Study On The Anchorage Depth

With the development of the world shipping market and the increase of oil, bulk cargo, container traffic, the trend of large-scale ship is very obvious in recent years, new larger ports are increasing year by year. These factors put forward more requirements to anchorage setting and planning. Because the anchorage depth is the key factor to determine whether ship can use it, so it is necessary to study anchorage depth, so as to provide theoretical support to anchorage setting as well as the safety of ships in the anchorage.This paper firstly analyzes the factors of influencing anchorage depth, these factors include the ship's draft, effects of ship trim and heeling, static rich depth sounding errors, and the ship sinkage due to wind and waves.Separately analyzing of these factors, we can know the ship's draft and heeling, static rich depth, sounding error usually has a specific value, therefore it is not difficult to see that anchorage depth depends on the calculation of the ship sinkage because of wind and waves.Ship singkage in the wind and waves at anchorage belongs to the areas of ship hydrodynamics; this paper mainly uses three-dimensional potential flow theory to research the movement of ships in waves, which reached range of the ship motion in waves.the calculation theory of ship singkage in waves is given a detailed description in the third chapter, we can see the ship equations of motion in waves is very complex.Computer software based on three-dimensional potential theory has been more and more at present, so that you can analyze the movement of ships in the waves using the way of computer simulations.This paper selects and use SESAM which is ship hydrodynamics software of DNV, using it to computer simulatly the selected five different displacement of tankers, container ships and bulk carriers, and finally come to curves that draft rate of the ship's vertical motion changes with displacement in different significant wave height (2.5m,3.5m,4.5m,5.5m,7.0m) when depth draft ratio are 1.3,1.5,1.6,1.8,2.0.Acorrding to statistics of draft rate of the ship's vertical motion in the different displacement, We can reach the maximum value of draft rate of the ship's vertical motion when significant wave height is 2.5 meters, Thus we can derive the calculation formula about anchorage depth.we can judge the safety of large ship at anchor, and can also provide reference to anchorage setting and planning according to these formulas.