Horizontal Datum Anomalies on Nautical Charts: A Solution

Abstract

A number of horizontal datums are used for positional control on nautical charts produced by the National Ocean Service (NOS). Inherent to these datums are anomalies which have surfaced over the years that affect the global accuracy of charted information. As more sophisticated electronic positioning systems become available to the mariner, these datum anomalies will become increasingly noticeable. NOS has studied the problem and determined that a new reference datum would be necessary to remove these anomalies. This new datum, the North American Datum of 1983 (NAD 83), has been developed and NOS has decided to adopt NAD 83 as the horizontal datum for the nautical charts produced of the continental waters of the United States, including the Great Lakes, Virgin Islands, Puerto Rico, and Hawaii.