Swan 391 vs Swan 46 Mk III
How do the Swan 391 and Swan 46 Mk III compare? Below, their dimensions, displacement, sail area and the standard design ratios side by side, followed by a data-driven summary.
Swan 391 
Swan 46 Mk III | Swan 391 | Swan 46 Mk III | |
|---|---|---|
| Length overall | 33.1 ft10.08 m | 46.6 ft14.20 m |
| Waterline length | 33.1 ft10.08 m | 39.6 ft12.06 m |
| Beam | 12.4 ft3.79 m | 14.0 ft4.26 m |
| Draft | 7.2 ft2.19 m | 7.2 ft2.20 m |
| Displacement | 18,900 lb8,573 kg | 32,408 lb14,700 kg |
| Ballast | 6,800 lb3,084 kg | 12,125 lb5,500 kg |
| Sail area | 767 ft²71.3 m² | 1,179 ft²109.5 m² |
| SA / Displacement | 17.30 | 18.56 |
| Displacement / Length | 233 | 234 |
| Comfort ratio | 30.8 | 35.8 |
| Capsize screening | 1.87 | 1.75 |
| Hull speed (kn) | 7.7 | 8.4 |
Swan 391 vs Swan 46 Mk III: the short version
- The Swan 46 Mk III is the larger boat at 46.6 ft14.20 m LOA versus 33.1 ft10.08 m for the Swan 391.
- The Swan 46 Mk III is heavier, displacing about 71% more, which usually means a steadier but slower-to-accelerate hull.
- On sail area/displacement the Swan 46 Mk III carries the more powerful rig (18.6 vs 17.3), favouring lighter-air performance.
- The Swan 46 Mk III scores higher on the Brewer comfort ratio, suggesting an easier motion in a seaway.
- By the capsize screening formula the Swan 46 Mk III rates better for offshore work (1.75 vs 1.87).
Ratios are guidelines computed from published specs; condition, layout and gear matter as much as the numbers.