Port and starboard

Port and starboard are nautical terms for left and right, respectively. Port is the left-hand side of or direction from a vessel, facing forward. Starboard is the right-hand side, facing forward. Since port and starboard never change, they are unambiguous references that are not relative to the observer.

The term starboard derives from the Old English steorbord, meaning the side on which the ship is steered. Before ships had rudders on their centrelines, they were steered with a steering oar at the stern of the ship and, because more people are right-handed, on the right-hand side of it. The term is cognate with the Old Norse stýri (rudder) and borð (side of a ship). Since the steering oar was on the right side of the boat, it would tie up at wharf on the other side. Hence the left side was called port.

Formerly, larboard was used instead of port. This is from Middle-English ladebord and the term lade is related to the modern load.Larboard sounds similar to starboard and in 1844 the Royal Navy ordered that port be used instead. The United States Navy followed suit in 1846.Larboard continued to be used well into the 1850s by whalers. In Old English the word was bæcbord, of which cognates are used in other European languages, for example as the present Dutch bakboord, the German backbord and the French term bâbord (derived in turn from Middle Dutch).

The navigational treaty convention, the International Regulations for Preventing Collisions at Sea—for instance, as appears in the Merchant Shipping (Distress Signals and Prevention of Collisions) Regulations of 1996 (and comparable US documents from the US Coast Guard),—sets forth the rights of way for maritime vessels, whether by sail or powered, and whether a vessel is overtaking, approaching head-on, or crossing. To set forth these navigational rules, the terms starboard and port are absolutely essential, and to aid in in situ decision-making, the two sides of each vessel are marked, dusk to dawn, by navigation lights, the vessel's starboard side by green and its port side by red.

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