Figure 6-9.An inverted gun tackle.
A TWOFOLD PURCHASE tackle consists of
two double blocks (fig. 6-11). It has a mechanical
advantage of 4.
A DOUBLE-LUFF tackle consists of a triple
block and a double block (fig. 6-12). It has a
mechanical advantage of 5.
Figure 6-10.A single-luff tackle.
Figure 6-11.A twofold purchase.
Figure 6-12.A double-luff tackle.