice, and the use of the Is-Was disk (you can make one yourself or use a mod that give you that in-game).
This method is the one I almost always use when first detecting long range hydrophone contacts. I do not use the "whole" methods, just the first three-four steps to obtain 3 estimated possible courses and speeds of tgt.
In this way I can plot them and so get a visual aid that help me much in analyzing the different tatical options at hand and finally choose an approach course that suit me the most.
I find it reasonable fast to use and "less annoying" than the four bearings method.

You can find detailed documents about this methods (and others) inside the [hsGUI v3.1] mod for SHIII.

I think that if you already had work out out and egaged the NAC to your tgt, then you could easly make a gross estimation of the OAC simply using the second method cited above while your are waiting to close range.

[TorpX]

I don't know how accurate Silent Hunter is in this regard, but that's a huge difference in endurance: 144 nm @ 3 kn versus 18 nm @ 6 kn. I expected a large difference, but not that large, so if you're submerged, choosing the intercept that lets you go as slow as possible (i.e. NAC) seems like it would outweigh other considerations much of the time.

The OAC seems to require knowing the target's course, so I imagine it's one of those things you'd use after you get close enough to see which way the target's headed.


From what I've read, battery issues were a major preoccupation of sub crews. The reality is even worse than what the game presents; batteries deteriorated a little with each charge cycle. So the capacity of your batteries would drop some with every patrol, until they had to be replaced.

The OAC is not usually too much off the NAC, so I consider it easier to rely mainly on the later. Anyway, it is easier to explain and remember.

1) First ther is the "four bearing method". It involves sampling the bearing to tgt in temporal steps and plotting. TMA done by hand, requires times and patience, but gives out good results. I rarely use this.


I read about some of the "four bearing method", or similar, but didn't really understand them well enough to use them. Also, it is rare for me to detect something so far away that this would make a big difference to me. Most of my contacts begin with a speck on the horizon, so sonar-only methods are not necessary.




Edit:

If anyone is interested in the actual USN methods of the era, here is where you can find the Submarine Fire Control Manual:

http://www.hnsa.org/doc/attack/index.htm

[banryu79]

From what I've read, battery issues were a major preoccupation of sub crews. The reality is even worse than what the game presents; batteries deteriorated a little with each charge cycle. So the capacity of your batteries would drop some with every patrol, until they had to be replaced.
Interesting. Somewhere I red that batteries charged not in a linear fashion but in a inversely proportional one: the more time spent on recharging the less charge stored per unit of time. So the most gain in charging was in the first 30 mitues or so, then progressively less. Getting a full charge required a long time.
So this aspect would definitely affects tacticts but (AFAIK) in the SH games is not modeled in that way.

I read about some of the "four bearing method", or similar, but didn't really understand them well enough to use them.
The "Four bearing method" is not difficult to understand but requires patience. I studied it on a doc shipped with the Mod I have cited in my previous post (I just downloaded the Mod not to use it but to get the goodies inside it... aka the document folder, it is full of interesting stuff to read). It is based on some "geometric tricks", actually simple stuff but clever applied. The main difficulty is that it is made of many steps to follow. The easy fact about it is that you do not need to "understand" it, just to learn by heart the single sequence of steps needed to apply it. The hard fact about it is that to apply it you need a lot of plotting manouvers and some of them are not so easy or fast to do with the default tools in SHIII (i.e. it is easier if I plot by hand with pen & paper).

Also, it is rare for me to detect something so far away that this would make a big difference to me. Most of my contacts begin with a speck on the horizon, so sonar-only methods are not necessary.
Ah sorry, I was referring to SHIII as a context. I never played SHIV, but in SHIII long range hydrophone detection at very low speed (1-2 Kts) occours to me on the range of 20 Kms and (sometimes) more.

[Pisces]

The 4-bearing method can just as easily be done with the periscope when in visual range. All that matters is getting a (true) bearing. If you can't distinguish the AOB from that speck, a bearing may be all you can get at that point. It's just that the hydrophone is required when outside of visual range. And the sooner you know more about the targets course and speed, the better you are prepared.

At closer range the bearings change more quickly, so you do not have to be too patient as with long distance hydrophone detections. Though when using the map drawing tools to get the geometry drawn, it might help to use the Pause button. Rushing yourself causes mistakes to be made.

[banryu79]

The 4-bearing method can just as easily be done with the periscope when in visual range. .
Personally, at that point, I prefer to opt for plotting with the "fixed wire method".


At closer range the bearings change more quickly, so you do not have to be too patient as with long distance hydrophone detections.

If, at this time (close range) I already know the tgt speed but not the course, I sometimes use the "AOB finder disk". It's useful only if you can sample a delta of 5 or more degrees in a choosen time, and if you are far away from tgt and the bearing change rate is small it takes forever... :haha:

[AdamMil]

I don't think I've estimated speed or computed a firing solution at any point in the last three patrols. I've just been intercepting the targets and doing snapshots at close range. Maybe I'm getting lazy. :-P

[banryu79]

I don't think I've estimated speed or computed a firing solution at any point in the last three patrols. I've just been intercepting the targets and doing snapshots at close range. Maybe I'm getting lazy. :-P
Well, my first need to know tgt course & speed is when I have a long range hydrophone contact, to predict it's movements, hence plot an interception course that will put me ahead of it in a given location at a given (desidered) time to start the "attack run" at the conditions I want if the situation is favourable or otherwise to compute a shadowing course.

For the attack itself I can get away without knowing the range at all, but I still need course & speed for precision, mostly to try to put the fishes in the soft spots of the tgt (well, as nearly as possible at least :)).

[AdamMil]

Well, my first need to know tgt course & speed is when I have a long range hydrophone contact, to predict it's movements, hence plot an interception course that will put me ahead of it...For me it's usually worked well enough to turn until the bearing rate zeros (i.e. onto an intercept course) and then turn a little bit more to end up ahead of the target. But I think if I ever encounter a convoy it'd be much more important to plan the approach carefully, so I'd probably give that four-bearing approach a try. (Still no convoys in GWX after 5 patrols... Thanks for the reference, though. I read the PDF and... it was complicated. But I've got it saved for when I need it :-)

I still need course & speed for precision, mostly to try to put the fishes in the soft spots of the tgtYeah, it is useful for that. :-) I can usually manage to hit the bow, middle, or stern if I try, but that's as precise as I can get. Even that's not guaranteed, so I mostly just go for the middle...

[banryu79]

Thanks for the reference, though. I read the PDF and... it was complicated. But I've got it saved for when I need it :-)

Not complicated... remember, it's made of small steps. just try to learn a single step a time, do not try to swallow the whole method in a single go :03:

Actually, to learn it (partially, as I said above I do not use the part useful to work out the range... its description it's too complicated and convoluted for me) it is useful if you try to isolate each single step and summarize it in a notepad using the minimum number of words. I made so and learn it very quickly.


I can usually manage to hit the bow, middle, or stern if I try, but that's as precise as I can get. Even that's not guaranteed, so I mostly just go for the middle...
Kudos to you then!
For a snapshoter, you are a sort of a marksman, sir :salute:

[TorpX]

The 4-bearing method can just as easily be done with the periscope when in visual range. All that matters is getting a (true) bearing. If you can't distinguish the AOB from that speck, a bearing may be all you can get at that point. It's just that the hydrophone is required when outside of visual range. And the sooner you know more about the targets course and speed, the better you are prepared.





Ah, that makes more sense to me.



***



Interesting. Somewhere I red that batteries charged not in a linear fashion but in a inversely proportional one: the more time spent on recharging the less charge stored per unit of time. So the most gain in charging was in the first 30 mitues or so, then progressively less. Getting a full charge required a long time.
So this aspect would definitely affects tacticts but (AFAIK) in the SH games is not modeled in that way.




Yes, the energy the batteries absorb per unit of time is not linear. The game model in not linear either, but is severely flawed in other ways. In stock configuration, the battery capacity (submerged range) doesn't work out to what is in the files. (This is clearly a coding flaw.) Ducimus came up with a good workaround to improve this aspect.

BTW, most US subs had one or two small auxiliary engines for topping off a battery charge. This allowed the sub to have a better operational surface speed, and made for better fuel economy.

I can't say what was typical, so far as charging times were concerned, but it is clear the USN expected their subs to be able to make a full recharge in 8 hours or less.

[AdamMil]

Not complicated... remember, it's made of small steps.I can do it. I just don't understand mathematically why it works. :-P

For a snapshoter, you are a sort of a marksman, sir :salute:Thanks, but not really. :-) I just get close enough -- 500 to 700 meters -- that it's hard to miss!

[banryu79]

Thanks, but not really. :-) I just get close enough -- 500 to 700 meters -- that it's hard to miss!
Well, that's the optimal range for me too but I always try to get all the possible and availabe data for a tgt in the safest way possible. It keeps me busy, mesuring and estimating, thinking, plotting and planning my approches.
That's the part of the game I like the most :yep:

Anyway, I sometimes experience misses at the shortest ranges (600-400) even after the elaboration of all the data above, both when firing with the "aid" of the TDC properly setted (usually a "90° fast attack") and when firing over-the-shoulder ("90° straight shot" method with the TDC turned off).
Yes, I like the 90° thing :hmmm: ... :har:

Well, I do not know for sure if they are misses or dud ones because I do not use the "event camera" feauture... That keeps me guessing... and it's fun!!

[Sniper297]

Couple observations;

1. The game programming is FUBAR, you can use one and only one sensor at a time. If the sonar guy has no contacts that's because the target is visible, and the game changed from sound to visual. In other words the sonar is disabled when the eyeballs are enabled, only one can be active at any given time. Ridiculous but that's how they coded it.

For that reason if the sound man seems to go brain dead at closer ranges, submerge and check both periscopes down - no visual contact turns the sonar back on again. Again ridiculous and unrealistic, but that's how the game works so you have to choose if you want to see or hear at any given moment since you can't do both at the same time. The crew sees the target OR hears the target, "AND" is beyond their capabilities.

2. Steady bearing plus decreasing range is a collision course, not a lead pursuit. If nobody changes speed or course the ships will collide. If the bearing is changing forward he's "gaining bearing" on you and will pass ahead. If the bearing is moving aft you are gaining bearing on him, that's a lead pursuit.

3. First part on any approach is figuring a rough course - point the bow at him, wait a few minutes and note which way the bearing changes. Double the angle, if it changed 10 degrees to port turn 20 degrees to port so you're leading him. It's easy to figure out from bearing changes alone if he's heading approximately east, southwest, northeast, whatever - good enough for now, if he's south of you heading northwest turn west for a rough interception course.

4. While continuing on the rough course refine it with range and bearing calculations until you have a more accurate track. Distance to the track is the Holy Grail, if you're not already inside torpedo range of the target track you need to do whatever it takes to get there. Heading directly toward the track is preferred if he's far enough from the firing point and moving slow, if he's closer and faster you'll probably need to aim for a point on the track further ahead. If the bearing draws aft you'll beat him to the firing point, if it's drawing forward you need to speed up and/or lead him more.

[banryu79]

1. The game programming is FUBAR, you can use one and only one sensor at a time. If the sonar guy has no contacts that's because the target is visible, and the game changed from sound to visual. In other words the sonar is disabled when the eyeballs are enabled, only one can be active at any given time. Ridiculous but that's how they coded it.

For that reason if the sound man seems to go brain dead at closer ranges, submerge and check both periscopes down - no visual contact turns the sonar back on again. Again ridiculous and unrealistic, but that's how the game works so you have to choose if you want to see or hear at any given moment since you can't do both at the same time. The crew sees the target OR hears the target, "AND" is beyond their capabilities.

I beg your pardon?
From my limited experience with the game (I started play SHIII about two mounth ago) I never observed this behavoiur... I remember well that in more than one occasion I was conducting a submerged attack at periscope depth with the sonarmen correctly calling out bearings to tgt WHILE I was observing it in the attack periscope... :06:

[Amazigh1337]

i would like to recruit my cats for hydrophone sound detection....

if i open a can of beans.... i don't see them... a can of corn beef.... i don't see them... can of little saucages... i don't se them....

but when i open a can of catfood, within 3 seconds they purring at my feet....

how the hell do they hear the difference so well? dahm they would be a good recruitment for hydrophones....

[AdamMil]

how the hell do they hear the difference so well?Perhaps it depends on time of day. Perhaps it depends on other sounds, like if your cat food is stored in a different cabinet than your human food. I don't know, but in any case that's certainly a fascinating observation. :-)

[TorpX]

Well, they definitely hear better than we do.

[Pisces]

The smell of fermented meat spraying out of a tin can under pressure might also have something to do with it.

[TorpX]

Maybe. :haha:

[Amazigh1337]

The smell of fermented meat spraying out of a tin can under pressure might also have something to do with it.

that would be correct if they would be in the next room or something.. but they are both outside :D

its the sound the can makes, thus why i would like to recruit them for my hydrophones :D

[Shkval]

http://i1130.photobucket.com/albums/m526/TorpX/Misc/NAC_zps911eb74a.png

This is what I call a "45 degrees approach"... funny I thought I invented it :har::har:... I was guided by a fact that a cannon ball has it's largest range when fired at the angle of 45 degrees... I use it when I have a small number of degrees... 30 or less of "time" to intercept on the T course (90 degrees approach), basically "constant distance" or "going away" contacts with small advantage in degrees... 10 or less. Of course if the advantage is too big... 20, 30, or more degrees I use parallel course to gain on him... these decisions are made after the 4 bearing method (hydrophone) or the radar plotting... It's good also against fast moving warships... at night... too risky during daylight...
I remember once I stumbled upon two cruisers... I think they were Maya class... moving at 22 knots at my 40 or so degrees on T course but out of range of torpedoes... with this approach I managed to cut the distance to about 7 Km, dive, sneak in a few more hundreds of meters and fire heavy salvo of slow Mk14... sunk one, other got away...

[merc4ulfate]

Where is the mod to add battery power to the motors while the diesels are also running? That was a real life thing and provided a bit more speed in emergencies ...

I'd love to see a mod for this that could be used across U-Boat and Fleet Boat and with all mega mods.

[TorpX]

This is what I call a "45 degrees approach"... funny I thought I invented it :har::har:...




Yeah, when I was just starting with SHCE, I worked out a geometric proof of this. (Don't ask how, I can't remember that far back.) I figured if I could work it out, the Navy tacticians certainly could. Of course they did, and lots of more sophisticated things besides.

There is a corollary to the NAC, that is not obvious. If say, you are submerged, and want to evade a destroyer making a depth charge run, there is a Normal Evasion Course. This is simply the reciprocal of the NAC, that is, 180 degrees from the NAC. This gets you as far away from the enemy's track as possible. All you need to know is the enemy's bearing, and the direction it is moving.

http://i1130.photobucket.com/albums/m526/TorpX/Misc/NEC_zps751a21de.png



***



Where is the mod to add battery power to the motors while the diesels are also running? That was a real life thing and provided a bit more speed in emergencies ...

I'd love to see a mod for this that could be used across U-Boat and Fleet Boat and with all mega mods.

Detailed engine propulsion mechanics are probably in the category of things would dearly like, but have to do without.

However, it exists in an abstract fashion. I put in my ISP mod a 'Special Ability' that allows a so-gifted crewman, to increase your speed a small amount, for a couple hours. This is to simulate use of the battery. The game is such, that the battery does not run down (or for that matter your fuel consumption does not go up), so I put in a pretty short duration.

I wouldn't think this was appropriate for U-boats though, as they were direct drive, not diesel-electric.