Ms Mar, Unless you have a very specific reason to start in Belize I believe the preferred route would be to start in St. Thomas, BVI or St. Martin; down Island and then head west. This would be a more traditional and more comfortable route taking into account the prevailing winds.
If you only desire to sail the Western Caribbean you could depart from the same area and sail South to Venezuela or the Islands off the mainland and then sail west. This would put you in position for the ABC Islands, Columbia, and San Blas Islands before heading into the Western Caribbean. Of course you could also just head west from the Virgins to Puerto Rico, Dominican Republic and Jamaica but that isnít considered as interesting a route. This and other sailing routes are explained in Jimmy Cornellís, World Cruising Routes.
In addition there will be more opportunities to find a yacht to accomplish this if you start in this area. You gave very little information in your request so I apologize if you are already familiar with this information. Good Luck
PS If you PM me with more specifics I will attempt to give you ideas on how you might accomplish what you have in mind. Time and budget of course would determine what is possible.
Edited by ragman (11/04/11 03:16 PM)
Edit Reason: pm
Somewhere on a beach in Belize