AMF 2100 vs Viper 640
How do the AMF 2100 and Viper 640 compare? Below, their dimensions, displacement, sail area and the standard design ratios side by side, followed by a data-driven summary.
AMF 2100 
Viper 640 | AMF 2100 | Viper 640 | |
|---|---|---|
| Length overall | 21.1 ft6.43 m | 21.1 ft6.43 m |
| Waterline length | 17.6 ft5.36 m | 19.1 ft5.82 m |
| Beam | 8.0 ft2.44 m | 8.2 ft2.49 m |
| Draft | 4.0 ft1.22 m | 4.5 ft1.37 m |
| Displacement | 2,200 lb998 kg | 750 lb340 kg |
| Ballast | 850 lb386 kg | 262 lb119 kg |
| Sail area | 209 ft²19.4 m² | 211 ft²19.6 m² |
| SA / Displacement | 19.77 | 40.90 |
| Displacement / Length | 181 | 48 |
| Comfort ratio | 11.4 | 3.6 |
| Capsize screening | 2.46 | 3.60 |
| Hull speed (kn) | 5.6 | 5.9 |
AMF 2100 vs Viper 640: the short version
- The AMF 2100 and Viper 640 are close in length (21.1 ft6.43 m vs 21.1 ft6.43 m ).
- The AMF 2100 is heavier, displacing about 193% 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 19.8), favouring lighter-air performance.
- The AMF 2100 scores higher on the Brewer comfort ratio, suggesting an easier motion in a seaway.
- By the capsize screening formula the AMF 2100 rates better for offshore work (2.46 vs 3.60).
Ratios are guidelines computed from published specs; condition, layout and gear matter as much as the numbers.