This paper presents a methodology for determining the components related to the heel of liquefied natural gas (LNG) carriers, excluding the heel of the vessel due to waves. The described method was applied to the description of under keel clearance of vessels approaching the outer port of Świnoujście. The method includes the determination of heel components caused by: draught reading errors, wind, current, tugboats and vessel maneuvers. Determination of the last component was carried out using a 2-stage method. In the first stage, simulation methods were used to identify the parameters of ship movement. In the second stage, the maximum heel of LNG carriers was calculated by analytical methods.