Alternative Speed & Distance measurements

[Capt. EJ]

Hey all,

Wanted to ask for advice after missing two absolute sitters on my last patrol.

1st Instance: Modern EU Liner dead ahead, moving 90 degrees starbord to port across my bow, approx 600 yards distance. I fire 4 torpedoes...all miss!

2nd Instance, same ship, same setting except ship is now zig-zagging but manage to fire at around 500 yards when his side is facing me, 2 torps, both fire slightly ahead, miss again!

I think the issue I had was incorrect range and speed calculations to the TDC. My main method for both is to use the stadiometer for range and repeated readings to calculate speed. The problem in both cases was the sea was pretty choppy so impossible to get an accurate reading, as such the speed approximation was varying between 4 knots to 16 knots. Seeing as it was moving at "Medium", I settled for 9 knots and 10 knots, obviously incorrectly.

As such, can anybody share any alternative methods to determine speed and range, especially in choppy seas where the stadiometer becomes almost useless?

[TG626]

I use auto targeting, but I'm practicing to take off the training wheels.

I watch and wait for a fresh sonar line, mark the end point, and start the clock.

3 minutes later I mark the new line.

Measure the distance and divide the yards by 100. Answer is the speed in knots.

So far I've been pretty accurate compared to the speed I get when I up-scope and lock on.

[Sniper297]

"moving 90 degrees starbord to port across my bow, approx 600 yards distance. I fire 4 torpedoes...all miss! "

Those liners generally run about 12 or sometimes 18 knots, but unless your speed was way off something else was probably wrong. Most common mistake is failing to update AOB before firing, or even getting it backwards - "90 degrees moving starboard to port" meaning from YOUR right to YOUR left, so HIS port side is facing you - that would be AOB port 90, if you had starboard 90 set in the gyros in the fish would send them the wrong way since the TDC would assume AOB port 90 meant he was moving from YOUR left to YOUR right.

Best method to compensate for speed errors is to fire a spread - aim at the very tip of the bow, click the "Send range and bearing to TDC" button, fire. Shift aim to the tip of the stern, click button again, fire. Shift aim just ahead of center, click button, fire, shift behind center, click button, fire. At least one fish will miss completely, but with a spread like that you should get at least one hit. (Which unfortunately would probably be the dud with 100% realism on.) If the fish aimed at the stern hits near the bow and all the rest miss ahead, either he was going slower than your estimate or he slowed down and/or turned. If the one aimed at the bow hits the stern he sped up and/or turned or he was going faster than you thought. Make a note of which one hit where if you only get one hit, that will tell you if the target was traveling faster or slower than your calculations so you can improve them on the next try.

[Sniper297]

I should probably add here, I rarely play with manual targeting since there's too much to do in too short a time by one guy, in real life they had a whole team doing the plotting and calculating and inputs to the TDC while the captain just called out ranges and bearings then loafed around looking important while his officers did all the work. :rock: So I cheat even on that, speed zero AOB zero crank range to 1200 and leave it, then use Kentucky windage to guesstimate the lead angle. And get in close so the evil culprits can't screw me up by dodging the fish. :/\\!!

[TorpX]

Wanted to ask for advice after missing two absolute sitters on my last patrol.


I think the issue I had was incorrect range and speed calculations to the TDC. My main method for both is to use the stadiometer for range and repeated readings to calculate speed.

You don't say how you are using readings to calculate speed. If you are using the little button to do it automatically, know that it is not very accurate. It is much better to do a plot and use distance over time. Also, in real life, plots usually required several observations; not just two. If conditions are difficult, it is especially worthwhile to make several, and "fair the plot" (as in obtain average values). This will reduce the effect of observational errors.

[Capt. EJ]

Thanks all for the feedback.

TG626, I will give that a try, should help me get a more accurate speed reading which so far the biggest problem I have in calculating due to the inaccuracy of my current method.

As for the initial shot, I get my port and starboard mixed up. The ship was moving left to right at 90 degrees at around 500 yards, so pretty much a perfect, non-missable shot (which I missed :/\\!!). AoB was dialled in correctly and so was range. I did fire a spread using my usual method, i.e first 2 fired aiming at the ship in "lock", 3rd at a 2 degree right angle, 3rd at a 3 degree right angle. When I am unsure of hitting I usually do 1 at 2 degree left, 2 centre and 1 2 degree right, which I did not do in this case.

I didn't get much time to see as a destroyer was on me but I think all shots overhit so probably had the speed set to high at 10 knots. But will try the mentioned method of spreads.

Also, just to throw it out there, what do you do when a torpedo does a circular run? That same attack I fired all stern tubes at an onrushing destroyer (to buy myself time to dive) and it work. LUCKILY I dived right after I fired as one of the fish went on a circular run, which I didn't even know until later. So, assuming this could happen again when I am not diving for my life, how best to prepare?

[Capt. EJ]

You don't say how you are using readings to calculate speed. If you are using the little button to do it automatically, know that it is not very accurate. It is much better to do a plot and use distance over time. Also, in real life, plots usually required several observations; not just two. If conditions are difficult, it is especially worthwhile to make several, and "fair the plot" (as in obtain average values). This will reduce the effect of observational errors.





I used the stadiometer to calculate range and then after multiple readings used the "calculate speed" option on the dial which is VERY inaccurate I know but didn't know another way to do so until now. Will use the chart to plot speeds going forward.

[Sniper297]

Best way to avoid circular running torpedoes is to not have circular running torpedoes, turn the duds off. :up:

In real life;
Captain: FIRE ONE!
Sonarman: Number one running hot straight and normal.
Captain: FIRE TWO!
Sonarman: Number two running hot straight and normal.
Captain: FIRE THREE!
Sonarman: Number three deviating to starboard.
Sonarman: Number three still deviating starboard, bearing now 030.
Sonarman: Number three now bearing 060.
Sonarman: NUMBER THREE 065 RANGE CLOSING! IT'S COMING BACK TOWARD US!
Sonarman: IT'S GONNA HIT US HEAD FOR THE *%#&@$#! BOTTOM!

Ingame not a peep from the sonarman, apparently he's a laid back lubber with no imagination. :dead:

[Pisces]

When using the speed calculation button, please realize that the game uses the last 2 stadimeter range measurements (and bearing at those times) to calculate the distance moved over time. If your measurements are crude then the distance between the two points will vary. Range is tough to get right with the stadimeter, due to possibly incorrect mastheigt values for that model, and maybe coarse graphic image on the screen. Unfortunately, the closer you are the better it works. Bearing can be unsteady if the boat is turning or rolling on the waves. So either keep it locked, or keep aiming at the same structure on it.

If you then took too little time to separate these measurements then the speed and target course will vary greatly! So DO NOT do multiple measurements in short intervals, but instead spread the last 2 out over a LONG period! Time averages all position errors to minimums. Just keep yourself unseen in the mean time. And hope it doesn't change course.

If you can keep the bearing steady, then it is best to stay in a position alongside the target, moving parallel at a distance. But if you are better at measuring range accurately then trailing the target (or stay ahead of it) to get it's course works better.

Don't worry about the position keeper yet. Keep it off for now. You need to know and set the speed and course first to make use of it.

[merc4ulfate]

This might sound easy but at 600 yards do not do a thing. Set your scope to zero and put your bow 10 degrees ahead of the lead ship. Doors open fish set to fast running with magnetic detonators.

Make sure your doors were open or you'll miss. When the first ship reaches that ten degree mark fire one, five degree fire two now wait for the next ship and do the same thing or turn your bow since he will most likely turn away.

I touch nothing ... I rarely miss that close and firing like that.

All your doing with this is leading the target by turning the bow... at 600 yards with a fish traveling at 46 knts ... it is harder to miss than hit it.

[Capt. EJ]

This might sound easy but at 600 yards do not do a thing. Set your scope to zero and put your bow 10 degrees ahead of the lead ship. Doors open fish set to fast running with magnetic detonators.

Make sure your doors were open or you'll miss. When the first ship reaches that ten degree mark fire one, five degree fire two now wait for the next ship and do the same thing or turn your bow since he will most likely turn away.

I touch nothing ... I rarely miss that close and firing like that.

All your doing with this is leading the target by turning the bow... at 600 yards with a fish traveling at 46 knts ... it is harder to miss than hit it.

Not a bad idea and I will give it a try "but", this is early 42 with GFO mod enabled. That means that (from my current experience), I have about a 60% dud chance with regular torps if I set them at Max speed and about a 90% chance for premature explosion if I use mag detonator. Srsly, I have had now 4 seperate instances where all 4 torps I fire at a ship fail.

As such, to minimise the dud chance I set at least 2 torp out of 4 to "Slow" and never use the magnetic detonator...just too great a chance of pre-explosion.

[Sniper297]

What I would suggest is try half a training wheel - uncheck the "no map contact updates" so you have the targets displayed on the map. When you get a target check range, bearing, and AOB with the periscope, then look at the map to see how far off you are. Estimate speed, then use the distance tool to draw a 2000 yard line ahead along the target's course. When he reaches the start hit the button on the stopwatch, hit again and see how many minutes it takes for him to travel that 2000 yard distance. (2000 yards is 6000 feet, 1 nautical mile is 6080 feet, close enough for government work.) Divide 60 by the number of minutes it took him to travel that 2000 yards and you have the speed in knots.

When you think you're fairly good at that, reverse it - manual targeting off, no map contact updates on, now you have automatic targeting with no target on the map. Use the range and bearing display to draw lines on the map until you get comfortable with that, note the size of different targets at various ranges with the periscope hashmarks (both zoomed and unzoomed) until you have mental pictures that will tell you how big the target SHOULD look at any given range. For bearings on the map it's somewhat difficult since the map tool draws true compass bearings and the periscope shows relative bearings to the sub's heading. For that use the sonar dial, the outer ring is relative bearing and the inner ring is true bearing (example, if your sub is heading 325 the inner ring is rotated with 325 under the 0 on the outer ring, so if the target bears 290 relative the inner will show the true bearing lined up with that, 255). Use the ruler with the tool helper open (gadget that looks like a lensmatic compass, adds a compass to the end of the ruler) to measure out the range and bearing from your sub to the target. At the end of that line draw a 500 yard circle with the compass, then use the eraser to delete the line. Each circle you draw will give you a series of marks where the target was at each observation, a line drawn through those gives you the target track. Reason I use circles instead of the pencil X is circular probability of error, for plotting purposes the smaller the circle the more certain you are about the accuracy of the plot.

Get comfortable with measuring - plotting - estimating - calculating and then go back to full realism. Unless you have done some real life aerial and/or nautical navigation and/or target tracking, you're starting with a handicap so learn the basic use of the plotting tools with training wheels. :know:

[Nisgeis]

You can use this mod to help with calculating spread sizes:

http://www.subsim.com/radioroom/showthread.php?t=144202

It's handy in that you don't need to do any calculation, just follow the lines, so good for high pressure situations for reducing errors.

There is also a paper printout version for use if you don't want to mod the map.

[Capt. EJ]

This might sound easy but at 600 yards do not do a thing. Set your scope to zero and put your bow 10 degrees ahead of the lead ship. Doors open fish set to fast running with magnetic detonators.

Make sure your doors were open or you'll miss. When the first ship reaches that ten degree mark fire one, five degree fire two now wait for the next ship and do the same thing or turn your bow since he will most likely turn away.

I touch nothing ... I rarely miss that close and firing like that.

All your doing with this is leading the target by turning the bow... at 600 yards with a fish traveling at 46 knts ... it is harder to miss than hit it.

So I tried this and it worked a charm :yeah: for the most part when the torps decided to work (not often :D ) and if the seas are not to violent. After a few tries managed to get some decent hits. A thing to note though I found is this only works for bow attacks. Cannot fire stern tubes this way, computer won't let you :down:

What I would suggest is try half a training wheel - uncheck the "no map contact updates" so you have the targets displayed on the map. When you get a target check range, bearing, and AOB with the periscope, then look at the map to see how far off you are. Estimate speed, then use the distance tool to draw a 2000 yard line ahead along the target's course. When he reaches the start hit the button on the stopwatch, hit again and see how many minutes it takes for him to travel that 2000 yard distance. (2000 yards is 6000 feet, 1 nautical mile is 6080 feet, close enough for government work.) Divide 60 by the number of minutes it took him to travel that 2000 yards and you have the speed in knots.

When you think you're fairly good at that, reverse it - manual targeting off, no map contact updates on, now you have automatic targeting with no target on the map. Use the range and bearing display to draw lines on the map until you get comfortable with that, note the size of different targets at various ranges with the periscope hashmarks (both zoomed and unzoomed) until you have mental pictures that will tell you how big the target SHOULD look at any given range. For bearings on the map it's somewhat difficult since the map tool draws true compass bearings and the periscope shows relative bearings to the sub's heading. For that use the sonar dial, the outer ring is relative bearing and the inner ring is true bearing (example, if your sub is heading 325 the inner ring is rotated with 325 under the 0 on the outer ring, so if the target bears 290 relative the inner will show the true bearing lined up with that, 255). Use the ruler with the tool helper open (gadget that looks like a lensmatic compass, adds a compass to the end of the ruler) to measure out the range and bearing from your sub to the target. At the end of that line draw a 500 yard circle with the compass, then use the eraser to delete the line. Each circle you draw will give you a series of marks where the target was at each observation, a line drawn through those gives you the target track. Reason I use circles instead of the pencil X is circular probability of error, for plotting purposes the smaller the circle the more certain you are about the accuracy of the plot.

Get comfortable with measuring - plotting - estimating - calculating and then go back to full realism. Unless you have done some real life aerial and/or nautical navigation and/or target tracking, you're starting with a handicap so learn the basic use of the plotting tools with training wheels. :know:

Will give it a try. For the most part I do not have an issue getting into a good fireing position, usually end up 600 yards with the target moving at a 90 degree angle off my bow, so a good shot. Got the speed estimation down but the issue I have now is still cannot hit as I think I am having serious issues inputting the distance in choppy seas. Any ideas on alternatives to the stadiometer for inputting distance as it is useless in choppy seas.

[HertogJan]

So I tried this and it worked a charm :yeah: for the most part when the torps decided to work (not often :D ) and if the seas are not to violent. After a few tries managed to get some decent hits. A thing to note though I found is this only works for bow attacks. Cannot fire stern tubes this way, computer won't let you :down:

Yes you can... press 'E' that'll select the stern tubs then set scope to 180* and set a range (1000yrds should do), set AoB to 0 - send to TDC and speed to 0 - send to TDC then turn scope 10* and you're good to go.

As for stadimeter, manualy set depth between 45ft and 50ft, that'll help with swells and a clearer picture.

Premature detonations primarily happen when you fire them to close together or set torpedoes to magnetic in rough seas, at least it does in my game.

[Sniper297]

Answered this in the other thread;

http://www.subsim.com/radioroom/showpost.php?p=2179528&postcount=5

"press 'E' that'll select the stern tubs"

E in default game, unmodified keyboard mapping, is blow ballast. W cycles through the tubes.

[HertogJan]

Answered this in the other thread;

http://www.subsim.com/radioroom/showpost.php?p=2179528&postcount=5

"press 'E' that'll select the stern tubs"

E in default game, unmodified keyboard mapping, is blow ballast. W cycles through the tubes.


Ooh... euhm....:oops:
I'm so used to TMO I forgot how Stock works

[TG626]

http://youtu.be/djsJVsK1i54

(Too bad we can't embed videos) :(

[Sniper297]

Yeah, that's why I said "unmodified keyboard mapping", many are using modified.

I'm considering modding mine just to add CTRL to keys like E (Emergency Surface) S (Surface) and ; ("Snorkel Depth", which I have set to something like 8 meters for decks awash) since it's a bad idea to surface when you meant to change tubes (W) or open a tube (Q). The ; key is also dangerous, right next to the ' and under the P, you don't want to come up to decks awash instead of periscope depth or when you just meant to order rudder amidships. Any accidental surfacing from hitting a different key by m!$t@k3 can be hazardous, so CTRL added to any of those is a good idea.

[TG626]

My fav is reaching for time compression and firing a torpedo instead. (Numpad enter instead of +)

[Sniper297]

Yeah, CTRL ENTER would be better, but at least with that you just waste a fish instead of popping to the surface 1000 yards ahead of Yamato or something. :dead:

[HertogJan]

Yeah, CTRL ENTER would be better, but at least with that you just waste a fish instead of popping to the surface 1000 yards ahead of Yamato or something. :dead:

TG626, if you want to change that you can easily added it in the commands.cfg.

Copy and Past this line in and remove the other:

[Cmd313]
Name=Fire_torpedo
Ctxt=1
Key0=0x0D,c,"Ctrl+Enter"

[TG626]

That is a good idea. I've already got a custom commands.cfg that enables the crtl-w weather reporting.....

[Sniper297]

Thanks HertogJan, just hacked it for CTRL E, CTRL S, CTRL ; and CTRL ENTER. Now I just gotta get used to it, at my age I'll be sitting there with my mind in neutral waiting for a torpedo to hit when I never actually launched one. :doh:

Curious, the actual mapping is done by the Key0=0x0D part, the part in the parentheses is merely a description of the key. Can someone point me to a list of key numbers? Or is that hex, 0D being number 13?

[Sniper297]

Almost forgot, reading over the beginning of the thread;

"moving 90 degrees starbord to port across my bow, approx 600 yards distance. I fire 4 torpedoes...all miss! "


If you're at 90 degrees to the track and looking for a zero gyro angle shot the AOB at impact should be port 90 or starboard 90. The AOB at the moment of firing would be port (or starboard) 70 to 80, and the closer the target gets the more rapidly the AOB changes. With manual targeting you have to anticipate that by setting the AOB to 75 when the target is within 2000 yards, then when he's at the firing position it actually will be within 5 degrees of the actual angle, so center the scope on him and hit the "Send range and bearing to TDC" button once more then fire away. Otherwise if you're 1000 yards off the track you'll have AOB 40 still dialed in when you fire, with the actual AOB 70-80. The TDC would then be under the assumption that the target is heading toward you at that angle, and aim to hit where the target would be if it was actually proceeding on the calculated course.

Some observations on a liner with autotargeting, sub stationary 1000 yards off the track;

6000 yards - AOB 10
5000 yards - AOB 11
4000 yards - AOB 15
3000 yards - AOB 22
2500 yards - AOB 30
2000 yards - AOB 40
1500 yards - AOB 52
1250 yards - AOB 72

As you can see the AOB changes a lot faster the closer the target gets, so after the 2000 yard observation you should dial in something like AOB 75 (AFTER sending the info to the TDC on that observation) which will be pretty close to accurate when you make the actual firing observation. Again, important to have the outer doors open and send to TDC just before you fire, otherwise the TDC will calculate the angle based on yesterday's news.

[Nisgeis]

Curious, the actual mapping is done by the Key0=0x0D part, the part in the parentheses is merely a description of the key. Can someone point me to a list of key numbers? Or is that hex, 0D being number 13?

Search for 'ASCII' in google. e.g.: http://www.ascii-code.com/