This paper addresses the hydrodynamic modelling of an inspection-class remotely operated vehicle using a viscous-flow solver for the accurate prediction of manoeuvring coefficients needed for control purposes. The 6-DOF differential nonlinear equation of motion for the ROV visor3 is first described with emphasis on hydrodynamic terms. Then, the hydrodynamic model of the ROV is assembled from data obtained using the Virtual Captive Test (VCT) approach, where experiments such as the Planar Motion Mechanism (PMM) are simulated using CFD. In this work, the Maritime Research Institute Netherlands' viscous flow solver ReFRESCO is used to solve the steady-state and unsteady Navier-Stokes equations for single-phase turbulent incompressible flow, using a detailed geometry of the ROV. Three scenarios are considered: steady-state computations of forces and moments for different values of inflow velocity's direction, steady-state computations of forces and moments for circular manoeuvres in the XY plane, and unsteady computations of forces and moments for rotation around the XYZ axes. The computation of manoeuvring coefficients using CFD allows one to develop a preliminary mathematical model for control purposes when there are limitations for performing physical tests.