A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Robert VanderPol II
Date: 2016 Mar 12, 20:46 -0800
Mis-labelled range-finder. Probably done intentionally so, so as to put among the instruments the correct group of buyers are going to be looking at. I would bet the normal group of folks looking at range-finders are hunters and this would not really be an instrument thet would be interested in. On the other hand the folks that would be looking at sextants are the kind of folks that might be interested.
As you say can work on a ship from any directions when measuring height. Really though you can do this with a regular sextant and the correct table.
There are also sextant tables for range using waterline to horizon and your height of eys, and height of mast to horizon and your height of eye when body of ship beyond the horizon.