No map contact - Target's course and range?

[Drakken]

I recently made the big jump and started playing GWX at 100% Realism without map contact updates. I am doing somewhat okey, but it is when I spot a ship that I have some trouble.

I know that first, I must acquire the target's course, speed, and range.

I try to do so using my Watch Officer's visual contact report, which gives me a bearing and a range, usually between 7 and 8000 meters. I then use my compass to circle the range, then the protractor to pinpoint the angle between my relative bearing (0) and the target's bearing. The reason I do so is because the sub's bearing circle disappear when zooming out, so I use the angle as a marker (for example, 279 would be (360 - 279 = 81 degrees port of relative bearing 0).

Mark 1 on the map where the circumference and the angle line cross.

After waiting 3.15 minutes, I redo the sames steps, retracting the compass and updating the protractor (after recentering them both on my sub's new position, of course) to the new range and bearing.

Mark 2 on the map.

However, the target's estimated course and AOB seems always wildly different from the target's visual course. So I must be doing something wrong.

I accept that the WO's estimated range might not be exact, but still... How do you veterans proceed with visually estimating a target's first course and speed when contacts are turned off? Especially at medium and long range.

Thanks for your help and your pro-tips!