This beginner’s guide from Boat Books explains how to read a nautical chart and understand the key information used when planning a voyage. It covers chart symbols, depths, scale, route planning and the differences between paper and electronic charts.
Here’s what you’ll learn:
- What nautical charts show
- How to understand chart symbols
- How to read depths and scale
- How to plan a route
Reading marine charts can feel intimidating for new boaters and sailing students. From chart depth symbols to learning how to use a scale, it can be difficult to know where to start.
This nautical chart guide from Boat Books explains the marine navigation basics, helping beginners understand how to read a nautical chart and interpret the information needed for safer voyage planning.
What Is a Nautical Chart?
A nautical chart is a specialised map designed for marine navigation. It shows information such as water depths, hazards, navigation aids, coastlines and other features important when planning a voyage.
Paper nautical charts provide a physical reference for identifying these features and planning routes.
Nautical Chart vs Road Map
Unlike a road map, nautical charts help you navigate bodies of water. They show details such as:
- Water depths and seabed features
- Buoys, beacons and other navigation aids
- Rocks, wrecks and underwater hazards
Understanding Nautical Chart Symbols
Nautical charts use standard symbols and abbreviations to communicate important navigational information. Common nautical chart symbols identify hazards, buoys, lights, anchorages and other marine features.
When reading marine charts, refer to the relevant official chart symbol reference, such as the Australian Chart 1 publication, to confirm unfamiliar markings.
Reading Depths and Soundings
Depth soundings indicate the charted water depth at specific locations, usually in metres on Australian charts. These depths are referenced to a chart datum rather than the water level at any particular moment.
When navigating shallow areas, consider tidal heights, your vessel's draught and the available under-keel clearance. Understanding chart depth symbols and soundings is essential for planning a safer route.
How to Use Chart Scale
Chart scale tells you how much real-world area is represented on the chart. A large-scale chart provides more detail over a smaller area, while a small-scale chart covers a wider area with less detail.
Planning a Route Using a Chart
Start by identifying your departure point and destination, then check for hazards, shallow water and navigation aids along the proposed route.
Use the chart's scale and depth information to plot your course, allowing for tides and your vessel's draught. Check that your charts are current and incorporate relevant navigational updates before departure.
Marine navigation guides can provide additional guidance on chart reading and route planning.
Paper Charts vs Electronic Charts
Electronic charts can display navigational information through compatible chartplotters and other digital systems. However, their usefulness depends on having suitable equipment, power and up-to-date chart data.
Paper charts provide a physical reference that doesn't depend on electronic equipment. Whichever format you use, ensure the charts are suitable for your intended waters and kept up to date.
Learning how to read a nautical chart is an important step towards safer, more confident boating. Boat Books offers charts, navigation resources and training materials to support Australian boaters. Contact our team for guidance on choosing the right resources for your needs.
FAQs
What information does a nautical chart show?
Nautical charts show depths, hazards, navigation aids, coastlines, seabed features, buoys, beacons, rocks and wrecks.
What do depth soundings mean on a nautical chart?
Depth soundings show how deep the water is at specific locations, usually in metres. When approaching shallow areas, charted depths should also be considered alongside factors such as tides.
What is the difference between large- and small-scale charts?
A large-scale chart provides more detail over a smaller area, while a small-scale chart covers a wider area with less detail.
