Sailboat mainsail furler
Z-Spars

These masts incorporate a vertical tube in the aft body of the mast to which the luff of the mainsail is attached. The tube is rotated by pulling on a rope wound round a helical drum attached to its lower end, thus reefing or furling the mainsail.
In-mast furling system spares

Isometric exploded view of furling drum

FEATURES

Helical drum furling mechanism - removable for easy maintenance
Easy access to halyard swivel
Minimum maintenance required
Integral track for storm trysail
Recirculating ball boom car
Integral clew block for mainsail
Control blocks supplied
Staightforward installation of sail
Slot cut to match length of mainsail luff

Dimensioned drawings of each mast section can be seen here.