I'm sorry to say this but having lived in Latin American I can tell you that petty theft is a constant and rampant problem in the islands and on the continent. If it isn't welded in place, it's gone. Americans are constant targets for thievery. "Panales hurrican" on the windows of one's house is only just enough protection to keep out the theives for a while. A "house sitter" is a necessity for long absences and then you may not be able to trust the sitter for very long.
The thinking by the local populace is that norteamericanos can well afford to replace whatever is stolen. "Respeto" for one's property if you are a norteamericano is not widely practiced.
The playas in the rural parts are generally the most likely places to have something stolen because, (1) it's less populated so the crime will less likely be witnessed, (2) the young people are much poorer and are more tempted, and (3) the local police will overlook the incidents as a minor problem and the young thieves take advantage of the practice. I finally started placing the broken rental car windows, windshield wipers, stolen watches, shoes, cameras, clothes, towels, suntan lotion, etc. on my expense account. It's a cost of doing business down there. You could be six feet away from your beach towel and have it taken. Mind you we did not look, talk or act like touristas from Hicksvilee, either.
Brazil would be a perfect place for sailors but the polarization of the classes is too striking to make it a desirable place to live unless you are born of the culture. There are many sociological and political factors to consider when moving to the perfect place for sailing.