tiply the sum by the common interval: the product will be the required area, nearly. Ultimate strain is the utmost strain or alteration of shape which a body can bear without breaking. 124. Ultimate Strength. Ultimate strength is the stress required to produce fracture in some specified way. 125. Unstable Equilibrium. The product of the displacement and length of the upsetting lever. The displacement being generally expressed in tons, and the lever in feet, the upsetting couple is given in foot-tons. 127. Upsetting Lever. When in a ship the Metacentre is located below the Centre of Gravity, and the ship is disturbed from the upright position, the vertical passing through the Centre of Gravity separates from that through the Centre of Buoyancy in the direction of the inclination, tending to upset the ship, hence the distance between the two verticals becomes an upsetting lever. 128. Useful Displacement. A term used exclusively by naval architects as applied to warships. It represents the total carrying power of the hull for offense, defense, motive power, endurance and personnel, and includes the weight of armor and machinery, ordnance and ammunition, coal, provisions, water and stores, rigging and equipment, boats, officers, crew, and effects. 129. Vanishing Point. The angle at which a ship, on being continuously inclined, becomes unstable. 130. Void Space. Any space in the ship not occupied and to which water can find access in case of leak or accident. 131. Waterline. The line which the surface of the water forms with the side of the ship at various successive depths of immersion. Same as Plane of Flotation." 132. Wedges of Emersion and Immersion. When a ship, floating upright and at rest, is inclined by some external force, the inclination takes place about an axis in or near the longitudinal middle line of the waterline, and as the displacement remains constant, the triangular shaped part forced into the water on the inclined side, which is called the wedge of "Emersion," must be balanced by a similar triangular shaped wedge on the opposite side, which is lifted out of the water, and which is called the wedge of "Immersion." 133. Weight Displacement. See "Displacement Weight." 134. Weight of Hull. The weight of hull of a ship is what is left after removing-besides all consumables-the engines and boilers, masts and riggings, cables, tanks, and all the portable equipment; and consists therefore of the weight of the structure proper and its fixed fittings. In armored ships, the armor and backing are also deducted. The weight of armored decks in. armored and protected ships is also usually deducted. 135. Winging Weights. Moving weights (already on board) from the middle line towards the sides; it increases the moment of inertia and tends to lengthen the period of the ship. 136. Working Buoyancy. A term applying to submarine vessels only. It represents the weight added or floating power subtracted, or their sum, in order to reduce the vessel from her maximum flotation to the condition of immersion, and generally amounts to from 3 to 5 per cent. of the total floating power. 137. Working Strength. Working strength is the utmost stress to which it is considered safe to subject a body during its ordinary use as part of a structure. |