- Ten Rater:
The Ten Rater is a very peculiar developmental class more than one hundred years old. In order to fit in the class rules, boats need to be designed based on a formula (invented in 1887 for full size sailboat racing) that considers waterline length and sail area:
R = L x S x 8
where L is the waterline length in meters and S is the sail area in square meters
The result calculated by this formula must be a number equal or less than 10 (here is the origin of the name “Ten Rater”). As the sailboat speed is a direct function of its waterline length and sail area (the bigger the waterline, the higher is the speed, the same being true for the sail area), the designer can only work on these parameters in an inversely relationship: as one goes up, the other must go down, otherwise the formula result will surpass 10. This rule based on a formula gives a lot of freedom for the designers to work on the best design for a certain local sailing condition. A lot of study and experience are necessary to design a successful Ten Rater. The "rigs" on Ten Raters are not limited only to soft sails, but may use rigid wings, or a combination of soft sails on wing masts. The greater emphasis is on design innovation, with a steady stream of new ideas coming from the drawing boards of both amateur and professional designers. Most of the boats are between 140 and 170 cm long and usually weight 5 to 7 Kg. Hull construction materials and techniques are often hi-tech and state of the art. Being one of the fastest and most technically demanding of all monohull model yacht classes, the 10 Rater is not a beginner's boat.