Port - starboard

In the language of sailing and of all water-borne vessels, the words port and starboard are used to avoid ambiguity. Both can be used as a noun or an adjective. They label the different sides of the boat, or ship. They always label the sides from the point of view of a person facing forwards, towards the bow, or front, or stem, of the boat. In this way, one is never confused when facing any other way by the use of word like 'left' or 'right'. These are used with reference to the person being talked of: one's left hand is always that on the same side as one's heart, but the ship's port side is not defined by reference to any person. Nor does the compass direction matter: if the boat is heading north, her port side is to the west; if she is heading south, it is her starboard side that is to the west.

• The port is on the left (facing the front of the vessel). At night, a ship should show navigation lights: port is shown by a red light. (Two mnemonics: first, to remember the direction - "when a ship has departed from harbour, she has 'left port"; and second, to remember her lights, "port wine is red.")
• Starboard is to the right. Starboard lights are green.

Their etymology may be of interest. The following is drawn from OED.

• • In the days of longships, before technology had advanced to a rudder (which is hung centrally at the back, or stern, of a boat), vessels were steered by an oar pivoting on the side of the vessel. This side was always the right-hand side, from the point of view of the steersman - who was looking where he was going. So it was called the steor ('steer[ing], or direct[ing the boat]') bord ('board' - 'ship's side', or 'plank [of a ship's side] - in modern English, starboard.
  • The other side was traditionally called the larboard.
    • The element lar- in it is a late (16th century) adaptation of Middle English ladde-, lade, lathe-, or late-, whose precise origin is not known. In Old English the term was bæcbord ('back-board'), or 'the side of the ship at the steersman's back'; 'the other side from the starboard'. This term, which is still used in Germanic languages, and has been adopted in French as bâbord, has disappeared from English. It has been suggested that port was adopted to avoid confusion in orders shouted during the confusion and noise of battle, or a gale: 'larboard' and 'starboard' are very similar in sound, differing only in their initial consonants.
    • The modern term port also has an unclear origin. Two separate origins have been proposed, both very similar in meaning: they are about harbour. To protect its steering oar, a vessel would be laid alongside a mooring at a quay or dock. So the side opposite the oar was the 'port side'; or, in an identical position, the loading 'port', or gap or 'door' in the side, would be placed next to the dockside to allow the cargo to be carried aboard.

See also -port- (etymology).