NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Plotting tools
From: Lu Abel
Date: 2008 May 27, 21:05 -0700
From: Lu Abel
Date: 2008 May 27, 21:05 -0700
Greg R. wrote:
On another note, my favorite plotter (for local coastal navigation, at least) is a non-longer-available device called the Pocket Instant Navigator. Incredibly simple device -- two clear plastic disks joined at their centers by a hollow rivet and able to rotate with respect to one another. Disks are inscribed 0-360 degrees. Back disk also has square grid at aligned N-S and E-W. Rotate the front disk by the amount of local variation and tape it to the back disk. Draw a course line with any convenient straightedge, slap the PIN down so the hollow rivet is over the course line, align it properly with the parallels and meridians on a chart and you've instantly got your magnetic course. Way easier to use than describe. Nearest currently available equivalent is the W&P Compute-A-Course that's shown below the Portland plotter.
Something I can't figure out is why many different designs of really good plotters (like the PIN) appear, but none seems to stick around except the traditional 4x15 plotter and parallel rules.
Lu Abel
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Navigation List archive: www.fer3.com/arc
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Several of the typically 4 x 15 inch plotters such as the Weems and Plath plotters do indeed feature distance scales for the common chart scales of 1:40,000 and 1:80,000. But that's useful only if these are indeed "common chart scales" In a cruise along the coast of Nova Scotia, I was more than a little surprised to discover that their coastal charts are not of a constant scale (eg, 1:80,000) the way US charts are scaled, but vary somewhat from place to place.--- Guy Schwartz <guyschwartz@sbcglobal.net> wrote:Edges are graduated in inches and centimetersIt would be a lot more useful (at least in my opinion) if it also had a scale that matched the plotting sheets, though I guess you could always use the inch scale and "do the math" mentally when plotting.
On another note, my favorite plotter (for local coastal navigation, at least) is a non-longer-available device called the Pocket Instant Navigator. Incredibly simple device -- two clear plastic disks joined at their centers by a hollow rivet and able to rotate with respect to one another. Disks are inscribed 0-360 degrees. Back disk also has square grid at aligned N-S and E-W. Rotate the front disk by the amount of local variation and tape it to the back disk. Draw a course line with any convenient straightedge, slap the PIN down so the hollow rivet is over the course line, align it properly with the parallels and meridians on a chart and you've instantly got your magnetic course. Way easier to use than describe. Nearest currently available equivalent is the W&P Compute-A-Course that's shown below the Portland plotter.
Something I can't figure out is why many different designs of really good plotters (like the PIN) appear, but none seems to stick around except the traditional 4x15 plotter and parallel rules.
Lu Abel
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Navigation List archive: www.fer3.com/arc
To post, email NavList@fer3.com
To , email NavList-@fer3.com
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