[ARDF] Re: Protractors

Tue Oct 26 13:21:31 CDT 2004

I've been gathering Russian ARDF secrets for several years now, and this is one of them. OK, it isn't exactly a secret, but I've found it to be simple, easy to use, and effective...

Place a large compass grid (what I call an Azimuth Grid) over your entire map. Center the grid at roughly the center of the hunt area. Make the azimuth grid lines red (or some other non-map-feature color). Don't use black (trails), green (forest), or blue (streams). The long, precise, grid lines lying atop your map will let you easily "eyeball" accurate bearings freehand. You simply find the grid line that is oriented at the same angle as your bearing, locate where you are on the map, then draw a line passing through your location that is parallel to the appropriate grid line. With the grid centered on your map, the parallel grid line is usually only a few centimeters to one side of where you need to draw your bearing line. With a little practice you'll get good at drawing lines that are straight and parallel. As an added benefit, the azimuth grid on your map may help you avoid silly (nervous) errors, like holding your map upside down, confusing 90 degrees with 270 degrees, e
 tc.

Ideally, you want your azimuth grid to be as large as your map, and for its lines to extend all the way to the map's edges. For the HUGE maps at this year's WC that would have been a tall order, but you'll do OK if you make your azimuth grid as large as practical.

You could make your azimuth grid from a piece of plexiglass. Scratch the lines on the underside of the plexiglass (you'll need to scratch a mirror image of the grid you want) and fill the scratches using a red china pencil. Attach the plexiglass on top of your map, and voila, rain protection for your map, a firm, smooth drawing surface, along with helpful grid lines! It will work great for many years.

Got a color printer? You can make cheap, fast, and very accurate azimuth grids, in large or small quantities. Buy some blank transparencies appropriate for your printer. Create or download some azimuth grid images. You are welcome to use mine: http://www.qsl.net/nz0i/projects/graphics/compassrose.htm . Then print the azimuth grids on your transparencies in whatever quantity you like. Place a printed transparency on your map and you're done. The transparencies may be placed between the map and the cover plate of your map holder, or on top of the map holder. If you're careful the grids are re-usable, but I usually wind up with some creases, or tape stickum on my transparency grid after a race, so I generally just use them once. Why not? They're cheap!

I make both landscape and portrait versions of my azimuth grids. At a competition I cary both versions with me. When I get my map I use the appropriately oriented azimuth grid, and toss the one I don't need. Why not? Did I tell you they're cheap?

BTW, if you're going to go the plexiglass route, print out an azimuth grid on a piece of paper, and place it under the plexiglass, and use it along with a straight edge, to guide your scratches. I use a sharpened nail an awl, and it works great. Why not? ... that's right!

73,
Charles
NZ0I

Message: 1
Date: Mon, 25 Oct 2004 15:55:34 -0500
From: "Kenneth E. Harker" <kenharker at kenharker.com>
Subject: [ARDF] Protractors
To: ardf at kkn.net
Message-ID: <20041025205534.GJ12843 at kenharker.com>
Content-Type: text/plain; charset=us-ascii

     For those who use protractors to plot bearings on a map while in 
the woods, what kind of protractor do you use?  The standard elementary
school variety (if so, how do you use it?) or something more complex like 
these:

     http://www.celestaire.com/catalog/products/4402.html
     http://www.celestaire.com/catalog/products/4407.html

     For those who don't use protractors, how do you plot bearings?

-- 
Kenneth E. Harker WM5R
kenharker at kenharker.com
http://www.kenharker.com/