Moon sites were common for navigation back in the good old days when clocks weren't so accurate or non existant. Vancouver used them to verify his clock derived fixes. Strangely, he often believed his clock fixes which were miles off rather than his good Moon sights. Joshua Slocum used them for navigation on his circumnavigation. If you don't know, his chronometer was a dime store alarm clock with only the hour hand. Moon sights are supposedly calculation intensive using very high level math. The moon tables were removed from Bowditch sometime around the 1920s as chronometers had become accurate enough to rely on for, the much simpler to calculate, star and sun shots and radio allowed accurate updates of time.