twofold purchase
noun
variants or twofold tackle
: a tackle of two double blocks with the standing part of the rope fast to the block from which the hauling part comes
the twofold purchase … is commonly used for hoisting boats 
Manual of Seamanship
Manual of Seamanship- change bowler
- change color
- change down
- change gear
- change hands
- change horses in midstream
- change house
- change key
- change note
- change of edge
- change of heart
- change of life
- change of pace
- change of plan
- change of seasons
- change of underwear
- change of voice
- change off
- change one's mind
- change one's mind (about)
- change one's mind about
- change one's opinion
- change one's opinion/views
- change one's story
- change one's tune