Thera II - NOR15091
Sailing performance analysis for a Arcona 410 (series year 2011), built by Arcona and designed by QUIBERGSTEFAN.
Data provided by the Offshore Racing Congress (ORC) · Certificate issued 03/09/2026
This cruiser-racer excels upwind, reaching an impressive 6.8 knots in 10 knots of wind. While it delivers solid performance on a reach at 8.0 knots in moderate winds, it tends to struggle downwind without a spinnaker, managing 5.4 knots in the same conditions. The jib is compact relative to the mainsail, designed for optimal upwind sailing.
Sailing performance as a polar diagram
A polar diagram shows boat speed at different wind angles and wind speeds. The distance from center represents boat speed in knots, and the angle represents the boats angle to the wind. The wind speed is shown as true wind speed (TWS), not apparent wind speed. Likewise, the wind angle is shown as true wind angle (TWA), not apparent wind angle.
Beat: Sailing upwind (toward the wind)
Beam Reach: Sailing across the wind
Run: Sailing downwind (away from the wind)
VMG Performance
Wind Speed (columns): True wind speed (TWS) in knots - the actual wind speed, not the apparent wind you feel on deck.
VMG (Velocity Made Good) is your effective speed toward your destination, not your actual boat speed.
Beat VMG (top bars): Speed made good when sailing upwind. Higher is better - it means you're reaching the windward mark faster.
Run VMG (bottom bars): Speed made good when sailing downwind. Higher is better - it means you're reaching the leeward mark faster.
Measured sails
Spinnaker measurements were not supported before this season's certificates. If no spinnaker is shown, that's why.
Measurements
Identity
Dimensions
Sail Areas
ORC Rating
Rated boat speeds
| Wind Speed (TWS) | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| 4 kt | 6 kt | 8 kt | 10 kt | 12 kt | 14 kt | 16 kt | 20 kt | 24 kt | |
| Beat VMG | 2.74 | 3.85 | 4.68 | 5.18 | 5.42 | 5.58 | 5.66 | 5.74 | 5.69 |
| 52° | 4.34 | 5.96 | 7.03 | 7.53 | 7.72 | 7.84 | 7.93 | 8.03 | 8.04 |
| 60° | 4.76 | 6.35 | 7.33 | 7.78 | 7.97 | 8.07 | 8.16 | 8.27 | 8.31 |
| 75° | 5.14 | 6.68 | 7.56 | 8.01 | 8.29 | 8.44 | 8.56 | 8.71 | 8.81 |
| 90° | 5.12 | 6.63 | 7.55 | 8.04 | 8.42 | 8.73 | 8.95 | 9.22 | 9.40 |
| 110° | 4.54 | 6.08 | 7.11 | 7.81 | 8.28 | 8.71 | 9.13 | 9.83 | 10.37 |
| 120° | 4.02 | 5.60 | 6.82 | 7.64 | 8.15 | 8.59 | 9.04 | 10.06 | 11.21 |
| 135° | 3.39 | 4.94 | 6.17 | 7.13 | 7.77 | 8.23 | 8.66 | 9.62 | 10.98 |
| 150° | 2.79 | 4.13 | 5.30 | 6.29 | 7.07 | 7.60 | 7.99 | 8.68 | 9.44 |
| Run VMG | 2.41 | 3.58 | 4.59 | 5.44 | 6.12 | 6.59 | 7.25 | 8.12 | 8.82 |
Boat speed (knots) at wind angle / wind speed