Rigging Dimensions
The four foretriangle measurements sailmakers need to quote a new suit.
I ?
33.75 ft
J ?
12.00 ft
P ?
30.00 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 | 165.0 | 15.3 |
| 100% ForetriangleI × J ÷ 2 | 202.5 | 18.8 |
| 150% GenoaTypical light-air headsail | 303.8 | 28.2 |
| Storm Jib~50% of foretriangle, high-cut | 101.3 | 9.4 |
| Symmetric SpinnakerEstimated from I, J | 729.0 | 67.7 |
| Total Working Sail AreaMain + 100% foretriangle | 367.5 | 34.1 |
Foretriangle Diagram
Drawn to scale from published I, J, P, E measurements — Masthead Ketch · Carl Alberg design
Performance Ratios
How the Cape Dory 30K carries its sail relative to its displacement.
SA/D Ratio
15.0
Moderate — comfortable coastal cruiser, not overcanvassed.
Mast Height (above DWL)
38.5 ft
Clears the 65 ft ICW fixed-bridge standard with room to spare.
Ballast Ratio
40%
Stiff enough to carry a 150% genoa comfortably into moderate breeze.
Typical Sail Inventory
What Cape Dory 30K owners usually carry and what's worth buying used vs. new.
Mainsail 165.0 ft²
Dacron cross-cut with 2 reef points is standard. Full-batten is a common upgrade.
Replace new
150% Genoa 303.8 ft²
The workhorse headsail. Most boats have one on a furler by now.
Replace new
110% Working Jib ~223 ft²
Good secondary sail for breezy days — used market is strong.
Buy used
Storm Jib 101.3 ft²
Bright orange recommended. Rarely used, hard to justify new.
Buy used
Asymmetric Spinnaker ~729 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 Cape Dory 30K — Dacron, laminate, and cruising performance tiers.