Bay Hen 21 vs Viper 640
How do the Bay Hen 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.
Bay Hen 21 
Viper 640 | Bay Hen 21 | Viper 640 | |
|---|---|---|
| Length overall | 21.0 ft6.40 m | 21.1 ft6.43 m |
| Waterline length | 18.3 ft5.56 m | 19.1 ft5.82 m |
| Beam | 6.3 ft1.91 m | 8.2 ft2.49 m |
| Draft | 3.5 ft1.07 m | 4.5 ft1.37 m |
| Displacement | 900 lb408 kg | 750 lb340 kg |
| Ballast | —— | 262 lb119 kg |
| Sail area | 175 ft²16.3 m² | 211 ft²19.6 m² |
| SA / Displacement | 30.04 | 40.90 |
| Displacement / Length | 66 | 48 |
| Comfort ratio | 6.3 | 3.6 |
| Capsize screening | 2.59 | 3.60 |
| Hull speed (kn) | 5.7 | 5.9 |
Bay Hen 21 vs Viper 640: the short version
- The Bay Hen 21 and Viper 640 are close in length (21.0 ft6.40 m vs 21.1 ft6.43 m ).
- The Bay Hen 21 is heavier, displacing about 20% 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 30.0), favouring lighter-air performance.
- The Bay Hen 21 scores higher on the Brewer comfort ratio, suggesting an easier motion in a seaway.
- By the capsize screening formula the Bay Hen 21 rates better for offshore work (2.59 vs 3.60).
Ratios are guidelines computed from published specs; condition, layout and gear matter as much as the numbers.