Roll period

I spoke yesterday with Frank Fox about some ship design issues. He had spoken with a professor at the Webb Institute about stability issues. We talked about calculating roll period. The formula is:

T=roll period in seconds
B=beam in feet
GM= metacentric height in feet
K= a constant that can vary in the range of 0.38 and 0.55

T=(B x K)/sqrt(GM)
Springsharp must use K=0.42, since the Ger/CB/1905 design has the following:
T=14.2 seconds
B=80ft
GM=5.6ft

Therefore

K=T x sqrt(GM)/B=14.2 x sqrt(5.6)/80=0.42