Trying to plot intercept corse??? What I am doing wrong

[oakdog2010]

Ok so I am in my NAV map and I can see that I just recieved a radio message that there is a new enemy convoy spotted at xy, xy course. Now I plan to intercept, when I start to select a new course on the map the map shows me the projected path of the enemy in and when I get to that location there is no enemy, also if you have time compresion on the enemy apears to acualy move backward.. SO I am I doing something wrong.. or is this a bug??? Anyone having the same problems? Also I have noticed that sometimes I will ramdomly see enemy ships on the map with out recieving radio message, Where do these ships come from and why?....

Thanks for your help

[kylania]

Hi Oakdog! Welcome aboard!

The ghost plot that you see assumes that the contact won't change course but sometimes it does. Also the scale of the map might mean that it looks like you're supposed to meet the convoy, but in fact you're 30-40km away. In cases like that, drop to periscope depth, turn off your motors and head to the hydrophone and give a listen yourself (Use the Home/End keys to turn the 'phones). You might hear it while your sonar guy won't.

The other little ship icons that pop up represent other reports of ships in the area from other friendly ships or other uboats. Just another way to make finding targets easier for you.

Eariler I was trying to intercept a convoy and plotted an intercept, but after a while realized I'd been underwater when I started it! So I surfaced, plotted a course far in advance of them, then back up along their path. Due to fog I didn't find the convoy till I was 2km away from them, I was actually INSIDE their destroyer screen. Niiice. heh

[gutted]

you could always do it the old fashioned way:

http://i857.photobucket.com/albums/ab138/gorey666/Intercept.png


When drawing the sub and target speeds.. use lines of the same scale.

If you will be travelling 20kts, draw your speed line either 200m, 2000m, 20km, 200km etc. etc.
If the target is doing 12kts, draw his line at either 120m, 1200m, 12km, 120km long.

Pick whichever scale you want, but use the same scale for both.

[slikster]

There is a really nice convoy interception tutorial here. (http://www.subsim.com/radioroom/showthread.php?t=118988)

The ghosted image is flat out wrong in many instances. It assumes certain conditions like some arbitrary speed you may be going, but doesn't update for different circumstances. I would call it bugged. If you follow that tutorial, you can get reliably where you want to be.

On that note, it would be nice if we could actually get a time stamp on the random ship sightings like in SH IV. Otherwise you have to pretty much see the contact appear on the map to get accurate intel.

[gutted]

There is a really nice convoy interception tutorial here. (http://www.subsim.com/radioroom/showthread.php?t=118988)

Sorry to break it to you, but that intercept tutorial is wrong.

He was doing fine right up until the point where he drew the circle for his speed.

Someone else posted that same method here (post #12):
http://www.subsim.com/radioroom/showthread.php?t=163641

If you follow our exchanges through to the next page you will see why.

[slikster]

Sorry to break it to you, but that intercept tutorial is wrong.


I'm sorry to break it to you, but it is only slightly misleading. When he mentions leading the boat by 7 units to give the player time to set up, that's fine. But you shouldn't scale that up lead time up if you need to scale the rest of the geometry.

Your method however, is wrong. Here is a quick proof.
We will make some an assumption to make things easy:

Both your intercept speed and your target speed are the same. Ergo, when both target and interceptor reach the intercept point, they will have travelled the same distance.

This is not the case with your method:
http://img7.imageshack.us/img7/1781/sh5proof.jpg (http://img7.imageshack.us/i/sh5proof.jpg/)

[Coldcall]

As others have pointed out those ghost tracks are only useful on contacts which are relatively close by (thereby reducing the chances it will change course by the time you intercept).

Those ghost tracks also dont seem to distinguish between land and ocean/sea as the tracks go right across land masses :-) Oops!

[gutted]

You know what, you are absolutely right. :up:

I have no excuse, and am actually kinda ticked that i didn't see my error sooner.. because i should have. I've done this type of thing a million times but for a different situation.. and for some reason i just mirrored what i was solving instead of solving for the different thing.

Not sure what my geometry teacher would think if he could see this thread LOL.