USCG Exam PracticeCargo gear and rigging
A two-leg wire rope sling is used to lift a load. As the included angle between the sling legs increases from narrow to wide, the tension in each leg:
- A. Decreases, because the load is distributed across more wire
- B. Remains constant, because the total load does not change
- ✓ Increases sharply, potentially exceeding the SWL of each legCorrect
- D. Increases slightly but is offset by the increased mechanical advantage of the wider angle
Why C is correct
NAVEDTRA 14343 §8-4 states that as sling legs spread from the vertical, the tension in each leg rises sharply, so wide sling angles greatly increase the load on each leg and its fittings. The SWL of the assembled rig is set by its weakest component, so a leg loaded beyond its SWL can fail even if the total lifted weight is within the hook's rating.
Cited:NAVEDTRA 14343 §8-4