There is no definitive answer to this question as the best time of year to sail the Caribbean depends on a number of factors, including your personal preferences and objectives for your trip. That said, many people believe that late fall or early winter (November-February) is the best time to sail the Caribbean, when temperatures are cooler and there is less chance of hurricanes.
Another popular time to sail the Caribbean is during the Christmas and New Year holidays, when many people take advantage of their vacation time to escape the cold weather in other parts of the world. However, keep in mind that this is also one of the busiest times of year in terms of tourism, so you may have difficulty finding accommodation and activities if you don't plan ahead.
In general, sailing conditions in the Caribbean are good throughout the year, with moderate trade winds blowing from east to west. The only exception is during hurricane season (June-November), when strong winds and large waves can make sailing dangerous. If you do decide to sail during this period, be sure to check weather reports regularly and have a contingency plan in case you need to head for shelter.