Mainsail reefing system

A mainsail reefing system for a sailboat comprising a mast, a boom and a mainsail supported by said mast and said boom, said boom having one end secured to the mast so as to enable the boom to pivot about a first pivotal axis parallel to and at a distance from the mast and about a second pivotal axis perpendicular to said first pivotal axis and to a longitudinal axis of said boom, said system comprising a winding tube mounted rotatably parallel to said boom longitudinal axis for winding and unwinding the mainsail, and drive means for rotatably driving the winding tube, mounted coaxially at an end of the latter situated on a side of said boom end secured to the mast, the mainsail being slidably mounted onto the mast by means of a bolt rope integral with the mainsail and sliding in a channel extending over the entire length of the mast, said channel having a longitudinal opening and a lower opening for inserting the bolt rope by an upper end thereof, said channel being made in a profiled member pivotally fixed parallel to and at a distance from the mast by means of support elements rigidly fixed to the mast and pivotally fixed to said profiled member so as to enable said profiled member to pivot about said first pivotal axis, an opened slot being formed between said profiled member and the mast and providing an aerodynamic slot effect, the profiled member being also fixed to and directly driven in rotation by the boom about said first pivotal axis, so that the longitudinal opening of the channel is maintained in a plane comprising the longitudinal axis of the boom and a longitudinal axis of the mast, and the lower opening of the channel is maintained vertically above an area for winding the bolt rope around the winding tube.