Float and a floatable structure

Abstract

A float ( 1 ) comprising a hollow pneumatically pressurisable ovoid shell ( 5 ) is provided with a damping plate ( 12 ) extending laterally outwardly around the shell ( 5 ) for damping vertical upward and downward movement of the float in water during stormy conditions, thereby minimising the effect of the buoyant upward propulsion force acting on the float when the float is submerged in stormy conditions. A keel ( 18 ) extends downwardly from the float ( 5 ) for minimising rolling movement of the float ( 1 ). A pair of coupling plates ( 22 ) extending from front and rear ends ( 19,20 ) of the shell ( 5 ) facilitate coupling of the float ( 1 ) between a pair of spaced apart tethering ropes used in mussel growing. A plurality of the floats ( 1 ) may be secured between a pair of spaced apart tethering ropes at spaced apart intervals along the tethering ropes for supporting the tethering ropes so that crop ropes impregnated with mussel spawn may be suspended from the tethering ropes for growing mussels. A navigational buoy ( 60 ) is also disclosed, which comprises a lower float ( 61 ) and a pillar ( 62 ) extending upwardly therefrom for carrying navigational and other instrumentation.

1 . A float comprising:
 a hollow shell having a front end and a rear end, the hollow shell defining an airtight hollow interior region and defining a first major plane coinciding with a horizontal plane, which in use extends through the hollow shell at its maximum horizontal cross-sectional area,   a damping means extending completely around and laterally outwardly from the hollow shell on opposite sides thereof for damping buoyant movement of the hollow shell in water in a generally vertical direction, the damping means defining a first plane extending parallel to the first major plane defined by the hollow shell, and   a pair of coupling means located in the damping means at the front and rear ends of the hollow shell for coupling the float to one of a tethering rope and a mooring rope.   
     
     
         2 . A float as claimed in  claim 1  in which each coupling means comprises a coupling plate, at least one bore extending through the coupling plate. 
     
     
         3 . A float as claimed in  claim 1  in which the hollow shell defines a submersible surface, and the damping means extends from the submersible surface. 
     
     
         4 . A float as claimed in  claim 1  in which the first plane defined by the damping means is spaced apart from and below the first major plane defined by the hollow shell. 
     
     
         5 . A float as claimed in  claim 1  in which the float is of buoyancy such that a normal water line of the float defines a third horizontal plane in use, and the first plane defined by the damping means extends in use at a level spaced apart from and below the third horizontal plane. 
     
     
         6 . A float as claimed in  claim 5  in which the first major plane defined by the hollow shell extends at a level spaced apart from and below the third plane defined by the waterline. 
     
     
         7 . A float as claimed in  claim 1  in which the damping means comprises at least one damping plate of a rigid material. 
     
     
         8 . A float as claimed in  claim 1  in which a keel defining a keel plane extends downwardly from the hollow shell for minimising rolling movement of the float. 
     
     
         9 . A float as claimed in  claim 1  in which a valving means is provided in the hollow shell for facilitating pressurising the hollow interior region with a gaseous medium. 
     
     
         10 . A float as claimed in  claim 1  in which the hollow shell is of a rigid material. 
     
     
         11 . A float as claimed in  claim 1  in which the hollow shell is adapted for sustaining pressure within the hollow interior region of the hollow shell of at least one and a half atmospheres. 
     
     
         12 . A float as claimed in  claim 1  in which the hollow shell is of ovoid shape, and the first major plane defined by the hollow shell coincides with a horizontal major plane of the ovoid, and a second major plane defined by the hollow shell coincides with a vertical major plane of the ovoid. 
     
     
         13 . A float as claimed in  claim 12  in which a plurality of spaced apart ribs extend radially outwardly from and around the float parallel to a fourth plane defined by the float which extends transversely of the first and second major planes defined by the float. 
     
     
         14 . A float as claimed in  claim 1  in which a pillar extends upwardly from the float. 
     
     
         15 . A float as claimed in  claim 1  in which the float is adapted for supporting a pair of spaced apart tethering ropes, with the float located between the respective tethering ropes and with the tethering ropes secured to the coupling means. 
     
     
         16 . A float as claimed in  claim 1  in which the float is of plastics material. 
     
     
         17 . A float comprising:
 a hollow shell having a front end and a rear end, the hollow shell defining an airtight hollow interior region and a first major plane coinciding with a horizontal plane, which in use extends through the hollow shell at its maximum horizontal cross-sectional area,   a damping means extending completely around and laterally outwardly from the hollow shell on opposite sides thereof for damping buoyant movement of the hollow shell in water in a generally vertical direction, the damping means defining a first plane extending parallel to the first major plane defined by the hollow shell, and   a keel extending downwardly from the hollow shell for minimising rolling movement of the hollow shell, the keel extending along the hollow shell and terminating in the damping means adjacent the front and rear ends of the hollow shell, and defining a corresponding keel plane extending perpendicularly to the first plane defined by the damping means.   
     
     
         18 . A method for damping buoying movement of a float in water in a generally vertical direction, the method comprising:
 providing a hollow shell having a front end and a rear end, the hollow shell defining an airtight hollow interior region and defining a first major plane coinciding with a horizontal plane, which horizontal plane in use extends through the hollow shell at its maximum horizontal cross-sectional area,   providing a damping means extending completely around and laterally outwardly from the hollow shell on opposite sides thereof for damping buoyant movement of the hollow shell in water in a generally vertical direction, the damping means defining a first plane extending parallel to the first major plane defined by the hollow shell, and   providing respective coupling means located in the damping means at the front and rear ends of the hollow shell for coupling the float to one of a tethering rope and a mooring rope.   
     
     
         19 . A method for growing marine molluscs, the method comprising:
 providing a plurality of floats, each float comprising a hollow shell having a front end and a rear end, the hollow shell defining an airtight hollow interior region and defining a first major plane coinciding with a horizontal plane, which in use extends through the hollow shell at its maximum horizontal cross-sectional area,   providing a damping means extending completely around and laterally outwardly from the hollow shell on opposite sides thereof for damping buoyant movement of the hollow shell in water in a generally vertical direction, the damping means defining a first plane extending parallel to the first major plane defined by the hollow shell,   providing a pair of coupling means located in the damping means at the front and rear ends of the hollow shell for coupling the float to one of a tethering rope and a mooring rope,   supporting an elongated tethering rope on the plurality of the floats floating in water and spaced apart from each other along the tethering rope by securing the tethering rope to one of the coupling means of each float, and   suspending crop ropes impregnated with a spawn of the marine molluscs from the tethering rope and/or the floats.   
     
     
         20 . A method as claimed in  claim 19  in which a pair of spaced apart tethering ropes are supported on the floats with the tethering ropes secured to the respective coupling means of each float and with the floats extending between the tethering ropes.