NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: DR navigation in the recreatiional fleet: was Role of CN at s ea
From: UNK
Date: 2004 Oct 13, 11:32 -0400
From: UNK
Date: 2004 Oct 13, 11:32 -0400
On Oct 13, 2004 6:33 AM, Jim Thompsonasked about teaching traditional techniques to beginners with electronic-only viewpoints. David Weilacher wisely suggested one try to scare one's students a bit by pointing out that GPS units (or the batteries they rely on) do die; waypoints can be mis-entered; rhumb lines can pass through nasty patches. I have introduced a few friends to coastal navigation since the arrival of easy-to-use Loran-C and GPS. Few have shown any interest in performing DR underway. However, I have always gotten them to agree that a non-trivial passage calls for non-trivial planning. I have gotten them to learn basic chart work, enough to be able to lay out buoy-to-buoy tracks and to measure the resulting courses and distances; plus the ability to take off the lat/lon of a charted object or plot a GPS position. I figure if they can do this much, they are not completely unarmed. The next hurdle is to get them to actually compare the GPS readout to their intentions. One way to do this is to get them to compare the GPS's bearing-and-distance-to-waypoint to the track they've laid out on the chart, and to ponder if they agree sufficiently -- and if not, why not. An alternative to plotting position from lat/lon is to take the GPS's distance-to-waypoint and off-track readouts to plot their position on or near the charted track. It doesn't require access to the chart's longitude scale and works better on folded charts in tight spaces. Finally, I try to get them to do something I always do: when plotting your position (GPS, DR, EP, whatever), always extend a course line from it to see what you're about to get into. The hardest part is getting them into a routine; getting them to write stuff down (notebook or chart); getting them to look ahead. (Well, actually the hardest part is making beginners understand compass deviation; to measure it; to correct it as much as possible; to allow for it. but that's another battle.) -- Peter