sonar overlay tutorial (finished, edited)

[greyrider]

SONAR OVERLAY AND TARGET COURSE SOLVER

INTRODUCTION

The following pages will demonstrate the sonar overlay and target course solver, that can be built on the
map, which represents the maximum listening range of the hydrophones. The sonar overlay will help you
see with your eyes, by plotting, what you hear with your ears, in the hydrophones. The sonar overlay
will help you establish bearing, range, and speed estimation, and the target course solver will solve
for target course, long before the target ship becomes visual. This can usually be accomplished at
ranges over 15 km away.

HYDROPHONE RANGE

The maximum range of the hydrophones is 34 kilometers. This is the maximum range that you, when
manning the hydrophones can hear out to. Your sonar operator will not hear very long range screw
sounds.

RELATIVE BEARINGS

The sonar overlay is placed on the map, with north, or 0 decrees relative to the u-boats north, or
its 12 oclock. This orientates the sonar overlay compass rose to the bearing dial of the hydrophones,
so that the sound bearing from the hydrophones, can be plotted, on the correct bearing on the map

SONAR OVERLAY

Below is a picture of the sonar overlay, composed of ten concentric circles. Each range circle
has a distance of 3.4 km. From the innermost circle to the outermost circle, the ranges are;
3.4 km, 6.8 km, 10.2 km,13.6 km,17 km,20.4 km,23.8 km,27.2 km,30.6 km, and 34 km. The
range circles are drawn using the compass tool. To build the sonar overlay , first make ten range
circles, at the aforementioned ranges above in this paragraph. Point all ten arrow lines in the same
direction of each range circle. I usually like to point these arrow lines away from the expected target
avenue of approach. Once all range circles have been drawn, zoom into the map , with the highest
magnification possible, then drag the 3.4km range circle, and place it at the center of the u-boat
icon, and align the arrow line along the stem of the u-boat icon. Then you repeat the process
with the rest of the range circles, placing them on top of each other over the u-boat icon. If
the circles have been drawn and placed correctly, the arrow line of the range circles will look
like one line only, as shown below, if not drawn correctly, the arrow line will appear heavy, or thicker.
So once the sonar overlay compass rose has been drawn correctly, the next thing we need to do
is to draw a norh/south line, and an east/west line, relative to the u-boat, of 68 kilometers long,
with the ruler tool of the map.
Sixty eight kilometers is the maximum listening diameter of the
hydrophones. Use the arrow line of the range circles to help you draw a straight north/south line,
for the east/west line, zoom in to the map, and use smaller, intermediate straight lines, then zooming
out , extend it to the range of sixty eight kilometers in length. erase any intermediate lines drawn
after the east/west has been drawn, to keep the sonar overylay as clean as possible.



Continuing the construction of the sonar overlay, the next step is to draw the bearing tool.The bearing
tool is drawn with the protractor tool of the map, and is the movable part of the sonar overlay. Click on the
protractor tool, and draw the bearing tool at the top of the north/south line, at the 34 km range. Bring the line
down straight, and anchor the protractor tool at the center of the u-boat icon. Then, extend the angle line of
the protractor tool back out to 34 km, and click it to make it permanent. Then zero the bearing tool at zero
decrees. After this has been done, the sonar overlay is ready to use. The picture below is the sonar
overlay with the bearing tool highlighted and ready to be dragged to any bearing on the sonar overlay
compass rose.



Allright, now that the instructions for building the sonar overlay has been written, its now time to have a go
at it and use it to track, plot and destroy a target ship. This will be demonstrated in the pages following.

1ST PLOT

07:10 The captain, "you", manning the hydrophones, scans the circumference of the listening range with
the hydrophones, scanning and rescanning, then over a bearing just scanned, he picks up low speed
screw sounds at bearing 311, long range, speed unknown, but turncount is 43 RPM. The target has just
entered the hydrophone listening range at 34 km. Looking at thebearing speed chart , produced by
cpt_nautilas, our target can be one of four ships, the small tanker at 8 knots, the t-3 tanker at 15 knots,
the troop transport at 10 knots, and the passenger liner at 17 knots. This means we would have to plot
for four different speeds. But the wise old captain rules out the troop transport, he's in the middle of the
atlantic, and he does not hear high speed screws travelling with the merchant. Now there are only three
ships to plot, but because this is a training aid, phase III of the sound trainer, i will eliminate the other
two ships, so that we can concentrate on the plots, without distractions. The target is a t-3 tanker, and its
not that difficult to plot for multiple ships with TSD solutions, eventually the TSD solutions, of the four
plotted ships, would make it evident which ship is the real target.
So again, at 07:10, sound contact at bearing 311. This is plotted in two steps on the sonar overlay. First,
click on the protractor, then click the bearing tool, and drag the bearing tool over to bearing 311, your
bearing tool will have a readout of 49 decrees. ( 360 - 49 = 311) See the picture below.



Next, click on the marker tool of the map, and mark the target at bearing 311, at 34 km.
See picture below.



TARGET COURSE SOLVER AND ANGLE FINDER BEARINGS

The target course solver and angle finder tool, which will be demonstrated, is used to find the targets course
after two or more position plots for the target have been plotted. The course solver tool is set up on the first
target position plotted. The first position plot is the pivot point, for finding the targets course from true north.
The bearings given by the course solver readout, are always given as true bearings.

TARGET COURSE SOLVER AND ANGLE FINDER

Once we have the targets first position plot, we can add the target course solver and angle finder tool to our plot. The instructions to build the target
course solver and angle finder tool is pretty easy. Click on the ruler tool of the map, then draw a north/south line threw the center of the target
position, ( mark 1 ). Make the straight line about 20 km, 10 km north of the mark, 10 km below the mark, as the picture below indicates.



To complete the target course solver and angle finder tool, we must ad the angle finder. Click on the protractor tool of the map again, anchor the
protractor tool on the top of the north bound line at 20 km, draw a straight line with the protractor tool all the way to the center of the targets
position mark, anchor the protractor at the center, then extend the protractor to make an angle, the click to make it permanent, then zero it, as the
picture below demonstrates.



So far, what we've got is our tools in place for plotting target information, a sound bearing at bearing 311, range 34 km, turncount 43 rpm,
course unknown, speed unknown.
end of part I

2nd plot

07:30 Twenty minutes have now passed since the first position plot of the target. Great bearing changes take time to develope at very
long ranges, twenty minutes should cause enough of a bearing change to take another position plot of the target. This is also
a good amount of time that can be time compressed, if you don't want to play in real time. So , after twenty minutes the captain
takes another sound bearing. Laying the bearing needle of the hydrophone bearing dial on the strongest sound bearing, the
captain identifies the sound bearing of the target to be 306 decrees, and closing, because the screws sounds are getting
louder. The first step to take in the second plot is to drag the bearing tool over to bearing 306. After dragging the bearing tool
over to bearing 306, the bearing tool readout will be 54 decrees. (360 - 54 = 306 ). see picture below.



The target is somewhere on our bearing line of 306 decrees, but where? Using the speed/rpm charts, and TSD calculations, we can pinpoint the
targets location along bearing 306. Before we can plot the targets position, we need to know how far it travelled in 20 minutes.
T-3 tankers, with an rpm turncount of 43 rpm, make a 15 knot speed. Now that we have the speed of the target ship, using a TSD calculation, we can
determine the distance travelled by the target in twenty minutes. Using the formula, SPEED X TIME / 60, we observe that the target travelled 9.26 km
in 20 minutes. (15 x 20 / 60 = 5 nm ), convert to km, and it travelled 9.26 km.

T= 20 MINUTES
S=15 KNOTS
D=9.26 KM

Now, with the ruler tool of the map, we need to measure a distance, from the center of the first position plot of the target, 9.26 km, along bearing line
306 decrees. Click on the ruler tool, anchor the ruler tool at the center of the target position mark, ( mark 1 ), and measure a distance of 9.26 km,
along the bearing line of 306 decrees. See picture below.



The next step of the second plot is to mark the targets new position with the marker tool of the map. Click on the marker tool, and mark the targets
new position where the distance measurement line intersects with the bearing line of 306 decrees. See picture below.



After the targets new position has been marked, erase the distance measurement line of 9.26 km, to keep the sonar overlay clean, zero the bearing
tool. See picture below.



Now that we have the targets new position plotted, we have this much information;

bearing = 306 decrees
speed = 15 knots
range = 24.74 km
course = unknown

At this point in the plot, we actually have enough information to establish target course.

end of part 2

TARGET COURSE SOLVED

With two target position plots available to work with, we can plot for target course using the target course solver and angle finder tool.
Click on the protractor tool of the map, then click the angle finder tool of the course solver. Drag the angle line of the angle solver threw
the center of the second position plot of the target. Extend the angle line beyond the u-boat into the right lower quadrant of the sonar
compass rose. Click it to make it permanent.The course solver readout reads 144 decrees. So the target is travelling on course
144 decrees. See picture below.



Now that we have plotted for target course, we now have this much information on the target;

bearing = 306 decrees
speed = 15 knots
range = 24.74 km
course = 144 decrees

We now have all the vitals to attack the target ship, and the sonar operator hasn't heard a thing. We could get going now, and maneuver
the u-boat into an attack position, somewhere along the target course line, but we will wait awhile longer, and wait for the sonar
operator, to hear the target and give us his report.

end of part 3

CLOSEST POINT OF APPROACH

So the captain decides to wait for sonar to give a report before he moves out, but in the meantime there is work to be done. He wants to
know his closest point of approach, where he will attack the enemy ship. He clicks on the protractor tool of the map, and draws a
90 decree angle on the sonar overlay, and drags one leg of the triangle, and places the leg over the targets course line. He draws the other
leg of the triangle and points it to the center of the u-boat. This is the closest point of approach and the course the u-boat will take to
approach the targets course at a 90 decree angle. See picture below.



Measuring the distance between the u-boat and the targets course line with the ruler tool along the northeast leg of the CPA triangle, is 7.4 km.
The u-boat will not be able to make the CPA submerged in time, it will have to surface at flank, and come to course 233 in order to meet the angle
requirements of the captain. See picture below.



end of part 4

3RD PLOT, SONAR OPERATOR HEARS TARGET

07:51 Sonar finally delivers the message the CO has been waiting for. The SO announces with urgency, "Sound contact sir ! Merchant
moving fast, closing, bearing 296 ! Long range."

Moving fast said sonar, had we continued to track the three other possible ships the target might have been, two would have been
wiped off the map after the sonar report, the small tanker, and the troop transport, as they were making a medium speed.

So now we must plot the targets new position. we plot by repeating the two step process, first swing the bearing tool to bearing 296.
The bearing tool readout will read 64 decrees. (360 - 64 = 296 ). See picture below.



Mark the target using the marker tool of the map where the bearing line of 296 intersects with the target course line. See picture below.



Quickly glancing at the targets new position, ( mark 3 ), we approximate the range to target to be about sixteen kilometers. But the u-boat cannot
attack the target in its current position, the u-boat will have to move to the CPA.
The captain now wants to know how far the target is from the CPA, and its ETA to the closest point of approach. By computing the targets eta,
we will also know how much time we have to maneuver into attack position for a submerged attack The estimated time of arrival of
the target should also be the time of torpedo impact.

end part 5

TARGET ETA TO CLOSEST POINT OF APPROACH

We begin with a distance measurement on the sonar overlay. With the ruler tool of the map, we draw a straight line from the center of mark three,
( targets current position ), along the targets course line, and anchor the ruler tool where the u-boats course to cpa intersects the target course
line. A distance of 14.2 kilometers is measured. Now all we need to do is one TSD calculation, this time solving for time.
Using the TSD calculation for time: DISTANCE / SPEED = TIME, we plug in our numbers, (14.2 km / 15 knots = 30.64 minutes ).

T = 30.64 MINUTES
S = 15 KNOTS
D = 14.2 KM



The target will arrive at the cpa at 08:21 hours. The target should be at zero decrees , and 08:21 should also be torpedo impact time. The commander
wants to know his own ETA to the cpa, he figures for the maximum speed of 17 knots flank speed surfaced, and 7 km distance.
Using the TSD formula for time, DISTANCE / SPEED = TIME, ( 7 KM / 15 KNOTS ) = 15.11 minutes. The u-boat can delay departure to cpa no
later than 08:06 hours.

The CO orders a last minute check on the u-boats course to the cpa. Dragging the bearing tool of the sonar overlay on top of the northeast leg of the
cpa triangle, to course two three three. The bearing tool readout reads 127 decrees. ( 360 - 127 = 233 ).



Now that all the TSD calculations have been done, and last minute checks on crew and equipment, the u-boat is ready to maneuver into position
and attack the merchant. " Lets roll, ahead flank, surface the boat, come to course two three three."

U-BOAT IN ROUTE TO CPA



end part 6

VISUAL SIGHTING !

08:07 The u-boat is on the surface, racing toward the cpa at 17 knots, tho not entirely on course 233, course 232 or 231 maybe. The co will
try to correct the course, as he approches the cpa, but for now, he is at the bridge, with binoculars, searching for the target that he
expects to see in the next few minutes.
From the chief engineer, the commander hears, "yes sir, periscope depth. The target has been sighted, and the crew automatically
takes her down to periscope depth. The captain ponders, less than ten minutes on the surface before a visual sighting of the target.
This short time on the surface minimizes the air threat, conserves fuel, and the element of surprise is still with the u-boat.




Looking threw the periscope, the targets is bearing zero six one, range about eight kilometers, closing, with a port AOB. The CO asks sonar for the
target bearing.


1ST SONAR BEARING

Sonar reports target bearing zero six zero.
Plotting bearing 060 on the sonar overlay, we must click on the protractor tool, and make it a bearing tool by anchoring the protractor tool on the
u-boats course line to the cpa. Bringing it down to the center of the u-boat and anchoring it there, then extending the angle line of the protracor
to 060 decrees along the targets course line, clicking it to make it permanent. See picture below.



With the marker tool of the map, we mark the targets new position where the bearing tool line intersects with the target course line. See picture below.



Now that things are happening fast, we make a range estimation using the distance line of the map in the lower left of the map. Using a piece of
paper with a straight edge, we make a replica of the distance line with ticks marks only, then hold it up to the map, centered on the targets new
position mark, and the center of the u-boat. The range approximation is 8.3 KM. All of our sensors are showing the same general range of 8 km.
Time is 08:08. If we calculated right, and plotted with accuracy, we should have the torpedo on target in 13 minutes.

end part 7

2ND SONAR BEARING

08:12 The commander has corrected his course , and is now on bearing 233. Sonar, ordered to follow contact, updates the targets bearing,
"merchant, now on bearing 057, closing, moving fast." The commander plots bearing 057, laying the bearing tool indicator to 057
decrees. The bearing tool readout reads 057 decrees. ( 0 + 57 = 57 ). He then marks the targets new position, ( mark 5 ).
Targets range to the u-boat is 4.5 km. targets range to cpa, 4.5 km. U-boats range to cpa, 3.3 km.
See below.



4 TH SONAR BEARING

08:20 A third sonar bearing was taken and plotted, see map, ( mark 6 ), and now sonar reports target bearing 036 decrees. The commander
plots the targets new position, and marks it on the sonar overlay, ( mark 7 ). Targets range to u-boat, 1.3 km. Targets range to cpa,
700 meters. U-boats range to cpa, 1.1 km. See below.



About one more minute to torpedo launch. The weapons officer sets the tdc.
Looking at the bearing speed chart, for a 44 knot torpedo speed, the weapons officer wants a zero decree gyro angle on the torpedo launch and
expects the target to be at zero decrees at torpedo impact. The u-boats course is at a ninety decree angle to the targets course. He knows the target
speed is fifteen knots, He checks to see what bearing he will fire the torpedo at. It is bearing 19, or 19 decrees starboard. He sets the tdc.
See picture below



PERISCOPE PRESET

The periscope is preset to the firing bearing of 19 decrees. Time is 08:20. See picture below.




end part 8

TORPEDO LAUNCH

The merchants direction has changed from closing to moving away. There is a sight error in the target course plot. The u-boat is not quite at a 90
decree angle to the targets course, but at this range, its not a problem, the ship will get hit, altho the captain will change his aiming point from
just under the smokestack, to another forward from the smokestack, to avoid missing the target. Target is unaware of the u-boats presence.
The commander, manning the periscope, waits for the target to get on bearing 19, at his new aiming point. When the target has reached bearing
19, the commander orders tube one fired, the weapons officer confirms the launch, " firing tube one, sir !" Time is 08:20. See picture below.



TORPEDO RUNNING STRAIGHT



The weapon has fired, torpedo wake seen in the periscope, in a few moments the crew should here the explosion of the torpedo striking the target.



Thirty two seconds after torpedo launch, the torpedo strikes the target aft of midship, target was hit at zero decrees, time of torpedo impact was
08:21, range to target at torpedo impact was 724 meters.

SURFACE ACTION

The targets speed has slowed, and the commander, not wishing to expend another torpedo to finish the tanker, orders the u-boat to the surface,
and the gun crew to prepare for surface action.



The u-boat surfaces, and the deck gun covers the target, the commander will wait a few minutes, to see if the tanker will sink on its own, if not
promptly, the watch officer will receive the command from the CO to finish the target, and the watch officer will then give the gun crew the
command to open fire and sink the merchant.


end of tutorial

[Dutch]

This is cool, never figured out how to really plot with the sonar before active sonar came about. I appreciate you going through all the hard work to get this done for the community.

Is it possible for one of those great modding minds to consider this and possible make a mod to incorporate this?

[jmr]

Very cool, greyrider. I made damn sure to print this out and save it on my drive for future reference. Thanks a bunch!

[XanderF]

Question - what's the point of all those concentric rings? I mean, as far as I can tell, only the 34km ring showing the max limit of passive range is meaningful, no?

[drEaPer]

Originally Posted by XanderF

Question - what's the point of all those concentric rings? I mean, as far as I can tell, only the 34km ring showing the max limit of passive range is meaningful, no?

Was asking myself the same while reading.

First of all, thanks for your work and for sharing


Some Questions I have:

How do you find out the RPM and speed from the tanker?

Can you be sure that the target is at 34km? Doesnt it depend on seastate and depth how far a noise can be heard via sonar? How do you know that the target is not around for some time already. are you manning the sonar manually _all the time_ to spot it as soon as it shows up?

What is the north-south line, centered on "Mark 1" good for?

[greyrider]

first of all i'd like to say thank you for all your interest in this. i have read the questions asked, and i would like to answer them, but i would like to finish this tutorial too, and i'm not finished yet, there is still more, i wanted to do a plot, (by the book plot) and so the finished product will be a by the book plot. this is a monkey on my back now that has to get off, i have been working on phase III of the sound trainer for about a month now, and i want to move on, so i have to get this done.

someone asked why do we need all the other range circles, that he thought only the 34km range circle had any meaning.

the mission that im demonstating in this tutorial, the ship just happens to enter the listening range of the hydrophones, so when a contact
enters like that, we know its range rite off the bat, because we know the maximum range of the hp. but if a target is already within the listening range, then to plot it, it will have to be done the way it was done in real life, by the sonar operator estimating range by sound intensity. phase II of the sound trainer covers this.

i bet a modder could dress this sonar overlay up, and make it look just like the 5091, or wazoos plotting board. my real aim however, is to bring something like this to the attention of the ubi dev team, to show them that we would like to have overlays like this in the game.
in real life, and in the real military, on a military map there could be as many as 7 overlays on a map, showing units,combat positions, composition and dispositions of combat and support forces, enemy positions, the hole 9 yards.
i have to cut this short, have to take my little one to mcdonalds, as arnold would say, i'll be back.

[Dutch]

One more question are you doing all the overlays in real time of do you have the game paused? I perfer the game still running at x1 but if it is necesarry to pause than so be it I would love to try this out on my own.

[greyrider]

Questions:

How do you find out the RPM and speed from the tanker?

this is all based on propeller pitch, we cannot use a true propeller pitch in sh3 at this time, maybe in the next edition of sh.
i modified the propeller pitch, by listening to every speed of the merchants, and british destroyers, then made a chart.
it would be nice if the dev team for sh4 could put a propeller pitch entry in the ship rec manual.

Can you be sure that the target is at 34km?

yes, because i made the mission, to try out the sonar overlay, and work with it.

Doesnt it depend on seastate and depth how far a noise can be heard via sonar?

this is true, but in this mission, the weather is clear, calm.
when im done with the tutorial, i change the weather to a 15 m/s wind, heavy rain, heavy fog, and test the sound range .

How do you know that the target is not around for some time already.

again, if it was around for awhile, then sound intensity of the ships screws has to be the way to go.


are you manning the sonar manually _all the time_ to spot it as soon as it shows up?

for this mission i did, when in campaign, running on high time compression, the ships clock slows down, frame rate slows down when a target is coming close, you can go to real time then and search.

What is the north-south line, centered on "Mark 1" good for?

this is a modified way that i use when im trying to figure a visual targets AOB. i was in the u s army for awile, in my younger days, and training goes on all the time. i adapted things that i learned from military land navigation courses, what works for land, can also work for the sea. i will cover visual AOB, in your head style, in phase IV of the sound trainer.

One more question are you doing all the overlays in real time of do you have the game paused?

no, this is done in real time, i take pictures of the tasks, when i have them all taken for a certain task, i do a alt-tab to get out of
the game while it is still running, go to the sh3 directory, organized the pictures in folders, for the tutorial, then alt tabbed back into the game. all the pics were taken in one game, the game was over days ago. its just the writing now.


I perfer the game still running at x1 but if it is necesarry to pause than so be it I would love to try this out on my own.

rest easy my friend, it can all be done in real time

[Rosencrantz]

Just one suggestion: Don't let your sub to stop but make 3 - 4 knots and you'll find this at least a little bit more interesting and of course, more realistic...

I think they didn't do much Target Motion Analysies those days, because of lack of good sonar. :hmm: BUT, knowone is telling you, YOU can't do it...

[greyrider]

Rosie, keep checking in , you'll see what you said.

[Rosencrantz]

Ok!

Greetings,
Rosie.

[VON_CAPO]

Originally Posted by greyrider

first of all i'd like to say thank you for all your interest in this. i have read the questions asked, and i would like to answer them, but i would like to finish this tutorial too, and i'm not finished yet, there is still more, i wanted to do a plot, (by the book plot) and so the finished product will be a by the book plot. this is a monkey on my back now that has to get off, i have been working on phase III of the sound trainer for about a month now, and i want to move on, so i have to get this done.

It is impressive!!! Thank you Master!!!!

[Rosencrantz]

SORRY to say this, but I think TMA is not that simple at all. Why? BECAUSE usually you don't know parameter Range-to-Target. It's allways just estimated. So:

1. You get a sonar contact. Maybe you are able to tell it's somewhere there, range between 20 - 30 kms. IF you are smart enough, you maybe are able to tell, it's somewhere there, range between 25 - 30 kms. BUT you don't know the range to the target EXACTLY. That's why targets position is also just estimated. This is the basic problem in greys example. Right in the beginning we assume, we KNOW the targets exat position. 5 kms error means a lot, if using WWII sub.
2. Your sub is very slow. If you could accelerate your boat to make let's say 30 knots, you could move yourself for example 5 miles in 10 minutes to get rather accurate crossbearing. BUT, this is something you can't do with the WWII boat. Just because it´s too slow. To move yourself 5 miles with stop speed requires at least 40 minutes which means your "crossbearing" is not a "crossbearing" at all. To get your boat on surface and then using your top speed might be helpful, but not very handy way.
3. Results: Yes. You can find out targets course overall, but not it's accurate course. Not just with 2 or 3 hearings. Actually, targets true course can easily be tens of degrees off what you thought. Basic information about routes, harbours etc. on the operation area can be a big help when trying to find it out, where the targets is going to.

If I'm wrong, what I don't believe, PLEASE be kind and correct me. I can send also examples if you would like me to do it, just PM is needed.

This post wasn't meant to be indentified as HOSTILE!

And, please, excuse me my not so proper english.

[greyrider]

its ok to doubt, and i dont take your post as hostile rosie, but seeing is believing, the actual course that i punched in for the t- tanker with the sh3 editor, was 145 decrees, but i only recorded
the course the way i heard it in the hydrophones, and as you can see, im off by 1 decree in the course. i gave this mission everything i could to prove me wrong.

[Rosencrantz]

Hello Grey!

I haven't done much TMA in SHIII. Usually I just make myself on the estimated Optimal Approach Course and race ahead surfaced or submerged, depending on the situation. Actually I have done TMA just twice. First time the target was far away and when I finally found it, I noticed my original estimation for the targets course was about 20 degrees off and I think this was caused by mistake in range estimation. Second time it was a foggy day and we got a contact coming closer. When she got close enough, I took a crossbearing to find out where she actually is and there she was. So, when the target was close enough for that I could get a crossbearing with using a different course and top speed, I succeeded. BUT, I didn't get enough time to find her exat course by sonar. It wasn't needed, I just raised the scope, got the Ab and down she went. :rotfl:

Have you done TMA in real situation, I mean when you don't have a single data about target, just bearing? It would be interesting to hear your experiences, even if I know you hate writing!

Have a Good Hunt!

Rosie