Measurement uncertainties are inevitable during physical wave tank tests. Therefore, when validating a numerical wave tank against experiments, knowledge of the uncertainties in the physical experiments, and the sensitivity of the body dynamics to such uncertainties, is crucial. Specifically, the inertial properties, as well as the location of the centre of mass (CoM), which are challenging to measure accurately, can have a significant influence on the system dynamics. On the basis of test cases of the Collaborative Computational Project in Wave Structure Interaction Blind Test Series 2, this paper presents a sensitivity analysis of the agreement between experimental and numerical data sets to the quality of the incident, focused wave, as well as the inertial properties and the location of the CoM. A significant influence on the modelled system dynamics can be observed when changing the system parameters, resulting in a variation of the observed error of up to 80 percentage points for pitch motion.