Questions about the Four bearings method, etc.

[HermannEhrhardt]

How do you find the "red line" in the Four bearings method and what are the procedures?

It seems that in every video that illustrates the Four Bearings method there's always a point in the video where it says "read Kuikeug's notes for this "red line" and I can't find anything on it, there is one pdf called Four bearings method v2 which tries to explain it but I just can't understand it.

Also are there any good videos out there shows how to intercept a ship or convoy that has appeared through radio or however those little boxed things on the map appear?

[B_K]

For the second question, it can be done with the attack disc called Angriffsscheibe. A fully professional manual is available in English somewhere on this forum.
About the first question, I will try to describe it later

[HermannEhrhardt]

Originally Posted by B_K

For the second question, it can be done with the attack disc called Angriffsscheibe. A fully professional manual is available in English somewhere on this forum.
About the first question, I will try to describe it later

Please take your time.

And I've found a nice tutorial about intercepting contacted ships in the Newbie Guide.

[Aktungbby]

HermannEhrhardt!

[Pisces]

It's not a video, but it is a classic thread explaining about intercepting (not 4-bearing hydrophone method). I'm not familiar with any videos showing this step.

http://www.subsim.com/radioroom/showthread.php?t=88961

Here is an image that explains it in condensed steps:

Dantenoc did make the following SH3 tutorials, videos showing how to attack a target, but only from the point where he got near the target and started plotting it's position. Not how he developed the intercept triangle drawing.

[Pisces]

4 bearing method(s) of Kuikeg:

Kuikeg has made 2 versions of his document explaining his 4-bearing methods. Each explaining different ways to derive the same solution. In both the red line has the same concept: the line being all potential positions at time 4 (with unknown range and speed) based on the first 3 bearings (taken at the same or moving positions). He will be somewhere on it. If the first 3 bearings were taken from a single position then the target course would be defined as well.To find the correct location of the target at time 4 on that line/bearing you need to move to a (radical) different vantage point where the true bearing is likely to cross perpendicular to the red line.

I too find it hard to follow these steps, but they are mathematically sound. Personally speaking, the initially stationary method works the best for me. Less chance to get the procedure wrong in the heat of battle as opposed to the moving methods. But the moving method might be crucial to get fast moving contacts.

Version 1

Version 2

[La vache]

Originally Posted by HermannEhrhardt

Also are there any good videos out there shows how to intercept a ship or convoy that has appeared through radio or however those little boxed things on the map appear?

Maybe this is a help.

A new hunting tutorial.

[Pisces]

That's a nice one too!

[Pisces]

Other thread:

Moderators, can you merge these threads?

[Sailor Steve]

Originally Posted by Pisces

Moderators, can you merge these threads?

Done.

[B_K]

To create a red line, having first three lines, you first plot completely random course line. It intersects all three lines and extends forward, where you expect your target in the future. This course line will be our base to determine the first point which the red line will be going through. Take a compass and along this hypothetical course measure the distance between first and second line. Let course intersection with the second line be p1. Move this length now from p1 towards the third line. Mark m1. Now at that mark draw the parallel to first line intersecting the third line at m2. Now take the compass and measure the distance from p1 to m2. Move the circle so so it begins at m2 now. Mark m3 at the arrow end. It is the first point of a red line. For the other random course line do the same to have the second point for red line.

[HermannEhrhardt]

Originally Posted by Pisces

4 bearing method(s) of Kuikeg:

Kuikeg has made 2 versions of his document explaining his 4-bearing methods. Each explaining different ways to derive the same solution. In both the red line has the same concept: the line being all potential positions at time 4 (with unknown range and speed) based on the first 3 bearings (taken at the same or moving positions). He will be somewhere on it. If the first 3 bearings were taken from a single position then the target course would be defined as well.To find the correct location of the target at time 4 on that line/bearing you need to move to a (radical) different vantage point where the true bearing is likely to cross perpendicular to the red line.

I too find it hard to follow these steps, but they are mathematically sound. Personally speaking, the initially stationary method works the best for me. Less chance to get the procedure wrong in the heat of battle as opposed to the moving methods. But the moving method might be crucial to get fast moving contacts.

Version 1

Version 2

Originally Posted by B_K

To create a red line, having first three lines, you first plot completely random course line. It intersects all three lines and extends forward, where you expect your target in the future. This course line will be our base to determine the first point which the red line will be going through. Take a compass and along this hypothetical course measure the distance between first and second line. Let course intersection with the second line be p1. Move this length now from p1 towards the third line. Mark m1. Now at that mark draw the parallel to first line intersecting the third line at m2. Now take the compass and measure the distance from p1 to m2. Move the circle so so it begins at m2 now. Mark m3 at the arrow end. It is the first point of a red line. For the other random course line do the same to have the second point for red line.

I am still perplexed.
I've been looking at the v1 of Kuikueg's method and it has somewhat cleared somethings for me.
But I am still confused by the part where you use a compass and marking these hypothetical courses.
I've also been looking at these two videos





trying to figure out what you guys are trying to explain to me.

[B_K]

By compass I mean the plotting tool that is available in SH3, not the tool showing directions.
Watch the first movie (the art of Hydrophone, the part where the red line is made) and simultaneously read what I wrote. I based on this tutorial. You will understand it.

[Pisces]

Originally Posted by HermannEhrhardt

I am still perplexed.
I've been looking at the v1 of Kuikueg's method and it has somewhat cleared somethings for me.
But I am still confused by the part where you use a compass and marking these hypothetical courses....

The compass tool is used because it simultaneously contains a measure of distance in all directions (from center to circle edge) and a direction (the radius vector). It can be easily dragged to project a future position along a line by aligning the center with the latest point. The assumption is that all time intervals are the same. Ownship motion may be irregular but the target moves in equal distances along a course.

The compass tool can also be used to copy the direction of a line and project parallel lines elsewhere in the drawing. The center is placed on a line and the radius arrow is then dragged along it. To project it elsewhere the center is dragged to make the radius pass through a desired point. The zoomlevel of the map does however give some limitations to the length of the arrow.

With 3 bearing lines originating from different positions (ownship is moving) you can create a hypothetical course going through a certain point on a bearing line. (version 2 explains this better) At that point along the bearing line it is a valid one because the distance to the intersections with the first and third bearing is the same. The course is hypothetical because it isn't the only course that can exist. It depends on where it is drawn. They will be in different directions for each chosen position along the same bearing line. You can however plot projected positions for time 4 on each of those hypothetical courses. And you will see that they all end up forming a line. This is the red line. You won't yet know where he is along that line. But he should be on it. (Assuming your drawing was accurate). Why is that? Some blame it on cropcircles or ALIENS!!! I say it is math.

Now comes the tricky part in choosing a course and speed that gets you in position to crosses the red line as perpendicular and close (but safe!).

[Spectre-63]

apologies for a little thread necromancy, but there's a component to this that I would like clarified:


in Stoianm's videos, he regularly references making bearing calculations where you subtract the bearing from 360....that only works if the bearing is greater than 180*, correct? If the bearing is less than 180, then what?