Polar Diagram
Polar diagram showing boat speed (knots) at different true wind angles. 0° is wind from ahead (top); starboard tack runs 0–180° and port tack is shown as 0 to -180°. Wind speeds: 6, 12, 20 knots.
Interactive Polar Tool
Enter your wind conditions to find target boat speed or optimal sailing angle
Enter your current wind conditions and angle to find your target boat speed
Range: 6 - 20 kts
Range: 52° - 150°
See How You Actually Perform
You have your Cape 31 target speeds. Now discover how your real sailing compares. ChartedSails analyzes your GPS data against these polars and shows you exactly where you're leaving speed on the table.
Analyze Your Cape 31 Performance →Target Speed Table
| True Wind Angle | Boat Speed (kts) | Point of Sail |
|---|---|---|
| 52° | 5.96 | Close reach |
| 60° | 6.26 | Close reach |
| 75° | 6.50 | Close reach |
| 90° | 6.41 | Beam reach |
| 110° | 6.51 | Broad reach |
| 120° | 6.39 | Broad reach |
| 135° | 5.69 | Broad reach |
| 150° | 4.76 | Running / Downwind |
Target boat speeds for Cape 31 at 6 knots true wind speed. Select different wind speeds above to see how targets change.
Similar boats
Other sailboats with comparable length and class — useful for cross-fleet target speed comparisons.
About the Cape 31
The Cape 31 is a performance racer/cruiser with a length overall of 9.57 meters. The polar data on this page is the median Velocity Prediction Program (VPP) output across 46 ORC certificates for this model — a real-world fleet average rather than a single boat's rating.
The polar diagram shows target boat speeds ranging from 4.8 knots to 13.7 knots across various wind conditions and angles. Use these targets to benchmark your upwind beat angle and downwind run angle, then check how your real sailing compares.