a) I know I don't have to download any tools, of course the .exe plays itself. Unfortunately the player is crap, and in order to play it in any other player one needs to convert it with the tools.

b) The quality is worse because I had to first convert it to an .avi, which I then encoded with x264 so that Vimeo would accept it. Vimeo also does it's own things, so that's three steps where quality gets a bit worse each step.

Hi,

this tutorial is what I was looking for. It's simple and well explained. Thanks!


But...
I tried this method 3 times and... I must be doing something incorrectly.

First try:
When my sonarman shouted contact I ordered engine stop. Only when in dead stop (I checked on the map) I took 1st bearing, started stopwatch, after 8 minutes another, after 8 minutes 3rd. Then I started engines again, after 8 minutes since last bearing I took bearing nr 4. Here I paused. I did all calculations required. Angles on triangles p1-m-c1 and m-p2-c2 were close to 90 degrees, so my circles were big.

As you can see on screenshots, I was able to calculate contact's position. I ploted an intercept course. I was really amazed that my guy is shouting 'long range', from my map it looked like the ship is less than 3km from me. After checking with periscope and hydro I surfaced and chased contact with all my speed. He was additional 7km away. It's course was more or less the same as I calculated by hydro-method.
http://img207.imageshack.us/img207/9329/miss01.th.jpg
screenshot nr 1


http://img259.imageshack.us/img259/5593/miss02.th.jpg
screenshot nr 2


Now I see that I could make mistake - I misplaced P1 with P2. Contact was on my left side, so P1 should be on left side of the helping circle, and I can see I used right end of a diameter as P1. My bad. I'm pretty sure that in other cases I was right though and this mistake is an exception :)

Second try:
After some time I heared another contact. I sailed towards it, so eventually my crew reported bearing. Again, only when I was in dead stop I started the Mittelwaechter's procedure.

Again, I heard 'long range', so I instantly knew the ship wasn't where it was suppose to be :)

This time however I tried to estimate. I assumed contact's course-direction is valid, so in order to find him I have to calculate distance between me and contact. I knew it was a merchant. I calculated distance it would travel in 8 and 24 minutes, and using angle calculated with Mittelwaechter's method (29 degrees in this example) I put circles on my map.

This may be confusing, so here's a screenshot:

http://img218.imageshack.us/img218/9674/miss03.th.jpg
screenshot nr 3

I assumed - if the contact's speed is constant he would travel x km. I calculated distance for (AFAIR) 5, 6, 7 and 8 knots. I was drawing circles over the protracted angle, aligning circle arrowhead with protractor, so later all I had to do was to put circle over the bearings.

Than I took another bearing, it was 313, 47 degrees to my port.

http://img21.imageshack.us/img21/3075/miss04.th.jpg
screenshot nr 4

This bearing line crossed my 4.4 cirlce. Accidentally, it the same spot it crossed the 4th (virtual) bearing to contact I would made if I wouldn't leave my first position.

Anywho, I was already going on perpendicular course. Now funny thing happened. For 14 minutes (game time) bearing to contact was 313 degrees. I was going 8 knots. When my speed changed to 7 (I don't why, I still had juice in batteries) bearing started to change. By this accident I knew two things: contact was doing 8 knots and I really was perpen... our courses would form 90 degrees angle :)

(maybe if my speed wouldn't drop I would be part of a sea collission? :) )

http://img524.imageshack.us/img524/2203/miss06d.th.jpg
screenshot nr 5

When I saw contact, I plotted it course etc. Turned out it was different than I calculated with hudro and I (my course hasn't change) was no longer perpendicular towards it. The difference between hydro and real course of the contact was ca. 10 degrees.

I sunk the merchant, but was starting to think I cannot use hydro to locate contact with precision. Or - I have badluck and in stock SH3 my merchants are zig-zaging.

http://img412.imageshack.us/img412/571/miss07.th.jpg
screenshot nr 6


3. This gave me a lot to think about. BdU gave me spotted contact on my map. I knew its course (+- 2 degrees). I tried to use hydro-method for the third time.


Again, from my calculations I learned that contact should be very close to me
. I didn't bother to mark that place on my map.

Those two small circles you can see on screenshot represents contact position marked by periscope observation. Note that real course of the contact was true to BdU report and was ca. 10 degrees off than my hydro calculations. BdU was right, not me.

http://img149.imageshack.us/img149/6087/miss08.th.jpg
screenshot nr 7


http://img141.imageshack.us/img141/2281/miss09.th.jpg
screenshot nr 8

Now to questions: what can be wrong? I'm 100% positive there's nothing wrong with my bearing. I can put things like that on my map. There's nothing wrong with my helping circle (except for example 1). I often pause the game to draw everything as perfect as possible. So?

I noticed one thing - the biggest challenge for me is to draw a 'virtual' bearing, one I would have made if I didn't start engines after initial 3 bearings. My problem is I'm having hard time judging distance. When I use angle calculated from helping circle (giving me course-direction) distance between 1-2 and 2-3 bearing are different. Eg. it's 2km in first 8 minutes, but 1,8km in the second. So how can I put that 'virual' bearing correctly? In your example Mittelwaechter you seem to use circle with radius = distance between 2nd and 3rd bearing. But in your picture this is the same as between 1st and 2nd.

:damn:

Can anyone help me?

Sorry for suprisingly long post :)
Kubryk

PS
I don't know how to put clickable thumbnails hence the link under every picture.

Hi Kubryk,

nice to see you are working on this, you are doing a good job there! :up:

Whenever the angle between first and second bearing is small, add a few minutes and ask for the second bearing again to reduce error probability.

The bearing of the hydrophone operator is a cone. In 20 km distance the bearing covers a width of ~ 350 meters (2r pi /360)
The SH3 map tools are not designed to do these 'hydrohunt' calculations.
Try to center the bearingline in the 350 meter cone.

The best way to calculate the virtual bearing is by dividing the complete distance travelled on coursedirection and add the average.

After third bearing estimate the virtual bearing and try to achieve a big angle for the fourth bearing. You may want to surface and go flank for some minutes. Start immediately and do the calculations while sailing.
Try to come to a full stop before asking for the fourth bearing.
Make sure to follow your U-boats coursepath and try to work the fourth bearing exactly.

I have no idea what's going on, but checking your screenshots the initial contact would have been in ~ 5 km distance - according to your fourth bearing and the resulting real courseline. Your hydro operator is not that bad.

There is allways a difference between the real courseline and the calculated courseline, due to the map tools limitations - but it is small enough to still get a proper target solution. Even the distance is irrelevant as long as you head perpendicular to the courseline.

Try to 'correct' the weapons officers perfect settings and change the AOB for +/-10° - you'll still score a hit. Change the distance - Pythagoras will give you a smile.
The real source of error would be the contact speed. But if you want, you can calculate the speed from the complete travelled distance!
(timestamp the initial contact report... :DL - or keep on restarting the stopwatch...)

The more you close in to your contact, the more error tolerant your setup.
Well, this all requires an exact 'cross bearing' to get your real contact position.

Have fun!


Edit: your conclusion about same speed is correct (your 8 knots story), but the assumption of a perpendicular course is not consequently correct.

Hello,

The link seems to be expired, could you please re-upload it ?
Thanks in advance :)

Contact: I have reuploaded the exe-version I have (stretches to fullscreen) to my Filefront page:

http://files.filefront.com/U42HydroH.../fileinfo.html

Thanks Pisces :up: - would you mind to host the AVI file too?

Here is a link to the 56 MB AVI - you can pause, zoom and jump with VLC or WMP or whatever player you prefer.

http://f.imagehost.org/download/0424/U42HydroHunt

MD5 D1661D8749333AB5C523440638FA3374


:salute:

Kubryk, I think you did the drawing perfect. The things you did 'wrong' (imho) was too short time intervals, and moving perpendicular to the target course. And perhaps you were too slow (submerged perhaps?). Note that it isn't really wrong, but it made the results less accurate than it could have been.

If you take more time between bearings the AOB calculation/drawing becomes more accurate. Do you remember how big the bearing differences were? Judging from your pictures I think they were about 5 degrees between 1st and 2nd, and 7 between 2nd and 3rd (or 12 between 1st and 3rd bearings), for the 29 degree AOB situation. Correct? Well, 2 degrees more than the first 5 is a bit crude, considering bearings are measured in 1 degree. Using a bit of magic I profecise ;) that if you had waited until the first bearing difference becomes 19 degrees, the 2nd difference (between bearing 2 and 3) becomes about 41 degrees. At the 3rd bearing the contact would have shown about 90 degrees AOB, and have the closest distance to your listening position. From 1st to 3rd bearing would have roughly taken 45 minutes. But that is a different kind of magic ;) :

time_1st_to_90AOB= 2*short_time_interval/(1- tan(AOB1)/tan(AOB3)

What I am trying to say here is patience is a virtue that pays well in accurate AOB and contact course. Perform some magic yourself, and see what variation in AOB you get for small deviations (0.5 degrees) in your bearings.

2nd point: You moved perpendicular to the contact's courseline. That does make you get closer to the courseline as quick as possible. But is that what you need? You really want to know where the 'virtual 4th' crosses the 'real 4th' line. For that to be accurate you need the biggest angle as possible between them. That means you need to start your move perpendicular to the 3rd bearing. With the 'magic suggestion' above that would also be parallel to the contact course.

See in this picture (showing a pure intercept) how the bearingline would start to turn when your speed is completely perpendicular and greater, than his perpendicular speed component.

http://members.home.nl/rico.v.jansen...pt_angles2.JPG

The quickest change of bearing is when you move in the direction where he came from (speeds on opposite side of bearing). But that could get him out of hydrophone range, and you need to catch up to it again later. If you move in the direction he is going (speeds on same side of bearing), and if you are as fast as possible (surface if you can), the bearing turns slower but still makes the 'virtual and real 4th' cross. Since the target is the one that decreases the range (remember you have no component along the bearing) the bearing-change will speed up over time.

Other than that, well done on your work.

Kubryk

(Not to hijack a thread but..) You might like to try Pisces' "3-Bearing AoB finder" as a supplemental tool. It's really slick. :up:

http://files.filefront.com/3BearingA.../fileinfo.html

Hush please... You uncovered my magic. ;)

But to return the praise. :salute:
Kubryk, if you like to try another way of drawing AOB based on 3 bearings, have a good look at the image in UberTorpedo's signature. This shows how it is done. (and where it is from)

Thanks for your reply! I noticed that small angle difference between bearings is somewhat inconvenient, still I'm worried that target would escape. It happened once, I took two bearings but third one I had to do manually, sonarman no longer could hear him. I will try to make that distance bigger though.

I try to accomplish two things thanks to your tutorial - it would be nice to know target's course just by hearing, and I would really like to sink at least one ship while submerged and without periscope. Must be a great feeling :)

I didn't know that bearing is a cone 350m wide, thanks for that info. I always try to center things, must be something wrong with my brain :) (I don't use this rule in photography, thank God :) )

I did all my calculations sumberged. I will surface after 3rd bearing and go flank, we'll see if it's going to help. Thanks for the tip!

I've been meaning to ask about this, I read that sort of statement a lot on subsim. How is it possible that distance doesn't really matter as long as you have speed and AOB correct? I don't get it, it's against my intuition :)

I only use weapons officer to see how long till loading a tube, I'm my own weapons officer for calculating firing solutions :)

I don't have a ruler on me so I will ask - same speed means same bearing ALWAYS? No matter how courses are related to each other?

It's true with parallel and perpendicular for sure, hm... maybe it's true always... no. It can't be.

Pisces and UberTorpedo,

thanks for your help. I downloaded both PDF's, I have to look at them in the morning when my body is clear from alcohol poisoning :)

Right now I'm not exactly sure I understand everything in post nr 52 in this thread. But I will give it a try tomorrow.

Thanks guys!

This video is strongly lacking comments.:nope: Or is it suppose to be for deaf people ? :DL

Anyway better than nothing. Thanks.

There is indeed no audio, which feels weird when you watch it. But the text in the video, and the resolution, makes everything clear enough.

The hydro-man only starts calling out within 20km or so (or was it 25km?). But you can hear upto 34km. That range is 70% bigger, and almost 3 times the area of 20km range. At the bearing where the contact has an AOB of 90 degrees it only halve-way through your hydrophone range. So there is usually plenty of time before you really loose it. Unless it happends to be very near the extreme end of the range. Oh well, can't have everything.

Listening yourselve for the soundbeam-sides where the sounds die out is tricky. You do loose a bit of bearing accuracy that way. But listening for maximum volume at the middle bearing is VERY tricky. Then bigger bearing differences are a must.

Use the smaller bearing difference drawing to estimate how much time there is before it is near 90 degree AOB, or it leaves hydrophone range (if you don't mind catching up to it later). Remember, speed of contact is constant, so any distance it has moved along the course is proportional to time between bearings. Then use halve of the time available as the new interval (but be conservative as it is very crude). Or use the old 3rd bearing as the new 2nd bearing if that 1st new interval has allready past, and double the interval before taking the new 3rd bearing. The 3rd bearing doesn't have to end up at 90 degree AOB. It just a way to not fall behind.

But you must be suffering from information overload now. I'll let you digest it first. And alcohol doesn't help. :()1:

Well, Herr Kaleun, your Navigator Konrad Schlumberger has been asigned to command his own U-Boot.
But during the last shoreleave Heinz Voigt - your hydrophone operator - visited the new hydrophone operator seminar at the U-Boot school in Kiel.

He came back with some great skills to support you in hunting contacts only with hydrophne.
He is able to calculate most of the tricky stuff to get the real courseline of an inbound contact under those conditions where the initial angles between the first three bearings are small. It indicates the contact is sailing along a course coming close to your position.

Heinz will give you constant reports of the bearings, including the information whether the contact is closing in or whether it sails in constant distance.
At the bearing this information changes, the AOB of the incoming contact is 60° (!).

Additionally Heinz reports proper distance statements and tells you if the contact is far away or at medium distance.

Whatever occurs first - note its bearing on the map. Draw a circle to represent the medium distance around your U-Boot.

(please someone provides the information what distance is medium in GWX - I changed my settings in Contact.cfg and didn't back up! I guess it was 8000 meters, but I'm not sure.)

At the time you have both informations, copy the courseline of the 60° AOB to the "medium distance" bearing at the point it intersects the medium circle.

You may want to change your position if the 60° AOB information comes first, of course heading perpendicular to the "courseline", to ensure the contact will cross your medium distance circle.

Well, the rest should be easy...

:salute: