[TorpX]

Originally Posted by edwardallen

In the real world would the aob be calculated by the navigator or weapons officer or estimated by the captain through the periscope.

• It could be determined by analysis of the plot, but this works only if the target is moving straight (which was usually not the case), and the plot is accurate.
• It could be calculated by using the aspect ratio, but this requires positive ID of the target, and knowing height and length, and takes time.
• It could be done visually, with the "Mk I eyeball". This wasn't foolproof, but did not require extra info, and was the fastest method.

Most often, it was estimated by the skipper, visually.

I've had reason to think more about this than I used to. I used to often do the plot-geometry thing, but consider it highly unrealistic now. Beyond what I mentioned above, if one uses the plot-geometry method, you are using the plot (produced without benefit of any AoB information) to estimate AoB (thus reproducing any plot error). Using the other methods makes use of independently obtained information, to improve the plot (thus minimizing plot error).