Rigging Dimensions
The four foretriangle measurements sailmakers need to quote a new suit.
I ?
31.25 ft
J ?
10.00 ft
P ?
29.50 ft
E ?
11.00 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 | 162.3 | 15.1 |
| 100% ForetriangleI × J ÷ 2 | 156.3 | 14.5 |
| 150% GenoaTypical light-air headsail | 234.4 | 21.8 |
| Storm Jib~50% of foretriangle, high-cut | 78.1 | 7.3 |
| Symmetric SpinnakerEstimated from I, J | 562.5 | 52.3 |
| Total Working Sail AreaMain + 100% foretriangle | 318.5 | 29.6 |
Foretriangle Diagram
Drawn to scale from published I, J, P, E measurements — Masthead Sloop · Ted Irwin design
Performance Ratios
How the Irwin 25 carries its sail relative to its displacement.
SA/D Ratio
16.4
Moderate — comfortable coastal cruiser, not overcanvassed.
Mast Height (above DWL)
34.3 ft
Clears the 65 ft ICW fixed-bridge standard with room to spare.
Ballast Ratio
41%
Stiff enough to carry a 150% genoa comfortably into moderate breeze.
Typical Sail Inventory
What Irwin 25 owners usually carry and what's worth buying used vs. new.
Mainsail 162.3 ft²
Dacron cross-cut with 2 reef points is standard. Full-batten is a common upgrade.
Replace new
150% Genoa 234.4 ft²
The workhorse headsail. Most boats have one on a furler by now.
Replace new
110% Working Jib ~172 ft²
Good secondary sail for breezy days — used market is strong.
Buy used
Storm Jib 78.1 ft²
Bright orange recommended. Rarely used, hard to justify new.
Buy used
Asymmetric Spinnaker ~563 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 Irwin 25 — Dacron, laminate, and cruising performance tiers.