Sailboat Description. The San Juan 21 was designed by Don Clark with a completely retracting keel, balsa cored deck. There are two versions of the San Juan 21The 2019 Western Nationals were held this past weekend on Lake Chelan WA. Seventeen San Juan 21s from all over the Western US and Canada participated in the The San Juan 21. Mark 1 Manual · Mark 2 Manual · Clark Company History · Registry of all SJ 21's; Join the International Class Association San Juan 21 is a 20′ 6″ / 6.3 m monohull sailboat designed by Don Clark and built by Clark Boat Company between 1970 and 1977. SAN JUAN 21. OWNER'S MANUAL. 35. SONOVAN. SONO. SAN by racing sailors, the San Juan is of the same high quality as all. Clark Boats. San Juan 21 Manual Sailing, Manual, 21st, San Juan, Candle, Textbook. Lori Cropp. 5k followers. More information. Sailing · Manual · 21st · San Juan. SanJuan21 Mark I Manual - Free download as PDF File (.pdf) or read online for free. User Manual for a San Juan 21 Mark I.