[B_K]

Hi!

the time between the two bearings must be fixed at 1 minute (for using the tool) or i am free to time as much i want between the two bearings ?

A LOS is a constantly changing thing. When you construct LOS diagram, you are "taking a photo" and operate on that photo. You enter data to BRC based on your estimations from a while ago. By the time you enter data to BRC those estimations also change. The BRC allows to obtain data which is valid at the moment of taking photo, but since changes are not so rapid, calculations are valid for some time, and also I assume you can use sine functions from the innermost disk to estimate range at any given target bearing (I don't know how yet, tough).

Also you can predict future data to enter to BRC and calculations will be valid when your target behave according to your predictions and is where you supposed it to be.

So bearing rate entered to BRC can be just fair enough mean based on most recent data. The closer the target - the more rapid change in bearing rate. So for distant contacts BR can be determined based on more time and for closer contacts it must be determined for less time. Bearing changes over time as arcustangent function and bearing rate as its derivative 1/(1+x^2).

also you say ''You multiplied your speed by sinus of target bearing angle'' ,the question is that this calculation will be done with a digital calculator ?

Multiplication by sine of a given angle is achieved in BRC by simply rotating the innermost disk and reading the value. No external calculators needed. For example for our application:

We must obtain total relative speed across the LOS which is made of ownship speed across the LOS and target's speed across the LOS. Across the LOS (ATL) means the speed component perpendicular to LOS. From trigonometry we know that to obtain component perpendicular (x) we must multiply base speed by sine of angle. Own component ATL is ownspeed * sine target bearing. So we point innermost disk's 90 degree on ownspeed and read what speed is where target bearing is. The same for target - you use target speed (obtained by any other means) and Angle on bow. Bearing is relative +-180 at each side. Also remember that sin(angle) = sin (180-angle).

The final range etsimation output of the tool is the range at first bearing or something else?

At the moment you enter data or precisely at the surrounding of that moment.

sorry atm I have no option to draw anything, maybe later.

Edit: made a mistake writing that bearing rate changes as tangent function. Corrected.