Buying a GPS Plotter & Depth Sounder is perhaps the most important upgrade you can make to your boat. Whether you do recreational fishing or professional navigation, choosing the right equipment is important.

In this guide, you will see what you should pay attention to before buying.

What are the GPS Plotter and the Depth Sounder?

• GPS Plotter: Shows your position on the map, helps with navigation and route planning.
• Depth Sounder: Measures depth and detects fish or seabed structure using sonar.
• Combo devices: Combine both — they are the most popular choice.

If you want a complete experience, it is usually worth going for a GPS plotter with built-in depth sounder.

What depths do you fish at?

Don’t start by looking at brands or inches. Start with the depth. Your answer determines the power (Watts) and frequencies (kHz) your Transducer should have:

• Up to 50 - 60 meters: A unit with 300W to 500W power and High CHIRP frequency is more than enough. You’ll see the bottom “crystal clear” without paying a fortune.
• From 60 to 150 meters: You need a 500W to 600W transducer with Medium or High CHIRP technology.
• From 150+ meters: Forget the recreational lines. You must go for a 1kW (1000W) transducer and Low/Medium CHIRP frequency, so the sonar has the power to “penetrate” the density of the water.

Sensor

The biggest mistake buyers make is putting the entire budget into the display and buying a cheap sensor. Remember: The display is the TV, the sensor is the camera. If the camera is bad, the TV cannot show a nice image.

Buying Tip: When you see the indication "No Transducer" in a product name, it means that only the display is being sold. Before completing your order, always check whether the sensor is included in the package or whether you need to select it separately.

How many screen inches do you really need?

Because modern units are "2 in 1", 90% of the time you will be using the screen split in half (Split-Screen): the nautical chart on the left, the depth sounder on the right.

• 4" to 5" inches: Ideal only for kayaks, small conventional inflatable boats, or as an auxiliary GPS. In split-screen mode, the readings become hard to read.
• 7" inches: Offers a very decent screen split without taking up much space on the console.
• 9" inches and above: The "sweet spot" for speedboats and cabin boats. It allows you to read the chart at a glance from two meters away, without leaning over the wheel.

(Note: Before choosing a size, physically measure your dashboard. A 9-inch unit has an overall external volume almost as large as a small laptop).

Touch, Buttons, or Hybrid?

The choice here is not a matter of aesthetics, but of practicality at sea:

1. Touchscreens: They are fast when you are planning the trip at the harbor. However, when we are moving at 20 knots in the waves or your hands are wet with seawater and scales, touch becomes difficult.
2. With Buttons: They give you absolute, foolproof control in extreme weather conditions.
3. Hybrid (Touch + Buttons): The top choice. You use touch in calm seas and the physical buttons when the weather turns rough.

Decoding the Fish Finder

• CHIRP: The technology that transmits multiple sound frequencies simultaneously. The result is that you see fish clearly and not as "blurry blobs". (Do not buy, in the year 2026, a device that does not have CHIRP).
• DownScan / DownVü: It gives you an almost photographic image of what is directly below the boat. Ideal for distinguishing wrecks, rocks, and seaweed.
• SideScan / SideVü: It "scans" the seabed to the right and left of the boat at distances of dozens of meters. It is the ultimate tool for quickly mapping an unknown bottom.

Charts & NMEA 2000

• Charts: GPS by itself only shows a dot in the void. To see depths, rocks, and harbors, you need a detailed nautical chart (the most popular are Navionics and C-MAP). Make sure the device you choose supports the chart card for your area.
• NMEA 2000 Network: If your boat’s engine is a recent model, by choosing a display with an NMEA 2000 port you can connect the engine to the plotter. This lets you eliminate the analog gauges and see on your screen fuel consumption per hour, RPM, temperature, and battery voltage.