Originally Posted by

**Albatross**
But this about to be is correct if we talking about increase of moment of inertia!

Moment of inertia is approximately: Ixx=f*DISPL*B^2 where f is coefficient depending on type of boat;

If we increase length L of boat by k=2, then beam B will be increased by k^0.76=2^0.76=1.69 times and displacement DISPL in k^2.26=2^2.26=4.79 times. Then, moment of inertia Ixx will be increased by 4.79*1.69^2=13.7 times. Height of rig needs also to be considered, but result will be similar.

Unfortunately in CW's book he says that **stability **is increasing 16 times, not **moment of inertia**! And anyway moment of inertia is not a direct measure of stability, it is only a part of equation describing roll, along with other more significant factors (inertial, damping and hydrostatic). See equation I posted before.

So we are coming back from what I have started: '*stability is increasing 16 times*' - is amteurish statement and it is sad that it appears in such valuable book.