SJ21 Boat

The Clark Boat Company San Juan 21 blends a combination of performance and ease of sailing.  They are very easy to set up and can be put in the water in as little as 25 minutes. With the swing keel, they ride low on the trailer and can be launched and retrieved from almost any ramp.

The San Juan 21 was produced from 1969 to about 1984 with over 2,600 produced. The SJ21 was part of the C-Lark, SJ23, SJ7.7, SJ28 and SJ34 family of Boats. Here is a photo of the original sales brochure for all boats.

There are three models of the San Juan 21, the Mark I, Mark II and Mark III.


  • Designer:         Don Clark
  • Manufactured  1969 to 1984
  • Number built    2,605
  • LOA:                 20' 6"
  • LWL:                 17'0"
  • Disp:                  1,400 lbs.
  • Ballast:             400 lbs.
  • Draft up:           1'0"
  • Draft down       4'6"
  • Sail area:          190 sq/ft
  • PHRF                 252, All Sails - 264, Working Sails 
  • Rig                     7/8 Fractional




They handle much like big dinghies being very quick and responsive, yet with the 400 lb. keel, they are self righting.  This is not of much concern as capsizing a San Juan 21 is not easy.  Initially tender, the San Juan 21 heels to 15 degrees rather easily but firms up when there and once past 40 degrees, the helmsman has to make a rather big mistake to get it to go more.  Once past 50 degrees or so, the sturdy little boat will round up and head into the wind.  


They are also easy to single-hand with the fractional rig’s small working jib and large main.  In a blow, dumping the main will right the boat with out having to dump the jib as well.


Cost of Ownership

The other factor that surprises a lot of people is the low cost of ownership. Many people think these boats must have cost $20,000 to purchase and thousands each year to maintain. Good condition boats can be had for $2,000 to $3,500 and yearly maintenance can be as little as $350.00 a year which includes saving up for new sails every 5 years.


Sail Inventory

The Sail Inventory consists of a large mainsail, a small 110% working jib, a 135% Genoa, and a Spinnaker.  Being a one design  class, rules limit the sails to be made from Dacron and the spinnaker from Nylon.  This keeps costs down and the boats equal.