Deployment of Unmanned Underwater Vehicles

Abstract

An ROV docked to a tether management system (TMS) is lifted outboard into water beside a vessel while deploying an umbilical that effects communication with the ROV via a tether of the TMS. After undocking the ROV to swim away from the TMS while deploying the tether, the TMS is suspended over the water while the ROV performs a subsea mission. A mobile or transportable ROV support unit can be positioned on a deck of a vessel of opportunity to facilitate deployment of the ROV, the TMS and the umbilical and to control the ROV during the mission.

Claims

1. A method of deploying an unmanned underwater vehicle (UUV) from a surface vessel or platform to perform a mission underwater, the method comprising: moving the UUV, docked to a tether management system (TMS), outboard from the vessel or platform and into water beside the vessel or platform; deploying an umbilical that extends outboard from the vessel or platform to the TMS to effect communication with the UUV via a tether of the TMS; undocking the UUV from the TMS; swimming the UUV away from the TMS while deploying the tether; and while suspending the TMS over the water beside the vessel or platform, using the UUV to perform the mission while communicating with the UUV via the tether and the umbilical.

2. The method of claim 1, comprising fully submerging the UUV in the water before undocking the submerged UUV from the TMS.

3. The method of claim 2, comprising also submerging the TMS in the water before undocking the UUV from the TMS and then lifting and holding the TMS clear of the water while the undocked UUV performs the mission.

4. The method of any preceding claim, comprising using a crane to lift the UUV and the TMS outboard from the vessel or platform and to suspend the TMS over the water.

5. The method of claim 4, wherein the crane is fitted to the vessel or platform.

6. The method of any preceding claim, comprising moving the suspended TMS up and down relative to the vessel or platform during the mission in compensation for heave of the vessel or platform.

7. The method of any preceding claim, comprising deploying the umbilical in response to outboard movement of the TMS from the vessel or platform.

8. The method of claim 7, comprising pulling the umbilical from a storage location by virtue of the outboard movement of the TMS.

9. The method of any preceding claim, comprising stabilising the suspended TMS with elongate links that extend from the vessel or platform to the TMS.

10. The method of any preceding claim, further comprising the preliminary step of positioning a mobile UUV support unit on a deck of the vessel or platform and then moving the UUV and the TMS from the UUV support unit outboard of the vessel or platform.

11. The method of claim 10, also comprising deploying the umbilical from storage on the UUV support unit.

12. The method of claim 10 or claim 11, also comprising communicating with the UUV via the UUV support unit.

13. The method of claim 12, comprising controlling the UUV from the UUV support unit.

14. The method of claim 13, comprising controlling the UUV using control personnel located onboard the UUV support unit.

15. The method of any preceding claim, further comprising the subsequent step of returning the UUV to the TMS after the mission, while retracting the tether, and then docking the UUV with the TMS.

16. The method of claim 15, comprising lowering the TMS into the water before docking the UUV with the TMS underwater.

17. The method of any preceding claim, wherein the UUV is deployed from a vessel of opportunity.

18. A method of adapting a vessel of opportunity to support UUV operations, the method comprising positioning a mobile UUV support unit on a deck of the vessel, the UUV support unit including a UUV control system and a garage holding an assembly of a TMS and a UUV.

19. The method of claim 18, where the UUV support unit further includes a storage location for an umbilical that connects the TMS to the UUV control system.

20. The method of claim 18 or claim 19, wherein the UUV control system is arranged to accommodate control personnel for controlling the UUV.

21. The method of any of claims 18 to 20, further comprising effecting data communication between the UUV control system and a control system of a crane fitted to the vessel.

22. The method of any of claims 18 to 21, comprising subsequently lifting the assembly of the TMS and the UUV from the UUV support unit outboard of the vessel, using a crane fitted to the vessel.

23. A mobile or transportable UUV support unit that can be positioned on a deck of a surface vessel or platform, the support unit including: a UUV control system; a garage holding an assembly of a TMS and a UUV; a lifting formation on the TMS for lifting the TMS/UUV assembly from the garage using a crane; and an umbilical that effects communication between the UUV control system and the UUV via a tether of the TMS.

24. The UUV support unit of claim 23, wherein the UUV control system is arranged to accommodate control personnel for controlling the UUV.

25. The UUV support unit of claim 23 or claim 24, embodied as a vehicle.

26. The UUV support unit of any of claims 23 to 25, comprising wheels, tracks and/or rollers enabling the support unit to move around the deck of the surface vessel or platform.

27. A surface vessel or platform equipped with the UUV support unit of any of claims 23 to 26.

28. The vessel or platform of claim 27, wherein the UUV support unit is positioned within a lifting radius of a crane fitted to the vessel or platform, whereby that crane can lift the TMS/UUV assembly from the garage.

29. The vessel or platform of claim 28, wherein the UUV control system of the UUV support unit is in data communication with a control system of the crane.

Description

[0042] In order that the invention may be more readily understood, reference will now be made, by way of example, to the accompanying drawings in which:

[0043] FIG. 1 is a schematic part-sectional end view of a vessel of opportunity equipped in accordance with the invention, showing a crane of the vessel lifting a TMS/ROV assembly from a garage of a mobile ROV support unit placed on a working deck of the vessel;

[0044] FIG. 2 corresponds to FIG. 1 but shows the crane having slewed and then lowered the TMS/ROV assembly into the water beside the vessel;

[0045] FIG. 3 corresponds to FIG. 2 but shows the ROV undocking from the TMS under the water;

[0046] FIG. 4 corresponds to FIG. 3 but shows the TMS lifted back above the water by the crane while the ROV swims away to perform an underwater mission;

[0047] FIG. 5 corresponds to FIG. 4 but shows one of a pair of tag lines extending between the vessel and the suspended TMS to stabilise the TMS as the ROV performs the underwater mission;

[0048] FIG. 6 is a schematic top plan view corresponding to FIG. 5;

[0049] FIG. 7 corresponds to FIG. 3 but shows the ROV re-docking with the TMS beneath the surface after completing the underwater mission; and

[0050] FIG. 8 corresponds to FIG. 7 but shows the crane having lifted the TMS/ROV assembly clear of the water before slewing to return the assembly to the garage of the mobile support.

[0051] The schematic drawings, which are not to scale, show a vessel of opportunity 10 floating on the surface 12 of a body of water 14 such as the sea.

[0052] To operate a UUV exemplified here by an ROV 16, the vessel 10 is adapted in accordance with the invention by placing a transportable, self-contained ROV support unit 18 onto an open working deck 20 atop the hull 22 of the vessel 10. The ROV support unit 18 can be lifted aboard the vessel 10, for example using a crane 24 mounted on the working deck 20 of the vessel 10 or dockside, or may be driven onto or towed aboard the vessel 10.

[0053] In this example, the ROV support unit 18 is a mobile unit fitted with at least one pair of wheels 26 that enable the ROV support unit 18 to be positioned or repositioned at any convenient location on the working deck 20. The ROV support unit 18 may therefore be a vehicle, which may be a towable vehicle such as a trailer or a self-propelled vehicle such as a truck.

[0054] Once positioned on the working deck 20, the ROV support unit 18 may be tied down or anchored with suitable fastenings, such as chains or chocks, to ensure stability when the vessel 10 is at sea. Also, whilst the ROV support unit 18 could, in principle, provide its own electrical power from an on-board generator or from internal batteries, the ROV support unit 18 may conveniently be powered via a cable connection from an external source such as the electrical power system of the vessel 10. Such fastenings and power connections have been omitted from the drawings for simplicity.

[0055] The ROV support unit 18 hosts and supports a TMS/ROV assembly 28 that comprises a TMS 30 connected to the ROV 16. When not in use on a subsea mission, the ROV 16 is latched to the underside of the TMS 30 and hence is coupled mechanically and substantially rigidly to the TMS 30. Thus, the crane 24 can lift the TMS/ROV assembly 28 as a unitary load from the ROV support unit 18 into the water 14 before a mission and from the water 14 back to the ROV support unit 18 after the mission. The ROV support unit 18 therefore does not have, or need, its own crane or other lifting device.

[0056] When the ROV 16 is latched to the TMS 30 and the TMS/ROV assembly 28 is suspended in air on a wire 32 of the crane 24, the weight load of the ROV 16 is borne via the TMS 30. For this purpose, the TMS 30 is surmounted by a lifting formation on its upper side, such as a padeye 34, for engagement by a lifting tackle or a hook 36 suspended from the wire 32 of the crane 24.

[0057] When in the water 14, the ROV 16 can be unlatched and hence uncoupled mechanically from the TMS 30 to swim away from the TMS 30 to perform the mission. As is conventional, the ROV 16 is propelled to swim by on-board thrusters. After the mission, the ROV 16 swims back to or is pulled back to the TMS 30 to be latched and hence re-coupled mechanically to the TMS 30. Thus, the ROV 16 is surmounted on its upper side by a docking formation 38 that is engageable with a complementary remotely-operable latch formation 40 on the underside of the TMS 30.

[0058] While the ROV 16 is unlatched from the TMS 30 to swim underwater 14, the ROV 16 remains connected to the TMS 30 by a deployable, reelable tether 42. The tether 42 provides power and two-way data connections between the TMS 30 and the ROV 16, as required for the ROV 16 to perform the mission.

[0059] As is conventional, the TMS 30 comprises a reversible reel or winch 44 for deploying and retracting the tether 42 as appropriate. The length of the tether 42 deployed between the TMS 30 and the ROV 16 determines the maximum operational radius of the ROV 16 around and with respect to the TMS 30 for a given vertical separation between the ROV 16 and the TMS 30.

[0060] The ROV support unit 18 comprises an ROV control system 46, a garage 48 for the TMS/ROV assembly 28 and a storage location 50 for an umbilical 52. The umbilical 52 provides power and two-way data connections between the ROV control system 46 and the ROV 16 via the TMS 30 and the tether 42. The umbilical 52 is conveniently in a coiled configuration when it is stowed in the storage location 50, for example in a vertical-axis carousel, as shown, or on a reel.

[0061] The ROV control system 46 is exemplified here by an ROV van that accommodates ROV-operating personnel 54 such as pilots and/or other mission specialists. Displays 56 and control interfaces 58 provide for control inputs and for visual feedback between those personnel 54 and the ROV 16.

[0062] The plan view of FIG. 6 shows that the ROV control system 46 of the ROV support unit 18 is connected for data exchange with the control system 60 of the crane 24. This enables coordination between operation of the TMS/ROV assembly 28 and operation of the crane 24. In particular, the ROV control system 46 can control the crane 24 to lift the TMS/ROV assembly 28 into and out of the water 14 and to hold the TMS 30 steady by activating an optional heave compensation system of the crane 24.

[0063] In FIG. 1, the crane 24 is shown with its jib 62 slewed inboard to lift the TMS/ROV assembly 28 from the open-topped garage 48 of the ROV support unit 18. FIG. 2 shows the jib 62 then slewed outboard to lower the TMS/ROV assembly 28 into the water 14.

[0064] As the TMS/ROV assembly 28 is lifted away from the garage 48 and toward the water 14, the umbilical 52 is deployed by being pulled progressively out of the storage location 50 of the ROV support unit 18 as shown in FIG. 2. Deployment of the umbilical 52 is effected automatically, simply by pulling the umbilical 52 through the open top of the storage location 50. FIG. 2 shows that the deployed portion of the umbilical 52 lies on, and extends across, the working deck 20 and then hangs overboard between the working deck 20 and the suspended TMS/ROV assembly 28.

[0065] FIG. 2 also shows the TMS/ROV assembly 28 lowered into the water 14 to a depth of a few metres, advantageously beneath the potentially turbulent splash zone near the surface 12. The ROV 16 has substantially neutral buoyancy whereas the TMS 30 suitably has slightly negative buoyancy to maintain some tension in the wire 32 of the crane 24.

[0066] The ROV 16 is then undocked from the TMS 30, as shown in FIG. 3, to be free to swim to the depth required by the mission as shown in FIG. 4. FIG. 4 also shows that the wire 32 of the crane 24 is retracted to lift the TMS 30 clear of the water 14 while the ROV 16 performs the mission. The tether 42 is paid out by the reel 44 of the TMS 30 accordingly. The tether 42 then extends through the surface 12 of the water 14 between the TMS 30 and the ROV 16.

[0067] FIGS. 5 and 6 show the TMS 30 suspended on the wire 32 of the crane 24 above the surface 12 and, optionally, stabilised against swinging on or twisting about the wire 32 by a pair of tag lines 64 that act in tension between the TMS 30 and the hull 22 of the vessel 10. As can be appreciated in the plan view of FIG. 6, the tag lines 64 converge toward each other in the outboard direction toward the TMS 30 when viewed from above.

[0068] FIG. 5 also shows that the TMS 30 can optionally be moved up and down by a heave-compensation system that, cyclically, pays out and retracts the wire. This avoids heave, roll or pitch of the vessel 10 transmitting unwanted vertical forces to the ROV 16 via the tether 42. The heave-compensation system may conveniently be implemented in the control system 60 of the crane 24, shown in FIG. 6.

[0069] At the end of the mission, the TMS 30 is lowered back into the water 14 to a depth beneath the splash zone as shown in FIG. 7. The ROV 16 swims back to the TMS 30 as the TMS 30 retracts the tether 42 onto the reel 44. Alternatively, or additionally, retraction of the tether 42 onto the reel 44 of the TMS 30 can pull the ROV 16 toward the TMS 30.

[0070] Once the ROV 16 is docked again with the TMS 30, the TMS/ROV assembly 28 is lifted out of the water 14 as shown in FIG. 8 before the jib 62 of the crane 24 is slewed back inboard to lower the TMS/ROV assembly 28 into the garage 48 of the ROV support unit 18. The umbilical 52 is re-stowed in the storage location 50 of the ROV support unit 18, ready for future re-deployment as shown in FIGS. 1 and 2.

[0071] After use, the ROV support unit 18 can be lifted or driven off the vessel 10 to allow the vessel 10 to resume its primary duties. The ROV support unit 18 can then be used again on another vessel of opportunity. Alternatively, the ROV support unit 18 can be moved to a holding location elsewhere on the vessel 10 to be ready to support future ROV missions when required.

[0072] Many variations are possible within the inventive concept. For example, the ROV support unit could include a crane or hoist that is capable of lifting the TMS/ROV assembly into and out of the water. In that case, the vessel need not be fitted with a separate crane. Alternatively, a separate crane of the vessel need not be tied up when operating the ROV.

[0073] The ROV control system on board the ROV support unit could be a relay for conveying control data and visual feedback between the ROV and a separate master control unit, which could be located elsewhere on the vessel or indeed at another offshore or onshore location.

[0074] Elongate links other than tag lines, such as rods or other structures acting in tension or compression between the TMS and the vessel, could be used to stabilise the TMS when lifted clear of the water.

[0075] The ROV support unit could support two or more TMS/ROV assemblies or other subsea packages, each potentially with its own garage, umbilical and umbilical storage location or sharing an umbilical and an umbilical storage location. Alternatively, two or more ROV support units could be provided, each supporting a respective TMS/ROV assembly or other subsea package, conveniently with the option of sharing a common ROV control system between them. The crane of the vessel could thereby choose among a selection of ROVs or packages arrayed on the working deck of the vessel.