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Navigation
NAU 102
Lesson 5
Chart Corrections
•Objects move
Things Change!
•Printing errors
•New hazards discovered
Always use up to date charts!
Chart Corrections
•Buy a new chart (expensive)
Options:
Corrections are promulgated through:
Notices to Mariners
•Correct it yourself (tedious)
Chart Corrections
http://pollux.nss.nima.mil/untm/
Issued weekly
Downloaded online
Email subscription
Corrections for charts / publications
Chart Corrections
Chart Corrections
Chart Corrections
Nautical Charts
Before using a chart, always closely examine it.
Chart Title
Chart Information
Important information is found in the chart Title Block
•Title of Chart (e.g. Chesapeake Bay Entrance)
•Publisher (e.g. NOAA)
•Projection (e.g. Mercator)
•Scale (e.g. 1:80,000)
•Tidal information
Chart Title
Chart Title
Chart Title
Chart Information
Title Block (cont.)
•Sounding datum (e.g. Mean Lower Low Water)
•Reference for water depth
•Units of measure (e.g. feet)
•Vertical datum (e.g. High Water)
•Reference for height (bridges, etc.)
•Geodetic datum (e.g. WGS-84)
Chart Title
Chart Information
Chart Notes
•Important information, such as:•Local regulations
•Channel depth
•Cautions & Warnings
•Unusual conditions
•Can’t be shown by symbols/abbreviations
•Placed wherever they’ll best fit
Chart Notes
Chart Information
Distance•Usually in nautical miles•Measured using latitude scale (mercator)
•Sometimes measured using graphic scale
•Sometimes in statute miles (rivers)
•Or, kilometers (foreign)
Chart Information
•Latitude – marked on sides of chart
•Longitude – marked on top and bottom
•Degrees, minutes and tenths of minutes
•Divisions depend on scale
•Large Scale =
•Small Scale = degrees and minutes
•Degrees, minutes and seconds, or
Chart Information
Chart Information
Always check the divisions!
Chart Information
•Latitude – North is always up.
•North of the equator – latitude increases going up.
•South of the equator – latitude increases going down.
Chart Information
•Longitude – West is always to left.
•West longitude – longitude increases going left.
•East longitude – longitude increases going right.
Chart Information
Direction
•Measured on Compass Rose•Outer circle = true direction
•Inner circle = magnetic direction
Chart Information
Color
•Very important!
•Shows depth of water, shoal area, etc.
•Varies chart to chart
•Magenta is used vice red.
•Highlights navigation hazards
Chart Information
Lettering
•Style & font communicate information
•Vertical letters (roman type) = always dry
•Italics = submerged & floating
Chart No. 1
•Published by NOS and NGA
•Shows all symbols used on charts
Nautical Symbols, Abbreviations and Terms
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Contour Lines
Connect points of equal depth.
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Introduction to Navigation
Questions?
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