SUBSIM Radio Room Forums - Calculating Range

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Calculating Range

Hi everyone
Sorry for another thread but I have spent a few days now watching tutorial videos on manual navigation, interception and firing. I have one last piece of the puzzle missing before I feel I could do it alone.

So I get a bearing for smoke on the horizon, no problem, I can draw a line out from my current position and that shows me where the ship is. The problem comes when I want to calculate its range, I don't want to get too close on the surface or I might spook the ship. I can't pursue a long range vessel underwater as I can't achieve enough speed.

Thus... What tricks and methods do people use for range finding? The Stadimeter is great if you're at a 90 degree angle and the ship is only 2000m away, but I need something more reliable

Thanks

If the AoB is not 90 you can still use the stadimeter. First thing first, forget about perfect measurements. Do all the procedures considering a margin of error and you should be fine. That said during the attack phase you are supposed to do various measurements, every time you will be fine tuning your estimation.

So knowing what i said first, i would say that if you are preparing for a zero angle gyroshot you don't have to worry about perfect distance measurement, since range is not vital anymore.

I learned that it is more vital to learn how to estimate AoB and lately ship size both visually, combining this technique with a tool like the attack disc and you will become so effective to making the game become so easy.

So to answer your question, i would say that stadimeter offers already enough accuracy. IMO i would not even put this as a problem, as long as you don't leave the periscope for a long time, a few seconds and periscope down.

Thanks NightEagle, I see what you're saying. The only problem is, i'm spotting ships when they are just smoke on the horizon so i'd still struggle.

I've watched the 4 bearing method on YouTube and can see that working great, However I can only follow it to plotting the third bearing and then I get lost. Can anyone help a SubSimmer out??

Also, a message for BL!TZKREIG - if you read this, i've tried to PM you back but it says you do not accept PM's, i've befriended you so let me know when I can reply :salute::salute::up::up::up:

Well I sent this to you in a PM but I'll paste it here in case others can add to it or if I've made an error.

Quote:

Right ...

Imagine our sub. We know it's position. We will call our sub's position "S". (not shown)
http://i.imgur.com/1Z9Vc1S.jpg

We get 3 passive sonar directional readings at 5' (minute) intervals.
Great that you can do that.

A1 = first contact bearing (at 0 min)
B1 = second contact bearing (at 5 min)
C1 = third contact bearing (at 10 min)
We know the course of the target. We know this because we assume it is traveling on a constant heading at a constant speed. It's course will be parallel to the yellow lines. We know this because the distance it travels between crossing the bearing lines (A1, B1, C1) will be the same. Or in other words the distance between 1 and 2, and the distance between 2 and 3 will be the same.
http://i.imgur.com/R8SqYVm.png

D1 is the projected (or future bearing) that hasn't happened yet. We know that if we stayed stationary we would get a contact bearing at 15 minutes that would be along D1. The distance P1, P2, and P3 will all be the same because the speed of the target is constant.
We can measure the intercept of the yellow line and D1 directly by measuring the distance P1, P2 or P3 along the slope (yellow line). I've shown this distance as the blue segment along the yellow line.
Or we can draw parallel lines (as we did to determine the original slope of the yellow line) to find the intercept of the yellow line and D1.
http://i.imgur.com/HhS0xMg.jpg

So we move our ship forward for a few minutes and then halt so we can get a final directional contact (E1) at 15 minutes.
We need our navigator to tell us our position at S2.
And we must be stationary at S2.
Because we know that the target will be somewhere along D1 at 15' we can
use the new sound bearing (E1) to the contact to triangulate the location of the target.
http://i.imgur.com/g5FJPfN.png

Now that we know the location of the target we can determine it's speed. Because we know the targets course we can predict where it will be at 20 min or any other time. The target will be at 5 at 20' and at 6 at 25'. We know the course and because the speed is constant the distances between 1, 2, 3, 4, 5 and 6 are equal.
http://i.imgur.com/Mq45YLU.jpg

Hope this helps.

Now I'm convinced .... that if I were a ship in sub waters, I would vary course and speed.

Thank you macjim, I have started a career and am waiting for my contact so I can try this method out.

When I have practised, I can use the ruler to make my first bearing, but when it comes to my second, I cannot place a mark on top of my subs position due to a ruler mark already being there, it thinks I just want to move the existing mark, does anyone else have the same issue?

Quote:

Originally Posted by Captain Birdseye (Post 2419603)

Totally normal, a simple solution is to drag the line a bit over your actual position so it ends behind you.