Most terminals for tankers are piers and sea islands, while other types include single point moorings and multiple-buoy moorings. The LNG and LPG carrier moored to the jetty is a very common terminal for transfer of gas in open seas. It is important to estimate the motions and line tensions of the LNG carrier when it moors to a jetty in metocean environment. Normally, the motions of the LNG carrier would be restricted by the loading arm, which is connected to LNG carrier's manifold. An example of 125,000 m 3 LNG carrier moored to a jetty exposed to a set of environment conditions is given. A mathematical model which is based on the equations of motion in the time domain is used to the analysis of LNG moored to an offshore jetty exposed to waves, swell, wind and current. By means of a time domain computer program TERMSIM computations are carried out to determine and optimize the lay-out and / or orientation of the jetty and mooring gear in terms of forces in mooring lines and fenders and the envelope of motions of the loading arms. The purpose of this study is to determine the sensitivity of the mooring system and carrier motions to the combinations of wind waves with and without swell, steady wind and wind spectra. The results can be consulted by the designer in the design of jetties.