Working system for floating structure, floating structure, working ship, and working method for floating structure

1. A working system comprising:

a floating type floating structure; and

a working ship configured to perform at least installation or maintenance of the floating structure, wherein:

the floating structure includes a column section whose peripheral surface is located at a waterline when the floating structure is floating, a ballast section arranged below the column section, and a flange section arranged at an intermediate portion of the column section,

the working ship includes a gripping section capable of engaging with an underside of the flange section,

the floating structure includes a raising/lowering device configured to raise and lower the floating structure, and

with the gripping section of the working ship engaged with the underside of the flange section of the floating structure in a floating state, the floating structure is lowered such that weight of the floating structure is borne by the gripping section via the flange section, to secure the floating structure to the working ship.

2. The working system according to claim 1 , wherein the raising/lowering device is a ballast adjusting device provided in the ballast section of the floating structure.

3. The working system according to claim 1 , wherein the column section is slenderer than the ballast section.

4. The working system according to claim 1 , wherein the ballast section has a ballast tank to and from which water can be supplied and discharged, and water is supplied to and discharged from the ballast tank in accordance with lowering and raising by the raising/lowering device.

5. The working system according to claim 4 , wherein the working ship includes a controller configured to control the supply and discharge of water to and from the ballast tank, and a monitor configured to monitor posture of the floating structure.

6. The working system according to claim 1 , wherein the gripping section has a pronged unit with a recess corresponding in shape to a circumferential half of the peripheral surface of the column section and is arranged at a bow of the working ship.

7. The working system according to claim 1 , wherein the gripping section has an elastic member arranged at a portion thereof where the gripping section comes into contact with the floating structure, or a supporting member configured to restrict horizontal movement of the flange section.

8. The working system according to claim 1 , wherein the flange section is configured so as to be attachable and detachable.

9. The working system according to claim 1 , wherein the floating structure is a spar type floating body.

10. The working system according to claim 1 , wherein the floating structure has a wind power generation device, wind conditions observation equipment, a solar power generation device, lighting equipment, or radio communication equipment arranged above the column section.

11. A working method for performing work including at least installation or maintenance of a floating type floating structure on water, the floating structure having a column section whose peripheral surface is located at a waterline when the floating structure is floating, a ballast section arranged below the column section, and a flange section arranged at an intermediate portion of the column section, the working method comprising:

an engaging process of engaging a gripping section of a working ship with an underside of the flange section of the floating structure;

a securing process of securing the floating structure to the working ship by lowering the floating structure such that weight of the floating structure is borne by the gripping section via the flange section; and

a working process of carrying out the work including at least installation or maintenance of the floating structure.

12. The working method according to claim 11 , further comprising:

a releasing process of releasing linkage between the floating structure and the working ship by raising the floating structure; and

a retreat process of releasing engagement between the floating structure and the working ship by detaching the working ship from the floating structure.