Sailing is the art of controlling a sailing vessel. By changing the rigging, ruder and dagger or centre board, a sailor manages the force of the wind on the sails (main and/or jib) in order to change the direction and speed of a boat. Mastery of the skill requires experience in varying wind and sea conditions, as well as knowledge concerning sailboats. Today most people enjoy sailing as a recreational activity. Recreational sailing can be further divided into racing, cruising and "daysailing" or dinghy sailing. There are many production sailboats available, and several of these manufactured models have ownership associations, such as the Islander 36 association.