Review of San Juan 21
Basic specs.
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The hull is made of fibreglass. Generally, a hull made of fibreglass requires only a minimum of maintenance during the sailing season. And outside the sailing season, just bottom cleaning and perhaps anti-fouling painting once a year - a few hours of work, that's all.
Swing keel
The San Juan 21 is equipped with a swing keel. A swing keel is a pivoting lifting keel, allowing to sail both coastal and inland waters.
The boat can sail close to the beach as the draft is just 0.21 - 0.31 meter (0.69 - 0.99 ft) dependent of the load.
Sailing characteristics
This section covers widely used rules of thumb to describe the sailing characteristics. Please note that even though the calculations are correct, the interpretation of the results might not be valid for extreme boats.
What is Theoretical Maximum Hull Speed?
The theoretical maximal speed of a displacement boat of this length is 5.5 knots. The term "Theoretical Maximum Hull Speed" is widely used even though a boat can sail faster. The term shall be interpreted as above the theoretical speed a great additional power is necessary for a small gain in speed.
Sailing statistics
This section is statistical comparison with similar boats of the same category. The basis of the following statistical computations is our unique database with more than 26,000 different boat types and 350,000 data points.
What is Displacement Length Ratio?
The DL-ratio for San Juan 21 is 113 which categorizes this boat among 'ultra light racers'.
What is SA/D (Sail Area Displacement ratio)?
The SA/D for San Juan 21 with ISO 8666 reference sail is 25.0, with a 135% genua the SA/D is 28.9.
Maintenance
Dimensions of sail.
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If you need to renew parts of your running rig and is not quite sure of the dimensions, you may find the estimates computed below useful.
| Usage | Length | Diameter | ||
| Mainsail halyard | 18.8 m | (61.8 feet) | 8 mm | (5/16 inch) |
| Jib/genoa halyard | 18.8 m | (61.8 feet) | 8 mm | (5/16 inch) |
| Spinnaker halyard | 18.8 m | (61.8 feet) | 8 mm | (5/16 inch) |
| Jib sheet | 6.4 m | (21.0 feet) | 10 mm | (3/8 inch) |
| Genoa sheet | 6.4 m | (21.0 feet) | 10 mm | (3/8 inch) |
| Mainsheet | 16.0 m | (52.5 feet) | 10 mm | (3/8 inch) |
| Spinnaker sheet | 14.1 m | (46.2 feet) | 10 mm | (3/8 inch) |
| Cunningham | 2.7 m | (8.8 feet) | 8 mm | (5/16 inch) |
| Kickingstrap | 5.4 m | (17.6 feet) | 8 mm | (5/16 inch) |
| Clew-outhaul | 5.4 m | (17.6 feet) | 8 mm | (5/16 inch) |
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