The Coefficients of Equipment Number Formula of Ships

Abstract

For their mooring on the sea, ships are equipped with mooring utilities such as anchors, anchor chains, and winches. To determine the specifications of these equipment, the equipment number of each ship must be calculated, and the formula used for calculating this number is provided by the classification society. However, as the equipment number formula was derived based on the tanker at the time of development, it may not be suitable for relatively recent types of ships, such as container ships and liquefied natural gas carriers. Therefore, in this study, the suitability of the equipment number formula was verified, and modified coefficients are proposed for the types of ships. First, the formula for calculating the drag force acting on the ship due to the wind and current was derived and compared with the equipment number formula. The meaning of each coefficient in the equipment number formula was analyzed using this process. Additionally, the mooring equipment, such as anchor and anchor chain, was selected based on the equipment number, and the holding power of the mooring equipment and the drag force acting on the ship was compared to verify the suitability of the equipment number formula for each type of ship. Based on this verification result, a modified coefficient was proposed for each term in the equipment number formula.