Navigating the open water has evolved dramatically over the centuries, from relying on the stars and rudimentary compasses to employing advanced electronic systems that pinpoint a vessel’s location with remarkable precision. Today, two terms often dominate discussions among boaters: GPS and chartplotter. While they are frequently used interchangeably, they are not the same. Understanding the distinction between these two technologies is crucial for anyone looking to enhance their boating experience, whether for leisure, fishing, or long-distance cruising. This article explores the differences between a chartplotter and a GPS, how they function, their practical applications, and why one might suit your needs better than the other.
The Basics: GPS vs. Chartplotter
At its core, a Global Positioning System (GPS) is a satellite-based navigation system that provides raw location data in the form of latitude and longitude coordinates. Developed by the U.S. Department of Defense, GPS relies on a constellation of at least 24 satellites orbiting Earth, each transmitting signals that a GPS receiver on your boat can use to calculate its position. The result? A set of numbers—something like 38° 58′ 42.403″ N, 76° 29′ 31.858″ W—that tells you exactly where you are. While this is incredibly useful, it’s not inherently intuitive. Unless you’re adept at mentally mapping coordinates onto a chart, these numbers alone don’t provide a visual context for your surroundings.
Enter the chartplotter, a device that takes GPS technology a step further. A chartplotter integrates a GPS receiver with electronic nautical charts, displaying your position on a digital map in real time. This visual representation transforms raw coordinates into something meaningful: you can see your boat’s location relative to coastlines, hazards, waypoints, and destinations. Essentially, while all chartplotters use GPS to determine location, not all GPS devices are chartplotters. The key difference lies in the chartplotter’s ability to plot your position on a map, making navigation more accessible and practical.
How GPS Works
To appreciate the distinction, it’s worth understanding how GPS operates. A GPS receiver on your boat doesn’t send signals; it listens for them. By receiving transmissions from at least three satellites (though four or more improve accuracy), the receiver calculates its distance from each based on the time it takes for the signals to arrive. Through a process called trilateration, it then determines your precise location. The output is straightforward: coordinates, speed over ground (SOG), and sometimes additional data like distance to a destination or estimated time of arrival (ETA). However, without a map, interpreting this data requires additional tools—like a paper chart—or a strong mental picture of the area.
GPS accuracy has improved significantly since its early days, thanks to advancements like the Wide Area Augmentation System (WAAS) in North America, which enhances precision to within a few meters. Similar systems, such as Europe’s EGNOS or Japan’s MSAS, serve other regions. Yet, for all its precision, a standalone GPS unit remains a numbers game unless paired with a means to visualize the data.
How Chartplotters Work
A chartplotter bridges this gap by combining GPS data with electronic charts, often preloaded or downloadable from manufacturers or third-party providers. These charts detail coastal outlines, water depths, hazards (like reefs and sandbars), and navigational aids (buoys, lighthouses, etc.). When you turn on a chartplotter, it uses the GPS signal to place a marker—representing your boat—onto this digital map. As you move, the marker updates in real time, showing your heading, speed, and proximity to waypoints or hazards.
Beyond basic positioning, chartplotters offer robust features. You can set waypoints—specific coordinates marking key locations—and string them together into routes, which the device stores for future use. Some models hold hundreds or even thousands of routes, allowing you to revisit favorite fishing spots or retrace safe passages. If you veer off course, the chartplotter alerts you, recalculating the path to your next waypoint. For anglers, many chartplotters integrate sonar or fish-finding capabilities, displaying underwater structures or fish schools alongside navigational data. Additional overlays, like radar or weather information, further enhance situational awareness.
Why the Difference Matters
The distinction between GPS and chartplotters isn’t just technical—it’s practical. A standalone GPS is a minimalist tool: affordable, portable, and precise, but it demands more effort to use effectively. Plotting coordinates manually onto a paper chart, for instance, is a skill that takes time to master and requires you to carry physical backups. In contrast, a chartplotter automates this process, offering an intuitive interface that even novice boaters can grasp quickly. The trade-off? Cost and complexity. Chartplotters are pricier and rely on power, making them less resilient in emergencies like a battery failure.
Consider a real-world scenario: you’re navigating a coastal waterway with hidden shoals. A GPS might tell you your coordinates and speed, but you’d need to cross-reference them with a chart to avoid grounding. A chartplotter, however, shows the shoals on-screen, alerting you to steer clear without extra steps. For casual boaters or those in familiar waters, a basic GPS might suffice—especially with a compass as a backup. But for longer trips, unfamiliar regions, or serious fishing, a chartplotter’s added functionality becomes invaluable.
Types of Chartplotters
Chartplotters come in various forms, tailored to different needs and budgets:
- Handheld Chartplotters: Compact and affordable (typically $150–$250), these are ideal for small vessels like kayaks or dinghies. Models like the Garmin GPSMAP 78S offer a small screen, basic charting, and portability, though their limited display size can restrict visibility.
- Mounted Chartplotters: Priced between $250 and $500, these fixed units suit mid-sized boats. The Simrad Cruise-7, for example, provides a larger screen, preloaded coastal maps, and depth readings, balancing cost and capability.
- Multifunction Displays (MFDs): Starting at $500 and climbing into the thousands, MFDs like the Garmin GPSMAP 7408 or Raymarine Axiom 7 combine chartplotting with sonar, radar, autopilot integration, and more. These are the choice of serious mariners or anglers who need all-in-one solutions.
- Chartplotter Software: For those with existing devices (laptops, tablets, or smartphones), software like Nobeltec or OpenCPN paired with a GPS receiver offers a flexible, cost-effective alternative. However, it lacks the ruggedness and visibility of dedicated hardware.
Each type serves a purpose, from the budget-conscious handheld to the feature-rich MFD. Your choice depends on your boat size, navigation style, and intended use.
Key Features of Modern Chartplotters
Today’s chartplotters go beyond simple mapping. Here’s what to look for:
- High-Resolution Displays: Bright, clear screens (often 7–10 inches or more) ensure visibility in sunlight, with zoom and scroll functions for detailed views.
- Integrated GPS: Most chartplotters have built-in receivers, though some support external antennas for better signal strength.
- Sonar and Fish Finders: Devices like the Humminbird Helix 5 use CHIRP sonar to detect fish and underwater hazards, a boon for anglers.
- Connectivity: NMEA 0183/2000, Ethernet, USB, and Wi-Fi allow integration with radar, autopilots, AIS (Automatic Identification Systems), and mobile devices.
- Route Management: Store waypoints, track history, and adjust routes on the fly.
- Overlays: Radar, weather data, or AIS overlays enhance safety and planning.
These features make chartplotters versatile tools, but they also drive up costs. A basic model might lack sonar or networking, while high-end units offer everything short of steering the boat for you.
Cost Considerations
Price is a major factor in choosing between GPS and chartplotters. A standalone GPS can cost as little as $70, delivering raw coordinates without bells and whistles. Chartplotters start around $150 for handhelds and climb to $5,000 or more for advanced MFDs. The higher price reflects added functionality—larger screens, sonar, radar integration—but not everyone needs these extras. For casual boaters, a mid-range mounted chartplotter ($250–$500) often strikes the best balance between cost and utility.
Do You Need a Chartplotter?
The short answer: no, you don’t need a chartplotter. Mariners navigated for centuries using compasses, sextants, and paper charts, and these methods remain viable backups. A GPS alone, paired with a chart and compass, can get you far—especially if you’re comfortable plotting manually. However, chartplotters offer undeniable advantages:
- Accuracy: GPS precision (within meters) beats manual triangulation.
- Ease of Use: Real-time mapping eliminates guesswork.
- Safety: Hazard alerts and route tracking reduce risks.
The downside? Reliability. A power outage renders a chartplotter useless, underscoring the wisdom of carrying a compass and paper charts. For short coastal trips, a compass and landmarks might suffice; for offshore voyages, a chartplotter’s detail is hard to beat.
Before electronics, sailors relied on:
- Compass: Simple, reliable, and essential for orientation.
- Coastal Navigation: Using visible landmarks (rocks, lighthouses) to gauge position.
- Manual Chart Plotting: Plotting GPS coordinates or triangulating with a compass on paper.
- Celestial Navigation: Using a sextant and stars—complex but independent of power.
These methods are worth learning as backups, ensuring you’re never stranded if technology fails.
Top Brands to Consider
Several manufacturers dominate the market, each with strengths:
- Garmin: Known for user-friendly, affordable options like the GPSMAP 78S and high-end MFDs like the GPSMAP 7408.
- Simrad: Offers intuitive models like the Cruise-7, blending power and simplicity.
- Humminbird: Excels in fish-finding chartplotters, such as the Helix 5.
- Raymarine: Leaders in MFDs (e.g., Axiom 7), with strong sonar and networking.
- B&G: Specializes in sailing features, as seen in the Vulcan 7.
Conclusion
So, what’s the difference between a chartplotter and GPS? A GPS gives you your location; a chartplotter shows you where that location is on a map. For boaters, this distinction can mean the difference between a functional trip and a seamless one. A standalone GPS is cheaper and simpler, ideal for minimalists or as a backup. A chartplotter, with its visual interface and advanced features, elevates navigation to a new level of convenience and safety—albeit at a higher cost and with greater reliance on power.
Ultimately, your choice depends on your boating style. If you’re exploring unfamiliar waters or chasing fish, a chartplotter’s worth the investment. If you’re sticking to known routes and value redundancy, a GPS and compass might do. Whatever you choose, pairing it with traditional skills ensures you’re prepared for any adventure on the water.
Happy Boating!
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