Question Re: Strategies Using Realistic Settings

[Filson]

I have played SH3 and SH4 off and on over the last few years. I recently downloaded TMO and RSRD and have been playing on Realistic (100 Difficulty level). While I have managed to sink 4 merchants in three patrols, I have been having some difficulty.

The main thing I am struggling with is trying to figure out the general direction a contact is heading in so I can move my boat in front of it. Has anyone written up a guide on prosecuting a sonar contact on Realistic setting (i.e. no tails, no map markers, etc.)?

The other thing, is using the TDC with a zigzagging target. When I take distance measurements (the two red dots), does the speed and heading calculation compute the straight line equivalent heading and speed (blue line)? Or does it cheat it and calculate the actual heading and speed of the target (green line)?

http://img94.imageshack.us/img94/9143/shipheading.jpg

Thanks in advance,

C Filson

[Armistead]

Here's a good one using radar with contacts off. Sonar works almost the same way, except you have to guess range unless you decide to ping, but you can get a decent course figured out with marking sonar bearings. Once you get to a closer track, just keep taking sonar bearings until you get a perfect track. Once they're in view, you can fine tune it.
http://www.youtube.com/watch?v=J6kq4simwI0

Not sure of you stad question except it will give you the exact course at the moment they're, not a base course, ect...I seldom use the stad, but if I do and they're zigging, I'll measure with stad at each zig point right when they turn and then split the difference. As say the first leg course is 250, the next zig leg 300, I'll set the aob wheel to match a course of 275.

[jerm138]

Try this tutorial I made for tracking with sonar.

http://www.subsim.com/radioroom/showthread.php?t=160817

[Filson]

Jerm,

That is exactly what I was looking for with respect to hydrophone plotting. I had been sort of stumbling about and noticed some of the patterns in your guide (like the increasing and decreasing degrees for a regular time interval indicating whether it was moving towrd or away), but had not put it together into something really useful.

Too bad the parallel line tool (visibily referenced in the map tools in the game) cannot be used. :cry: It would make the plotting a bit easier.

Thanks again,

C Filson

[jerm138]

No problem.. glad it helps.

Yeah... the parallel line tool would be nice, but fortunately the compass tool works pretty well for the same function. I use that tool a LOT for things like that. Like when I have a target's course drawn with a line, and I want to follow the same course, parallel to him, I just trace his course with the compass tool, then move the center of the circle to my position, then plot my course along that line.

[Frederf]

The main thing I am struggling with is trying to figure out the general direction a contact is heading in so I can move my boat in front of it. Has anyone written up a guide on prosecuting a sonar contact on Realistic setting (i.e. no tails, no map markers, etc.)?

Do you want to find out a contact's motion in general or specifically using sound equipment only? In reality, a sound contact would be drove straight at at high speed on the surface until it was seen either visually or on radar. Then the pursuit is typically a Normal/Optimum Approach Course until in the 0-20° AoB cone in front of the target and then approached directly until submerging at a sensible range. Any portion of the approach can be carried out submerged but speed and range limitations reduce one's options.

The other thing, is using the TDC with a zigzagging target. When I take distance measurements (the two red dots), does the speed and heading calculation compute the straight line equivalent heading and speed (blue line)? Or does it cheat it and calculate the actual heading and speed of the target (green line)?

Blue line. When you are prosecuting zig zagging targets possibly with only sonar contact.... congratulations you have graduated! :know: You are in a class above the auto-magic notepad and further use is unwise; throw it away like you would training wheels! The notepad "two marks" method is extremely simplistic assuming uniform, straight-line motion on the part of the target. Beyond that it (I'm pretty sure) it assumes that the submarine is stationary between measurements! If you parallel at 9 kts a merchant such that he is (for example) bearing 090, 2000 yards for both marks the result will be shown as "merchant speed 0 kts" despite the obvious fact the merchant is going 9 kts.

All patrol logs from real fleet boats and such authentic text books I've ever read will have you study your zig-zagging target for sufficient time to establish his pattern. Zig zags in SH4 (even RSRD) are likely far for simple than the real life complex patterns which could take an hour to repeat. The primary variable in knowing your quary is time, namely time between zigs. You don't want to fire your torpedoes at a target that zigs-every-6-minutes when the target has been on a steady course for 5.5 minutes.

http://www.hnsa.org/doc/attack/index.htm Plates XIX though XXIV at the bottom should give some additional meat for thought. These are referenced higher up in the text.

The early goal is to plot the zigging target in sufficient detail to have a good clue as to his base course, speed, and time/distance between zigs. These are "backup" values in case you cannot get real values immediately before torpedo launch.

Maneuver qualitatively to a position close to his track. Once you've picked a likely leg to attack on and the target turns onto that leg... it's a race! Ideally you are in a position where the target was coming almost directly at you before the turn and made a turn to present an AoB in the 60-90° range. With a 6-minute zigging target you have 6 minutes minus the torpedo run time to identify a zig, gather targeting data, turn on the PK, verify solution, and shoot.

This is all rather involved even with the accuracy of radar. Sonar still makes this possible but range is rather limited (~5000 yd active ping historically) so it's possible to simply not be in a good position, gather enough data in time or lack battery power.

Bearing, range, and let the stopwatch run the whole time for a bearing-range plot. Get really good at plotting marks on the nav map quickly and accurately. Regular intervals (60 sec for shorter ranges) really helps patterns like zigging emerge visually. Average your sonar ranges over a few tries and know that the sonar bearing is to the engine noise and not the ship's center (which can be 1-3° ahead). SH4 doesn't model the bearing lag because sound takes time to travel though so you don't have to worry about that. Just for fun, know that the real TDC had a "sonar" input connection that automatically corrected sonar bearing for both the "engine is in the bacK" (target length had to be entered on a dial) and "sound takes a while to travel" effects.

The method of constant-interval hydrophone bearings works as well as your measurements are accurate, precise, and the target is moving in a straight line. The PDF is good for the tools that SH4 gives you. The reverse works better mathematically, plotting every regular bearing change and noting the times that it takes to traverse each bearing interval, but is not possible without special geometrical techniques. In fact mathematically it is possible to use arbitrary measurements but without a computer is unweildy. The special plotting paper used in Plate IX (Bearing rate) Plate XI and Plate XII (Bearing difference) uses non-Cartesian axes such that the result of a plotted straight line is a corrected (relative) course when viewed as Cartesian. The paper does the mathematical work of straightening out the data into a target course.

Another method is the "collision course" method which combines maneuvering and studying the target. If you are on a collision course (no bearing change) then there is a ratio of sines (lead angle, AoB) that relates to your speed ratio.

[Filson]

Do you want to find out a contact's motion in general or specifically using sound equipment only? In reality, a sound contact would be drove straight at at high speed on the surface until it was seen either visually or on radar. Then the pursuit is typically a Normal/Optimum Approach Course until in the 0-20° AoB cone in front of the target and then approached directly until submerging at a sensible range. Any portion of the approach can be carried out submerged but speed and range limitations reduce one's options..

That is more or less what I *had* been doing originally, but I found it pretty hard to prosecute a fast or medium speed target in daytime because I had to submerge pretty far out to prevent being seen (no radar yet . . . currently Spring 1942), and then my low submerged speed prevents me from getting into a good firing position, if any at all.

What I want to be able to is get a general sense of where the target is going from beyond visiual range and then move around further up that course at all haste and set myself up in a position to make a submerged attack.

I am starting to think fast targets are just a waste unless they are heading straight for you or you get really, really lucky.

I am currently having this problem on a mission at Kiska. Big fat, fast merchant escorted by a DD. I have tried using sound only approach. I have tried doing visual approach. Either they get away totally or I am hugging the ocean bottom praying the Japs don't hear me breathing.

I suspect you are right about the blue line being the one. I had a merchant that was basically turning back and forth with no straight aways. I took two visual measurements at the top of two zigs and he was dead on the money at the end of his fifth zig when I put 4 of 6 fish in him (one dud and one went wide because of the spread).

Thanks again,

C Filson

[Frederf]

That's why you submerge as close to AoB 000° as you can manage. However if you're losing the footrace to the target then you have to pick an optimum course (which is actually pretty tricky geometrically especially with a surface/submerged/torpedo split) to close with him and hopefully get a shot. Helpful hint, use the torpedo run time on the attack map to determine if the torpedo has enough gas to get to him, 31.5kt 9000yd is about 8 min) Plenty of real world attacks were foiled by simply being in an impossible position.

The usual end-around technique involves marginal visual/radar contact at maximum range (and bearing 090/270 +/-10 for spacing) of whichever sensor has the longest range. The primary problems with this are any air cover, enemy radar, and that it can be a bit tedious to mind the process so you don't wander too near or far.

Doing this BVR is how I used to do SH3 approaches, diving at regular intervals (30 min? too close and your average speed suffers), checking bearing, estimating range (very rough, "I can't see him but I can hear him so in the 8000yd to 20000yd gap) and being paranoid that he's sailing well away from me. This is all after the critical, brief "which way is he going" check which is done driving at him or stationary to check bearing change.

You'll can generally note when you're on the "parallel" leg or the "cross in front" leg by how fast the bearing changes. Overshooting around his nose changes the bearings in an awful hurry.

Oddly enough depth is not always stealth. The top layer of water is commonly better out of range of enemy listening and sonar due to the weather noise and the very flat angle. I would commonly be discovered trying to rise from the depths right in time for a convoy when a periscope depth approach would have kept me hidden.

[Filson]

I managed to sink that merchant off of Kiska. I tried not to meta game think it too much (it was like my fifth reload of the save game). I just wanted to prove to myself it was possible to pop him . . . and it was. 5 of 6 fish hit (one went wide I presume . . . I was hiding after launching the torps so I didn't see it).

Boy is evading a DD in TMO hard. He got a glancing shot with a DC, but it only did 1% hull damage and I skulked away successfully (CO2 was becoming a big problem, though).

In your last post, what does BVR stand for?

C Filson

[magic452]

Boy is evading a DD in TMO hard.

Welcome to the boat :salute: and to TMO. :damn:

BVR Beyond Visual Range. Out of sight.

Magic

[Filson]

Just got done with my best patrol yet (27K tons). Was working off the southwest coast of Pelielu and it was smorgasbord of Jap shipping. Only sour note was blowing 8 torpedoes on a midsized feighter and having to surface and deck gun her to death (lucky for me she wasn't armed).

So I got a Gato and also now have radar (it's Dec 1942). Is the "m" on the radar set meters? I watched a video tutorial on radar approaches and the guy who presented that was calculating the distances as if they were yards.

The other weird thing I noticed with my radar set, is that I can find stuff much further out with my hydrophones than I can with my radar. The sonarman won't see it, but if I manually go the hydrophone I find an "unknown." By the time it shows up on radar, it is halfway within the range of the "max" range and my sonarman has picked it up on the hydrophones. Seems kind of weird that hydrophones would be better than radar. Am I doing something wrong maybe?

Lastly, is there any way to tell whether a radar contact is an airborne or a seaborne contact when it is announced by a crewmember? I know they are detected on different pieces of equipment; the game should inform the player of the nature of the contact.

I think that's it.

Thanks in advance for sharing knowledge.

C Filson

[Filson]

One other little side note. The difference between a Tambor class and a Gato class is much, much more noticeable using Realistic settings and TMO/RSRD. I used to think there was not much significant difference, but having a Gato makes life much, much easier (increased underwater speed and deeper diving being the biggest advantage I have noticed so far).

I am having a blast with this. The modders have done a masterful job at making this game have legs.

C Filson

[Frederf]

Is the "m" on the radar set meters? I watched a video tutorial on radar approaches and the guy who presented that was calculating the distances as if they were yards.

I know any digital 3D readout is in meters... I can't remember if the A-scope is in meters or not. I should do a test about that.

The other weird thing I noticed with my radar set, is that I can find stuff much further out with my hydrophones than I can with my radar.

20,000 yards (action bubble) is rather good performance for a merchant sized radar target. Less than ideal conditions can reduce range considerably. The hydrophones in SH4 (at least from player hearing) are a bit simplistic and don't really put practical limits on performance like those shown with AI use. Mostly this is the reason... player hydrophones are too good. Real life contacts could be lost as easily as suffering the noise of a torpedo shutter or a depth change.

Lastly, is there any way to tell whether a radar contact is an airborne or a seaborne contact when it is announced by a crewmember? I know they are detected on different pieces of equipment; the game should inform the player of the nature of the contact.

TC drop is typical. 1x for airborne (any sensor) 8x for surface (any sensor). If that is not telling then simply seeing (or not) the contact on the PPI or A-scope should let you know. If you can't find it with a sweep, it's a plane! Alternately you can dive to about 50-55 ft and once the radar contact is lost (timeout?) you can raise the SD antenna and see if that detects something. If SD sees it, it's a plane. Planes can be seen on the SJ set as well, but they are obvious due to their speed.

The radars should definitely work better but modders have done a lot of probing in this area to no result. One of my biggest griefs is that SD in game gives bearing but no range while in reality it did the opposite.

[Filson]

Well, my first 100% realism career came to an inglorious end. I ran my boat aground on a small island off Formosa (stupid TC mistake and not zooming in closer on the map to plot my course). I actually managed to get off the shoal with 98% hull damage. I couldn't submerge because so much was trashed and an ASW air patrol finished the job. Made it to mid 1943 with just shy of 100,000 tonnes of shipping sent to the bottom.

RIP, brave crew of the USS Drum.

Started a new career in the Phillipines 1941. We'll see how that goes.

C Filson