
Lesson 4 - Nautical Charts
Charts
In this lesson, we’ll explore:
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What they are
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How to use them
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Why they’re essential for mariners.
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Key Purposes
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Source of information:
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Tool for calculations:
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Record of navigation:
Chart Scales
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Large-scale
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Medium-scale: Coastal navigation.
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Small-scale
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Paper Charts:
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Reliable, time-tested, no tech required.
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Require manual updates to stay current.
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Electronic Charts:
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Modern standard.
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Raster Charts: Digital scans of paper charts, non-interactive.
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Vector Charts: Interactive, real-time updates, GPS-compatible.
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Always carry a paper backup!
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Chart Projections:
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Mercator Projection
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Gnomonic Projection
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Universal Polar Stereographic (UPS)​​
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Rhumb Lines:
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Constant compass bearing.
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Straight line on Mercator charts.
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Best for shorter routes.
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Great Circles:
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Shortest route between two points.
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Appears curved on Mercator charts.
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Saves time/fuel on long voyages.
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Publications:
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Updates via Notices to Mariners:
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Weekly bulletins with instructions for changes.
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Block Corrections:
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Printable patches for big updates.
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Temporary Notices:
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Cover short-term changes like exclusion zones.
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Tide Tables:
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Predict tidal rise and fall.
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Tidal Stream Atlases:
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Show tidal current direction and strength.
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Lists of Lights:
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Details on lighthouses and navigational aids.
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Radio Signal Lists:
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Frequencies and communication station details.
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Yachtsmen’s Almanacs:
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Condensed navigation guides for small craft.
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Pilots and Sailing Directions:
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Descriptions of coasts, harbors, and hazards.
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