Question about postion keeper?

[JT1981]

i am a new guy,my question is about the pk...

what the difference between the "true bearing to target" and "bearing to target"?

can someone give me a manual about pk of sh4?

[THEBERBSTER]

Hi JT

See my tutorial post #49 might be of interest to you.

http://www.subsim.com/radioroom/showthread.php?t=211804

Peter

[JT1981]

Originally Posted by THEBERBSTER

Hi JT

See my tutorial post #49 might be of interest to you.

http://www.subsim.com/radioroom/showthread.php?t=211804

Peter

thank you very much,i will read it

[TorpX]

Originally Posted by JT1981

i am a new guy,my question is about the pk...

what the difference between the "true bearing to target" and "bearing to target"?

can someone give me a manual about pk of sh4?

The "bearing to target" is the relative bearing. This means relative to your boat. 0 is always straight ahead, 180 is always behind you, regardless of what direction you are going.

The "true bearing" is relative to the earth itself. This means that 0 is always North, 180 is always South, etc.,etc.

The position keeper computes the position of your boat, and the target in real-time, and allows the TDC to update the firing solution. Without the PK, any firing solution it computes will only be good until the target, or your boat move an appreciable distance. This could be in mere moments. Note that it permits you to maneuver your boat, and conduct your approach dynamically, and this was a big advantage.

Players often tend to overthink the TDC (and the PK), and often don't use it to it's best advantage. It was a big advance for the modern fleetboats.

[Sniper297]

Simplest way to find the true bearing when the relative bearing is known is by looking at the sonar;




In this example the relative bearing is 090 (red line), since the sub isn't heading exactly north if you want the true bearing to draw on the chart with the protractor, you read that off the inner ring next to the relative bearing on the outer ring, in this example the true bearing is about 067 degrees true. If the relative bearing was 154 (white pointer) the true bearing would be 128.

As for the PK (Position Keeper) click the little white button on the lower right corner and it will turn red. Assuming the target is not zigzagging and doesn't change course or speed, the TDC will continue to update the calculated position of the target while the periscope is down and you can no longer see the target, or allow you to unlock and rotate the periscope to look around while still tracking the target. Advisable to click the red button to deactivate the PK before firing, then get a new lock on the target so the data is more accurate. And don't forget to open the torpedo tube outer doors at least five seconds before firing, otherwise it will automatically open the outer doors then fire when the solution is outdated, practically guaranteeing a miss.

[THEBERBSTER]

Hi JT

I use this method if the target is not zig zagging.

Get the targets speed.

Get the targets course line using the ruler (TCL)

Put a 90ᴼ protractor angle on the TCL.

Move the sub on to it.

When stopped position the protractor to the subs middle.

Move the 90ᴼ protractor angle 10ᴼ to the left or right depending which way
the target is coming to give you 80ᴼ AOB.

Your periscope firing position will either be 10ᴼ or 350ᴼ

Lock the target.

Use the ID icon to identify the target and send the mast height to the TDC.

Unlock the target.

Set up the torpedoes.

Use the Q key to open the doors.

With the ruler draw from the sub’s middle down the 80ᴼ line to the TCL to get the Range.

Put your periscope bearing on 10ᴼ or 350ᴼ and enter the Range, Speed and AOB in to the TDC pressing the Red Button each time.

When the target gets nearer pause the game and recheck your TCL and adjust if necessary.

The only change usually needed is the range and at this point I add 25 to the new range.

Lock the target and lower your periscope a bit so you can still track it.

When the target moves to periscope bearing 10ᴼ or 350ᴼ press the Position Keeper and F6 to see your firing position on the attack map.

I am usually accurate enough to fire the torpedoes.

If you feel you need more time then change 80ᴼ to 70ᴼ = 20ᴼ or 340ᴼ periscope bearing go to F6 to check your firing solution and you will still have time to make any adjustments should you need to.

You do not need to use the stadimeter with this method.

Hope this gives you a better idea of what to do.

Peter

[JT1981]

Originally Posted by TorpX

The "bearing to target" is the relative bearing. This means relative to your boat. 0 is always straight ahead, 180 is always behind you, regardless of what direction you are going.

The "true bearing" is relative to the earth itself. This means that 0 is always North, 180 is always South, etc.,etc.

The position keeper computes the position of your boat, and the target in real-time, and allows the TDC to update the firing solution. Without the PK, any firing solution it computes will only be good until the target, or your boat move an appreciable distance. This could be in mere moments. Note that it permits you to maneuver your boat, and conduct your approach dynamically, and this was a big advantage.

Players often tend to overthink the TDC (and the PK), and often don't use it to it's best advantage. It was a big advance for the modern fleetboats.

thank you,the pk is very helpfull on targeting only one boat...and if the boat is heading to the North,the "true bearing" and the bearing will be the same,am i right?

and when the data(range,aob and speed) is set up,i could down the periscope,and keep approching the target,,sometime later,when the time is right,up the periscope and read the data of the pk,,if the "bearing of the target" what i read from the pk is the same to periscope's bearing,,,,,,my fireing solution will be right,,am i right?

[Crannogman]

Originally Posted by JT1981

thank you,the pk is very helpfull on targeting only one boat...and if the boat is heading to the North,the "true bearing" and the bearing will be the same,am i right?

and when the data(range,aob and speed) is set up,i could down the periscope,and keep approching the target,,sometime later,when the time is right,up the periscope and read the data of the pk,,if the "bearing of the target" what i read from the pk is the same to periscope's bearing,,,,,,my fireing solution will be right,,am i right?

Pretty much

[TorpX]

Originally Posted by JT1981

thank you,the pk is very helpfull on targeting only one boat...and if the boat is heading to the North,the "true bearing" and the bearing will be the same,am i right?

Yes.

and when the data(range,aob and speed) is set up,i could down the periscope,and keep approching the target,,sometime later,when the time is right,up the periscope and read the data of the pk,,if the "bearing of the target" what i read from the pk is the same to periscope's bearing,,,,,,my fireing solution will be right,,am i right?

Ideally, yes, but any inaccuracy in your solution will tend to increase over time. Let's say you input range, speed, Aob, and bearing into the TDC, and all are accurate except the speed is half a knot low. The TDC will update the solution, but the updated position will fall behind about 50 ft. per minute. If you didn't correct this over the course of several minutes, it could be very significant, but if you only go a couple minutes, it might not matter much.

I know this may be a little too much information, but I think it is worthwhile for people to know how the actual TDC's were operated. As they started tracking a target, estimates of speed, Aob, range, and bearing are fed into the TDC at every observation. Initially, these estimates, based on long range observations, were likely to be inaccurate. As more observations are made, the corrections required would be less, and this would lend confidence that the solution is good. Note that both the target and the boat would likely be altering course as this process unfolds, so it wasn't a quick, cut and dried matter. Once the skipper considered that conditions were favorable, the torpedoes could be launched at any time. It wasn't necessary (or even desirable imo), to alter the set-up to a certain angle/track, nor was it required to launch when the target reached a certain bearing. (Many players become fixated on getting a "perfect" 90 degree, or whatever, track angle.)

I should also point out that the RL TDC had no provision for turning off the position-keeper. In fact, it was somewhat more complicated than the game version we use.

[JT1981]

Originally Posted by TorpX

Yes.

Ideally, yes, but any inaccuracy in your solution will tend to increase over time. Let's say you input range, speed, Aob, and bearing into the TDC, and all are accurate except the speed is half a knot low. The TDC will update the solution, but the updated position will fall behind about 50 ft. per minute. If you didn't correct this over the course of several minutes, it could be very significant, but if you only go a couple minutes, it might not matter much.

I know this may be a little too much information, but I think it is worthwhile for people to know how the actual TDC's were operated. As they started tracking a target, estimates of speed, Aob, range, and bearing are fed into the TDC at every observation. Initially, these estimates, based on long range observations, were likely to be inaccurate. As more observations are made, the corrections required would be less, and this would lend confidence that the solution is good. Note that both the target and the boat would likely be altering course as this process unfolds, so it wasn't a quick, cut and dried matter. Once the skipper considered that conditions were favorable, the torpedoes could be launched at any time. It wasn't necessary (or even desirable imo), to alter the set-up to a certain angle/track, nor was it required to launch when the target reached a certain bearing. (Many players become fixated on getting a "perfect" 90 degree, or whatever, track angle.)

I should also point out that the RL TDC had no provision for turning off the position-keeper. In fact, it was somewhat more complicated than the game version we use.

I am a new player,and now,i have used some mods,the list is below:
1_TriggerMaru_Overhaul_2-5
2_RSRDC_TMO_V502
3_RSRDC_V5xx_Patch1
4_1.5_Optical Targeting Correction 031312 for RSRDCv502
5_1.5_OTC for 8 to 5 Aspect Ratio RSRDCv502
6_Webster's Real Lifeboats Fix for v1.5
7_sobers better sand II
8_sobers better rock Ver 2 mod
9_Fixed Zero Bomb Load RSRDC
10_TMO_Visuals_for_RSRDC

today,i have found a ijn's merchant,Akita Maru,and i use the stadimeter,and read the range is 700m,(but the real distance is 1400m),,,so i estimate the speed ,which is 5knots,(but real speed is 8knots).....i fired many terpedos,,but nothing...so i rechecked the data from sonar,,i found the reason why i cant hit,,,because the distance is not right...

i resume the game,and begain a sub school mission,,the torpedo training mission,,,i used the stadimeter to estimate the range of the crusier,,but this time the range is correct....i am confused....why....

and how could i fix the error of the stadimeter?

sorry about my english...thanks!!

[JT1981]

Originally Posted by TorpX

Yes.

Ideally, yes, but any inaccuracy in your solution will tend to increase over time. Let's say you input range, speed, Aob, and bearing into the TDC, and all are accurate except the speed is half a knot low. The TDC will update the solution, but the updated position will fall behind about 50 ft. per minute. If you didn't correct this over the course of several minutes, it could be very significant, but if you only go a couple minutes, it might not matter much.

I know this may be a little too much information, but I think it is worthwhile for people to know how the actual TDC's were operated. As they started tracking a target, estimates of speed, Aob, range, and bearing are fed into the TDC at every observation. Initially, these estimates, based on long range observations, were likely to be inaccurate. As more observations are made, the corrections required would be less, and this would lend confidence that the solution is good. Note that both the target and the boat would likely be altering course as this process unfolds, so it wasn't a quick, cut and dried matter. Once the skipper considered that conditions were favorable, the torpedoes could be launched at any time. It wasn't necessary (or even desirable imo), to alter the set-up to a certain angle/track, nor was it required to launch when the target reached a certain bearing. (Many players become fixated on getting a "perfect" 90 degree, or whatever, track angle.)

I should also point out that the RL TDC had no provision for turning off the position-keeper. In fact, it was somewhat more complicated than the game version we use.

You said half a knot?i thought the speed in the game is all integer,,am i wrong?i have tried in the game,set 8.5knots,but the pk shows 9knots...there is not half a knot can be set...

[razark]

Originally Posted by JT1981

You said half a knot?i thought the speed in the game is all integer,,am i wrong?i have tried in the game,set 8.5knots,but the pk shows 9knots...there is not half a knot can be set...

The display will only show whole numbers, but if you set the target's speed to 8.5, it will use 8.5 for the calculations.

[JT1981]

Originally Posted by razark

The display will only show whole numbers, but if you set the target's speed to 8.5, it will use 8.5 for the calculations.

you mean the ship in the game will sailling in 8.5(or some speeds like this),i usually set speed to whole numbers,,,,

[razark]

Originally Posted by JT1981

you mean the ship in the game will sailling in 8.5(or some speeds like this)

Correct.

[TorpX]

Originally Posted by JT1981

You said half a knot?i thought the speed in the game is all integer,,am i wrong?i have tried in the game,set 8.5knots,but the pk shows 9knots...there is not half a knot can be set...

As razark said, ships can have speeds other than integer values. Even if you wanted ships to always have integer speeds, the speeds would be changing whenever they turned or changed speed. Weather would make them loose a little, sometimes.

I don't know why the game displays are so sloppy, but it seems to permeate the game. Like when you set your own speed to 10 knots, and your crew says it is 9 knots, or when you are rotating the hydrophone heads, the bearing indication can be either 0 or 360. The game seems to have trouble with rounding values.