page_title: Axes conventions
section_title: Conventions for sea vehicles
hierarchical_section_title: Axes conventions / Earth bounded axes conventions / Frames mounted on vehicles / Conventions for sea vehicles
caption_attribution_description: English: Roll-pitch-yaw angles of ships and other water vehicles
context_page_description: In ballistics and flight dynamics, axes conventions are standardized ways of establishing the location and orientation of coordinate axes for use as a frame of reference. Mobile objects are normally tracked from an external frame considered fixed. Other frames can be defined on those mobile objects to deal with relative positions for other objects. Finally, attitudes or orientations can be described by a relationship between the external frame and the one defined over the mobile object.
  The orientation of a vehicle is normally referred to as attitude. It is described normally by the orientation of a frame fixed in the body relative to a fixed reference frame. The attitude is described by attitude coordinates, and consists of at least three coordinates.
  While from a geometrical point of view the different methods to describe orientations are defined using only some reference frames, in engineering applications it is important also to describe how these frames are attached to the lab and the body in motion.
  Due to the special importance of international conventions in air vehicles, several organizations have published standards to be followed.
context_section_description: As well as aircraft, the same terminology is used for the motion of ships and boats. Some words commonly used were introduced in maritime navigation. For example, the yaw angle or heading, has a nautical origin, with the meaning of "bending out of the course". Etymologically, it is related with the verb 'to go'. It is related to the concept of bearing. It is typically assigned the shorthand notation ψ.
caption: RPY angles of ships and other sea vehicles
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