GSK Exit Exam • Set 4 Question 9 of 30
To rig a threefold purchase what blocks are required
✓
Direct Answer
Option D: Two 3 -sheave blocks
A threefold purchase, which provides a mechanical advantage of 3:1, requires a block with three sheaves attached to the load (moving block) and a block with three sheaves at the fixed point (standing block). Thus, two 3-sheave blocks are needed.
All Options
A
One 2- sheave bock and a single sheave block
B
Two 2- sheave blocks
C
One 2 -sheave and one 3 sheave block
D
Two 3 -sheave blocks
(Correct Answer)
Detailed Explanation & Context
A threefold purchase, which provides a mechanical advantage of 3:1, requires a block with three sheaves attached to the load (moving block) and a block with three sheaves at the fixed point (standing block). Thus, two 3-sheave blocks are needed.
Relevant Framework: STCW 2010 Manila Amendments • DG Shipping E-Learning & Exit Exam Standards • General Ship Knowledge (GSK).
Advertisement
Practice Full GSK Set 4
Test yourself with 30 interactive questions, live timer, and instant score.