[REL] Radar Training for Nisgeis' 3D TDC and Radar Range Unit UPDATED: 7/31/10

[bowfin]

The outside circle is relative target bearing. 302 this goes in the TDC.
The inside circle is true bearing. 235 this can be used on the map for plotting...



The ruler tool helper is in true bearing. Start the ruler on your sub and when the line goes through 235 you have the bearing. Using true bearing for plotting takes less steps and introduces less error into your plot.
But the TDC still NEEDS the relative bearing !

[Nisgeis]

Relative means relative to your own boat, with 000 being your own bow, so a target that is at a relative bearing of 090 is on your starboard beam when you are pointing North. If your boat were turned without moving forward or backward through 180 degrees to point due South, then the target would be be at a relative bearing of 270. The True bearing doesn't change, as that's taken relative to North, with North being 000, so with your boat pointing North, the true bearing would be 090 and with yout boat pointing South, the target would still be at a true bearing of 090.

[Roger Dodger]

Originally Posted by I'm goin' down

Are you saying the bearing displayed on the ceiling of the A scope is the true bearing? That appears to be what you mean to say.

If that is the true bearing, I wonder why the periscope view is referred to as the relative bearing. It seems that the periscope view is more accurate (i.e. true) than the true bearing you describe.

If I understand you, it is a good shortcut unless Nisgeis says you are crazy, or something like that.

Ship courses are given in True (Magnetic) bearings. The Periscope gives you the Relative (your bow = 0 degrees) bearings. Radar Bearings are also given in Relative bearings.

If the target bearing is 90 degrees (relative), then the target is 90 degrees to the right (off your bow) from your heading, no matter what your true course is.

When plotting the target's course, use the ruler with the compass open to get a True course. Start your line at your first mark, then continue through the rest. Read the true course right on the compass. You then plot the target's true course into the TDC which should give you the AOB. Your own gyro repeater (ship's compass) will auto update the TDC with your course (true).

If that isn't correct, then someone send me to the boatswain's locker for a pint of realative bearing grease.

[I'm goin' down]

Bowfin. You confused me. I understand relative and true bearing. All you are saying, aren't you, is that when you have plotted two, three or four range and bearing readings, you can use the compass/ruler tool to draw the target's true course on the Nav Map? I knew that, and it is very old news. However, if you are using the compass/ruler tool to plot the various bearings and ranges, which I believe you cannot do (note that Mr. Channing recommends using the protractor tool and the ruler [or compass/ruler] tool for plotting the varioujs range and bearing readings), then you have lost me. My short answer to your post is that it did not occur to me that you were offering an explanation to a question I did not pose. Using the compass/ruler tool to draw (plot?) true course is well established.

Nisgeis and Roger/Dodger - thanks for the explanations, but Bowfin lost me in his translation. See the paragraph above. BTW-- good explanations of true course vs. relative course in any event.

Nisgeis, I posted 3 questions above. Provide me whatever information you can muster, please.

p.s. I am at the Battle of the Philipine (spell?) Sea in TMO2.0/RSRDC. My boat is pointing in the wrong direction. The task force on radar is at 26,650 yds. at 185 degrees. Hmm. Aft tubes? Pretty scary for my first action with map contacts off! I may turn the boat...

[sergei]

Originally Posted by I'm goin' down

First, in Channing's tutorial he notes that after plotting 3 or 4 entries one has determined the target's preliminary range, course and speed. Actually, you one has not determined preliminary speed. One has determined preliminary range and course only. I think the comment re speed is a mistake

Sure you have.
You have a nomograph, don't you?
It's on the right of your nav map.

Take a note of what time you start the plot. Then whenever you add a mark, measure the distance from the first mark to the current mark, note the elapsed time, and use the nomograph to estimate speed.
This is how I have been estimating speed, with very good results.
No need to mess around with the stopwatch, or estimate speed button, or make your plots exactly 3 minutes apart.
Also has the advantage that over time, as the plot develops, it will tend to become more accurate, as minor deviations in the plot become less important.

[I'm goin' down]

I used to have a nomograph on my Nav Map, but I am using nisgeis "brilliant" torpedo angle calculator mod, and it canceled and disabled my poor nomograph. Just kidding! I couldn't resist....

re your post:

Excellent idea! Very good post and a great tool I never thought to apply in this situation. The three minute rule re plotting on the Nav Map is not workable in my opinion. Too much plotting, and dealing with the stop watch is too confusing given that you are also plotting at the begining and end of the 3 minute period. The Nomograph, on the other had, is fast and EASY. I can rest easy now, confident that tomorrow will be a bad day for the bad guys.

[Mescator]

Originally Posted by sergei

Take a note of what time you start the plot. Then whenever you add a mark, measure the distance from the first mark to the current mark, note the elapsed time, and use the nomograph to estimate speed.
This is how I have been estimating speed, with very good results.
No need to mess around with the stopwatch, or estimate speed button, or make your plots exactly 3 minutes apart.
Also has the advantage that over time, as the plot develops, it will tend to become more accurate, as minor deviations in the plot become less important.

Actually i've been meaning to ask for clarification on that. How on earth do you read it? I've been sort of figuring parts of it out myself after reading the tutorial once and that's the one thing i never figured out lol.

Also, how do you guys get a course? Once i have a few plot point's i just use the compass with the ruler and figure the course out with that but i never get it perfectly accurate. I saw someone using a different method so i figure I'm probably butchering the process.

I've got it down accurate enough to fire on someone with only very minor visual adjustment's via periscope once they are in range regardless, which is still fantastic. Again, props Nisgeis!

[sergei]

Yeah.
The thing about the 3 minute rule is that unless your plots are extremely accurate, you can easily get an error of a few hundred yards, which will translate to an speed estimate error of one or two knots (or even more!).
Easily enough to miss the target.

If you are measuring the distance travelled in for example 20 minutes, an error of a few hundred yards is going to have a negligible effect.
If the plot ends up taking an hour, or more (quite likely), then an error of several hundred yards will have virtually no effect at all on your speed estimate.

Originally Posted by I'm goin' down

I can rest easy now, confident that tomorrow will be a bad day for the bad guys.

Good luck IGD, go get 'em

[I'm goin' down]

Originally Posted by Mescator

Actually i've been meaning to ask for clarification on that. How on earth do you read it? I've been sort of figuring parts of it out myself after reading the tutorial once and that's the one thing i never figured out lol.

Also, how do you guys get a course? Once i have a few plot point's i just use the compass with the ruler and figure the course out with that but i never get it perfectly accurate. I saw someone using a different method so i figure I'm probably butchering the process.

I've got it down accurate enough to fire on someone with only very minor visual adjustment's via periscope once they are in range regardless, which is still fantastic. Again, props Nisgeis!

I am too tired to give an explanation of the Nomograph. It is easy and someone can post a screenshot that will explain it.

As for true course, it is very easy. Assume you have two plots of range and bearing that are accurate. Open the compass/ruler tool and drag the tool from the first plot to the second plot. You will note that the compass is is part of the open tool. Read where the line you have drawn intersects the compass as you drag it -- that is the true course. E.g. A line running from east to west (i.e. from 270 degrees to 90 degrees is on a course of 90 degrees. A ship on traveling on that line has a relative heading of 0 degrees and a true course of 90 degrees. Note that the line on the compass/ruler tool intersects the compass at 90 degrees.) See the screenshot by Bowfin and note where the line intersects the compass. The intersection point is the true course.

[sergei]

Originally Posted by Mescator

Actually i've been meaning to ask for clarification on that. How on earth do you read it?

Give me a few minutes, I'll take some screenies and post an explanation.

[sergei]

The nomograph is basically a calculator.
You have 3 variables in this calculator - time, speed and distance.
If you know any two of these values, you can quickly and easily calculate the third, by just lining up the known values with the ruler.

Example - calculating speed.

I know my target has travelled 6000 yards in 15 minutes.
Take the ruler, start on the 15 minute mark, drag it over the 6000 yard mark, and extend it past the speed estimate line.



As you can see, my target has a calculated speed of 12 knots.

Oh man, how easy was that!

Example 2 - time to intercept

I know a task force is headed my way. It's making 20 knots, and is about 6 miles away. So that I don't panic, I want to know how much time I have to prepare.

Take the ruler, start on the 20 knot mark and drag it through the 6 mile mark.



I can see from my calculation I have about 18 minutes before they run over me.

The nomograph, a massively useful tool - don't leave home without it.

[bowfin]

Sorry about that. I wasn't trying to answer anyone's question. I just noticed that JC was plotting range and bearing with protractor and ruler using relative bearing off the subs course. I do indeed plot range and bearing with just the ruler and true bearing. It was just a tip to anyone that might find it easier and didn't know you could do it that way. It saves time and messing about... There is so much to learn. I am always learning new ways of looking at it not trying to confuse anyone

[Mescator]

@ I'm goin down. Thanks for Clarification. That's basically what i was doing, so i'm glad i got that right.

@ Sergei, Many thanks. It's one of those thing's that's really so simple once it gets pointed out to you. I appreciate the help

[John Channing]

Originally Posted by I'm goin' down

Uoading of screenshots turned into a disaster. I quit trying.

Here is an update. I figured out the 3D TDC target course setting protocol. In determining a target's course I do not know why one would fiddle with the target dial on the upper left of the 3D TDC by dragging the white triangle to match its plotted course. That dial appears useless when initially inputting a target's course. The dial that initially affects the target's course is the target dial on the upper RIGHT of the 3D TDC. That is what worked for me. First, I open the stadimeter to the Aob dial. Second, I open the 3D TDC and set the target's course via the target dial on the upper RIGHT. Third, I open the the stadimeter's Aob dial and send the target's course to the TDC. Fourth, I open the 3D TDC to verify it has accepted the data re the course change. If the course change has been accepted, the target dial on the upper left on the 3D TDC snaps to the new course. If this procedure is correct, then I have solved the target course problem I was having. I used this procedure to sink the slow target in the the third training mission.

Here are some other questions and comments.

First, in Channing's tutorial he notes that after plotting 3 or 4 entries one has determined the target's preliminary range, course and speed. Actually, you one has not determined preliminary speed. One has determined preliminary range and course only. I think the comment re speed is a mistake.

Second, what is the point of turning the radar off. Two times in the tutorial, the reader is instructed to turn radar off. His initial instructions notes that turning of radar is an important step. I do not understand why or the importance of doing so. It this instruction necessary or important?

Third, and this is a major question. The tutorial instructs the reader to set speed via the 3 minute rule. This is a pain the ass, and using the stop watch in combo with range/bearing readings is not precise because you are taking a range and bearing, starting the watch, switching screens to plot, switiiching screens to send the range, and at the end of three minutes, doing it again. Question No. 3: Why can't the reader rely on the watch button on the stadimeter speed dial, take two range and bearing readings, and rely the radarman's calculation of speed? I believe URGE or Hitman noted that this was an alternative. I would save time and needless plotting.

Once the TDC is in operation, one can verify if the course is accurate on the Attack Map. If it appears inaccurate, additional range and bearing readings will assist in providing correct information. If range is the only issue, one can adjust it via the range dial on the stadimeter.

I note that I missed six shots at the second tanker in the Mission 3 tutorial (the one approaching from 70 degrees starboard), but not by much. The tanker approached fairly quickly, and I was compelled to turn my boat 90 degrees to starboard to have a better (but not great) angle for an attack. I measured the tanker's speed at 14.25 kts. which was probably too slow. Its course was 220 degrees which appeared fairly accurate. The shots missed aft of the tanker by a few hundred yds. The problem here was the closing speed of the tanker, as it was passing my boat before I had a completed the set up. If I had spotted it at 20K yds. rather tan 12K yds., I might have fared better. Comments are appreciated.

I had map contacts on during this exercise, but my range and bearing for both tankers (the slow and faster one) we accurate. I simply had more time to set up for the slower target, plus I used the speed announced by the radarman for the slower target and I used the 3 minute speed rule for the faster one.

OK... let's deal with some of your unanswered questions.


1) The only reason for using the "Target " dial is that it makes the outer arrow on the "Target Course" dial move much faster than just clicking in the "Target Course" dial. You can get to the speed quicker. If just working with the "Target Course" dial works for you, go with it.

2) Already answered (and call me John )

3) Part 1- There is a bug in the game that when you leave the radar "station" it will go from "Focus" to "Sweep" mode. There is no way to prevent it. Turning off the radar means the radar bearing sweep will stay in the position that it was in when you turned it off. In fast developing scenarios you don't want to waste time finding your blips!

Part 2- Sometimes I find the "watch button" unreliable. It's important to note that even today they till have a full manual tracking party developing a solution alongside the BSY Series combat systems. Having two systems mens better results. OK... it a personal thing. I don't trust some of the game mechanics.

Lastly if you have a rapidly closing target just move to about 1200 yds off his track and change your course to match his and match his speed. Now he isn't closing anymore and you will have all the time you need. Once you are happy with your solution slow down, change course to close his track, submerge and shoot.

JCC

[Nisgeis]

Originally Posted by bowfin

Sorry about that. I wasn't trying to answer anyone's question. I just noticed that JC was plotting range and bearing with protractor and ruler using relative bearing off the subs course. I do indeed plot range and bearing with just the ruler and true bearing. It was just a tip to anyone that might find it easier and didn't know you could do it that way. It saves time and messing about... There is so much to learn. I am always learning new ways of looking at it not trying to confuse anyone

I thought your explanation was very clear and very helpful. The previous version of the radar mod had the radar train bearing indicator (the thing in your first screenshot) calibrated accurately, as the stock one is quite badly off as the textures aren't centred, so you'll get errors creeping in if you read the values off it of a couple of degrees in some cases, which can cause problems with your plot.

Would it help if I put in some digital readouts of the true bearing? The way the real indicator worked (with the concentric dials) was good, but the eye's resolution is far greater than what you can show easily and clearly on the screen.

Originally Posted by John Channing

1) The only reason for using the "Target " dial is that it makes the outer arrow on the "Target Course" dial move much faster than just clicking in the "Target Course" dial. You can get to the speed quicker. If just working with the "Target Course" dial works for you, go with it.

As this dial seems to be causing some confusion, I'm thinking about remodelling it. First, to give the proper AOBs rather than just the visual indication you get now and second to add a pointer, that will go the other way that will point to the target course. E.G. if you queue a change of the AOB from 70 starboard set to 50 degrees starboard, then one pointer would go to 50 Degrees Starbaord and one pointer would go 20 degrees in the other direction to point at the new course. I think this would be clearer. Any thoughts on this anyone? This is an evolving project after all.