MIL-PRF-89202B
3.3 Datum
3.3.1 Horizontal datum. For new production, and as map/chart
sheets are revised or updated for periodic maintenance, the WGS
84 or NAD 83 datum shall be used. Where appropriate, a revised
Military Grid system based on WGS 84 or NAD 83 as applicable
shall be depicted as the primary grid. The old (local) grid
will be depicted as the secondary grid with tick marks along the
border of the sheet. A grid conversion note shall also be
placed in the marginalia of the chart. Additionally, both the
old and new 100,000-meter square two-letter identifiers shall be
depicted on the map/chart, if applicable. Appropriate margin
notes shall be added to explain the dual lettering.
3.3.2 Vertical datum. In areas where tides are significant
(generally greater than 0.3 meter range), Littoral Planning
Charts will reference three vertical datums. The contours and
heights of topographic features are referenced to Mean Sea
Level. Coastal Shoreline is referenced to Mean High Water.
Hydrographic features are referenced to a vertical datum based
on a low water tide level, called the sounding datum or
hydrographic datum. The specific low water datum used depends
on the type of tide in the area or the number and magnitude of
high and low tides in one tidal cycle. In areas where tidal
range is not significant, i.e. less than 0.3 meters, Mean Sea
Level (MSL) may be used as the vertical datum for hydrography,
shoreline, and elevations.
3.4 Adjoining data set and chart match.
3.4.1 Overlap area. Adjacent Littoral Planning Charts shall
have an area of overlap with adjoining charts. This practice
makes it easier to transfer plotted positions from one chart to
the next.
3.4.2 Chart detail. When adjoining charts are compiled at the
same time, chart detail in the overlap area must be identical,
except in cases where the newest Littoral Planning Chart is
based on later date sources. In these cases, the new Littoral
Planning Chart shall show the later information. If the
differences in the overlap area are critical for safe
6
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business