Rigging Dimensions
The four foretriangle measurements sailmakers need to quote a new suit.
I ?
19.50 ft
J ?
15.00 ft
P ?
722.00 ft
E ?
188.57 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 | 68,073.8 | 6,324.3 |
| 100% ForetriangleI × J ÷ 2 | 146.3 | 13.6 |
| 150% GenoaTypical light-air headsail | 219.4 | 20.4 |
| Storm Jib~50% of foretriangle, high-cut | 73.1 | 6.8 |
| Symmetric SpinnakerEstimated from I, J | 526.5 | 48.9 |
| Total Working Sail AreaMain + 100% foretriangle | 68,220.0 | 6,337.8 |
Foretriangle Diagram
Drawn to scale from published I, J, P, E measurements — Masthead Sloop · German Frers design
Performance Ratios
How the Gannet 40 carries its sail relative to its displacement.
SA/D Ratio
19.5
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
46%
Race-oriented ballast ratio — stiff and powerful.
Typical Sail Inventory
What Gannet 40 owners usually carry and what's worth buying used vs. new.
Mainsail 68,073.8 ft²
Dacron cross-cut with 2 reef points is standard. Full-batten is a common upgrade.
Replace new
150% Genoa 219.4 ft²
The workhorse headsail. Most boats have one on a furler by now.
Replace new
110% Working Jib ~161 ft²
Good secondary sail for breezy days — used market is strong.
Buy used
Storm Jib 73.1 ft²
Bright orange recommended. Rarely used, hard to justify new.
Buy used
Asymmetric Spinnaker ~527 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 Gannet 40 — Dacron, laminate, and cruising performance tiers.