Port and starboard vessel's starboard side by green and its port side by red. Aircraft are lit in the same way. Port and starboard Port and starboard are nautical and aeronautical terms of orientation that deal unambiguously with the structure of vessels and aircraft. Their structures are largely bilaterally symmetrical, meaning they have mirror-image left and right halves if divided long-ways down the middle. One asymmetric feature is that on aircraft and ships where access is at the side, this access is usually only provided on the port side. To understand which is which, when a person is facing the bow on a
Navigation light the starboard side (the right side from the perspective of someone on board facing forward), a red light from dead ahead to two points abaft the beam on the port side (left side) and a white light that shines from astern to two points abaft the beam on both sides. Power driven vessels, in addition to these lights, must carry either one or two (depending on length) white masthead lights that shine from ahead to two points abaft the beam on both sides. If two masthead lights are carried then the aft one must be higher than the forward one.