The effect of the independent variables on an LNG carrier fleet resizing

The aim of this paper is to illustrate the main relationship between the independent variables that heavily contribute to fleet resizing. Commonly a shipping company has a fleet for transporting the goods from one port to another around the world. This fleet consists of a group of carriers that transports a fixed amount of cargo between two ports over a period of time and for a fixed cost. The number of carriers in the fleet is heavily dependent on the amount of goods to be delivered annually as stated in the contract. The number of carriers can vary according to the size and speed of the vessels. In addition, fleet operations, scheduling, routing and fleet design can contribute to the development of the overall configuration of the shipping fleet. Specialised long haul carriers with known operating routes such as liquefied natural gas (LNG) carrier transportation depends on the following factors: the ship's daily running costs, voyage costs, costs at sea, costs at port and daily lay-up costs, as well as the number of round voyages per year, lay-up costs of the carrier and number of lay-up days per year. It is clear that there are many different input parameters that are required for fleet optimisation. The objective of fleet optimisation is generally to find the ideal number of ships to deliver the goods according to the contract and to reduce overall fleet costs. The costs are referred to as capital and operational costs. The capital costs or initial expenses are all of the costs that are incurred prior to the commissioning and entry into service of the LNG carrier. Meanwhile, other fixed and variable costs, or future expenses, are all costs that are incurred after delivery of the vessel. However before carried out any fleet optimisation, comprehensive study regarding relationship between all the parameters that affect the fleet size should be established.