33 CFR § 117.4 - Definitions.
The following definitions apply to this part:
Appurtenance means an attachment or accessory extending beyond the hull or superstructure that is not an integral part of the vessel and is not needed for a vessel's piloting, propelling, controlling, or collision avoidance capabilities.
Automated drawbridge means a drawbridge that is operated by an automated mechanism, not a drawtender. An automated drawbridge is normally kept in the open to navigation position and closes when the mechanism is activated.
Drawbridge means a bridge with an operational span that is intended to be opened for the passage of waterway traffic.
Drawspan means the operational span of a drawbridge.
Lowerable means a non-structural vessel appurtenance that is or can be made flexible, hinged, collapsible, or telescopic so that it can be mechanically or manually lowered.
Nonstructural means that the item is not rigidly fixed to the vessel and can be relocated or altered.
Not essential to navigation means that a nonstructural vessel appurtenance, when in the lowered position, would not adversely affect the vessel's piloting, propulsion, control, or collision-avoidance capabilities.
Public vessel means a vessel that is owned and operated by the United States Government and is not engaged in commercial service, as defined in 46 U.S.C. 2101.