3:1 Purchase

A 3:1 low friction sheave is used below the furling drum to adjust luff tension in the sail. 3:1 Friction sheaves are designed to be used under a code zero or asymmetric furling drum. This is used to apply tension to the luff of the flying sail. A 3:1 can be used to apply more load to the sail luff / torsional cable than a 2:1 Purchase, for the same winch load. The tackline is attached (spliced) first to the becket on the bottom of the 3:1 Friction sheave it then goes round x1 sheave at deck level (normally at the end of a bowsprit) back up around the friction bearing surface of the sheave and back down to a second block and then led back to the cockpit. A double block can be used at deck level or x2 single blocks can also be used.