A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: John Brown
Date: 2015 Nov 25, 10:36 -0800
If the calculator is in degree mode, forget about radians. I use the excellent and inexpensive Texas Instruments TI30xa, which is useful for all kinds of navigational calculations, including sight reduction. Many other "scientific" calculators also have the polar to rectangular/rectangular to polar functions.
The TI30xa instructions for using these functions occupy a space about the same size as a credit card, in a few lines of very legible type.
In nav terms (r) represents distance, (theta) represents course
(x) represents dlat and (y) represents dep.
Examples are given in the instructions, together with the very few key presses needed to get results.
A separate calculation, division by cos lat, converts dep into dlon.
A longer explanation would make it all sound much more complicated than it really is. I am a fairly lazy person and found these functions very useful for advancing a DR or finding the distance and course run between two positions in Lat/Lon, when sailing long distances.