Dear Alessandro,
I’m glad you solved your problem.
Unfortunately, the mooring model in FAST v7 is quite a bit simpler than those available in FAST v8. It is not possible to model mooring system clump weights in FAST v7 (without modification of the source code).
We are currently working on full-system linearization in OpenFAST for floating offshore wind systems, including the linearization of HydroDyn and MAP++. This new functionality should be available later this summer.
Best regards,