Rigging Dimensions
The four foretriangle measurements sailmakers need to quote a new suit.
I ?
38.38 ft
J ?
12.30 ft
P ?
32.32 ft
E ?
11.15 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 | 180.2 | 16.7 |
| 100% ForetriangleI × J ÷ 2 | 236.0 | 21.9 |
| 150% GenoaTypical light-air headsail | 354.1 | 32.9 |
| Storm Jib~50% of foretriangle, high-cut | 118.0 | 11.0 |
| Symmetric SpinnakerEstimated from I, J | 849.7 | 78.9 |
| Total Working Sail AreaMain + 100% foretriangle | 416.2 | 38.7 |
Foretriangle Diagram
Drawn to scale from published I, J, P, E measurements — Masthead Sloop · E. G. Van De Stadt design
Performance Ratios
How the Harmony 31 carries its sail relative to its displacement.
SA/D Ratio
13.9
Heavy and modestly canvassed — a comfortable cruiser, not fast.
Mast Height (above DWL)
— ft
Air draft not published — measure yours before any bridge transit.
Ballast Ratio
42%
Stiff enough to carry a 150% genoa comfortably into moderate breeze.
Typical Sail Inventory
What Harmony 31 owners usually carry and what's worth buying used vs. new.
Mainsail 180.2 ft²
Dacron cross-cut with 2 reef points is standard. Full-batten is a common upgrade.
Replace new
150% Genoa 354.1 ft²
The workhorse headsail. Most boats have one on a furler by now.
Replace new
110% Working Jib ~260 ft²
Good secondary sail for breezy days — used market is strong.
Buy used
Storm Jib 118.0 ft²
Bright orange recommended. Rarely used, hard to justify new.
Buy used
Asymmetric Spinnaker ~850 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 Harmony 31 — Dacron, laminate, and cruising performance tiers.