GB925800A - Improvements in or relating to apparatus and methods for exploring the topography of he sea bed - Google Patents

Abstract

925,800. Measuring electrically. ELECTRICITE DE FRANCE-SERVICE NATIONAL. Dec. 21, 1960 [Dec. 22, 1959; Dec. 9, 1960], No. 43939/60. Class 40 (1). [Also in Group XIX] Apparatus for exploring the topography of the sea bed comprises a pipelike test element dragged along the seabed and distorting in accordance with irregularities in the surface covered, the distortions being measured by internal, recording extensometers. The test element is similar in rigidity and weight to a submarine cable to be laid on the sea bed. As shown (Fig. 1), a vessel 2 carries the test element 3 along the sea bed over the proposed route for the cable. One section of the member 3 contains two mechanical extensometers, each comprising two circular plates 21, 22 (Fig. 3), each held inside the cable by three points 24 spaced 120 degrees apart (Fig. 4). A central shaft 42 between a pair of plates 21, 22, carries a recording drum 43. Three pairs of arms 51, 52 are hinged to the plates at 53, 54 and guided in supports 57, 58, each arm carrying a recording pen 45, 46. As the test element 3 is dragged along, the distortions due to the irregularities in the sealed produce movement of the styli 45, 46 which are recorded on the drum 43. A further section of the test element 3 carries electrical extensometers comprising a magnetic wire 66 (Fig. 7) stretched between plates 67, 68 and forming part of the magnetic circuit of a coil 69. The natural frequency of vibration of each of these units, indicative of the stress and distortion between plates 67, 68, is transmitted electrically via an amplifier to a recording tape together with a signal representing time.