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
Stem (ship) the stem. Stem (ship) The stem is the most forward part of a boat or ship's bow and is an extension of the keel itself. It is often found on wooden boats or ships, but not exclusively. The stem is the curved edge stretching from the keel below, up to the gunwale of the boat. It is part of the physical structure of a wooden boat or ship that gives it strength at the critical section of the structure, bringing together the port and starboard side planks of the hull. There are two styles of stems: plumb and raked. When