San Juan 21  The San Juan 21 is an American trailerable sailboat, that was designed by Don Clark as and first built in 1970. The design was built by the Clark Boat Company in Kent, Washington, United States, but it is now out of production. A total of 2600 San Juan 21s were completed. The design was introduced at the 1970 Seattle Boat Show and was well received. The San Juan 21 is a small recreational keelboat, built predominantly of fiberglass, with wood trim. It has a fractional sloop rig, a raked stem, a slightly reverse transom, a transom-hung rudder controlled by a tiller and a centerboard keel. The boat has a draft of with the centerboard extended and with it retracted, allowing beaching or ground transportation on a trailer. The boat is normally fitted with a small outboard motor for docking and maneuvering. The design has a hull speed of . Similar sailboats