Glossary — U

9 terms starting with U.

• Ullage
  The empty distance between the surface of a liquid in a tank and a fixed reference point at the tank top; the measurement tankers use to determine cargo volume.
• Ultra Large Container Vessel (ULCV)
  Container ships >= 14,500 TEU — too large for the new Panama locks; restricted to Asia-Europe and Asia-East-coast-US-via-Suez routes.
• Ultra Low Sulphur Fuel Oil (ULSFO)
  Residual marine fuel with ≤ 0.10% sulphur, used to meet Emission Control Area limits.
• Ultrasonic Thickness Measurement (UTM)
  Non-destructive ultrasonic gauging of plate thickness to monitor wastage; required at intermediate / renewal class surveys.
• Unattended Machinery Space (UMS)
  A classification notation permitting the engine room to operate without a watchkeeper at night, subject to enhanced alarms and automation.
• Under Keel Clearance (UKC) (UKC)
  The vertical distance between the ship's deepest point + the seabed — a company-set safety-margin parameter for shallow-water navigation.
• United Kingdom Maritime Trade Operations (UKMTO)
  Royal Navy office in Dubai serving as the primary point of contact for merchant vessels in the Indian Ocean / Gulf high-risk areas.
• United Nations Convention on the Law of the Sea (UNCLOS)
  The international treaty defining rights and responsibilities of nations in their use of the world's oceans, including maritime zones.
• Unmanned Machinery Space (UMS)
  Engine room operated without engineer watch present, relying on automation, alarms, and a duty engineer on call.