WEC-Sim is a midfidelity numerical tool for modeling wave energy conversion devices. The code uses the MATLAB SimMechanics package to solve multibody dynamics and models wave interactions using hydrodynamic coefficients derived from frequency domain boundary element methods. This paper presents the new modeling features introduced in the
latest release of WEC-Sim. The first feature discussed is the conversion of the fluid memory kernel to a state-space approximation that provides significant gains in computational
speed. The benefit of the state-space calculation becomes even greater after the hydrodynamic body-to-body coefficients are introduced as the number of interactions increases exponentially with the number of floating bodies. The final feature discussed is the capability to add Morison elements to provide additional hydrodynamic damping and inertia. This is generally used as a
tuning feature, because performance is highly dependent on the chosen coefficients. In this paper, a review of the hydrodynamic theory for each of the features is provided and successful implementation is verified using test cases.