Dynamics of an abrupt flooding case are studied by comparing fully dynamic and quasi-static flooding simulation methods. Transient asymmetric flooding is traditionally modelled by dividing the compartment into smaller parts with bulkheads representing different obstructions in the flooded compartment. The implications of this assumption are studied by varying the size of the opening on the dividing bulkhead. The importance of the inflooding jet to the response is shown. The jet i.e. the inflooding momentum flux is modelled as force acting on the lumped mass. When the flooded compartment does not have significant obstructions it is important to account for the inflooding momentum flux.