ULCC - Ultra Large Crude Carriers. Tankers larger than 300,000 dwt.
Category: - Maritime - Acronym

Ullage Hatch - A small hinged opening on a tank for gauging or sampling cargo. The ullage is the distance from the top of this hatch to the top of the cargo. It is the 'opposite' of innage.
Category: - Maritime

Uncertainty - A situation where the outcome can only be estimated, and the probability distribution is unknown
Category: - Risk

Under way - Vessel neither at anchor nor made fast to shore, nor aground.
Category: - Maritime

Units - The standardized measurement increments for values within and attribute.
Category: - GIS

Unknown Incident - An incident which commences as a search and rescue incident of unknown type and the source of which is untraced. "incident de source inconnue"
Category: - SAR

Unmanned Machinery Spaces - A space where alarm bells are installed on the bridge of a ship to trace or rectify any machinery faults. The computerized devices will report any fault immediately it appears and the engineers on board can attend to the necessary ramifications.
Category: - Maritime

Unseaworthiness - The state or condition of a vessel when it is not in a proper state of maintenance, or if the loading equipment or crew, or in any other respect is not ready to encounter the ordinary perils of sea.
Category: - Maritime - Risk

USAF - United States Air Force
Category: - Acronym

USCG - United States Coast Guard
Category: - Maritime - Acronym