A system for managing maintenance (100, 200) for a ship including at least one sealed and thermally insulating tank for transporting liquefied gas, the system including: - at least one tank filling level sensor (121, 230) for measuring a current level of filling of the at least one tank, - a device for evaluating movements of the ship (122, 123, 130, 230) able to determine a current state of movement of the ship, - a processing means (110, 210) configured: - to determine a current sloshing index (IBi) from the current level of filling of the tank and the current state of movement of the ship, taking into account the position and the geometry of the tank, in which determining the current sloshing index (IBi) consists in determining a probability of deterioration of the tank when it is subjected to the current state of movement of the ship, in which the current sloshing index (IBi) is obtained by reading a value in a multiple entry correspondence table, an entry corresponding to the filling of the tank, at least one entry corresponding to the current state of movement of the ship and the read value representing a probability of deterioration of the tank; - integrating the current sloshing index (IBi) determined into a wear index (IUi) that takes into account a history of the sloshing indices, - comparing (430, 450) the wear index to a first threshold, - a warning device indicating if an inspection of the at least one tank must be carried out (440, 460) as a function of the result of the comparison. - at least one tank filling level sensor (121, 230) for measuring a current level of filling of the at least one tank, - a device for evaluating movements of the ship (122, 123, 130, 230) able to determine a current state of movement of the ship, - a processing means (110, 210) configured: - to determine a current sloshing index (IBi) from the current level of filling of the tank and the current state of movement of the ship, taking into account the position and the geometry of the tank, in which determining the current sloshing index (IBi) consists in determining a probability of deterioration of the tank when it is subjected to the current state of movement of the ship, in which the current sloshing index (IBi) is obtained by reading a value in a multiple entry correspondence table, an entry corresponding to the filling of the tank, at least one entry corresponding to the current state of movement of the ship and the read value representing a probability of deterioration of the tank; - integrating the current sloshing index (IBi) determined into a wear index (IUi) that takes into account a history of the sloshing indices, - comparing (430, 450) the wear index to a first threshold, - to determine a current sloshing index (IBi) from the current level of filling of the tank and the current state of movement of the ship, taking into account the position and the geometry of the tank, in which determining the current sloshing index (IBi) consists in determining a probability of deterioration of the tank when it is subjected to the current state of movement of the ship, in which the current sloshing index (IBi) is obtained by reading a value in a multiple entry correspondence table, an entry corresponding to the filling of the tank, at least one entry corresponding to the current state of movement of the ship and the read value representing a probability of deterioration of the tank; - integrating the current sloshing index (IBi) determined into a wear index (IUi) that takes into account a history of the sloshing indices, - comparing (430, 450) the wear index to a first threshold, - a warning device indicating if an inspection of the at least one tank must be carried out (440, 460) as a function of the result of the comparison.