UBC

 Universal Bulk Carrier

UCT

 Universal Co-ordinated Time

UFL

 Upper Flammable Limit

UHF

 Ultra High Frequency

UKC

 UK Continent

ULCC

 Ultra Large Crude Carrier

ULCS

 Ultra Large Containership

UMS

 Unmanned Machinery Space

UNCTAD

 United Nation's Conference On Trade And Development

USAC

 United States Atlantic Coast

USC

 Unless Sooner Commenced

USCG

 United States Coast Guard

USEC

 United States East Coast

USG

 United States Gulf

USNH

 United States North of Cape Hatteras

USSH

 United States South of Cape Hatteras

USWC

 United States West Coast

UT

 Universal Time

UU

 Unless Used

UUIWCTAUTC

 Unless Used In Which Case Time Actually Used To Count