To determine the parts of line, an operator must do what?

To determine the parts of line, it is crucial to understand the relationship between the suspended load and the hoist's safe working load. Dividing the suspended weight by the safe working load of the hoist rope allows the operator to ascertain how many parts of the line are required to safely lift the weight without exceeding the limitations of the hoist.

This calculation is essential in rigging and lifting operations, as it ensures that the load does not put undue stress on the hoist equipment, thereby promoting safety in the operation. By knowing the number of parts of line, the operator can effectively manage the lift and ensure compliance with safety protocols.

The other choices involve hypothetical operations that do not accurately address the calculation needed to determine the parts of line. For instance, multiplying or adding weights could provide misleading information about the hoist's capacity and the actual mechanics of lifting. Similarly, deducting the load weight from a total does not help in assessing how many parts of line are necessary for a given suspended weight. Thus, understanding the operational mechanics of the hoist with respect to safe working loads is essential for effective and safe lifting practices.