In rigging, “surge” refers to an unexpected movement or fluctuation of a load being lifted or moved. This movement can be caused by a variety of factors, including incorrect load placement, imbalanced loads, improper rigging, or mechanical failure. Surge can be dangerous and can put workers, equipment, and the load itself at risk of damage or injury. Therefore, riggers must be cautious when rigging loads and take steps to prevent surge, such as carefully calculating the center of gravity, using appropriate rigging equipment, and securing the load to prevent shifting during movement. The video below shoes a simulation of the surge effect due to misplacement of lift points in relation to the center of gravity of the load.
Surge is the condition that exists when the load moves in an uncontrolled manner during a turning operation when the CG gets outside the lifting/support points. Press play on the video below to see a simulation of the “surge” effect.