Rigging Dimensions
The four foretriangle measurements sailmakers need to quote a new suit.
I ?
50.00 ft
J ?
19.00 ft
P ?
43.50 ft
E ?
19.50 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 | 424.1 | 39.4 |
| 100% ForetriangleI × J ÷ 2 | 475.0 | 44.1 |
| 150% GenoaTypical light-air headsail | 712.5 | 66.2 |
| Storm Jib~50% of foretriangle, high-cut | 237.5 | 22.1 |
| Symmetric SpinnakerEstimated from I, J | 1,710.0 | 158.9 |
| Total Working Sail AreaMain + 100% foretriangle | 899.1 | 83.5 |
Foretriangle Diagram
Drawn to scale from published I, J, P, E measurements — Masthead Sloop · Ted Irwin design
Performance Ratios
How the Irwin 42 carries its sail relative to its displacement.
SA/D Ratio
15.3
Moderate — comfortable coastal cruiser, not overcanvassed.
Mast Height (above DWL)
— ft
Air draft not published — measure yours before any bridge transit.
Ballast Ratio
41%
Stiff enough to carry a 150% genoa comfortably into moderate breeze.
Typical Sail Inventory
What Irwin 42 owners usually carry and what's worth buying used vs. new.
Mainsail 424.1 ft²
Dacron cross-cut with 2 reef points is standard. Full-batten is a common upgrade.
Replace new
150% Genoa 712.5 ft²
The workhorse headsail. Most boats have one on a furler by now.
Replace new
110% Working Jib ~523 ft²
Good secondary sail for breezy days — used market is strong.
Buy used
Storm Jib 237.5 ft²
Bright orange recommended. Rarely used, hard to justify new.
Buy used
Asymmetric Spinnaker ~1,710 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 42 — Dacron, laminate, and cruising performance tiers.