The analysis of danger zone ranges for LNG in the coastal area is an important task on account of, inter alia, the safety of human life. It is not an easy process, which is why we consider an danger situation for various weather conditions in the function of constant wind speeds and for various wind speeds in constant weather stability. Pasquill weather stability scale and Beaufort scale with regard to terrain roughness were adopted for the analysis. Both scenarios were considered in the example of Q-flex type vessels in the Świnoujście terminal for two methods of LNG release, i.e. related to a sudden explosion and slow release caused by a leak. The analysis was conducted and considered for the values in the top and bottom flammability limit. Modelling of the danger zone range was analysed with DNV PHAST software, version 7.11. In the process of comparison of the situation related to the risk of explosion in the function of various weather stabilities according to Pasquill scale and constant wind speeds, the values of 1.5 m/s and 5 m/s were adopted, corresponding to 1 and 3 wind force on the Beaufort scale. Those speeds correspond to the water conditions featuring tiny ripples and small waves, the crests of which start to break. The adopted weather stabilities analysed for wind speed equal to 1.5 m/s are A, B, D. A-type stability signifies the least stable atmospheric conditions, and D-type means neutral conditions. In turn, for the wind speed of 5 m/s B, D and F parameters in Pasquill scale were selected. Furthermore, ranges for variable wind speed values were analysed for the selected Pasquill stability.
Ship operational state is a sequence of temporary values of state variable parameters expressing the properties of a particular object and which are recognised as significant for a specific problem. They are the key elements of the operational tasks and essential to determining the Energy Efficiency Operational Indicator for a specialised vessel. In that case, the method refers directly to specific operational states and their significance for a particular operational task in the time function. Based on the surveys conducted on a population of people employed by the ship owner and involved in the ship operation, one has analysed the significance of the operational states for that vessel. The differentiated perception of the operational states of the subjected vessel results from, inter alia, the tasks performed by the responders as their duties, their experience and the level of their engagement in the ship operation. A qualitative and quantitative analysis of the states enables to conduct the planning process in terms of operational tasks of the specialized ship for effective and efficient operation.