Marine Electronics Glossary
Marine electronics are filled with technical terms, acronyms and proprietary technology names that can make comparing products difficult. Whether you're shopping for a chartplotter, fishfinder, radar, VHF radio, autopilot or emergency beacon, understanding the terminology helps you choose the right equipment and use it more effectively on the water.
This glossary explains common marine electronics, navigation, communication, radar and sonar terms used throughout the boating industry. Use it as a quick reference when researching marine electronics systems and accessories.
- Navigation & GPS Terms
- Radar Technology Terms
- Sonar & Fishfinder Terms
- VHF & Communication Terms
- Emergency Beacon Terms
- Networking & Connectivity Terms
- Frequently Asked Questions
Navigation & GPS Terms
Auto Guidance 3.0: Garmin navigation technology that automatically creates routes based on chart data and vessel dimensions while helping avoid charted hazards.
Bearing (BRG): The compass direction from your current position to a waypoint or destination.
Course Over Ground (COG): The actual direction your vessel is moving over the earth's surface.
Cross Track Error (XTE): The distance your vessel has deviated from the planned route.
Distance To Go (DTG): Remaining distance between your current location and the selected waypoint.
GPS (Global Positioning System): Satellite navigation system that provides accurate positioning information worldwide.
GLONASS: Russian global satellite navigation system that complements GPS coverage.
Galileo: European Union satellite navigation system designed for global positioning services.
Waypoint: A saved geographic location used for navigation and route planning.
Speed Over Ground (SOG): Your vessel's actual speed over the earth's surface.
Velocity Made Good (VMG): Speed being made directly toward a waypoint or destination.
Track (TRK): Historical record showing where your vessel has traveled.
Radar Technology Terms
ATX Radar Target Separation: Raymarine technology that improves radar target distinction and resolution.
Beam Sharpening: Radar processing that improves target separation and clarity.
CHIRP Pulse Compression Radar: Radar technology that improves target detection and resolution while reducing power consumption.
Doppler Radar: Radar technology that detects moving targets and determines whether they are approaching or moving away.
Fantom Radar: Garmin solid-state radar featuring MotionScope Doppler technology.
Halo Radar: Simrad solid-state radar utilizing pulse compression and CHIRP technology.
MARPA Target Tracking: Mini Automatic Radar Plotting Aid that tracks vessel movement and collision risks.
MotionScope Technology: Garmin Doppler radar feature that highlights moving targets for improved situational awareness.
Pulse Expansion: Radar feature that enlarges target returns to improve visibility on screen.
VRM and EBL: Variable Range Markers and Electronic Bearing Lines used to measure distance and bearing to targets.
Sonar & Fishfinder Terms
CHIRP Sonar: Sonar technology that transmits across a range of frequencies to improve fish separation and target detail.
CHIRP Scanning Sonar: High-frequency sonar that produces detailed, image-like views beneath the boat.
ClearVü: Garmin's down-looking scanning sonar technology.
SideVü: Garmin side-scanning sonar that displays structure and fish to either side of the vessel.
CHIRP DownVision: Raymarine's high-definition downward imaging sonar.
DownScan Imaging: Navico's down-looking sonar imaging technology.
StructureScan HD: Lowrance technology combining side and down scanning sonar views.
StructureScan 3D: Three-dimensional sonar imaging that displays underwater terrain and structure.
Panoptix LiveVü Forward: Garmin live sonar technology providing real-time forward-looking underwater views.
FrontVü: Garmin forward-looking sonar designed to help boaters avoid underwater hazards.
ForwardScan: Simrad forward-looking sonar system for shallow-water navigation.
Transducer: Underwater component that sends and receives sonar signals.
Thermocline: Layer where water temperatures change significantly and fish often concentrate.
VHF & Communication Terms
Digital Selective Calling (DSC): International VHF radio safety system that transmits emergency information digitally. :contentReference[oaicite:0]{index=0}
MMSI (Maritime Mobile Service Identity): Unique vessel identification number required for DSC operation. :contentReference[oaicite:1]{index=1}
Coaxial Cable: Cable used to connect VHF radios to antennas.
Dual Watch: Feature allowing simultaneous monitoring of a working channel and Channel 16.
Tri-Watch: Feature monitoring Channel 16, Channel 9 and a selected working channel.
Priority Scan: VHF function that monitors selected channels while giving priority to emergency channels.
Weather Alert: NOAA weather warning notification feature available on many VHF radios.
Loud Hailer: Marine public address and intercom system often integrated into premium VHF radios.
Emergency Beacon Terms
EPIRB (Emergency Position Indicating Radio Beacon): Emergency beacon that alerts search and rescue authorities during severe emergencies. :contentReference[oaicite:2]{index=2}
Category I EPIRB: Automatically deploys and activates when submerged.
Category II EPIRB: Requires manual deployment and activation.
PLB (Personal Locator Beacon): Personal emergency beacon designed for individual rescue situations. :contentReference[oaicite:3]{index=3}
AquaLink: ACR Electronics line of Personal Locator Beacons.
ResQLink: ACR Electronics personal locator beacon product family.
GlobalFix: ACR Electronics EPIRB product line.
Networking & Connectivity Terms
NMEA 2000: Industry-standard marine electronics networking protocol that allows devices to share information.
SimNet: Navico's NMEA 2000-compatible networking system.
Wi-Fi: Wireless networking technology used to connect marine electronics and mobile devices.
Garmin Helm: App allowing remote control of compatible Garmin chartplotters.
GoFree: Navico platform for downloading charts, updates and apps.
WebWatch: Shakespeare marine internet and hotspot connectivity solution.
Frequently Asked Questions
What does CHIRP mean in marine electronics?
CHIRP stands for Compressed High-Intensity Radiated Pulse. It uses multiple frequencies instead of a single frequency to provide better target separation, fish identification and bottom detail.
What is the difference between GPS and GLONASS?
GPS is operated by the United States, while GLONASS is operated by Russia. Many modern marine electronics use both systems simultaneously for improved positioning accuracy.
What is DSC on a VHF radio?
Digital Selective Calling is a safety feature that allows VHF radios to transmit digital distress alerts, vessel identification and GPS position information during emergencies.
What is an MMSI number used for?
An MMSI identifies your vessel within DSC communication systems and is required for digital distress and calling functions.
What is the advantage of Doppler radar?
Doppler radar can identify moving targets and indicate whether they are approaching or moving away, improving collision avoidance and target awareness.
Browse Marine Electronics & Navigation Gear
- Chartplotters, GPS units and navigation displays
- Marine radar systems and radar accessories
- Fishfinders, sonar and CHIRP transducers
- VHF radios and marine communication equipment
- AIS receivers and transceivers
- EPIRBs and Personal Locator Beacons
- Autopilot systems and instruments
- Marine networking accessories and sensors