Deck General · Blocks & Purchases
A gun tackle consists of two single blocks. What is the mechanical advantage (MA) when hauling on the hauling part?
- A1
- B2✓ Correct
- C3
- D4
Explanation
Mechanical advantage in a simple purchase equals the number of parts of rope at the moving block. A gun tackle has two single blocks with two parts at the moving block, giving MA = 2. This means a 200-lb load requires approximately 100 lbs of hauling force (ignoring friction).
Authority: Deck Seamanship (USCG deck topic)
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