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 Issued weekly Downloaded online subscription Corrections for charts / publications

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 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

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

Chart No. 1

Contour Lines Connect points of equal depth.

Chart No. 1

Introduction to Navigation Questions?