Abstract: A method for assisting the management of a vessel comprising at least one tank configured to contain liquefied gas and a vapor phase treatment system capable of sending boil-off gas exiting the tank to a propulsion engine of the vessel or to a gas combustion unit on board the vessel and capable of extracting a portion of the liquid phase contained in the tank and of evaporating this portion in order to send it to the propulsion engine. The method comprises: generating at least one tank management scenario defining an evolution of the pressure of the gas phase contained in the tank along a path of the vessel; computing a cost function that at least depends on a total amount of boil-off gas generated in the tank along the path; and displaying to a user the tank management scenario as a function of the computed cost function.