Mary,
The weight of the sailor required to be competitive in a given sailboat class is in the boat designer's hands. If the boat is designed with a high sail area to righting moment ratio, the boat requires heavier weight people to sail the boat. If the designer designs the boat with a lower sail area to righting moment ratio, smaller weight people can sail the boat to its max performance.
Generally designers strive to design faster and faster boats. To a large degree this means have more sail area than the competition. This increased sail area to be faster than the competition requires larger people to hold the boat down and drive the sails to their max capacity.
The solution to this "larger sail area/heavier sailors required" spiral is to make the boats wider. It is torque or righting moment that is required to hold the boats down and drive the sails to their max capacity. Righting moment or torque is a function of sailor's weight and "lever arm". For a given required righting moment, required sailor's weight goes down as lever arm goes up.
Example: If we took all of the present 8ft and 8.5ft wide catamaran designs and made them 12ft wide, women would rule the race courses and catamaran sailing would be a womens' sport. Two momen at 120 pounds each on a 12ft lever arm can generate the same righting moment as two men at 180 pounds on an 8ft lever arm. Both righting moments equal 2880 ftlbs of torque. This calculation is simplified to make it easy for non engineers to understand but you get the point: Wider takes less weight. Make it wide enough and women can do it, sail the boat to its max performance. Wider is simple.
Bill