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Eng ID Term Definition
5761
ultra high frequency (UHF)
See FREQUENCY: RADIO.
5762
ultrashort wave
See WAVE.
5763
ultrasonic
(adj.). Having a FREQUENCY above the audible RANGE.
5764
ultrasonic depth finder
See ECHO SOUNDER.
5765
ultrasonics
The science and technology relating to SOUND WAVES of FREQUENCIES above the audible RANGE.
5766
ultraviolet
(adj.). Having a FREQUENCY immediately beyond the violet end of the visible SPECTRUM. Said of RAYS of shorter WAVE LENGTH than visible light... more
(adj.). Having a FREQUENCY immediately beyond the violet end of the visible SPECTRUM. Said of RAYS of shorter WAVE LENGTH than visible light but longer than X-RAYS.
5767
uncontrolled mosaic
A MOSAIC composed of uncor­rected PRINTS, the detail of which has been matched from print to print without GROUND CONTROL or other ORIEN­TAT... more
A MOSAIC composed of uncor­rected PRINTS, the detail of which has been matched from print to print without GROUND CONTROL or other ORIEN­TATION.
5768
uncovered
(adj.). Above water. The opposite is SUBMERGED.
5769
uncovers
See COVERS AND UNCOVERS.
5770
undercliff
A TERRACE or lower CLIFF formed by a LAND­SLIDE. Also written as two words.
5771
undercurrent
A CURRENT below the surface, par­ticu­larly one flowing in a direction or at a SPEED diffe­ring from the SURFACE CURRENT.
5772
underground mark
A STATION MARK set and plumbed below the centre of a SURFACE MARK and separated therefrom so as to preserve the STATION in case of accident ... more
A STATION MARK set and plumbed below the centre of a SURFACE MARK and separated therefrom so as to preserve the STATION in case of accident to the SURFACE MARK. Also called subsurface mark.
5773
underkeel clearance
The distance (usually a required minimum distance) between the lowest point of a ship's hull and the SEABED.
5774
underkeel allowance
The minimum UNDERKEEL CLEARANCE estimated, or specified by a relevant authority for a defined area or vessel type, to account for vessels' s... more
The minimum UNDERKEEL CLEARANCE estimated, or specified by a relevant authority for a defined area or vessel type, to account for vessels' static and dynamic characteristics, SEA STATE, CHART reliability, and variance from predicted HEIGHT of TIDE.
5775
undertow
A seaward FLOW near the BOTTOM of a sloping BEACH. The subsurface return by gravity flow of the water carried up on SHORE by WAVES or BREAKE... more
A seaward FLOW near the BOTTOM of a sloping BEACH. The subsurface return by gravity flow of the water carried up on SHORE by WAVES or BREAKERS. See also BACKRUSH.
5776
underwater acoustics
A special field of technical acoustics dealing with the physics of sound propagati­on in the water.
5777
underwater ice
See ANCHOR ICE.
5778
underwater navigation
See NAVIGATION.
5779
underwater photogrammetry
See PHOTOGRAMMETRY.
5780
underwater position fixing
A method of position fixing for surface vessels, submersibles or towed devices in relation to a network of underwater acoustic beacons on th... more
A method of position fixing for surface vessels, submersibles or towed devices in relation to a network of underwater acoustic beacons on the seabed with known relative positions.