by Bill Mauney
A nautical chart is the treasure map (chart) for all of your coastal paddling adventures. In nautical parlance a map is called a chart. The chart differs from a map in that a map focuses on the land, its topography, its features and manmade structures, roads, etc. These maps are helpful when you want to explore the land at the coast, you are looking for a campsite or a friendly beach, etc. The chart, however, focuses on the water, water depths, the land around the water, the interaction of the tide with the land, aids to navigation such as buoys, day marks, lights, etc., geographical and manmade features that will aid in navigation, etc.
Charts are a cornucopia of nautical information, both in symbol and written form. The National Oceanic and Atmospheric Administration is the source for nautical charts. Your computer link for NOAA Nautical Charts is: http://www.nauticalcharts.noaa.gov
Click on “Nautical Charts and Pubs” to access links to:
- Chart Catalogs
- Dates of Latest Editions (DOLE)
- NOAA’s On-Line Chart Viewer
- U.S. Chart No. 1 (A book of chart symbols, abbreviations and their meanings)
- Chart updates from Local Notice to Mariners and Notice to Mariners
Charts can be purchased from NOAA directly or from authorized NOAA Chart Dealers in your area. By law, they must sell you the latest edition. You can check the DOLE on the above website to make sure you have the most up to date chart.
This article cannot cover all you need to know to read and use a nautical chart, but I will give you a basic overview.
- Tan/Yellow = Land
- Green = Foreshore that covers and uncovers with the tide
- Blue = Relatively shallow water (important for deep draft vessels to know)
- White = Deep water (safe for deep draft vessels)
Numbers in the water
- The numbers in the water are soundings or depths of the water measured from low water level
- These numbers represent feet, fathoms or meters. Check the chart legend to be sure.
- High and low tide cycles occur twice a day (check tide tables on the NOAA website)
- The actual depth = charted depth + tide height at time of day and date on tide table for that position (interpolation may be required)
- The scale is printed on the chart
- Large scale charts cover small areas
- Ideal for kayakers needing as much detail as possible along the shoreline
- 1:40,000 or larger are best for kayakers. 1” = 40,000”
- U.S. Chart No. 1 unpacks what all of the symbols, abbreviations and terms are.
- Printed in multiple places is a Compass Rose showing both True North and Magnetic North
- A distance scale is printed showing distances measured in nautical miles (15 % longer than a statue mile that we use on land) and in yards.
- Distances can also be measured from the latitude scale nearest the position (one degree of latitude = 60 nautical miles, thus one minute of latitude = 1 nautical mile (6,080 feet)
This should give you a basic overview of what is on a nautical chart. For a more in depth study of the subject, I suggest you pick up a copy of Sea Kayak Navigation by David Burch at one of our shops. This book covers the art of navigation from the deck of a sea kayak.
Again, nautical charts open up an entire new world for you to explore and enjoy. Learning to read and use them will make both your next coastal paddling adventure and its preparation more enjoyable and fun.
Read More in our Coastal Paddling Series