Ullage. This is a measurement of space between the surface of liquid in a tank and the top of the tank inner surface.
Unseaworthiness. If the condition of a vessel is such that she is not reasonably fit in all respects to encounter the ordinary perils of the sea, either by insufficient maintenance and repairs, incomplete crew, insufficient equipment or wrong stowage of cargo, etc., she is referred to as being unseaworthy.
Underdeck tonnage. Space below the “tonnage deck”, above the double bottom tanks, open floors or ceilings and between inboard faces of frames or sparring and including protuberances such as shaft bossings, bulbous bows, and so on. (The “tonnage deck” is the second deck from above except in the case of single-decked vessels in which case it is the upper deck.)
U.S.G. United States Gulf. This is part of the Gulf of Mexico between North America and South America on the Eastern seaboard of the North American Continent. Geographically, the Gulf is not part of the U.S.A., yet the abbreviation refers to ports in the U.S.A., such as Tampa, Mobile, New Orleans, Galveston and Houston , from which vessels are chartered.