Navigation Charts 101
Just like navigating on land, safe marine navigation requires planning and situational awareness. Navigation charts, whether paper or electronic, provide the critical information you need to chart a course, avoid hazards, and reach your destination. Most charts are based on data from NOAA or equivalent hydrographic authorities. Understanding the different types of charts—and how to read them—helps ensure safe and efficient time on the water.
Understanding Chart Scale and Detail
The scale of a navigation chart determines how much area it covers and how much detail it includes. Small-scale charts (like sailing charts) cover large areas but with less detail—great for passage planning. Large-scale charts (like harbor charts) show smaller areas with great detail, ideal for entering ports or navigating close to shore.
What Are Soundings?
Soundings are the depth readings displayed on navigation charts. They represent water depths at the lowest tide level (usually mean lower low water) to provide a conservative safety margin when anchoring or navigating in shallow areas. They may be shown in feet, fathoms, or meters depending on the chart’s origin.
Paper Navigation Charts
Paper charts remain a vital backup for electronic navigation. West Marine offers traditional rolled charts, print-on-demand options, and convenient chart books that bundle regions together. Choose waterproof options for durability or store your charts in a protective case to shield them from water damage.
Chart Books and Print-on-Demand Options
Chart books are bound collections covering specific regions and are especially useful for coastal cruisers. Print-on-demand charts are updated before printing, ensuring you have the most recent information. Both formats are excellent for planning and redundancy when cruising unfamiliar waters.
Electronic Charts and Digital Navigation
Electronic navigation charts (ENCs) provide real-time positioning, seamless zooming, and layering of chart details. They're used with chartplotters, mobile apps, or computer software. Electronic charts require compatible hardware and should be updated regularly to maintain accuracy.
Devices for Viewing Digital Charts
Chartplotters are rugged and waterproof, ideal for exposed helms and cockpits. Laptops or PCs are suitable for interior navigation stations. Many recreational boaters also use smartphones or tablets with GPS apps for casual cruising and redundancy.
Why You Still Need Paper Charts
Digital navigation is powerful, but it depends on electricity, signal reception, and software. Paper charts don’t crash or lose power, and they’re essential for dead reckoning if electronics fail. Always keep an up-to-date paper chart for your primary cruising area onboard.