NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Iwancio
Date: 2023 Mar 28, 12:58 -0700
David:
The latest edition of Bowditch has tables for vertical angle distances (where the angle is measured between the top of the object and the horizon in front of it) for objects up to 46.5 miles away (for an object 600 m [2000 ft] above the height of your eye). Elsewhere, they compute their geographic range tables out to a distance of 49.2 miles (for a 35 m height of eye and a 300 m high light). Absent anything better from anyone else, "50 miles" seems as reasonable a rule of thumb as any.
Older editions from the 1940's have tables which go out to 85 miles (for objects up to ~4800 m high), but use a separate sub-table for a refraction correction based on estimated distance; the newer tables account for refraction directly.
Regardless, the math will always require a dip correction first, so if you're using a shoreline instead of a sea horizon you'll need to account for that in determining dip.
