GB980575A - A method of submerging and positioning constructions on the bed of deep waters and a pontoon for executing the method - Google Patents

Abstract

980,575. Subaqueous foundations. M. LASSEN-NIELSEN. Dec. 2, 1963 [Nov. 30, 1962], No. 47504/63. Heading E1H. [Also in Division B7] A method of positioning a construction unit 7 on the bed of deep water includes the use of a pontoon (see Division B7) having sufficient buoyancy to carry the construction unit 7 suspended therefrom, wherein the pontoon is moored to anchors 8 on the bed by chains 9 co-operating with winches 11 such that when the chains are hauled in, the pontoon and construction unit are submerged. As shown for loading, the cross-boom 14 is raised by gantry cranes 13. At one end the suspension of the boom 14 is from a nut 15 engaging a screw shaft 16 and at the opposite end by a chain 18 passing over a fixed pulley 19. The construction unit 7 is attached to the boom 14 by hooks 21. When the construction unit thus hooked on is ready to be lowered, the buoyancy of the pontoon is regulated by means of ballast tanks 2 and 3. to ensure that anchor chains 9 remain vertical and permit the hauling down of the pontoon by hauling in the chains 9. The cranes are then set to lower the boom 14 so that construction unit 7 will hit the bed before the pontoon. When the unit is in position on the bed hooks 21 are opened e.g. by pulling cords 22 and the pontoon is then refloated by slacking the anchor chains. The pontoon may be fitted with wheels and driving mechanism in order to more exactly position the anchors on the bed prior to loading the unit 7.