San Juan 21
Description
The San Juan 21 is the entry-level model in the San Juan series, a fractional sloop designed by Don Clark and built by the Clark Boat Company in Kent, Washington, USA, from 1970 to 1977. As the smallest and most trailerable in the lineup, it's celebrated for introducing thousands to sailing with its lightweight fiberglass construction, swing keel for shallow drafts, and one-design racing heritage. Over 2,600 were produced, fostering active fleets worldwide. Variants include the Mark I (longer cockpit, smaller interior) and Mark II (raised deck, more cabin space, shorter cockpit). It's a day-sailer/weekender par excellence—nimble, affordable, and fun—but tender in gusts, suiting protected waters over open ocean.
Construction Details
| Designer | Don Clark |
|---|---|
| Builder | Clark Boat Company |
| Length | 20.500 ft |
| LOA | 20.500 ft |
| LWL | 17.000 ft |
| Beam | 7.000 ft |
| Displacement | 1250 lb |
| Ballast | 400 lb |
| Max Draft | 4.000 ft |
| Min Draft | 1.000 ft |
| Year Built | 1970 |
The standard boat dimensions
| i | 22.50 ft |
|---|---|
| j | 8 ft |
| p | 23 ft |
| e | 8.75 ft |
| p2 | - |
| e2 | - |
| i2 | - |
| j2 | - |
| I | J | P | E | P2 | E2 | I2 | J2 |
|---|---|---|---|---|---|---|---|
| 22.50 ft | 8 ft | 23 ft | 8.75 ft | - | - | - | - |
Documents
Sails
San Juan 21 - MAINSAIL
| Luff | 23 ft - (7010 mm) |
|---|---|
| Foot | 8.75 ft - (2667 mm) |
| Leech | * 24.29 ft - (7404 mm) |
| Tack Angle | * 89.24 ° |
| Diagonal | 24.5 ft - (7468 mm) |
| Head (inches) | 4.5 in - (114 mm) |
| Area | * 104.41 ft² |
| Edit in Calculator | |
San Juan 21 - JIBSAIL
| Luff | 20 ft - (6096 mm) |
|---|---|
| Foot | 9 ft - (2743 mm) |
| Leech | 18.25 ft - (5563 mm) |
| Percentage LP | * 102.5 % |
| Length Perpendicular | * 8.2 ft - (2499 mm) |
| Deck Angle | * 4.69 ° |
| Area | * 82.05 ft² |
| Edit in Calculator | |
San Juan 21 - GENOA
| Luff | 22.25 ft - (6782 mm) |
|---|---|
| Foot | 12.167 ft - (3709 mm) |
| Leech | 20.5 ft - (6248 mm) |
| Percentage LP | * 138.62 % |
| Length Perpendicular | * 11.09 ft - (3380 mm) |
| Deck Angle | * 4.73 ° |
| Area | * 123.36 ft² |
| Edit in Calculator | |
San Juan 21 - GENOA
| Luff | * 22.69 ft - (6916 mm) |
|---|---|
| Foot | * 15.02 ft - (4578 mm) |
| Leech | * 21.19 ft - (6459 mm) |
| Percentage LP | 170 % |
| Length Perpendicular | * 13.58 ft - (4139 mm) |
| Deck Angle | * 5.74 ° |
| Area | * 154.04 ft² |
| Edit in Calculator | |
San Juan 21 - DRIFTER
| Luff | * 22.69 ft - (6916 mm) |
|---|---|
| Foot | * 13.66 ft - (4164 mm) |
| Leech | * 20.13 ft - (6136 mm) |
| Perc LP | * 150 % |
| Length Perp | * 12 ft - (3658 mm) |
| Deck Angle | * 8.97 ° |
| Area | * 136.13 ft² |
| Edit in Calculator | |
San Juan 21 - ASYMMETRICAL
| Luff | * 22.69 ft - (6916 mm) |
|---|---|
| Foot | * 13.2 ft - (4023 mm) |
| Leech | * 20.87 ft - (6361 mm) |
| Perc LP | * 165 % |
| Area | * 225 ft² |
| Edit in Calculator | |
San Juan 21 - SPINNAKER
| Stays | 22.5 ft - (6858 mm) |
|---|---|
| MidGirth | 13.83 ft - (4215 mm) |
| Foot | 13.83 ft - (4215 mm) |
| Perc LP | * 180 % |
| Area | * 264 ft² |
| Edit in Calculator | |
San Juan 21 - SPINNAKER
| Stays | * 22.69 ft - (6916 mm) |
|---|---|
| MidGirth | * 14.4 ft - (4389 mm) |
| Foot | * 14.4 ft - (4389 mm) |
| Perc LP | * 180 % |
| Area | * 278 ft² |
| Edit in Calculator | |
San Juan 21 - STORMJIB
| Luff | * 13.13 ft - (4002 mm) |
|---|---|
| Foot | * 6.14 ft - (1871 mm) |
| Leech | * 10.47 ft - (3191 mm) |
| Perc LP | * 60 % |
| Length Perp | * 4.8 ft - (1463 mm) |
| Deck Angle | * 18.97 ° |
| Area | * 31.53 ft² |
| Edit in Calculator | |
Disclaimer. Boats are not all the same -- even when produced in the same factory of the same model. Sailrite does its best to publish accurate dimensions, but we often find it worthwhile to have our customers measure their boats carefully before we produce kits for them. You should take the same precautions, especially when the data is not from Sailrite. The information on this site is not guaranteed to be accurate. Sailrite offers this content as a service to our community, but takes no responsibility for the reliability of the data provided.