-------- Original Message --------
Subject:        Re: Question regarding soundings on nautical charts
Date:   Thu, 03 Feb 2011 11:07:42 -0500
From:   Joel Kovarsky <[log in to unmask]>
To:     Maps, Air Photo, GIS Forum - Map Librarianship
<[log in to unmask]>



On 2/3/2011 10:46 AM, Angie Cope wrote:
> but can anyone tell us what the small number
> to the lower-right of the sounding depth number is called?
This subscript does not appear on early maps, but represents a fraction
of a measured depth on some more modern charts:

     "Soundings. At the top and bottom of the chart you will see the unit
     of measurement used for the soundings in large block letters on this
     chart. SOUNDINGS IN FATHOMS, indicates that soundings are in fathoms
     and fractions of fathoms. One fathom is six feet. SOUNDINGS IN
     FATHOMS AND FEET, indicates the soundings are in fathoms with
     subscript in feet. For spot depths, the fathom will be the larger
     number while the fraction of fathoms or feet will be the smaller
     subscript number. For example, you might see a spot depth on the
     chart of 42. This indicates a depth of 4 fathoms and, if the
     soundings are in fathoms and feet, the small 2 indicates two feet,
     so in this case the depth is 4 fathoms plus 2 feet or 26 feet.
     SOUNDINGS IN METERS, indicates that the soundings on this chart are
     in meters and decimeters. The larger number on the spot depths are
     in meters while the smaller number is tenths of a meter. Use the
     depth conversion scale provided to convert between meters, feet and
     fathoms."

The site for the above citation is:
http://www.sailnet.com/forums/learning-sail-articles/18842-all-about-charts.html

.

Joel Kovarsky