## 4 Discussion
The tendency of the _Gazebo_ model to over-predict performance in the high-amplitude conditions observed in Figure 8c was also seen in Figure 9a, where agreement was within less than 30 W except for a few high-energy sea states where the error ranged from 140 to 240 W. _WEC-Sim_'s ability to predict higher-energy sea states more accurately than _Gazebo_ was evident in Figure 9b, with its error ranging from 80 to 115 W for the high-energy sea states. In summary, when considering the percent difference between simulation and field data over all observations, _Gazebo_ overestimated mean electric power by 12.7%, while _WEC-Sim_ overestimated it by 22.2%. The heightened agreement observed in the _Gazebo_ model is likely attributed to the fact that a significant portion of its simulation parameters were finely tuned. The estimated time required to adjust the _Gazebo_ parameters based on field and bench testing data was a few hours. This is in contrast to the _WEC-Sim_ model, which relied more directly on data or component specifications directly obtained from the physical system bench testing or manufacturer specifications. Possible parameters that could improve the agreement of the _WEC-Sim_ model with field measurements include the stiffness and damping properties of the tether setup, adding simulation buffers in the hydraulic system to aid in solving stiff equations, or including extra identified inertia in the PTO model not already represented by the Simscape blocks. Further, the results from both models revealed that the inclusion of mooring and asymmetric heave cone drag did not have a beneficial effect regarding statistical measures considered here. In the present iteration of the simulation models employed in the study, the computational time for the _WEC-Sim_ model was approximately six times greater than that of the _Gazebo_ model, which required roughly 1.5 min computation time per 1 min of simulation on a standard laptop. Each of these models are well suited to different applications. The user-friendly nature and modularity of Simulink makes the _WEC-Sim_ model an appealing option for quick model modifications, such as studying the effects of changing PTO piston diameter or the integration of a different hydraulic motor. Simulink tools allow for an immediate simulation analysis of multiple runs, and selecting signals for analysis is easily achieved with a simple click in the model. On the other hand, the _Gazebo_ model directly replicates the control system of the actual hardware, making it an ideal platform for prototyping controllers and other algorithms before their deployment on the physical device. **Author Contributions:** Conceptualization, C.D., R.C., A.H., and G.B. ; methodology, C.D., D.F., A.H., and M.A; software, C.D., D.F., A.H., and M.A. ; validation, C.D., D.F., A.H., and M.A. ; formal analysis, C.D., investigation, C.D. ; resources, R.C., D.F., A.H., and T.B. ; data curation, C.D., D.F., and A.H.; writing--original draft preparation, C.D. ; writing--review and editing, R.C., D.F., A.H., T.B., and M.A. ; visualization, C.D. ; supervision, R.C., D.F., A.H., and T.B. ; project administration, R.C. and A.H.; funding acquisition, R.C. and G.B. All authors have read and agreed to the published version of the manuscript. This paper had funding support from the US Department of Energy's Water Power Technologies Office, grant number DE-NA0003525. They are located in Washington, DC, USA. Field measurements used in this analysis are available online at [[https://mhkdr.openei.org/submissions/530](https://mhkdr.openei.org/submissions/530)]([https://mhkdr.openei.org/submissions/530](https://mhkdr.openei.org/submissions/530)). This work was supported by the US Department of Energy's Water Power Technologies Office.