Boats in the International Ten Rater (10R) class are not limited in length by the class rules and usually have overhangs extending beyond their waterline endings. They are generally light, narrow, stable, seaworthy and fast. This IRSA international rule is based on the 1887 "length and sail area rating rule" which allows shorter waterline length boats to have higher sail areas, while longer LWL boats have smaller sails. It is an ‘open’ rule with great freedom to develop design and construction, particularly in rigs and sail plans. Many different hull forms can be found in the 10R class. A modern 10R will usually be made almost entirely of carbon fibre - hull, foils, spars and fittings.