Nautical charts bear witness all the features necessary for your safe navigation from here to there. To go that data, even so, you must know how to read a chart.
Several outstanding boating condom organizations teach people how to use nautical charts, and every boater should use those opportunities. Earlier you lot have a class – or even if you're a seasoned sailor plotting your next cruise – it helps to familiarize yourself with mutual nautical chart elements.
Depths and dangers: The minor numbers on a nautical nautical chart are h2o depths at "Mean Lower Low Water," which is the average depth at the lower of each twenty-four hours's two low tides. Measurements at this level help boaters determine the closest underwater clearance possible for their gunkhole. Depths (also called soundings) are shown in either feet, fathoms (half dozen anxiety), or meters (three.28 feet). To come across which unit of measurement of mensurate the chart is using, check the large magenta letters at the top correct corner of the chart. Subscripts, such as 52, bear witness depths in fathoms and feet (5 fathoms and ii feet) or decimal meters (five.2 meters). Dangers like rocks, reefs, wrecks and other obstructions are depicted with a variety of symbols, depending on the type of danger, its depth, and other characteristics. Dangers in less than 66 feet of h2o are surrounded by a ring of blackness "danger dots," and have a blue interior.
Aids to navigation: U.Due south. waters have more than twoscore,000 buoys, beacons, and lights that mark dangers, and show prophylactic water and limits of dredged channels. NOAA nautical charts depict them all, using dissimilar symbols that point the purpose of each.
Scale: Nautical charts come in dissimilar "scales," the ratio of a given distance on the nautical chart to the actual distance. When you are sailing in open waters, you'll probably use a pocket-sized chart (1:100,000 or higher) that covers a big expanse. When you are close to shore, and more at gamble from shoals and other dangers, your big-scale chart (ane:20,000 to 1:80,000) will provide more than detail over a smaller surface area.
Distance: Charts of the Great Lakes, other inland lakes, and the Intracoastal Waterway prove distances in statute miles, the unit of measurement of measure you use on country. Most other charts use the "nautical mile" (1.15 statute miles), the length of one minute of latitude. Traveling i nautical mile in ane hour is a speed of ane knot.
Nautical chart notes: To avert cluttering the parts of the chart showing navigable water, cartographers show details about certain features, dangers, restrictions, and warnings in "chart notes" elsewhere on the chart. Some notes are about the entire nautical chart; others relate to a specific characteristic or portion of the chart that uses a nearby label, such equally "(see Note B)." Around the outside of the chart, in the lower left corner, is the chart's edition number and publication date. In the lower right corner is the title and scale of the chart. The total nautical chart title, chart notes and other information are stacked underneath the NOAA logo.
DIY NAUTICAL CHARTS
Free resources
PDF "dictionary" for chart symbols: To assist mariners – whether old salts or new boaters – with chart symbols, the federal authorities problems U.Due south. Nautical chart No. i, a 130-page volume that describes every symbol used on newspaper, digital, and electronic nautical charts. Download a complimentary PDF of U.S. Chart No. 1 at nauticalcharts.noaa.gov/mcd/chartno1.htm.
Chart locator: NOAA nautical charts cover 95,000 miles of U.South. shoreline and the Great Lakes, and include 3.four million square nautical miles of U.S. jurisdiction, which extends 200 nautical miles from shore. NOAA'due south charts are available in a variety of formats to meet the needs of everyone from commercial shippers to the 13 1000000 boaters in the U.S. Notice the chart you need at nauticalcharts.noaa.gov.
NAVIGATING SHALLOW Water
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