The hour lines for the bowstring equatorial sundial are laid out on the inner surface of the equatorial band. Every hour is 1/24 of a day, or exactly 15 degrees wide. The shadow of the gnomon (or style), cast among the hour lines on the equatorial band, shows the time. The meridian band ("bow") bisects the equatorial band ("time scale"); the 12 o'clock noon hour line is located on the time scale where the two bands intersect (since solar noon occurs when the Sun crosses the observer's meridian). Facing north, morning times are located on the left side of the equatorial band; afternoon times are on the right.

In contrast to the classic equatorial sundial, the primary advantage of the bowstring equatorial sundial is that the style shadow is cast upon a single time scale all year long (regardless of whether the Sun is north or south of the Celestial Equator). Unlike the classic equatorial sundial, the bowstring equatorial sundial should work on the day of the equinoxes (although the author has not witnessed this firsthand).