Drums should be sized to accommodate the length of line equal to the actual distance a load will travel.

As shown in the illustration below, the load cannot travel any further than the first change of direction sheave. Therefore, the drum needs to be sized to accommodate this distance, not the distance from the load to the hoist or winch.

In applications utilizing multiple parts of line, the drum capacity must be increased to accommodate the extra line used for this type of rigging.