RADAR - (Radio Detection and Ranging) uses electromagnetic waves to determine the range, altitude, direction, speed of objects like planes, ships, land vehicles, and weather.

RODE - The anchor line and/or chain.

ROMEO - Letter R in the Marine Radio Alphabet.

ROPE - In general, cordage as it is purchased at the store. When it comes aboard a vessel and is put to use it becomes line, sheet or halyard.

RUDDER - A vertical plate or board for steering a marine vessel.

RUN - To allow a line to feed freely.

RUNNING LIGHTS - Lights required to be shown on marine vessels underway between sundown and sunup.