I have been conducting some free decay analysis on the 5-MW-wind turbine model provided by Simpack in the workshop. I wanted to compare the free decay results with OPENFAST simulation. Hence, I applied a initial displacement of 1m on the tower top in the Y direction. While comparing the results with OPENFAST the decay seems to match in the Y direction but the decay along X-direction seems to vary in magnitude(see snapshot below). SIMPACK has a higher magnitude of decay which could be due to the offset in C.M of the nacelle and the Hub. I also found out that there is an offset in the overhang length between SIMPACK and OPENFAST.

Can anyone explain why there is an offset in the OVERHANG length what do the values represent in the subvar RotOvrHang on SIMPACK? Does the Offset affect the free decay? (check attached)

Appreciate your help on this matter.