33 C.F.R. § 117.4
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.
Deviation means a District Commander's action authorizing a drawbridge owner to temporarily not comply with the drawbridge opening requirements in this part.
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 .
Remotely operated drawbridge means a drawbridge that is operated by remote control from a location away from the drawbridge.
Removable span bridge means a bridge that requires the complete removal of a span by means other than machinery installed on the bridge to open the bridge to navigation.
Untended means that there is no drawtender at the drawbridge.
33 C.F.R. §117.4