[joegrundman]

Hi greyrider

ok you are using max hydrophone range to give you an exact bearing, range and time fix. This of course is the missing piece of information to make it all come together

I think with slow ships, hydrophones are not that reliable, and also i do not think that historical hydrophones had such a fixed cut-off point. In the right conditions you can hear very long distance sounds, but equally sometimes only short sounds.

I'm not sure they were so reliable that you could ever consider them to provide a bearing and range in one go.

the other thing is, you still seem to be assuming you know target course, and target course IS aob after a quick conversion, which means again you require an aob solution for speed

however one possibility is once on a collision course, solve the target speed for different aobs. then once you are at a range where a visual sighting is easy, up scope, check aob, then look up the correct speed for it from the list you already made.