Fn=U / (gL)0.5, is kept the same between full scale and model scale
structures, the Froude scaling is followed,which ensures the ratio of the
inertia and gravity forces the same between the model scale structure
and the prototype. In the Froude number, U is the characteristic velocity,
g is the gravitational acceleration and L is the characteristic length of
the model. The STC model was downscaled by Froude scaling with a
ratio of 1:50. The scaling factors for the different variables are listed in
Table 1. For extreme sea states, a large H / D and a small πD / L are applied,
where H is the wave height, D is the characteristic dimension
and L is wave length. For the STC, D = 20 m for the torus and 6.45 m
for the spar, assuming H=30 m, then H/D b 5, drag may become relatively
important in suchwave conditions as compared to smaller waves