Dear @TianYuan.Wang – It looks like you posted very similar questions to @Lei.Xue, which I’ve answered above.
Dear @Lei.Xue – If you are only generating the first-order solution from WAMIT for use by HydroDyn, WAMIT does not need to know the system mass, center of mass, or mooring properties. (That said, these properties would be needed for WAMIT to generate the second-order solution.) See the guidance for using WAMIT to generate potential flow solutions for use in HydroDyn for more information: 4.2.8.4. Modeling Considerations — OpenFAST v3.4.1 documentation.
Best regards,