Present mid-fidelity modeling approaches for floating offshore wind generators (FOWTs) have been discovered to underpredict the nonlinear, low-frequency wave excitation and the response of semisubmersible FOWTs. To look at the reason for this underprediction, the OC6 undertaking is utilizing computational fluid dynamics (CFD) instruments to analyze the wave masses on the OC5-DeepCwind semisubmersible, with a give attention to the nonlinear difference-frequency excitation. This paper focuses on assessing the uncertainty of the CFD predictions from simulations of the semisubmersible in a hard and fast situation underneath bichromatic wave loading and on establishing confidence within the outcomes to be used in enhancing mid-fidelity fashions. The uncertainty for the nonlinear wave excitation is discovered to be acceptable however bigger than that for the wave-frequency excitation, with the spatial discretization error being the dominant contributor. Additional, undesirable free waves on the distinction frequency have been recognized within the CFD answer. A wave-splitting and wave load-correction process are introduced to take away the contamination from the free waves within the outcomes. A preliminary comparability to second-order potential-flow idea exhibits that the CFD mannequin predicted considerably greater difference-frequency wave excitations, particularly in surge, suggesting that the CFD outcomes can be utilized to raised calibrate the mid-fidelity instruments.