Swan 391 vs Swan 651
How do the Swan 391 and Swan 651 compare? Below, their dimensions, displacement, sail area and the standard design ratios side by side, followed by a data-driven summary.
Swan 391 
Swan 651 | Swan 391 | Swan 651 | |
|---|---|---|
| Length overall | 33.1 ft10.08 m | 55.1 ft16.80 m |
| Waterline length | 33.1 ft10.08 m | 55.1 ft16.80 m |
| Beam | 12.4 ft3.79 m | 17.4 ft5.30 m |
| Draft | 7.2 ft2.19 m | 11.5 ft3.50 m |
| Displacement | 18,900 lb8,573 kg | 79,366 lb36,000 kg |
| Ballast | 6,800 lb3,084 kg | 31,700 lb14,379 kg |
| Sail area | 767 ft²71.3 m² | —— |
| SA / Displacement | 17.30 | — |
| Displacement / Length | 233 | 212 |
| Comfort ratio | 30.8 | 49.6 |
| Capsize screening | 1.87 | 1.62 |
| Hull speed (kn) | 7.7 | 9.9 |
Swan 391 vs Swan 651: the short version
- The Swan 651 is the larger boat at 55.1 ft16.80 m LOA versus 33.1 ft10.08 m for the Swan 391.
- The Swan 651 is heavier, displacing about 320% more, which usually means a steadier but slower-to-accelerate hull.
- The Swan 651 scores higher on the Brewer comfort ratio, suggesting an easier motion in a seaway.
- By the capsize screening formula the Swan 651 rates better for offshore work (1.62 vs 1.87).
Ratios are guidelines computed from published specs; condition, layout and gear matter as much as the numbers.