The ideal wind speed for sailing is between 8-12 knots
The easiest wind to maneuver small and mid-sized boats is between 8-12 knots, while still being able to reach good speeds.
Anything between 5-8 knots is ideal for beginners that are trying to learn to sail. Anything under 5 knots gets tediously slow.
The average wind speed in the British Virgin Islands is 9 knots which makes the BVI one of the premier sailing destinations in the world.