• 1) Newman (1994, Applied ocean research) provided the formula which is widely referred, and the component due to gravity is missing from the paper.
• 2) Senjanovic (2008, Ocean Engineering) shows a complete one where gravity is included. Though the term due to pressure variation is assumed to be identical to the one given in Huang (2000), it is actually shown as they are transpose to each other and Huang (2000) is in agree with Newman (1994)
• 3) Senjanovic (2012, Journal of Engineering Mathematics) gives a revised form which it is believed to be more correct one. It shows that the C_p+C_nh is now in agree with Newman (1994), but again, transpose to each other. The gravity components is the transpose as the version given in Senjanovic (2008)

The question is then any conclusion on which form is the correct one? Since the formulation should be able to apply on the rigid modes. A test on C42 and/or C24 can be perormed. With 1) we can get C42 (due to hydropressure)=-ROU*g*Displacement, this can be balannce out with the gravity component given in 2) as m*g. Seems, neither the formulation in 2) or 3) can get such a concellation so that the total C24 and C42 are both zeros.

Anyone has been noticed this and any reflections?