C&C SR 21 vs Viper 640
How do the C&C SR 21 and Viper 640 compare? Below, their dimensions, displacement, sail area and the standard design ratios side by side, followed by a data-driven summary.
C&C SR 21 
Viper 640 | C&C SR 21 | Viper 640 | |
|---|---|---|
| Length overall | 21.1 ft6.43 m | 21.1 ft6.43 m |
| Waterline length | 18.0 ft5.49 m | 19.1 ft5.82 m |
| Beam | 8.0 ft2.44 m | 8.2 ft2.49 m |
| Draft | 4.5 ft1.37 m | 4.5 ft1.37 m |
| Displacement | 1,380 lb626 kg | 750 lb340 kg |
| Ballast | 439 lb199 kg | 262 lb119 kg |
| Sail area | 204 ft²19.0 m² | 211 ft²19.6 m² |
| SA / Displacement | 26.33 | 40.90 |
| Displacement / Length | 106 | 48 |
| Comfort ratio | 7.1 | 3.6 |
| Capsize screening | 2.87 | 3.60 |
| Hull speed (kn) | 5.7 | 5.9 |
C&C SR 21 vs Viper 640: the short version
- The C&C SR 21 and Viper 640 are close in length (21.1 ft6.43 m vs 21.1 ft6.43 m ).
- The C&C SR 21 is heavier, displacing about 84% more, which usually means a steadier but slower-to-accelerate hull.
- On sail area/displacement the Viper 640 carries the more powerful rig (40.9 vs 26.3), favouring lighter-air performance.
- The C&C SR 21 scores higher on the Brewer comfort ratio, suggesting an easier motion in a seaway.
- By the capsize screening formula the C&C SR 21 rates better for offshore work (2.87 vs 3.60).
Ratios are guidelines computed from published specs; condition, layout and gear matter as much as the numbers.