UH
Unity of hydrometry.
UHSLC
University of Hawaii Sea Level Center.
ULR
Université de La Rochelle (La Rochelle university).
Under-keel clearance
Safety margin to take account of random variations in the water level.
Unity of height
Half tidal range of the mean equinoctial (semi-diurnal tide) or solstice spring tide (diurnal tide).
Universal Time
Greenwich civil time. Its acronym is UT.
UPF
Université de Polynésie française (University of French Polynesia).