A RAISEABLE FLOATING STRUCTURE AND A METHOD FOR RAISING THE SAME IN A WATER COLUMN

Abstract

A floatable structure has a cage with a surrounding wall and a bottom, the cage being arranged for fish farming. A surrounding skirt extends in a downward direction from the bottom, wherein at least a portion of the bottom from the skirt towards a center of the cage is tight. The portion of the bottom and the skirt forming a bottom section are arranged to be filled with a gas giving the floatable structure additional buoyancy.

Claims

1. A floatable structure comprising a cage with a surrounding wall and a bottom, the cage being arranged for fish farming; wherein a surrounding skirt extends in a downward direction from the bottom, wherein at least a portion of the bottom from the skirt towards a center of the cage is tight, said portion of the bottom and the skirt forming a bottom section arranged to be filled with a gas giving the floatable structure additional buoyancy.

2. The floatable structure according to claim 1, wherein the bottom section comprises at least one of a gas inlet and a gas outlet.

3. The floatable structure according to claim 1, wherein the bottom section comprises at least one bulkhead dividing the bottom section into at least two buoyancy sections.

4. The floatable structure according to claim 1, wherein at least one bulkhead is arranged in a radial direction relative to a vertical center axis of the floatable structure.

5. The floatable structure according to claim 3, wherein the bottom section comprises an even number of bulkheads, forming an equivalent number of opposing buoyancy sections.

6. The floatable structure according to claim 3, wherein a portion of at least one bulkhead is arranged in a non-radial direction.

7. The floatable structure according to claim 1, wherein the skirt comprises at least one door giving access from the outside of the bottom section and to the inside of the bottom section.

8. A method for raising a floatable structure comprising a cage with a surrounding wall and a bottom, the cage being arranged for fish farming; wherein a surrounding skirt extends in a downward direction from the bottom, wherein at least a portion of the bottom from the skirt towards a center of the cage is tight, said portion of the bottom and the skirt forming a bottom section arranged to be filled with a gas giving the floatable structure additional buoyancy in a water column, the method comprises the steps of: connecting a supply line for a gas to the bottom section; and supplying the gas into the bottom section.

9. The method according to claim 9, wherein the bottom section is divided into at least a first and a second buoyancy section, the method further comprising a step of: supplying the gas into at least the first and the second buoyancy sections, where the gas is supplied in a sequence and with a volume arranging the floatable structure to raise in the water column keeping the vertical center axis substantially in its vertical position.

10. The method according to claim 8, wherein the method further comprises the following steps: supplying gas in a plurality of buoyancy sections, giving sufficient buoyancy for lifting the bottom to a height above a sea water surface giving room for a floating service means below the bottom; opening a first door to the first buoyancy section, accessing the first buoyancy section with the floating service means and servicing the first buoyancy section, leaving the first buoyancy section and closing the first door; filling the first buoyancy section with gas to increase buoyancy; opening a second door to the second buoyancy section, accessing the second buoyancy section with the floating service means and service the second buoyancy section, leaving the second buoyancy section and closing the second door; filling the second buoyancy section with gas to increase buoyancy; and repeating the steps above until all selected buoyancy sections are serviced.

11. The method for raising a floatable structure according to claim 8, wherein the method further comprises the step of: supplying an unequal amount of gas in at least two buoyancy sections, giving the floatable structure a heel, enabling water inside the closed cage to move to one side of the closed cage.

12. The floatable structure according to claim 2, wherein the bottom section comprises at least one bulkhead dividing the bottom section into at least two buoyancy sections.

13. The floatable structure according to claim 2, wherein at least one bulkhead is arranged in a radial direction relative to a vertical center axis of the floatable structure.

14. The floatable structure according to claim 4, wherein the bottom section comprises an even number of bulkheads, forming an equivalent number of opposing buoyancy sections.

15. The method according to claim 9, wherein the method further comprises the following steps: supplying gas in a plurality of buoyancy sections, giving sufficient buoyancy for lifting the bottom to a height above a sea water surface giving room for a floating service means below the bottom; opening a first door to the first buoyancy section, accessing the first buoyancy section with the floating service means and servicing the first buoyancy section, leaving the first buoyancy section and closing the first door; filling the first buoyancy section with gas to increase buoyancy; opening a second door to the second buoyancy section, accessing the second buoyancy section with the floating service means and service the second buoyancy section, leaving the second buoyancy section and closing the second door; filling the second buoyancy section with gas to increase buoyancy; and repeating the steps above until all selected buoyancy sections are serviced.

Description

EXAMPLES OF THE INVENTION

[0075] In the following are described examples of preferred embodiments illustrated in the ac-companying drawings, wherein:

[0076] FIG. 1 shows a side view of a floatable structure;

[0077] FIG. 2 shows a perspective view of the floatable structure from below;

[0078] FIG. 3 shows a top view of a first embodiment of the bottom section;

[0079] FIG. 4 shows a top view of a second embodiment of the bottom section;

[0080] FIG. 5 shows a side view of the floatable structure in a first floating position;

[0081] FIG. 7 shows a side view of the floatable structure in a service position; and

[0082] FIG. 8 shows top view of the floatable structure in a service position.

[0083] FIG. 1 shows a side view of a floatable structure 1 comprising a closed cage 10 and a bottom section 20. The floatable structure 1 is shown in a typical operational position, where a water surface W1 inside the cage 10 is at the same level as an outside water surface W0, the outside water surface W0 shown as a sea water surface. A centre axis CA is vertical when the floatable structure 1 is levelled.

[0084] The closed cage 10 comprises a wall 11 and a bottom 12. The wall 11 being provided with buoyancy elements (not shown) keeping the structure floating when the closed cage 10 is filled with water.

[0085] A bottom section 20 is formed by the bottom 12 and a surrounding skirt 21. The skirt 21 extends in downwards direction from the wall 11. The skirt 21 has an upper edge 210, a lower edge 211 and a plurality of doors 24. The doors 24 are arranged in the skirt 21 and the bulkheads 23, giving access for a floating service means 85, shown as a boat in FIGS. 7 and 8 to the buoyancy sections 22.

[0086] An underside 25 of the bottom section 20 is open, giving the bottom section 20 a shape as an air bell.

[0087] FIG. 2 shows a perspective bottom-up view of the floatable structure 1. The bottom section 20 is here shown with eight bulkheads 23, dividing the bottom section 20 into eight buoyancy sections 22. Each bulkhead 23 comprising a door 24.

[0088] FIG. 3 shows the floatable structure 1 from the underneath. The bottom section 20 comprises eight radial arranged bulkheads 23, dividing the bottom section 20 into 8 buoyancy sections 22.

[0089] FIG. 4 shows the bottom section 20 comprising eight radially arranged bulk heads 23 and eight non-radial arranged bulkheads 26, dividing the bottom section 20 into 16 buoyancy sections 22. The non-radial bulkheads are shown as curved bulkheads forming a circle.

[0090] FIG. 5 shows the floating structure 1 in a first floating position. The closed cage 10 is filled with water and the bottom section 20 is filled with a gas, the gas giving sufficient buoyancy for lifting the floating structure 1 a height h. The inside water surface W1 has a height h above the outside water surface W0, the height difference generating a pressure P inside the closed cage 10, where the overpressure P equals the height h.

[0091] FIG. 6 shows the floating structure 1 in a second floating position, the floating structure 1 having a heel A. The heel A is achieved by filling the buoyancy sections 22 with an uneven amount of gas, giving the floating structure 1 the uneven buoyancy. The heel A is arranged such that the water inside the closed cage 20 flows to an outlet 13. The outlet 13 is connected to a well boat 80 via a hose 81, the hose 81 arranged for transferring fish from the cage 10 and to the well boat 80. The bottom 12 in FIG. 6 is shown with a conical shape.

[0092] FIGS. 7 and 8 show in a cross-section view (FIG. 7) and a top view (FIG. 8) the floating structure 1 in a third floating position, more specifically in a service position. The service position shown in FIG. 7 is applicable for a closed cage 10 which is empty of water or an open cage 10.

[0093] The bottom section 20 comprises eight buoyancy sections 22-1 to 22-8. The six buoyancy sections 22-1-2-4-5-6-8 are filled with gas, giving the floatable structure 1 enough buoyancy for the bottom 12 to be positioned above the water surface W0, giving room for the service boat 85 to operate below the bottom 12.

[0094] The two remaining buoyancy sections, 22-3 and 22-7, have no buoyancy as their doors 24 are open to air, giving access for the service boat 85. When the buoyancy sections 22-3 and 22-7 are serviced, the service boat 85 leaves the bottom section 20. The doors 24 are then closed and buoyancy sections 22-3 and 22-7 are filled with gas. Then two other adjacent buoyancy sections, for instance 22-8 and 22-4, may be opened and made available for the service boat 85.