Definition of Port Lamp
Port lamp refers to the red navigation light positioned on the left side or port side of the bow of a boat. It must shine straight ahead and to the left side 22.5 degrees behind the beam of the boat, forming an arc of 112.5 degrees.
The port lamp indicates to fellow seafarers the direction from which a vessel is approaching.
For example, the position of the red port lamp in the diagram below indicates that the yacht is crossing your path from your starboard side to your port side.
To be effective, a port lamp must be visible from a minimum of 1 nautical mile distance for boats smaller than 39 feet and 2–3 NM for larger boats.
The safest way to ensure compliance is to install a light approved by the U.S. Coast Guard, such as the Vertical Port Starboard Lamp Kit.
Example of Port Lamp in a Sentence
"The port lamp on the ship shone a steady beam of red light to guide us through the dark and stormy night."
Synonyms: red navigation light
Related Terms for Port Lamp