Below is a list of acronyms used in the past.
If there are other marine abbreviations you need an explanation for, or some you think we should include, email us and we'll do our best to answer or add them.
ACR: An automatic charge relay is a one-way gate for voltage that allows the second battery in a system to be charged when the motor is feeding the system via the alternator without having to select "both" on your battery selector switch.
AIS: Automatic Identification System (displays real-time ship and marine traffic positions).
APP: Not strictly an acronym, but shorthand for application (for mobile phones and tablets).
AWA: Anchor Watch Alarm
CPA: Closest Point of Approach, the predicted minimum distance between your vessel and a target on radar or AIS if you both continue at present course and speed
DSC: Digital Selective Calling (allows a distress signal to be sent from a VHF)
DSM: Digital Sounder Module, also called a black box in some cases, a microprocessor dedicated to interpreting and improving sonar displays on your fishfinder
EBL: Electronic Bearing Line, bearing to a target as displayed on a radar screen OR Exposed Location Buoy if you're talking aids to navigation
EPIRB: Emergency Position Indicating Radio Beacon (used to alert services in an emergency)
GPS: Global Positioning System (a satellite navigation system providing location and time)
IP: Internet Protocol, just a name for how devices speak to each other
LED: Short for Light Emitting Diode, a form of semiconductor that gives off light when an electrical current is applied. Far more efficient than incandescent bulbs, they also have a longer lifespan (when fed proper voltage) because there's no filament to break or burn up.
LCD: Liquid crystal display, just another way of making images appear on a screen
MFD: Multifunction display. Your chartplotter, can do more than show you charts, hence the "multi" part
MFI: Depending on where you see it, it could be Made for Apple (iPhone, iPad, etc) or Multi-port fuel injection, if you're talking engines
MMSI: Maritime Mobile Service Identity (the number that identifies your boat. Important in an emergency.
MOB: Man Overboard
NMEA: National Marine Electronics Association
PLB: Personal Locator Beacon (portable transmitter capable of sending an emergency distress signal)
RTE: Route, in shorthand, or Radar Target Enhancer if you are being fancy with your radar reflector
VHF: Very High Frequency, the designation for the frequency bandwidth that marine radios operate on. Specifically from 156-163 MHz. Distinct from UHF (Ultra High Frequency) where cordless phones and baby monitors work
VRM: Variable Range Marker, the rings on a radar display that indicate distances from your vessel at the center.