Safe Analysis Of Icing Of Ship And Anchoring In Ice Zone

Ship dragging and ship icing are two of the common disasters of sea ice when the ships are at sea. Under severe ice conditions, small and medium sized vessels are easy to drag, being caused collisions, groundings and other serious accidents. Currently, the study of ship anchoring in ice zone mostly remains on empirical methods. Lack of quantitative calculation, there are limitations of empirical method in practical application. In addition, in suitable weather conditions, icing of sea spray causes hazards to the ship that can not be ignored, or even leads the ship to capsize. However, the hazards do not cause enough attention in practice. Therefore, quantitative calculation and analysis of force of anchoring ship and hazards of icing, enable the crew to quantitatively knowledge force of anchoring ship, and recognize hazards of ship icing, take appropriate measures.This paper analyzes failure of sea ice when ice acts on the ship, cites static ice force formula between sea ice and structures, takes wind and current into account, then computes the external force of anchoring ship. On this basis, assuming that anchor can play the maximum grip strength in all conditions, the minimum chain length under external loads of ship can be calculated.Known from the calculation, under normal weather conditions, sea ice of thickness around 4cm leads 3000-ton ship to drag. Sea ice of thickness around 9cm leads ship in the 10 thousand ton class to drag. Therefore, the light-tonnage vessel should avoid anchoring in the ice zone.In this paper the model of sea spray is analyzed, and the following-ship coordinate system being suitable to calculate sea spray is set up. On this basis, empirical formula of sea spray on small and medium sized ship is quote. Taking into account the movement and cooling of droplets, the ice distribution is calculated. According to the ice distribution, the ship's buoyancy and stability can be calculated. Assuming that ship icing for 24 hours, known from the calculation, as the top angle from 0°to 45°, the number of ship stability criteria decreases with the top angle; as top angle from 45°to 90°, it increases; as top angle from 45°, it comes to minimum, and in the larger vessel's as the wind speed, boat speed increased, it decreases. Therefore, considering various factors, the ship should navigate with smaller top angle and the smaller speed. If the wind is expected to increase, vessels choose to shelter from the wind.Through analysis and quantitative calculation, crew can deeply know the force of anchoring ship and hazards of icing.lt can provide safe navigation decision-making when the ships are at sea.