NAUTICAL CHARTS I Purpose of Nautical Charts Nautical

NAUTICAL CHARTS

I. Purpose of Nautical Charts • Nautical charts are different from maps in that they specifically depict water areas, while maps concentrate on land area, roads, landmarks, etc. • Land areas and features on charts are sketchy and are noted only for their interest to the boater. • Unlike maps, the nautical chart conveys much information specifically designed to assist in safely navigating the area that the chart covers

II. How to use a nautical chart for a boating trip • Study your chart thoroughly. • Look at the position from which you will start and visually follow along the course you wish to take. • Look for "notes" - water depths, obstructions (especially under water), bridges, power lines or any other unusual items that may be a hazard to your progress. • Look for visual objects featured on your chart that you should be able to observe and identify to confirm your position.

III. Reading a Nautical Chart A. Look for the chart title at the top right of the chart.

III. Reading a Nautical Chart B. CHART ORIENTATION TRUE NORTH is at the top of the chart. EAST is at the right-hand side of the chart. WEST is at the left-hand side of the chart. SOUTH is at the bottom of the chart.

III. Reading a Nautical Chart MAGNETIC NORTH Magnetic North moves over time. For the SF Bay, it is currently about 15° East of North. THE COMPASS ROSE TRUE NORTH True North is the point around which the earth rotates.

III. Reading a Nautical Chart C. SOUNDINGS Soundings are in meters, feet, or fathoms (6 feet per 1 fathom) Sounding Numbers reflect the depth of the water Map Colors - shallow water is tinted a darker blue and deeper water is a lighter blue and white.

Soundings

NAUTICAL CHARTS SOUNDINGS CONT. • Depths of water are the mean depth for that area. • Water depth can be affected by the storms, the moon, wrecks, and shoaling (sandbanks), and winds

D. Other Symbols • There are 39 different types of bottom for the ocean floor. • If an area’s bottom is known it will be displayed on the chart M = Mud

D. Other Symbols LIGHTS AND AIDS TO NAVIGATION (ATON)

E. Latitude & Longitude • Points of latitude and longitude are plotted like X, Y coordinates • Latitude = X coordinate • Longitude = Y coordinate (Latitude, Longitude) • Latitude and Longitude are measured in degrees. One degree is broken into 60 minutes

E. Latitude & Longitude = 1 Minute SMALL SCALE LARGE SCALE

Can you find the coordinates for the red X? Latitude = 39° 57’ min N Longitude = 24° 53’ E Coordinates: (39° 57 min N, 24° 53 min E)

Emergencies Nautical Charts are not only used for navigation, but for emergency situations as well. Knowing your location allows responders to get to you quicker. In fact, one of the first things the Coast Guard does is plot the position to get a visual reference of the person in distress, then they dispatch resources to that location to search. The video linked from below is an example of a rescue operation that started with a distress call in which the boat captain provides his position as a lat & long coordinate. Fishing vessel northern belle