Swan 391 vs Swan 431
How do the Swan 391 and Swan 431 compare? Below, their dimensions, displacement, sail area and the standard design ratios side by side, followed by a data-driven summary.
Swan 391 
Swan 431 | Swan 391 | Swan 431 | |
|---|---|---|
| Length overall | 33.1 ft10.08 m | 33.3 ft10.16 m |
| Waterline length | 33.1 ft10.08 m | 33.3 ft10.16 m |
| Beam | 12.4 ft3.79 m | 13.4 ft4.09 m |
| Draft | 7.2 ft2.19 m | 7.5 ft2.30 m |
| Displacement | 18,900 lb8,573 kg | 27,558 lb12,500 kg |
| Ballast | 6,800 lb3,084 kg | 11,900 lb5,398 kg |
| Sail area | 767 ft²71.3 m² | 896 ft²83.2 m² |
| SA / Displacement | 17.30 | 15.71 |
| Displacement / Length | 233 | 332 |
| Comfort ratio | 30.8 | 40.2 |
| Capsize screening | 1.87 | 1.78 |
| Hull speed (kn) | 7.7 | 7.7 |
Swan 391 vs Swan 431: the short version
- The Swan 391 and Swan 431 are close in length (33.1 ft10.08 m vs 33.3 ft10.16 m ).
- The Swan 431 is heavier, displacing about 46% more, which usually means a steadier but slower-to-accelerate hull.
- On sail area/displacement the Swan 391 carries the more powerful rig (17.3 vs 15.7), favouring lighter-air performance.
- The Swan 431 scores higher on the Brewer comfort ratio, suggesting an easier motion in a seaway.
- By the capsize screening formula the Swan 431 rates better for offshore work (1.78 vs 1.87).
Ratios are guidelines computed from published specs; condition, layout and gear matter as much as the numbers.