A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Robin Stuart
Date: 2018 Mar 18, 13:28 -0700
Recent threads on nomography prompted me to revisit that topic and as an exercise I have produced a couple of nomograms to calculate dip short of the horizon which I think are an improvement on the one mentioned here .
Draw a line from the “Height of Eye” scale through the desired “Distance to Waterline” and read off the Dip Short where it intersects the “Dip Short of Horizon” axis on the right.
Other scales to the left give the dip and horizon distance for a given height of eye. Actually these can also be crudely extracted from the dip short nomogram itself. Draw a line from the “Height of Eye” scale that is tangent to the “Distance to Waterline” curve and extend it until it intersects the “Dip Short of Horizon” axis. The intersection point is the dip of the horizon and the point of tangency is the horizon distance. These nomograms have the nice feature that the “Height of Eye” and “Dip Short of Horizon” are linear and therefore are easily extended for values outside the given range.