I don't see how a change in base displacement of 0.3% could slow a ship down by
2kn. There was also no change in the Standard displacement, we changed the
Normal displacement and the maximum displacement.
The maximum displacement and a "base speed" value is definitely involved, and the
"base speed" value is not a public number.
No where in this equation is there is maximum displacement mentioned.
The C value, however, was changed. Before the Normal displacement change, the C
value was 25889, after the change it was 34101. (pre change speed was 22kn base
speed, after patch was 19kn base speed).
If you then put the old C value into the speed equation, and simply add in the
displacement from the 1.5k increase, the base speed should be 21.81,etc etc, not
19kn.
Adalbert's formula works if the values of ships are not changing, because the C value
remains constant. When Maximum displacement and SDE's "base speed" value are
changed, Adalbert's formula does explain how the C value changes