Aligning equipment in ships and other structures

Claim 1

A method of obtaining information for use in establishing the alignment of equipment on a structure, using instruments each of which has a sensitive axis and gives an electrical signal which, for a range of attitudes, is a function of the magnitude of the angle between that axis and the direction of the earth''s gravitational field at any moment, the method comprising: a. installing a first such instrument on the structure, either on a first mounting or on a piece of equipment, with provision for rotation of the instrument relatively to the structure about a rotation axis which is approximately vertical, the sensitive axis being perpendicular to this rotation axis, b. likewise installing a second such instrument on said structure on a second mounting or piece of equipment, c. bringing the two instruments to rotational positions about their rotation axes each with its sensitive axis approximately aligned with a common direction in the structure, and taking the instantaneous differencee of the signals of the two instruments, thereby obtaining an output the magnitude and polarity of which varies in accordance with the magnitude and polarity of the angle between the rotation axes when projected onto the vertical plane containing the common direction, d. thereafter rotating each instrument about its respective rotation axis in the same polarity through the same angle, and again taking the instantaneous difference of the signals of the two instruments, e. adjusting at least one mounting or piece of equipment, having regard to the differences taken under steps (c) and (d), so as to bring the rotation axes into exact parallelism, f. tilting the structure about a horizontal axis into an inclined attitude such that the rotation axes are substantially out of the vertical, g. taking the instantaneous difference of the signals of the two instruments while the structure is in this inclined attitude, and h. rotating one of the instruments about its rotation axis until the difference is zero.

Claim 2

A method of obtaining information for use in establishing the alignment of equipment on a structure, using instruments each of which has a sensitive axis and gives an electrical signal which, for a range of attitudes, is a function of the magnitude of the angle between that axis and the direction of the earth''s gravitational field at any moment, the method comprising: a. installing a first such instrument on the structure, either on a first mounting or on a piece of equipment, with provision for rotation of the instrument relatively to the structure about a rotation axis which is approximately vertical, the sensitive axis being perpendicular to this rotation axis, b. likewise installing a second such instrument on said structure on a second mounting or piece of equipment, c. bringing the two instruments to rotational positions about their rotation axes each with its sensitive axis approximately aligned with a common direction in the structure, and taking the instantaneous differencee of the signals of the two instruments, thereby obtaining an output the magnitude and polarity of which varies in accordance with the magnitude and polarity of the angle between the rotation axes when projected onto the vertical plane containing the common direction, d. thereafter rotating each instrument about its respective rotation axis in the same polarity through the same angle, and again taking the instantaneous difference of the signals of the two instruments, e. adjusting at least one mounting or piece of equipment, having regard to the differences taken under steps (c) and (d), so as to bring the rotation axes into exact parallelism, f. tilting the structure about a horizontal axis into an inclined attitude such that the rotation axes are substantially out of the vertical, g. taking the instantaneous difference of the signals of the two instruments while the structure is in this inclined attitude, and h. rotating one of the instruments about its rotation axis until the difference is zero.