Abaqus - Aqua Module Question

I used the Aqua module in Abaqus for wave load calculation. Using the same model, in the analysis step, I turned on geometric nonlinearity, and the output results were close to the experimental results. However, the curve was very shaking, which should be relatively smooth and close to sine. Turning off geometric nonlinearity, the curve was relatively smooth, but there was a significant difference between the results and the experimental values. How to handle this situation? Thank you!