plotting course passive sonar only

[XLjedi]

Originally Posted by RSColonel_131st

Basically yes, you plot the bearing lines at set time intervals (they will likely fan out, especially if you are stopped), and then you will either need two range/bearing combos or a good speed estimate. You want to find the target course that crosses your bearing lines at appropriate speed (i.e. 500 yards between two bearing lines taken at three minutes means 5 knots, if you know the target makes 9 knots, then you need 900 yards between the lines, which then results in a course and range).

Just remember... If you're not stopped, you're not plotting true motion either.

If you want to take bearings and keep moving, the relative motion plot/solution has to be converted (with vector addition) to true motion.

You can also predict future bearings to target and then triangulate on the exact target position. Knowing the position you can solve for distance, knowing the distance you can solve for speed. So you don't absolutely need to ping the distance, or try to get range, or a speed guesstimate. It is possible to do it all by analyzing the bearing motion from 50m below.

Now keep in mind, while doing all this there's a good chance your target will be out of firing range by the time you've solved for course, speed, location. At this point you surface a good 8000m away and do a surface run end-around. It's not that easy to keep track of all this without a good attack course plotter to help you manage the data (perhaps like a tracking team would?). But, I s'pose it could be kept track of on the in-game map and with a paper-pencil moboard. You'd probably need to make yourself some sawtooth speed rulers to help with a paper-pencil solution.

Obviously, I prefer to use MoBo.

[RSColonel_131st]

Originally Posted by aaronblood

Just remember... If you're not stopped, you're not plotting true motion either.

If you want to take bearings and keep moving, the relative motion plot/solution has to be converted (with vector addition) to true motion.

Easier to just draw the bearing lines on the map always starting from your sub, and try to solve it that way.

[XLjedi]

Originally Posted by RSColonel_131st

Easier to just draw the bearing lines on the map always starting from your sub, and try to solve it that way.

Yeah... assuming you're stationary. If you try to apply the same concept to a maneuvering board solution (ownship at center, even when moving), it results in a RM plot that needs to be converted to TM. It's not particularly difficult... just a fact.

...be easier in the game if you maybe had a sawtooth speed ruler gadget to use. I know modders can add gadgets to the game, don't know if they can add rotatable ones though. I s'pose it's easy enough to just hold up a paper one to the screen. You ever tried that?

[RSColonel_131st]

Not what I meant.

You could in theory just draw a line for the sonar bearing every 3 minutes (even if your own ship is moving) which would result not in a "fan" of bearings but a bunch of more or less parallel/convergent/divergent lines.

Then get the ruler out and see if you can draw a line across all bearing lines that has the same distance between each - for which a better drawing gadget would indeed be needed.

Not sure why movement of ownship would be a problem, as long as you are marking down every bearing line directly on the map?

[XLjedi]

Your ownship's movement is not important if determining target true course and speed are not important.

If you're playing with map updates turned on it's pretty much a non-issue, the bearing line terminates at the target location. Also, drawing the line from your ship as it's plotted (with God's eye assistance) is arguably a bit of cheat. Some would argue not a cheat, the tracking party updates it for the captain. Depends on if you want to play the role of the tracking party or not?

[surf_ten]

Back when I was playing SHIII I used this method with great success.
http://www.subsim.com/radioroom/showthread.php?t=110619

Since I encounter lots of poor visbility conditions in the North altantic this method worked brilliantly. In fact I started to use it for every contact since I found myself submerge most of the time due to pesky aricraft dropping bombs on me.

Mittelwaechter had a matching video unfortnately the rapidshare link he used no longer works. Wished he would post it up on youtube.

[Pisces]

Originally Posted by surf_ten

Back when I was playing SHIII I used this method with great success.
http://www.subsim.com/radioroom/showthread.php?t=110619

Since I encounter lots of poor visbility conditions in the North altantic this method worked brilliantly. In fact I started to use it for every contact since I found myself submerge most of the time due to pesky aricraft dropping bombs on me.

Mittelwaechter had a matching video unfortnately the rapidshare link he used no longer works. Wished he would post it up on youtube.

First you couldn't see it . Now you can!

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

I'm afraid uploading to youtube isn't as simple. Mittelwaechter used a special compression software that youtube mostlikely doesn't accept. (and it seems to pay of in quality) It's in the form of an .exe. I know, scary wrt virusses and trojans and all. But it's been on my harddrive for a year and AVG never complained about it during scans. Still, download at your own risk.

Also, for the original poster, this post of mine might help: (but DO read further along the thread aswel)

http://www.subsim.com/radioroom/show...0&postcount=10

I have created a circular version of the tool but it isn't completely to my taste yet. However I have decided to upload this prototype since I have to live up to the promise somehow.

Filefront description:
Sliderule to compute Angle On Bow (when stationary, if moving Direction of Relative Movement wrt the first bearing) based on 3 bearings only, in 2 equal time intervals. Intended for use with Silenthunter 3 or 4. Inspired by a linear design ("Another Course Computer") on this site: http://www.gizmology.net/silenthunter/

DIY-sliderule PDF:

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


1. Print out
2. Cut out
3. Don't forget the window on front disk
4. Laminate both disks
5. Make a hinge in the center.
6. Instructions for use are on the front disk.

7. Be patient! It takes time for a good meaningfull AOB value. Forget the 3m(15s)-rule for this thing.

[Rockin Robbins]

Originally Posted by aaronblood

Your ownship's movement is not important if determining target true course and speed are not important.

:rotfl: Quote of the thread so far!