A method for controlling the trim of a transport ship without seawater ballast, the ship having a length L along the longitudinal axis (x'x) of the ship and a width l along a transverse axis (y'y) of the ship and including a lower hull a cross section of which takes the form of a trapezium comprising a part forming a flat bottom of the ship from which respectively extend two flanks of identical inclination, said ship having an unladen weight P v between 20% and 60% inclusive of its total weight P T, allowing for a given maximum load weight P TC, according to the formula: P T = P v + P TC said ship including at least one bow closed liquid tank and one stern closed liquid tank not communicating with the sea, said tanks (2, 3) being in communication via at least one line for the transfer of liquid from one to the other, said tanks (2, 3) being positioned facing one another essentially along the longitudinal axis (x'x) and at a distance d from one another, considering the respective geometric center of each of said tanks (2, 3), where d ≥ L/4, the method including the step of transferring liquid into the bow tank when the load of the ship has a weight less than P TC /10 to straighten the waterline of the ship, the liquid being either pure water or water slightly charged with minerals, the mass of which is established between 0.95 kg and 1.05 kg per liter. the total weight P RT of said tanks (2, 3) when entirely filled with the liquid representing between 2% and 8%, preferably between 3% and 6%, of said total unladen weight P V, the ship further including a mooring tank, that mooring tank being independent of the bow tank and of the stern tank, the ship further including a line for supplying sea water to the mooring tank and a line for draining the mooring tank, said mooring tank being at the bow of the ship, the method further including the step of transferring sea water into the mooring tank via the supply line in order to straighten further the waterline of the ship if the ship transports no load and has an inclined trim when the ship enters or sails in a port zone or enters a dry dock. said ship having an unladen weight P v between 20% and 60% inclusive of its total weight P T, allowing for a given maximum load weight P TC, according to the formula: P T = P v + P TC said ship including at least one bow closed liquid tank and one stern closed liquid tank not communicating with the sea, said tanks (2, 3) being in communication via at least one line for the transfer of liquid from one to the other, said tanks (2, 3) being positioned facing one another essentially along the longitudinal axis (x'x) and at a distance d from one another, considering the respective geometric center of each of said tanks (2, 3), where d ≥ L/4, the method including the step of transferring liquid into the bow tank when the load of the ship has a weight less than P TC /10 to straighten the waterline of the ship, the liquid being either pure water or water slightly charged with minerals, the mass of which is established between 0.95 kg and 1.05 kg per liter. the total weight P RT of said tanks (2, 3) when entirely filled with the liquid representing between 2% and 8%, preferably between 3% and 6%, of said total unladen weight P V, the ship further including a mooring tank, that mooring tank being independent of the bow tank and of the stern tank, the ship further including a line for supplying sea water to the mooring tank and a line for draining the mooring tank, said mooring tank being at the bow of the ship, the method further including the step of transferring sea water into the mooring tank via the supply line in order to straighten further the waterline of the ship if the ship transports no load and has an inclined trim when the ship enters or sails in a port zone or enters a dry dock.