A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2015 Dec 18, 18:17 -0800
Jim Stephens, you wrote:
"One of the protractors is actually a star chart (page 64). The text describes this as "a common type of star map with polar coordinates, favored by navigators for star identification, and formerly published by the Hydrographic Office, Washington D,C., under the authority of the U.S. Navy." (By the time of the book's publication (1978) the hydrographic Office had been superseded by the Naval Oceanographic Office.) I haven't seen a star chart like this and would like to find one, anyone familiar with its name?"
It's a solid bet that this is the very same star finder that is currently under discussion in the "Rude star finder" topic. It's frequently known by its "Hydrographic Office" designation: the H.O. 2102-D star finder. The base plate is a protractor-like polar star chart. At the time the book you mention was published in the late 1970s, it was a bit laborious to produce such a chart by hand and borrowing the pre-existing star finder base would save some trouble. Of course today it would be quite easy to generate your own equivalent.