Why are all the anchor chains on the hatch of a ship round?

Side Scuttle, located on the outer side of the hull of a ship, for the comprehensive development of human beings and on the outer field wall of the gangway, is a structural perforation on the hull that can bear and transmit the necessary structural forces of the hull. It is a tightly sealed circular window, usually composed of a main window, laminated glass bending machine, hurricane cover, etc. The ship's hatch cover connected to its laminated glass and the unsecured anchor chain cover (hurricane cover) should be of sturdy construction and should also be properly closed to ensure tightness.

Why are all the anchor chains on the hatch of a ship round

In China, the standard for unsecured anchor chains for ship hatch covers is Gb/T 14413-2009, which is divided into A, B, and C composite types.

Type A, ultra heavy hatch cover without anchor chain, application field: container ship gangway or rib gangway below, with allowable drilling positions on both sides of the fully loaded water level, and specified tightness and airtightness.

B-type, small and medium-sized hatch cover without anchor chain, application areas: the sides of the gangway or rib gangway in amusement parks, or the beam ends for the comprehensive development of people; The first step in the comprehensive development of people on both sides and ends of the non amusement park rib springboard.

C-type, lightweight hatch cover without anchor chain, application areas: first step on the left and right sides of amusement park gangway or rib gangway, and comprehensive development of people on both sides, side and rear development departments; The first step in the comprehensive development of the left and right star tile sheds is to develop the side and rear end of the non amusement park rib springboard.

Why are the hatch covers of ships all round

Why are all the anchor chains on the hatch cover without gears round? This is because, according to the basic principles of structural mechanics, circular structures are more capable of bearing compressive and shear stresses than other forms. The ship is subject to strong winds and waves during its voyage, resulting in significant interaction forces between the hatch and the waves; The combined effect of strong winds and waves, as well as the change in load, can cause deformation of the vessel. The interaction force of this deformation will immediately act on the outer side of the vessel, especially below the hatch.

If a rectangular frame or a rectangular hole is used for the anchor chain of the hatch without a stop, the deformed stress will easily converge on the top of the rectangular frame, causing stress. When the stress borne by a certain corner exceeds the shear strength, the hatch corner will deform or crack, which will greatly reduce the compressive strength of the ship's hull structure and endanger the safety of the ship's voyage. But the circular hatch is different. When it is subjected to external force at a certain position, it can evenly distribute the force to each position, which can prevent damage caused by excessive concentration of stress at a certain location to a large extent.

Train people based on mathematical thinking to understand that for a ring and other shapes with the same total area, the diameter of the other shapes must be longer than that of the ring; On the contrary, under the same diameter standard, the total area of the ring must be larger than that of all other shapes, which means that for the same amount of construction work, the light exposure of the ring hatch without anchor chains is greater. Another circular drilling is easier to carry out engineering construction; A shorter diameter actually results in stronger sealing performance. In addition, the circular shape also looks more unique. Therefore, the hatch covers of ships are designed in a circular shape.

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