Thanks for the info. You know, it maybe cool to try to reproduce those tables and banjo thingy to do it the old fasion way, no modern calculator.
One other question, in SH3 someone did have a way to determine speed by listing to the number of revolution of the screws via hydrophone. It was bit hard to use depending on what ship you were listening too. iRL you did not know this ship's ID.
If the hydrophone does not work at PD, you can still get range via an active sonar ping to the target. I am surprised that a warship's passive sonar guy did not hear that. Is that realistic> pinging the target to get range via active sonar at PD? without spooking the warship.
Modern ships/subs would hear that immediately. I guess in the old days, it was hard to hear that one or two pings unless they got real lucky.