Essential electronic equipment for navigation
Marine navigation electronics have evolved enormously in recent years. What was once exclusive to professional vessels is now within reach of any recreational boat. Well-chosen electronics improve safety, simplify navigation, and make every passage a more comfortable experience.
Some equipment is mandatory by regulation and some is optional but highly recommended. Let us review all the key systems.
GPS and chart plotter
What it is and what it does
A GPS chart plotter combines a satellite positioning receiver with a nautical chart display. It is the modern replacement for paper charts (though these are still required as a backup) and allows you to:
- Know your exact position at all times
- Plan routes with waypoints
- Calculate speed, heading, and estimated time of arrival
- View depths, buoys, lighthouses, and hazards
Selection criteria
- Screen size: for a recreational boat, a 7 to 9-inch plotter is usually sufficient. For offshore sailing, consider 12 inches or more
- Charts: make sure it is compatible with the charts for your area. Navionics and C-MAP are the most popular worldwide
- Connectivity: look for models with WiFi and Bluetooth for chart updates and smartphone connection
- Touchscreen vs buttons: touchscreens are more intuitive, but buttons work better with wet hands
- Brightness: it must be readable in full sunlight (minimum 1,000 nits)
Leading brands
- Garmin: excellent value for money, intuitive interface, good built-in cartography
- Raymarine: industry benchmark, seamless integration with other Raymarine equipment
- Simrad: popular on fishing boats, large screen options
- B&G: specializes in sailboats, with regatta-specific features
Radar
Why you need a radar
Radar is the only device that allows you to detect obstacles, other boats, and the coastline in reduced visibility: fog, heavy rain, or night navigation. Unlike AIS, it detects any object, including those without a transponder.
Types of marine radar
Pulse radar (magnetron): - Traditional technology, more affordable - Higher power consumption - Poor near-target detection (dead zone of 20-50 meters)
Solid-state radar (broadband/pulse compression): - Lower power consumption (ideal for sailboats with limited energy) - Better near-target detection - Instant startup (no magnetron warm-up) - Higher price
Doppler radar: - The most advanced technology, detects whether targets are approaching or moving away - Highlights moving objects in different colors (automatic MARPA) - Highest price point
Range and power
For coastal navigation, a radar with 24-36 nautical miles of range is more than sufficient. Typical power output is 2 to 4 kW for recreational vessels. You do not need a 25 kW radar unless you are doing professional ocean navigation.
Autopilot
How it works
An autopilot maintains the heading automatically by acting on the tiller or the hydraulic steering system. It can follow a fixed magnetic heading or a route programmed on the GPS plotter.
System components
- Control unit: the brain of the autopilot, with the steering algorithms
- Fluxgate compass: high-precision magnetic heading sensor
- Actuator: the motor that moves the rudder (linear for boats under 35 feet, hydraulic for larger vessels)
- Control panel: the user interface with heading buttons
Types by vessel
- Tiller autopilots (small sailboats): self-contained unit that attaches to the tiller. Easy to install and remove. Suitable for boats up to 30-35 feet
- Hydraulic steering: requires a hydraulic pump connected to the steering system. More powerful and precise, ideal for boats over 35 feet
- Mechanical steering: uses a linear actuator connected to the rudder quadrant
Usage tips
- Calibrate the compass after every installation and at least once a year
- Adjust the gain (rudder response) parameters according to sea conditions
- Never rely blindly on the autopilot: always maintain a lookout
- In congested waters or near the coast, disengage it and steer manually
AIS (Automatic Identification System)
What information it transmits
AIS allows boats to identify each other by transmitting via radio:
- Vessel name and MMSI number
- Position, heading, and speed
- Vessel type and dimensions
- Navigation status (anchored, underway, not under command)
Types of AIS
- Class A: mandatory for commercial ships, transmits at higher power and frequency
- Class B: designed for recreational vessels, lower power, more affordable
- Class B+: enhanced version with higher transmission frequency and text message capability
- Receive-only: does not transmit your position, but you can see others. The most affordable option
Integration with other equipment
AIS connects to the GPS plotter and displays nearby vessels on the chart with their name, heading, and speed. Some models include an MOB (man overboard) function that transmits an emergency alert if a crew member falls overboard.
VHF and DSC
Marine VHF
The VHF radio is the basic and mandatory communications device on any vessel. It allows you to communicate with other boats, ports, marinas, and emergency services on channel 16.
DSC (Digital Selective Calling)
The DSC function allows you to send an automated distress call with your GPS position at the push of a single button. For it to work you need:
- The radio connected to the GPS
- A registered MMSI number
- A completed DSC test with the maritime authority
Handheld vs fixed VHF
- Fixed: higher power (25W), external antenna with better range, integrated DSC. Required depending on the navigation zone
- Handheld: 5-6W of power, essential as a backup and for communication from the dinghy. Look for models with buoyancy and water resistance (IPX7 or IPX8)
Depth sounder and fish finder
The depth sounder is a basic instrument that measures the depth below the keel using ultrasound. Modern models offer:
- Depth reading: real-time with shallow-water alarm
- Water temperature: useful for navigation and fishing
- Fish finder: shows bottom structure and schools of fish
- Side imaging: lateral bottom image for advanced fishing
Transducers can be through-hull (greatest accuracy), transom-mount (simple installation), or in-hull (glued inside the hull on fiberglass boats).
System integration: NMEA 2000
What is NMEA 2000
NMEA 2000 is the communication standard that connects all electronic equipment together via a single backbone cable. This way the GPS can send position data to the autopilot, AIS can display on the plotter, and the depth sounder can feed data to the multifunction display.
Advantages of an integrated system
- All data available on all screens
- Less wiring (a single data bus)
- Easy expansion: adding a new sensor is just plugging in a cable
- Centralized diagnostics for all equipment
Installation tips
- Use genuine NMEA 2000 connectors and terminators (no DIY splices)
- Maximum backbone length is 100 meters
- Place resistive terminators at both ends of the backbone
- Avoid running data cables alongside power cables (engine, alternator) to prevent interference
Approximate budget
| Equipment | Price range | |---|---| | 7" GPS Plotter | 500-1,200 EUR | | Broadband radar | 1,000-2,500 EUR | | Autopilot (35' sailboat) | 1,500-3,500 EUR | | Class B AIS with antenna | 300-800 EUR | | Fixed VHF with DSC | 150-400 EUR | | Depth sounder/fish finder | 200-800 EUR |
Maintaining onboard electronics
- Protect from moisture: use anti-corrosion spray on connectors at least twice a year
- Update software: manufacturers release firmware updates that improve performance
- Inspect antennas: check that coaxial cables are undamaged and connections are watertight
- Clean screens: use specific products, never solvents that damage anti-glare coatings
- Annual professional inspection: a marine electronics technician can verify the operation of all equipment and detect problems before they fail at sea
