The ship's rail refers to the parapet around the deck of a ship or vessel. It is sometimes erroneously used to refer to the bulwark or the guardrail of boats and ships
On sailed ships, the ship's rail is a wooden or iron wall around the upper deck topped by compartmentalized caisson where crew hammocks are placed, the latter covered by a canvas for protection from the elements and humidity.
By extension, this term may also refer to a ship's guard rails and gunnels.