If you want the "best" place to
refit, it is in the
USA, where prices are reasonable for the quality you can get, and everything is available. You can spend a lot less in
Cartagena, especially on labor, but you will have to bring your own materials in many cases, and supervise the
work like a hawk, and even then it will be hard to get quality work done. Plus, it is very hot and humid there during the summer or the rainy season, so it will be like working in a steam bath, which is not good for quality painting or
fiberglass work. I would suggest refitting a
new boat in
Maine before you leave, then working your way down the coast in the fall eventually going to the
Bahamas after the hurricane season, then island hopping down the Caribbean chain. It is never a good idea to take off on a long, arduous, and potentially difficult trip (NY to Grenada) in a boat you are unfamiliar with and you know needs work. An alternative, if the boat is in decent shape, is to
cruise Maine and
New England in the summer, then work your way south via the Chesapeake, etc. with a plan to haulout and get the work done in
Florida before heading to the Caribbean in the
winter months.
Florida tends to be much cheaper than
New England, but with great quality and craftsmen available too.