Hello Francisco,
I am speaking from the point of view of the so called 'shroud extension system'. There is much more to this system than the 'shroud extenders' but as long as that is what everybody wants to key on, let's call it that.
The 'shroud extender lever' is just one key part of the system but it is not all of the system by a long shot. The shroud lever when opened takes the tension out of the rig and that is its total job in the righting system. The next step is to pull the clevis pin, a push button Avibank pin, at the lower end of the shroud. Then there is a parallel shroud extension wire connected to the chainplate that slides down the main shroud and extends the overall length of the shroud about 18 inches. This allows the upper hull to move 18 inches away from the sails in the water while the lower hull moves 18 inches toward the sails. This 36 inch relative position change between the hulls changes the upper hull from a position of 'retarding the righting of the boat' to 'helping to right the boat'. This greatly reduces the weight required to right the boat, like from two people to one person.
When the shroud was extended, it is possible for the mast to come unstepped if your boat is not equipped with a captive mast step and ball. If this is the case, then it is necessary to rig a connecting line between the bottom end of the mast and the main beam. This line is in place and slack at all times while normal sailing. In the case of a turnover, step number one, is to tighten this line and cleat it in a cleat located on the main beam and pull all of the slack out of it. This will keep your mast base on the ball when the shroud is extended.
Extending the upper shroud and allowing the hulls to change relative position by three feet makes it possible for one small to medium size person to right the boat. The harder the wind is blowing, the smaller the person can be, like 120 pounds.
When the boat is righted, the unchanged, unextended, shroud is to windward. Hold the helm down and keep the boat on same tack it was righted on while reconnecting the leeward shroud, the extended shroud. Once the pin is back in place and the lever is tight, continue sailing.
This is 1976 SuperCat technology and is on every SC of every size ever produced.
Good Sailing,
Bill