NO20230039A1

NO20230039A1 - Cable deployment vessel and method for arranging cable carousel on such vessel

Info

Publication number: NO20230039A1
Application number: NO20230039A
Authority: NO
Inventors: Espen Martin Lange
Original assignee: Espen Martin Lange
Priority date: 2023-01-17
Filing date: 2023-01-17
Publication date: 2024-07-18
Also published as: WO2024155193A1

Description

The present invention relates to a method for arranging a cable carousel on cable deployment vessel as indicated by the preamble of claim 1. According to another aspect, the invention relates to a cable deployment vessel as indicated by the preamble of claim 7.

Background

In relation to energy production offshore, such as in the form of wind mill parks arranged offshore and solar cells arranged offshore, there is a need to interconnect the different production units and/ or to connect the production facilities to land based structures for further energy distribution.

Growing demand for sustainable energy has led to a large increase in these types of energy production facilities and the demand is believed to increase in the coming years.

For the purpose of establishing such interconnection and connection to land based structures boats or vessels carrying cables arranged on large cable carousels have been developed and used. Generally, such vessels are well suited for the purpose. There is, however, a need for connecting auxiliary equipment to the cables in order to secure safe and long-lasting connection of the cables at the different connection points.

In the sea, the cables are exposed to a number of forces that will negatively influence their lifetime unless counteracting measures are taken. Such forces have a number of origins, such as the weight of the cables themselves and movement of the cables in the sea due to waves and other external forces. To reduce the negative effects, the cables are typically provided with cable protection systems (CPS) such as protecting elements round the cable and/or e.g buoyancy elements at strategic points along the cables in order to avoid excessive forces to the cables along their length and in particular close to their connection points.

Such auxiliary equipment needs to be stored on the deployment vessels and it is a problem that the large cable carousels takes up a large space of the deck and in particular makes transportation of equipment between the foredeck and the aft deck very difficult. Generally, the aft deck is occupied by the means to deploy the cable from the cable carousel, which means that only the foredeck is available for storage of such auxiliary equipment. On the other hand, it is at the aft deck, from which the cable is deployed, that the auxiliary equipment must be connected to the cable during its deployment.

Due to the mentioned problems of transporting equipment between the foredeck and the aft deck, equipment has been stored also on the aft deck where there is hardly and space available with the consequence that the aft deck has been overloaded and problematic or even dangerous situations have occurred.

Objective

It is thus an objective of the present invention to arrange the deck of a cable deployment vessel in a manner allowing better use of the total space available thereon.

It is a particular objective to arrange the deck in a manner which avoids overloading of the aft deck with auxiliary cable equipment.

The present invention

The above mentioned objectives are fulfilled by the method as defined by claim 1, representing a first aspect of the present invention as well as a cable deployment vessel defined by claim 7, representing a second independent aspect of the present invention.

Preferred embodiments of the present invention are disclosed by the dependent claims.

The described method and cable deployment vessel allow transportation of auxiliary equipment between the foredeck and the aft deck, e.g. using forklift trucks and other mechanical means due to the manner with which the cable carousel is arranged. The arrangement of the cable carousel on a slewing bearing and the support of the structure comprising the cable carousel and the slewing bearing beneath deck, allows a flat deck beneath the cable carousel, beyond the periphery of the slewing bearing, with a free passage for transportation of goods between foredeck and aft deck, the free passage having a height of at least 2 meters, which is sufficient for the transportation of the required auxiliary equipment. Also the width of the passage is typically at least 2 meters.

In practice, this means that the storage problems of auxiliary equipment to be attached to the cable during deployment is eliminated since there is no longer any need to store such equipment aft of the cable carousel in order to have it readily at hand when needed.

In the following, the present invention is described in further detail in the form of non-limiting exemplifying embodiments with reference to the accompanying drawings, wherein:

Figure 1 is a schematic and simplified top view of a cable deployment vessel according to the present invention.

Figure 2A is a schematic and simplified transverse sectional view of the vessel shown in Figure 1

Figure 2B is an enlargement of a part of Figure 2A.

By “schematic and simplified” is understood that

- a number of details and elements that will typically be present on the vessel are omitted for the sake of simplicity,

- the scale of certain elements may be out of proportion, and that

- the elements are shown more or less as block elements, i.e. without any specific design.

Figure 1 shows a cable deployment vessel 11 with a foredeck 12 and an aft deck 13 provided with a cable carousel 14 resting upon a rotational rolling element bearing 16, hereinafter also denoted a slewing bearing. A cable 15 is deployed from the cable carousel 14 at the aft of the deck.

The rotational rolling element bearing is typically a slewing bearing but other bearings with similar or comparable functionality can also be used. For simplicity, slewing bearing is used as the general term for the rotational rolling element bearing below.

Figure 2A shows the vessel 11 with hull 21 in a front sectional view, showing that there is a free space with height h to the left and to the right of the circular slewing bearing 16 with diameter d. The deck 12/13 beneath the cable carousel 14 is maintained as a flat surface as preferably also in major parts of the foredeck 12 and the aft deck 13. The height h is preferably at least 2 – 2.5 meters, thus allowing a fork lift to pass under the cable carousel for transportation of equipment from the foredeck 12 to the aft deck 13 and vice versa. The diameter d of the slewing bearing is typically between 6 and 12 meters, more typically between 7.5 and 10 meters. The slewing bearing and the load distributing ribs below are preferably dimensioned to support and distribute a weight load of at least 3000 tons and more preferred of at least 7000 tons.

As illustrated by Figure 2A, there is space for forklift trucks to pass the slewing bearing 16 at both lateral, peripheral sides thereof, left and right. Depending on the arrangement of the cable outlet from the cable carousel, not illustrated in the drawings, one of the peripheral sides may have a more limited passage than the other without jeopardizing the benefit of the present invention.

A structure or assembly of load distributing elements 22 in the form of longitudinally extending stiffened panels are schematically illustrated as broken lines under the deck. Additional stiffened panels will be included, typically ribs extending transversely within the hull of the vessel. The specific type, orientation, material etc. of these load distributing stiffened panels may vary within wide limits, the essential point being that these elements are arranged under deck to allow a free space under the cable carousel for transportation of equipment on a mainly flat surface. The number, orientation and dimensions of the load distributing stiffened panels will be determined and designed in accordance with the specified load (weight) and based on calculations well known in the art.

This means that e.g. buoyancy elements and CPS elements may be stored on the foredeck and transported to the aft deck for connection to the cable only at the time required during deployment of cable, thereby avoiding undesired storage of equipment on the aft deck where the main activity takes place during cable deployment.

List of Figure details

11 vessel

12 foredeck

13 aft deck

14 cable carousel

15 cable

16 rotational rolling element bearing

21 vessel hull

22 load distributing stiffened panels

23 forklift truck

Claims

1. Method for arranging a cable carousel (14) on a cable deployment vessel, characterized in arranging the cable carousel (14) on a rotational rolling element bearing (16) on deck (12/13) and arranging load distributing elements (22) beneath deck (12/13) to distribute the weight load from the cable carousel (14) to the vessel hull (21).

2. Method as claimed in claim 1, wherein maintaining the deck (12/13) around the rotational rolling element bearing (16) with a free passage for transportation of goods between foredeck and aft deck of the vessel at least at one lateral side of the rotational rolling element bearing (16).

3. Method as claimed in claim 1, wherein using a rotational rolling element bearing (16) of a diameter in the range between 6 and 12 meters, more preferred between 7.5 and 10 meters.

4. Method as claimed in any one of the preceding claims, wherein using load distributing elements (22) having the form of longitudinal and transversal stiffened panels.

5. Method as claimed in claim 4, wherein using load distributing elements dimensioned to distribute a weight load of at least 3000 tons, more preferred at least 7000 tons.

6. Method as claimed in any one of claims 2-5, wherein the free passage is of a height of at least 2 meters and a width of at least 2 meters.

7. Cable deployment vessel (11) comprising cable carousel (14), characterized in that the cable carousel (14) is arranged on a rotational rolling element bearing (16) on deck (12/13) while an assembly of load distributing elements (22) is arranged beneath deck to distribute the weight load from the cable carousel (14) to the vessel hull (21).

8. Cable deployment vessel as claimed by claim 7, further comprising a free passage for transportation of goods between foredeck (12) and aft deck (13) of the vessel at least at one lateral side of the rotational rolling element bearing (16).

9. Cable deployment vessel as claimed by claim 7 or 8, wherein the rotational rolling element bearing (16) has a diameter in the range between 6 and 12 meters, more preferred between 7.5 and 10 meters.

10. Cable deployment vessel as claimed by any one of claims 7 to 9, wherein the rotational rolling element bearing (16) is a sewing bearing.

11. Cable deployment vessel as claimed by any one of claims 7 to 10, wherein the load distributing means (22) have the form of longitudinal and transversal stiffened panels.

12. Cable deployment vessel as claimed by claim 11, wherein the stiffened panels are dimensioned to distribute a weight load of at least 3000 tons, more preferred at least 7000 tons.

13. Cable deployment vessel as claimed by any one of claims 8 to 12, wherein the free passage h is of a height of at least 2 meters and a width of at least 2 meters.