USCG Exam PracticeCargo gear and rigging
In a yard-and-stay (burton) rig, the SWL of the assembled rig compared to a single boom used alone is:
- A. Equal, because both booms share the load equally
- B. Higher, because two runners support the cargo hook
- ✓ Lower, because of the high combined pull on the married falls when the load is midway between the boomsCorrect
- D. Lower, because the union guy reduces the topping lift capacity
Why C is correct
NAVEDTRA 14343 §9-3 explicitly states that the SWL of the yard-and-stay rig is lower than the SWL of a single boom used alone. When the load is midway between the two boom heads, the combined tension in the married falls can be very high, overloading the guys and union purchase if the single-boom SWL is used.
Cited:NAVEDTRA 14343 §9-3