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.