Nautical Cartography - U.S. Office of Coast Survey - NOAA

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Cartographers in NOAA's Office of Coast Survey, Marine Chart Division practice the art and science of designing, compiling, updating, and distributing nautical charts. Nautical charts are a special type of map specifically tailored to the needs of marine navigation. Charts show water depths and the delineation of shoreline, prominent topographic features and landmarks, aids to navigation, and other navigational information. A nautical chart is a work area on which the navigator plots courses, ascertains positions, and views the relationship of the ship to the surrounding area. It assists navigators in avoiding dangers and arriving safely at their destination. When a ship grounding, collision, or other marine accident occurs, the nautical chart in use at the time is a critical legal record used to assist in reconstructing the event and assigning liability.

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Learning how to use a boat also means learning how to read and use nautical charts. Today, apps like savvy navvy provides digital solutions to instantly check your position, review electronic chart data, weather forecasts and even plot routes. However, it is still important to fully understand charts and be confident reading them so that you can cross-check your digital and traditional navigation plans. 

Nautical charts contain a wealth of information, including charted depths, key landmarks and navigational aid symbols. Understanding these symbols is crucial for safe navigation.

In this guide, we will take a look at some of the most common nautical chart symbols and what they mean.

1. Depths: Depth information is one of the most important features on a nautical chart as they help you ensure there is enough clearance between the underside of your hull/keel and any obstacles around or below you. Depth information is typically represented by contour lines that indicate the depth of the water at a specific location. The contour lines are usually marked with numbers that represent the depth in feet. In addition to the contour lines, there may be symbols that indicate shallow areas, such as rocks or shoals.
2. Navigational Aids: Navigational aids are markers that help mariners navigate the waters safely. They are typically represented by symbols that indicate their type and location. For example, a lighthouse may be represented by a symbol that looks like a tower with a light on top. Buoy symbols may indicate the type of buoy and its colour. Within savvy navvy you can also see the name of the buoy and its light flashing sequence. 
3. Obstructions: Obstructions are hazards that mariners need to be aware of. Examples of obstructions include rocks, shoals, wrecks, and other obstructions that may require avoiding. Obstructions are typically represented by symbols that indicate their location and type. For example, a rock may be represented by a symbol that looks like a small island, while a wreck may be represented by a symbol that looks like a shipwreck.
4. Anchorages: Anchorages are areas where mariners can safely anchor their vessels. They are typically represented by anchor-like symbols that indicate safe anchorage locations or no-anchor zones. Anchorages may also be marked with depth information, so mariners can determine if the water is deep enough to anchor their vessel.
5. Channels: Channels are routes that mariners can follow to navigate the waters safely into a given marina, anchorage or passageway. They are represented by symbols that indicate their location and width. Channel symbols may also indicate the direction of flow and any hazards that mariners need to be aware of as well as any recommended course of entry.
6. Landmarks: Landmarks are features on the land that can be used as an aid for navigation. They are typically represented by symbols that indicate their location and type. For example, a church may be represented by a symbol that looks like a small building with a cross on top.
7. Fishing Areas: Fishing areas are areas where commercial and recreational fishing is permitted. They are often represented by symbols that indicate their location and the type of fishing that is allowed.
8. Military Zones: Military zones are areas where military activities are taking place. They are usually represented by symbols that indicate their location and the type of military activity that is taking place.

How to read nautical chart symbols?

Nautical chart symbols represent various features and navigational hazards on a nautical chart. 

Here are some tips on how to read nautical chart symbols:

1. Understand the colour coding: Nautical charts use a system of colours to indicate water depth. Blue indicates deep water, while green, yellow, and brown indicate progressively shallower depths.
2. Know the difference between land and water features: Land features are usually shown in brown, while water features are shown in blue or green. Common land features include shorelines, mountains, and buildings, while common water features include buoys, channels, wrecks and shoals.
3. Identify navigational hazards: Symbols for navigational hazards such as rocks, wrecks, and underwater obstructions are usually shown in black or red. Pay attention to these symbols, as they indicate potential dangers to navigation.
4. Look for additional information: charts often contain additional information such as depth soundings, tides and currents, and navigation aids such as buoys and lighthouses. Pay attention to these details to ensure safe navigation.
5. Consult the legend: The legend or key on a nautical chart contains important information about the symbols used. Take the time to familiarise yourself with the symbols and their meanings before using the chart.
6. Consider using electronic charting systems: Electronic charting systems, such as those found on modern GPS devices or apps like savvy navvy boat navigation app, can simplify the process of reading nautical charts by providing more detailed information and allowing you to zoom in and out as needed. However, it's important to remember to always carry a paper backup chart as well, in case of electronic failure.

Understanding nautical chart symbols

Nautical chart symbols are graphical representations of features and hazards in a marine environment. Here are some common nautical chart symbols and their meanings:

1. Depth Soundings: These are shown by a series of numbers along a contour line and indicate the depth of water at that point. 
2. Lighthouses and Beacons: These symbols are used to mark locations where navigation is particularly hazardous. They are often depicted as a tower with a light on top.
3. Rocks, Shoals, and Obstructions: These symbols indicate potential hazards to navigation, and are often represented by a circle or other shape with a dot in the middle.
4. Wrecks: These symbols indicate the location of sunken vessels, and are often shown as an "X" or other distinctive shapes.
5. Channels: These symbols indicate the location and depth of navigable channels. They are often shown as lines with depth soundings on either side.
6. Anchorage symbols: indicate locations where vessels can safely anchor. They are often shown as an anchor icon.
7. Buoyage: These symbols indicate the location and type of navigational buoys, which can be used to mark channels, hazards, and other features. Their colour and shape depict the type of buoy they are and it’s a good idea to look up their lighting sequences as well as this will aid you when navigating at night.

There are of course many more symbols to explore other than those listed above. It is important for mariners to be able to understand and interpret nautical chart symbols in order to navigate safely and efficiently. The International Hydrographic Organisation (IHO) has established standard symbols and abbreviations for nautical charts to ensure consistency and clarity in their use.

Navigational symbols and abbreviations

Marine navigational symbols are often abbreviated so they can be concisely used on charts to communicate important information about navigational hazards, aids to navigation, and other features of the waterway. Here are some common examples:

• Lat: Latitude
• Long: Longitude
• CHTS: Charts
• DR: Dead Reckoning
• Hdg: Heading
• Fathoms: Depth measurement
• M: Magnetic
• True: True direction
• ANCH: Anchorage
• ATON: Aids to Navigation
• Brg: Bearing
• CH: Church
• CRAN: Crane
• DNG: Danger
• FISH: Fishing
• HW: High water
• LW: Low water
• RACON: Radar Beacon
• SHL: Shoal
• SNDG: Sounding
• SP: Signal Post
• WDSP: Windsock

These are just a few examples of the many symbols and abbreviations used in marine navigation. It's important for mariners to have a thorough understanding of these symbols and abbreviations to ensure safe navigation.

Safety symbols

Nautical safety symbols are graphical representations used on marine charts, maps, and publications to convey information about hazards, navigational aids, and other important information related to maritime safety. Some common nautical safety symbols include:

1. Anchorage symbol: A circle with an anchor inside indicates the location of a safe anchorage.
2. Buoy symbol: indicates the location of a floating device used as a navigational aid or to mark hazards.
3. Rocks or shoals symbol: A symbol that looks like a group of rocks or a triangle with a dot in the centre is used to indicate the location of rocks or shoals that pose a hazard to vessels.
4. Wreck symbol: A symbol that looks like a sunken ship or a crossed-out anchor indicates the location of a sunken vessel.
5. Safe water mark symbol: A symbol that looks like a diamond with horizontal stripes indicates the location of safe water, which is free from obstructions and navigational hazards.
6. Restricted water symbol: A symbol that looks like a diamond with vertical stripes indicates the location of restricted water.
7. Depth contour symbol: A symbol that looks like a series of concentric circles indicates the depth of the water in a particular area.
8. Landmark symbol: A symbol that looks like a small building or tower indicates the location of a prominent landmark that can be used for navigation.
9. Compass rose symbol: A symbol that looks like a star with directional arrows that indicates the orientation of the chart and the direction of true north.

These are just a few examples of the many nautical safety symbols used in marine navigation. It's important for mariners to be familiar with these symbols and to use them to safely navigate through coastal waters and inland waterways.

Using nautical charts

Here are some tips for using nautical charts:

1. Understand the symbols: Make sure you understand what each chart symbol means before setting out on your journey.
2. Use a compass rose: Nautical charts include a compass rose that is used to show the orientation of the cardinal directions. 
3. Calculate distances: charts provide distance scales that can help you calculate distances between two points. However, keep in mind that these distances are measured in nautical miles, which are slightly longer than regular miles.
4. Take note of tide and current information: charts often provide information about tides and currents, which can be very useful for planning your route and avoiding dangerous conditions.
5. Check for updates: ensure your charts are updated regularly to reflect changes in the environment, such as changes in water depth or the location of navigational aids. Be sure to check for updates before setting out on your journey to ensure you have the most current information. Electronic charts, such as savvy navvy charts, often do this automatically.
6. Use a Chartplotter: Many modern boats are equipped with chart plotters, which use GPS technology to display your boat's location on a nautical chart in real-time. Most boaters also use navigation apps like savvy navvy to view their live GPS location. This can be very helpful for navigating unfamiliar waters.
7. Practice safe navigation techniques: Always use a combination of tools and techniques to navigate safely, including nautical charts, GPS, and visual observations. Never rely solely on one method of navigation.

Nautical chart symbol differences

Nautical charts use various symbols to represent different features and navigational hazards. Here are some examples of symbol differences you may encounter:

1. Depths: Depths are represented by different colours and contour lines. In some charts, deeper waters are represented by blue colours, while shallow waters are represented by lighter colours such as green or white. In others, depths are represented by contour lines that show the shape of the sea bottom.
2. Rocks and reefs: Rocks and reefs are depicted with different symbols depending on their nature and their location. Some charts may use different colours to indicate their presence, while others use a symbol resembling a dot or a star.
3. Lighthouses: Lighthouses are depicted with different symbols depending on their type and function. For example, a lighthouse that emits a continuous light is depicted with a solid triangle, while one that emits a flashing light may be depicted with a triangle with a broken line.
4. Buoys: are depicted with different symbols depending on their colour and shape. 
5. Wrecks and obstructions: Wrecks and obstructions are depicted with different symbols depending on their location and their nature. Some charts use a symbol resembling a cross to indicate their presence, while others use a symbol resembling a wrecked ship.

It's important to consult the key or legend of a nautical chart to understand the specific symbols used on that chart.

The summary

In conclusion, understanding nautical chart symbols is crucial for safe navigation. By familiarising yourself with these symbols, you can navigate the waters with ease and avoid hazards. Remember, always consult the nautical chart and use caution when navigating in unfamiliar waters. It is also a good idea to use a combination of digital and paper charts to ensure you have more than one information source. 

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Are you getting ready to go sailing? Find out how to plot a course to steer on a nautical chart. Read savvy navvy blog for more information! 

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