Dear KongLi.Goh,
The mass, CM, and inertias of the OC3-Hywind system are given in my Nov 16, 2012 post in the following forum topic: Inertial Moments of OC3-Hywind Components. The mass of 7,466,330 kg is only of the spar (including ballast); the total mass of the system pertinent to the RAO calculation is 8,066,000 kg, as given in the post linked above. I’m not sure what you mean be VCG = 1, but the VCG should be -78 m, as given in the post linked above.
Best regards,