b-2) Design of Attachments by DBA and Use of New Materials
Lashing rod
Turn buckle
Twistloc
Stacker
Flush socket
Pedestal socket (used for container ships)
Lashing plate
The points are:
1) when they are designed based on a preset external force, taking the occurrence of stormy weather into consideration, they need to satisfy a specified safety factor; and
2) when they are designed based on the external force conditions, deterioration over time needs to be taken into consideration.
Action Items
In a recent trend in analysis, an analysis of a hatch cover body only is insufficient for safety and consideration needs to be given to distortion caused by the movement of the fixed point of the lashing of the hatch cover; therefore, the hatch cover needs to be analyzed with the fixed point of the lashing moving with its body. In addition, packing needs to have an ability to block water as an important technical requirement.
The spring stiffness or dynamic effect has so far not reached the stage of standardization in each of the ship class associations, and accordingly, individual manufacturers must select analysis conditions on their own.
