GB447259A - Improvements in or relating to a system and device for stabilizing ships - Google Patents

Abstract

447,259. Stabilizing ships. BOELLA, M., 23, Martin Piaggio, Genoa, Italy. Aug. 13, 1934, Nos. 23361, 23362, and 23363. Convention dates, Aug. 12, 1933, Dec. 30, 1933, and Feb. 8, 1934. [Class 113 (i)] Ships are stabilized against rolling by bringing into play controlling means responsive to the momentary or periodic difference of height of the water level on the two sides of the ship due to transverse waves. The control means described are responsive to the hydrostatic pressure difference on points permanently submerged on opposite sides of the ship and apply a transverse movement equal and opposite to the heeling moment. In one of its simplest form, the stabilizing means comprise a pair of pistons 16, 17, Fig. 4, working in cylinders 14, 15 exposed to the hydrostatic pressure on opposite order of the ship. The common piston rod 18 is controlled by springs 19 and the motion of the pistons is conveyed by the gear 73-76 to a motor 13, Fig. 2, controlling a pump wheel 9 which causes a flow of stabilizing fluid from the tank 6 to the tank 7 and vice versa through the conduit 8. A Wheatstone bridge form of control is shown in Fig. 5. in which two limbs are formed by mercury contacting with coiled wire contacts 22, 23 in the curved tube 21 to the ends of which the hydrostatic pressure prevailing on opposite sides of the ship is applied. The other two limbs of the bridge are similarly constructed with the tube 26 and mercury in contact with the wires 27, 28. The tube 26 is however rotatable by means of the gear shown from the motor 13. Displacement of the mercury in the tube 21 cause imbalances in the Wheatstone bridge and consequent operation of the pump. A follow-up device such as floats 60, 61, Fig. 6, connected by a band 64 cause through suitable gearing the rotation of the tube 26 and restoration of the balance. Fig. 8 shows an arrangement for eliminating the influence of a permanent list of the ship from the hydrostatic system. The effect of the list angle is conveyed by the gyroscope 92 or list-angle indicator by the shaft 93 to one member of a differential gear. A measure of the difference in hydrostatic level due to list is conveyed to the element 88 of the gear and neutralizes that due to the gyroscope. ' Only the differences in hydrostatic pressure due to mere rolling are conveyed to the shaft 95 and hence to the driving motor through the gear 99. The effect of list due to rudder action is similarly eliminated by a sleeve sliding on a straight and inclined feather in a shaft. In Fig. 11 is shown a device for eliminating list due to centrifugal action when turning. Long and short period pendulums 111 and 113, the action of the latter being damped by a dash-pot device are combined at the gear wheel 123 and are fed through the shaft 93 to one element of the differential gear 88. The hydrostatic pressures prevailing at various points on the ship's side are fed to and integrated by the differential gears 134-134<11> and are further integrated with the correction for list supplied through the shaft 93 in the differential gear 88. The motion is finally fed to the driving motor through the shaft 100, to which is also applied the follow-up correction applied through the gear wheel 102 to the differential gear 96.