GB832421A - Improvements in or relating to measuring arrangements for determining the mean draught, the mean heeling position, or the mean trim position of a ship - Google Patents

Abstract

832,421. Electric measuring systems. SIEMENS & HALSKE A.G. Sept. 17, 1957, No. 29289/57. Class 40 (1). [Also in Group XXXIII] Apparatus for determining the mean draught of a ship comprises four pressure gauges located at symmetrical positions around the ship and at equal depths in calm water, the pressures being translated into corresponding values of resistances which are included in a circuit to cause the resistance of a receiver to vary in accordance with the average value of depth at the measurement points, this value being indicated on a crossed coil meter. Pressure gauge construction (Fig. 1). The water pressure P at each measuring point acts on a diaphragm 3 against a spring 2, any difference in force displacing a rod 5 about a fulcrum 6 to close contacts 10, 11 or 10, 12, thereby causing motor 15 to move the backplate 19 on which the spring 2 is mounted until balance is restored. The motor also repositions the slider 22 of a potentiometer 21 which therefore indicates the magnitude of the water pressure, and thus the depth below the water surface of the measuring point. Electrical circuit (Fig. 5). Each of four symmetrical measuring points have pressure gauges as above, one having a single potentiometer 21, and the others having dual gauged potentiometers 28, 29, 30. Current is fed through two parallel paths, one containing the tapped-off portions of the potentiometers to a motor 39, and the second containing the remaining portions of the potentiometers to a motor 38, the motor shafts feeding into a differential gear 40, and it is shown that the angular displacement of the output shaft 41 in a given time period is proportional to the value of the mean draught at the four measuring points. The timing mechanism comprises a timer 46 and two relays 48, 49. At starting the timer 46 drives a rotary contact arm 471 whilst shaft 41 drives the slider of potentiometer 43. When contact 471 breaks the timer circuit at 473, relay 48 is energized, contacts 482 are closed to cause crossed coil meter 44 to read the current flowing through potentiometer 43, relay 49 is energized, relay 48 falls and the pointer 443 of meter 44 is clamped at a position indicating the angular displacement of shaft 41 in the time period, which is proportional to the mean draught. Shaft 41 continues to rotate until a further rotary contact arm 421 re-energizes the timer 46 and the cycle restarts. A further embodiment (Fig. 7, rot shown), describes similar apparatus for measuring the heeling angle or the trimming angle of the ship.