AppCleaner might be good for genuine Mac software
. But OpenCPN might perhaps not be recognized by AppCleaner.
Usually OpenCPN from opencpn.org write several files in your home directory: ~/Library/Preferences/
navobj.xml and navobj.xml.1 to navobj.xml.5
perhaps also navobj.xml.changes
possibly cm93 directory
and possibly directories called s63 and SENC
and in directory: ~/Library/Application Support/
Keep your navobj.xml file because it holds all your routes, tracks and waypoints. Others might be deleted and will be rebuild
by new configuration of OpenCPN.