Spiess TMA (aka Four Bearings)

[B_K]

hello B_K,

i didn't said that is a 'historical' method.i made the video with sh3 thats why you see it here.
I explained at the description of the video why i used the hydrophone lines.Of course,there were not back then hydrophones with super accuracy ,not even today. Even today , bearings from whatever passive device (even periscope's bearings) are not super accurate.All of them have a little 'cone' and crew is following extra procedures for minimazing the errors at outputs,procedures that demands special equipment.
The purpose of the video is to show the principles of Spiess TMA

Sorry I didnt' point it out good enough, but apart from historical issues, you did a great job of explaining Spiess TMA and finally naming it properly. I wish Dangerous Waters had manual plotting available... It could be great.

As far as Spiess method is concerned, plotted course should be paralell to the axis of symmetry of the curve which is tangent to all bearing lines. It seems to be true here.

Did you study what conditions (proportions of paralell and perpendicular speed components) should be met to make all bearing lines intersect in exactly one point (what are the conditions for speed and course of both vessels to be in pure lag LOS?)