What windsurf sail size to choose: a table by weight and wind
Sail size follows your weight and the knots, but windsurfing has the highest entry threshold of any sport in this app: below a certain wind you do not plane, and not planing changes the whole day. Here is the table, and that threshold in numbers.
Starting table (freeride, planing)
| Rider weight | 12-16 kn | 16-20 kn | 20-25 kn | 25-30 kn |
|---|---|---|---|---|
| 60-70 kg | 5.5-6.5 m² | 4.7-5.5 m² | 4.2-4.7 m² | 3.7-4.2 m² |
| 70-85 kg | 6.5-7.5 m² | 5.5-6.5 m² | 4.7-5.5 m² | 4.2-4.7 m² |
| 85-100 kg | 7.5-8.5 m² | 6.5-7.5 m² | 5.5-6.2 m² | 4.5-5.0 m² |
| Above 100 kg | 8.5-9.5 m² | 7.5-8.0 m² | 6.0-6.5 m² | 5.0-5.5 m² |
For freeride gear on a matching board. A small board needs more sail to plane; a big one lets you take some off.
The threshold that decides the day
In this app windsurfing turns green at 16 knots, against 13 for kite and 12 for wing foil. That is not arbitrary: it is the line between planing and not planing, and it is what the verdict and the alerts run on.
On Lake Garda that means most thermal days light up first for wing and kite, and only later — if it builds — for windsurf. If you do both, the same spot shows you two different start times under two different sports, and that is correct.
What to change when the sail is not enough
- The board before the sail: more volume under your feet gets you planing sooner than half a square metre of cloth.
- The fin: a longer fin helps you hook into planing in light wind, and wants shortening when it builds.
- Entry-level gear does not hold the same range: a 7.0 with few battens is a different tool from a 7.0 with cambers, at both ends.
Frequently asked questions
How many sails cover a season?
Two, spaced about 1.5 m² apart, cover most rideable days at your home spot. A third only makes sense if your spot genuinely has both light and strong days — and the measured wind history tells you that better than memory does.
Why is the same day green for wing foil and not for windsurf?
Because thresholds differ by sport: 12 knots for wing foil, 16 for windsurf. At 13-14 knots a wing flies and a windsurfer does not plane — same measurement, two verdicts.