A control system for controlling a vessel, a method for controlling dynamic positioning of the vessel or ship, and a computer program for carrying out the method are disclosed. The vessel includes an electrical power grid, at least one combustion engine driven power generator, and an energy storage medium. The power grid is arranged to provide power to an electric motor driving one or more thrusters or propellers of the vessel. The control system further includes a control unit arranged with computer programs and hardware configured to: calculate a Remaining Operation Window time for carrying out dynamic positioning powered by the energy storage medium, generate and display information including a time period for the Remaining Operation Window of dynamic positioning, and carry out an automatic control action in relation to at least one of a power generator or power consuming device connected to the power grid.