1981 American Practical Navigator - Bowditch - Volume 2 - Hardcover Book

Volume II of the 1981 American Practical Navigator (“Bowditch,” Pub. No. 9) was published by the Defense Mapping Agency Hydrographic/Topographic Center under the subtitle Useful Tables, Calculations, Glossary of Marine Navigation. In the agency’s words, it provides the tables, formulas, data and instructions needed for many of the computations of dead reckoning, piloting and celestial navigation.

Part One holds 41 tables, among them traverse and compact traverse tables, meridional parts, distance of the horizon, distance by vertical angle, geographic range, true wind, barometer and humidity corrections, amplitudes, natural trigonometric functions, logarithms, haversines and the Ageton method. Later parts explain navigational mathematics and interpolation, compass conversions, distance and time calculations, celestial navigation calculations and sextant altitude corrections. The volume closes with an extensive glossary.

NGA’s foreword to the 2024 Volume II notes that the 1981 edition became the main reference the U.S. Coast Guard used for merchant mariner license testing, until the National Maritime Center moved to the current edition in 2022, and that many mariners still prefer it. This is Paradise Cay’s 7 x 10 inch hardcover reprint.