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U

Ultramarine Blue. See Paint.

Umbrella. A metal shield in the form of a frustrum of a cone, riveted to the outer casing of the smoke stack over the air casing to keep out the weather.

Under-Deck Tonnage. The enclosed volume of a vessel below the tonnage deck expressed in tons of one hundred cubic feet.

Under Way. A vessel is under way according to the navigating laws, "when she is not at anchor, made fast to the shore or aground." Generally speaking, it means that she is proceeding on a course.

Underhung Rudder. See Rudder, Underhung.

Union. A fitting used to connect pipes, particularly where it is not desirable to disturb the position of the pipes as must be dome with coupling.

Union Jack. A mall flag flown from a jack staff forward. It is set out on Sundays and when dressing ship. The design embodies that of the upper inner corner of the national ensign. In the United States the design is stars on a blue field. In Great Britain the design is composed of the crosses of St. George, St. Andrew -and St. Steven, on a blue field.

Universal Joint. A joint designed to transmit torsional effort from a given length of shafting to another independent of alignment.

Unship. To remove anything from its accustomed or stowage place; to take apart.

Unstable Equilibrium. See Equilibrium, Unstable.

Upper Deck. See Deck, Upper.

Upper Deck Sheerstrake. The strake of outside plating adjacent to the upper deck.

Upper Deck Stringer. See Stringer, Upper Deck.

Upper Deck Stringer Bar. See Bar, Stringer.

Upper Works. Superstructures or deck erections located on or above the weather deck. Sometimes used with reference to a vessel’s entire above water structure.

Upsetting Lever. See Righting Lever or Arm.

Upsetting Machine. A machine designed for increasing the diameter or size of the ends of bar stock or pipe for a desired distance as in the case of boiler stay rods and tubes.

Upsetting Moment. The product of the displacement and the upsetting lever. The displacement is usually expressed in tons, and the lever in feet and the upsetting couple stated in foot-tons.

Uptake. A sheet metal conduit connecting the boiler smoke box with the base of the smoke stack. It conveys the smoke and hot gases from the boiler to the stack and should be made double thickness with an air space between to prevent radiation.

Useful Load. That portion of a vessel’s designed displacement which is devoted more or less definitely to the particular object for which the vessel is intended. In merchant vessels it includes cargo, fuel, stores and water, both potable and reserve feed. In naval vessels it includes protection proper, battery, ammunition, fuel, stores and water, both potable and reserve feed. When reference is made to merchant vessels the term is synonymous with "dead weight." Like this latter term, it relates exclusively to weight, not volume.

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