Heave-damped caisson vessel

Abstract

A floating structure includes an elongate caisson hull and at least one plate set coupled to the hull. The plate set includes multiple heave plates located about an outer edge of the hull so as to form a discontinuous pattern generally symmetric about a vertical axis of the hull.

What is claimed is:  
     
         1 . A floating structure comprising: 
 an elongate caisson hull;    at least one plate set coupled to the hull, the plate set comprising a plurality of heave plates located about an outer edge of the hull so as to form a discontinuous pattern generally symmetric about a vertical axis of the hull.    
     
     
         2 . The floating structure of  claim 1  wherein the individual heave plates are contained within an imaginary bounding box formed by a square centered on a vertical axis of the hull having a side length no greater than 120% of a diameter of the hull.  
     
     
         3 . The floating structure of  claim 1  wherein a cross-section of the hull is octagonal and the individual heave plates are located at one or more elevations in four diagonal corners of the hull.  
     
     
         4 . The floating structure of  claim 1  wherein a cross-section of the hull is Greek cross and the heave plates are located within recesses of the cross.  
     
     
         5 . The floating structure of  claim 1  wherein the heave plates are located at more than one elevation.  
     
     
         6 . The floating structure of  claim 1  further comprising a plurality of support structures reinforcing the heave plates, the support structures being located at multiple locations along the length of the hull and forming a pattern which disrupts the flow of water in a horizontal direction so as to impede formation of global vortices.  
     
     
         7 . The floating structure of  claim 1  wherein one or more of the individual heave plates further comprise one or more perforations adapted to increase damping forces provided by the heave plates.  
     
     
         8 . A floating structure comprising: 
 a deep draft caisson hull having a generally prismatic shape;    a plurality of heave plates forming a discontinuous ring about a circumference of the hull.    
     
     
         9 . The floating structure of  claim 8  wherein the discontinuous ring of heave plates a pattern generally symmetric about a vertical axis of the floating structure.  
     
     
         10 . The floating structure of  claim 8  wherein a cross-section of the hull is octagonal and the heave plates are located at one or more elevations in four diagonal corners of the hull.  
     
     
         11 . The floating structure of  claim 8  wherein a cross-section of the hull is a Greek cross and the heave plates are located within recesses of the cross.  
     
     
         12 . The floating structure of  claim 8  wherein the heave plates are located at more than one elevation.  
     
     
         13 . The floating structure of  claim 8  wherein the hull has a positively buoyant upper portion and a negatively buoyant lower portion, such that a combined center of gravity for the floating structure is located below a combined center of buoyancy for the floating structure.  
     
     
         14 . The floating structure of  claim 8  further comprising a plurality of support structures reinforcing the individual heave plates, the support structures are located at located at multiple locations along the length of the hull and form a pattern adapted to disrupt the flow of water in a horizontal direction so as to impede formation of vortices.  
     
     
         15 . The floating structure of  claim 8  wherein one or more of the individual heave plates further comprise one or more perforations adapted to increase damping forces provided by the heave plates.  
     
     
         16 . A floating structure comprising: 
 a vertical columnar hull having a diameter and an outer shell having at least four sides,    one or more heave plates attached to the hull wherein the heave plates are contained within an imaginary box formed by lines parallel to tangents to the four sides, wherein each parallel line is located within a distance of 10% of the hull diameter from the tangent.    
     
     
         17 . The floating structure of  claim 16  wherein a cross-section of the hull is octagonal and the heave plates are located at one or more elevations in four diagonal comers of the hull.  
     
     
         18 . The floating structure of  claim 16  wherein the heave plates form an array comprising one or more plate sets, the plates sets comprising a pattern of individual heave plates symmetric about a vertical axis of the floating structure.  
     
     
         19 . The floating structure of  claim 16  wherein the individual plates of a plate set are located at more than one elevation.  
     
     
         20 . The floating structure of  claim 16  wherein the hull has a positively buoyant upper portion and a negatively buoyant lower portion, such that a combined center of gravity for the floating structure is located below a combined center of buoyancy for the floating structure.  
     
     
         21 . The floating structure of  claim 16  wherein the array of heave plates further comprises a plurality of support structures reinforcing the individual heave plates, the support structures adapted to impede formation of vortices induced by movement of water about the hull.  
     
     
         22 . The floating structure of  claim 16  wherein one or more of the individual heave plates further comprise one or more perforations adapted to increase damping forces provided by the heave plates.  
     
     
         23 . A floating structure comprising: 
 a buoyant hull having a diameter and a vertical axis, and    an array of heave plates attached about the diameter of the hull, wherein 
 the array of heave plates fit within an imaginary bounding box in the horizontal plane that is centered about a vertical axis of the hull, the bounding box having sides of length no greater than 120% of the diameter of the hull.  
   
     
     
         24 . The floating structure of  claim 23  wherein the bounding box is a square.  
     
     
         25 . The floating structure of  claim 23  wherein the hull has an octagonal cross-section and the heave plates are located at one or more elevations in diagonal corners of the hull.  
     
     
         26 . The floating structure of  claim 23  wherein the array of heave plates is composed of one or more plate sets, the plates sets comprising a pattern of individual heave plates symmetric about a vertical axis of the floating structure.  
     
     
         27 . The floating structure of  claim 23  wherein the individual plates of a plate set are located at more than one elevation  
     
     
         28 . The floating structure of  claim 23  wherein the hull has a positively buoyant upper portion and a negatively buoyant lower portion, such that a combined center of gravity for the floating structure is located below a combined center of buoyancy for the floating structure.  
     
     
         29 . The floating structure of  claim 23  wherein the array of heave plates further comprises a plurality of support structures reinforcing the individual heave plates, the support structures adapted to impede formation of vortices induced by horizontal movement of water about the hull.  
     
     
         30 . The floating structure of  claim 23  wherein one or more of the individual heave plates further comprise one or more perforations adapted to increase damping forces provided by the heave plates.  
     
     
         31 . A method of construction comprising: 
 constructing a caisson hull in a horizontal orientation upon a support structure which allows a keel of the hull to be elevated a distance above a ground level; and    attaching a plurality of heave plates to the caisson hull at one or more locations along a length of the hull.    
     
     
         32 . The method of construction of  claim 31  wherein the caisson hull has an octagonal crosssection and the heave plates are polygonal in shape and adapted to attach in a symmetric pattern in diagonal comers of the octagon without interference with the support structure or ground.  
     
     
         33 . The method of construction of  claim 31  wherein the heave plates form an array, the array comprising one or more sets comprising a plurality of individual heave plates, wherein the individual heave plates form a generally symmetric pattern about a central axis of the hull.  
     
     
         34 . The method of construction of  claim 31  wherein the caisson hull and heave plates are adapted to provide substantially horizontal floatation of the hull sufficient to enable the hull to be launched as a single piece.  
     
     
         35 . The method of construction of  claim 31  wherein the horizontal floatation occurs at a draft of less than thirty feet.  
     
     
         36 . The method of construction of  claim 31  wherein the keel elevation is less than ten feet.  
     
     
         37 . A method of increasing the heave natural period of a floating structure comprising: attaching a plurality of heave plates to a buoyant hull having a draft in excess of 300 ft, wherein: 
 the heave plates are attached at one or more elevations and arranged so as to form a discontinuous pattern generally symmetric about a vertical axis of the hull, and    the heave plates are located vertically along a length of the hull so as to increase the added mass of the hull in the heave direction.    
     
     
         38 . The method of  claim 31  wherein more than one heave plate is placed in a general vertical line relative to one another, wherein the heave plates are spaced a distance apart vertically so as to increase the virtual mass of the floating structure in the heave direction.  
     
     
         39 . The method of  claim 31  wherein the heave plates comprise generally flat plates having a substantially horizontal orientation so as to impeded the flow of water in a vertical direction along the hull but so as to permit the flow of water in the horizontal direction about the hull.  
     
     
         40 . The method of  claim 31  wherein a cross-section of the hull is octagonal, and the heave plates comprise triangular geometry and are located at one or more elevations in four diagonal corners of the hull.