Rigging Dimensions
The four foretriangle measurements sailmakers need to quote a new suit.
I ?
30.00 ft
J ?
9.50 ft
P ?
26.00 ft
E ?
8.00 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 | 104.0 | 9.7 |
| 100% ForetriangleI × J ÷ 2 | 142.5 | 13.2 |
| 150% GenoaTypical light-air headsail | 213.8 | 19.9 |
| Storm Jib~50% of foretriangle, high-cut | 71.3 | 6.6 |
| Symmetric SpinnakerEstimated from I, J | 513.0 | 47.7 |
| Total Working Sail AreaMain + 100% foretriangle | 246.5 | 22.9 |
Foretriangle Diagram
Drawn to scale from published I, J, P, E measurements — Masthead Sloop · Bruce Kirby design
Performance Ratios
How the San Juan 24 carries its sail relative to its displacement.
SA/D Ratio
18.2
Powerful cruiser/racer — quick in light air, reef early in a blow.
Mast Height (above DWL)
— ft
Air draft not published — measure yours before any bridge transit.
Ballast Ratio
52%
Race-oriented ballast ratio — stiff and powerful.
Typical Sail Inventory
What San Juan 24 owners usually carry and what's worth buying used vs. new.
Mainsail 104.0 ft²
Dacron cross-cut with 2 reef points is standard. Full-batten is a common upgrade.
Replace new
150% Genoa 213.8 ft²
The workhorse headsail. Most boats have one on a furler by now.
Replace new
110% Working Jib ~157 ft²
Good secondary sail for breezy days — used market is strong.
Buy used
Storm Jib 71.3 ft²
Bright orange recommended. Rarely used, hard to justify new.
Buy used
Asymmetric Spinnaker ~513 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 San Juan 24 — Dacron, laminate, and cruising performance tiers.