OpenCPN is a free software (GPLv2) project to create a concise chartplotter and navigation software for use as an underway or planning tool. OpenCPN is developed by a team of active sailors using real world conditions for program testing and refinement.
Seafarer: Seekarten Viewer / Navi Software für Linux/Mac
This system reads S-57 ENCs, DNC, and SevenCs directENC Data; compatible with LINUX, and Windows 2000/XP