How to Read Your Simrad® Chartplotter A Simple Guide to Contours, Bathymetry & Smarter Navigation
Whether you're navigating unfamiliar waters or looking for productive fishing structure, understanding what you see on your Simrad® chartplotter is one of the most valuable skills you can have on the water. Simrad chartplotters are engineered to work seamlessly with C-MAP® charts, which are purpose-built to take full advantage of Simrad hardware, processing power, and the NEON™ operating system on newer devices*. With features like contour lines, depth shading, high-resolution bathymetry, and satellite imagery, C-MAP charts deliver the clarity and detail required for confident navigation and smarter fishing. This guide breaks down how to read these chart layers, what each one tells you, and how to use them together to plan a better day on the water.
1. Understanding Contour Lines — The Foundation of Every Chart
Contour lines are the backbone of marine charts. They show changes in depth and reveal the shape of the seafloor beneath your boat.
What Contour Lines Tell You
- Depth: Numbers printed on or near contour lines indicate depth (feet, meters, or fathoms depending on your settings).
- Steepness:
- Tightly packed lines = steep drop-offs, ledges, or channels
- Wide spacing = gradual slopes or flats
- Structure patterns:
- Circular or oval shapes often indicate humps or depressions
- Jagged lines suggest rocky or hard bottom
- Smooth curves typically indicate sand or mud flats
Learning to read contours allows you to build a mental picture of the underwater terrain—even before you look at sonar.
Why Contours Matter
- Helps identify sudden depth changes when navigating unfamiliar areas
- Highlights productive fishing edges, points, and ledges
- Supports better anchoring decisions
- Helps avoid shallow hazards and obstructions
C-MAP® charts for Simrad chartplotters are known for their clean, readable contour presentation—making these details easy to interpret at any zoom level.
2. High-Resolution Bathymetry — Ultra-Detailed Seafloor Awareness
High-resolution bathymetry (HRB) delivers a dramatically more detailed view of the underwater world.
What High-Res Bathymetry Shows
- Micro-contours and subtle ledges
- Rock piles, ridges, and bottom transitions
- Offshore banks and rises
- Troughs or depressions not visible on standard charts
- Fine structure that influences current flow and fish movement
Why High-Res Bathy Matters
- Pinpoint Structure: Identify smaller, more precise bottom features
- Better Route Planning: Understand bottom profiles near shoals, bars, and channels
- Smarter Fishing Decisions: See exact contour breaks where bait and predators concentrate
3. Depth Shading — Faster, More Intuitive Chart Reading
Depth shading allows you to color-code specific depth ranges directly on your Simrad display, making critical information easier to spot at a glance.
How Boaters Use Depth Shading
- Navigation: Highlight safe operating depths based on your boat’s draft
- Fishing: Emphasize depth bands where target species commonly hold
- Anchoring: Quickly locate depths suitable for your anchor setup
- Hazard Awareness: Shallow areas stand out clearly for safer navigation
4. Chart Layers & Tools on Simrad Chartplotters
Simrad chartplotters let you customize your view by turning chart layers on or off to match your activity and conditions. Multiple layers can be used together for a more complete navigational picture.
Common Layers to Understand
- Navigation Chart: Your base layer showing coastlines, depth numbers, buoys, markers, and hazards
- C-MAP® Safety Alerts: Highlights charted hazards, shallow areas, and obstructions to help improve situational awareness
- AIS: Displays AIS-equipped vessels nearby, helping you monitor traffic and maintain safe distances
- Radar Overlay: Overlays real-time radar returns directly onto the chart, allowing you to correlate targets with charted features
When using a C-MAP® REVEAL® or REVEAL X chart, you gain access to premium chart features designed to improve clarity and situational awareness, including:
- Shaded Relief: Adds a 3D-like visual effect that enhances how bottom structure and contours appear
- Satellite Overlay Imagery (select regions): Combines real-world satellite imagery with chart data for coastal exploration, sandbars, beaches, and shallow water detail
Tip:
You don’t need every layer enabled at once. The clearest, most effective views often come from combining two or three intentional layers based on your day’s objective.
5. NEON™ OS Mini Inspector — Instant Chart Details at a Tap
On NEON™ OS-based Simrad chartplotters*, the Mini Inspector tool allows you to quickly tap on chart objects to view detailed information without leaving the chart screen.
With a simple tap, you can access details such as:
- Depth information
- Aids to navigation
- Hazards and markers
- Charted features and objects
The Mini Inspector provides fast, intuitive access to critical information while keeping your chart view clean and uncluttered.
6. Putting It All Together — Reading Charts With Purpose
Experienced boaters and anglers don’t just look at charts—they interpret them.
For Navigation
- Use navigation charts to identify channels, hazards, and marks
- Apply depth shading to highlight unsafe areas
- Use high-resolution bathymetry near inlets, bars, and contour-based passages
- Tap objects with Mini Inspector for quick, detailed insight
For Fishing
- Start with high-res bathymetry to locate breaks, humps, and edges
- Use contour lines to identify travel routes and holding areas
- Layer depth shading to highlight productive depth zones
- Confirm structure with sonar once you arrive
For Exploring New Areas
- Combine satellite overlay imagery with bathymetry to see both shoreline detail and underwater structure
- Add points of interest for marinas, fuel docks, ramps, and anchorages
Chart reading is a skill—and the more familiar you become with C-MAP charts on your Simrad system, the more confidently you can explore unfamiliar water.
7. Quick Tips to Improve Your Chart Reading Today
- Zoom in and out frequently to understand both macro and micro detail
- Adjust depth shading colors to what’s easiest for your eyes
- Review routes at multiple zoom levels before leaving the dock
- Keep your charts updated for the latest data and corrections
- Practice matching chart features with what you see on sonar
Understanding how to read contours, bathymetry, and chart layers helps turn your Simrad® chartplotter into a more powerful navigation and fishing tool. The more familiar you become with your charts, the more confidently you can plan routes, explore new water, and find productive structure.
*Simrad® chartplotters running the NEON™ operating system include NSX®, NSX® ULTRAWIDE, NSS® 4, and future models released in 2026 and beyond.
