To the editor: The recent article on electronic chart types by Ev Collier (“A welter of acronyms,” Issue No. 156, September 2006) implies that the ENC programs suitable for NOAA charts will be suitable for use with electronic charts available from the NGA (National Geospatial-Intelligence Agency). I have not found this to be true. NOAA charts have an S-57 coding specification that does not appear to work with the NGA DNC charts.
Ev Collier responds: The article does not mean to imply that charting software that can read and display ENC charts will also read and display DNC charts. However, “implication,” like “beauty,” is found in the eye of the beholder and further clarification can only be a good thing.
DNC charts from the NGA comprise the largest body of non-S-57 conforming data available and are, therefore, a rich source of navigation data especially for circumnavigators and long-distance passagemakers. Such ocean travelers would be well served to have access to this database. It is also a good idea when purchasing electronic charting software programs to make sure that they will be compatible with the charts you plan to use.