SH3 ship speed always 0

[captainadccdacaptain]

Im having trouble getting a decent estimate for ship speed, as when I use the stopwatch and periscope, the ship speed will always be 0 no matter what the AOB or range is. Is it a bug or am I just doing it wrong? This isnt my first time on 100% realism but for some reason its not working right now

[Drakken]

Make sure to use the periscope lock button and that it remains locked on the ship while you measure her speed. This is much harder to do when at higher range or in rough weather, because the lock won't remain for very long on your target.

Also, the target's range and her AOB must both be computed before measuring speed through the Notepad method.