GB1321025A - Aligning equipment in ships and other structures - Google Patents

Abstract

1321025 Aligning equipment in ships BRITISH AIRCRAFT CORP Ltd 16 May 1972 [18 May 1971] 15591/71 Heading G1N Two theodolites equipped with electrolytic inclinometers are used to check the axial directions of a piece of equipment relative to a datum line of the body on which the equipment is mounted, e.g. a gun on a ship. Each inclinometer comprises a bubble 14 (Fig.3) in an electrolyte 16 in a curved container 18, forming a differential resistance between end electrodes 20, 22 and central electrode 24. A first theodolite is lined up with a reference datum line on the ship, the second with a datum line on the gun. The levelling screws 44 (Fig.2) of the latter are adjusted so that inclinometers 12 have the same output signal for each 90 degrees rotation of both theodolites. The ship is then tilted to a roll angle of say 3 degrees. The upper part 40 of the first theodolite is rotated about its nominal vertical axis until the inclinometer output is balanced and the theodolite locked. The second theodolite is similarly adjusted and both horizontal displacement scales set to zero. With the ship restored to its normal attitude, subsequent displacements of both telescopes about the vertical axes are accurately measured by the theodolite scales. In another embodiment the inclinometers are mounted on horizontal platforms with their axes parallel in plan and the ship rotated about a vertical axis. The difference between the inclinometer readings is plotted against angular rotation to enable corrections to be applied to the gun direction.