USCG Exam PracticeCargo gear and rigging
What is the theoretical mechanical advantage of a luff tackle?
- A. One — it provides only a change of direction
- B. Two or three, depending on which block is the moving block
- ✓ Three or four, depending on which block is the moving blockCorrect
- D. Five, based on a standard safety factor of five to one
Why C is correct
NAVEDTRA 14343 §8-2 states that a luff tackle, consisting of a double and a single block, gives a mechanical advantage of three or four depending on which block moves. A gun tackle (two single blocks) gives two or three; a single whip gives no mechanical advantage.
Cited:NAVEDTRA 14343 §8-2