I second BEERMAN and others who recommend the classes. I sailed an 18 foot Hobie for several years -- just enough to get the sailing basics. But taking off on my own with a 47 foot cat was nothing I wanted to take on without some formal instructions.
If you don't feel comfortable ...take the classes !!!
As with COTTAGEGIRL, we did a week-long live aboard with Virgin Island Sailing School out of St. Thomas. Sure glad we did !!!