Swan 431
Oy Nautor AB · designed by Olin Stephens · 1976
swept fin keelBermuda rigFinland
The Swan 431 is a 33-foot bermuda rig sailboat designed by Olin Stephens and built by Oy Nautor AB, first launched in 1976.
General
| Builder | Oy Nautor AB |
|---|---|
| Designer | Olin Stephens |
| Years built | 1976 |
| Hull type | swept fin keel |
| Rig type | Bermuda rig |
| Construction | — |
| Origin | Finland |
Dimensions
| LOA | 33.33 ft10.16 m |
|---|---|
| LWL | 33.33 ft10.16 m |
| Beam | 13.42 ft4.09 m |
| Draft (max) | 7.55 ft2.30 m |
| Displacement | 27,558 lb12,500 kg |
| Ballast | 11,900 lb5,398 kg |
| Sail Area | 896 ft²83.2 m² |
Design ratios
Computed from the specs above using the standard formulas. Try the sailboat calculators with your own numbers.
SA / Displacement 15.71 Under-canvassed — heavy-air / motorsailing
Ballast / Displacement 43.2 % Higher = stiffer / more sail-carrying power
Displacement / Length 332 Heavy — bluewater displacement
Comfort Ratio 40.2 Heavy offshore
Capsize Screening 1.78 Suited to offshore passages (≤ 2.0)
Hull Speed 7.7 kn Theoretical max displacement speed
How these numbers are calculated
- SA / Displacement
SA ÷ (Disp ÷ 64)^(2/3)— Power-to-weight. < 16 under-canvassed, 16–20 cruiser, > 20 racer.- Ballast / Displacement
Ballast ÷ Disp × 100— Stability/stiffness. Higher carries sail better.- Displacement / Length
Disp(lt) ÷ (0.01 · LWL)³— < 100 ultralight, 100–200 light, 200–300 moderate, > 300 heavy.- Comfort Ratio (Brewer)
Disp ÷ (0.65 · (0.7·LWL + 0.3·LOA) · Beam^1.33)— Motion in a seaway. Higher = more comfortable offshore.- Capsize Screening
Beam ÷ (Disp ÷ 64)^(1/3)— ≤ 2.0 favored for offshore; > 2.0 better for coastal use.- Hull Speed
1.34 · √LWL— Theoretical max displacement speed in knots.
Estimated price
$30,000 typical range $24,000 – $36,000
⚠ Rough estimate only — not market data. Derived from a simple model based on length and hull age; actual asking prices vary widely with condition, equipment, engine hours and location.
