I know nothing about
South America, but in the eastern and especially the
Gulf Coast in the US, you start to run into trouble beyond about 6 feet of draft. Lots of channels are dredged to 6 feet, but the ones deeper than that tend to be
commercial ports rather than the recreational and yacht-oriented harbors.
The rocky coasts of the northeast US will be okay for you, but the sandier Chesepeake, southeast/Florida, and the
Gulf Coast tend to be more shoal-draft territory.