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NGA to update Bowditch, seeks public input

 Sept. 29, 2015

 Carling Uhler
 Office of Corporate Communications

Nathaniel Bowditch’s “The American Practical Navigator,” often simply called “Bowditch” and regarded by mariners as the premier navigational reference, is due for an update, and the National Geospatial-Intelligence Agency wants input from mariners the world over.

The first edition of “The American Practical Navigator” was a revision of “The New Practical Navigator,” the most popular navigational text of the 1700s. Bowditch, a famous mariner and mathematician, worked with other experts of that era to revise and update the original publication and published it in 1802.

NGA and its predecessor organizations have been responsible for reviewing the publication and ensuring it meets the demands of the modern mariner since the 19th century. The U.S. government purchased the rights to the book in 1867 for $25,000. The U.S. Navy Hydrographic Office, an NGA predecessor, assumed responsibility for updating the publication in 1868, and it has been regularly updated ever since. Now in its ninth edition, the publication is freely available for download  from NGA.

To keep pace with the rapidly changing world of navigation, each edition has included revisions to dated material, addition or deletion of new and antiquated methods, corrections to current publications, and further updates to maritime fundamentals, piloting, electronic navigation, electronic and celestial navigation, navigational mathematics, and navigational safety measures. Some past updates have included deleting obsolete LORAN information and adding bottom contour navigation and digital nautical charting techniques.

Collecting and publishing the most updated techniques, information, methods and data ensures “The American Practical Navigator” remains the reference resource for modern, practical marine navigation. "For the past two centuries, Bowditch has provided each new generation of sailors the theory and science behind the art of modern marine navigation,” said Gerard Clifford, NGA Maritime Safety Office.

The deadline for users to insure their comments and feedback are considered for the new edition is June 30, 2016. The next edition of Bowditch is expected to be published and released by NGA in 2017.

To submit contributions and feedback for the next edition of Bowditch, please visit the NGA Bowditch survey website , download the survey files, and send an email to Contributions may also be emailed directly to