Rigging Dimensions
The four foretriangle measurements sailmakers need to quote a new suit.
I ?
48.10 ft
J ?
13.75 ft
P ?
46.75 ft
E ?
17.22 ft
Sail Area Breakdown
Calculated from rigging dimensions. Use these as your starting point when ordering a new suit.
| Sail | Area (ft²) | Area (m²) |
|---|---|---|
| MainsailP × E ÷ 2 | 402.5 | 37.4 |
| 100% ForetriangleI × J ÷ 2 | 330.7 | 30.7 |
| 150% GenoaTypical light-air headsail | 496.0 | 46.1 |
| Storm Jib~50% of foretriangle, high-cut | 165.3 | 15.4 |
| Symmetric SpinnakerEstimated from I, J | 1,190.5 | 110.6 |
| Total Working Sail AreaMain + 100% foretriangle | 733.2 | 68.1 |
Foretriangle Diagram
Drawn to scale from published I, J, P, E measurements — Fractional Sloop · Umberto Felci design
Performance Ratios
How the Dufour 40 carries its sail relative to its displacement.
SA/D Ratio
20.9
Powerful cruiser/racer — quick in light air, reef early in a blow.
Mast Height (above DWL)
57.9 ft
Clears the 65 ft ICW fixed-bridge standard at normal tide.
Ballast Ratio
36%
Typical cruising ballast — balanced stability underway.
Typical Sail Inventory
What Dufour 40 owners usually carry and what's worth buying used vs. new.
Mainsail 402.5 ft²
Dacron cross-cut with 2 reef points is standard. Full-batten is a common upgrade.
Replace new
150% Genoa 496.0 ft²
The workhorse headsail. Most boats have one on a furler by now.
Replace new
110% Working Jib ~364 ft²
Good secondary sail for breezy days — used market is strong.
Buy used
Storm Jib 165.3 ft²
Bright orange recommended. Rarely used, hard to justify new.
Buy used
Asymmetric Spinnaker ~1,190 ft²
Popular downwind upgrade — easier than symmetric for shorthanded sailing.
Optional
Replacement Cost Estimator
Get a rough price range for a new mainsail and genoa for the Dufour 40 — Dacron, laminate, and cruising performance tiers.