A moon pool drag reduction device

Abstract

The present invention relates to a moon pool drag reduction device, comprising a bottom plate shaped like a moon pool opening, the bottom plate can be placed on a platform protruding inwardly provided at the bottom of the moon pool; symmetrically arranged notches are provided around the bottom plate to allow water pipes above and below the bottom plate to pass; at least one pressure balance hole device is provided in the middle of the bottom plate, the pressure balance hole device comprises a through hole provided on the bottom plate, a pressure balance hole guide plate with a front part tilted upward is provided above the through hole, and a pressure balance hole is formed between the front part of the pressure balance hole guide plate and the bottom plate. The present invention adopts a non-watertight open steel plate beam structure cover plate in combination with a manual clamping device, which has a simple structure, ingenious design, convenient implementation and low cost; it does not adopt devices such as hydraulic cylinders and control systems, which greatly saves construction costs and later maintenance and repair costs.

Description

Technical Field

[0001] The invention relates to a moon pool drag reduction device, belonging to the technical field of ship moon pools. Background Art

[0002] On ships such as diving support vessels and drilling ships, a well-shaped structure that runs through the deck to the bottom plate in the middle of the hull is usually set up due to operational needs. This is called a moon pool. Although the moon pool brings convenience to the special operations of the ship, its huge opening causes a significant increase in the hull resistance when the ship is sailing. Technicians have designed some solutions to reduce the resistance of the ship, including special moon pool shapes, special guide plates, and hydraulic doors at the bottom of the moon pool. Among these solutions, the solution of optimizing the opening shape and the guide plate can only slightly optimize the resistance performance. After all, the large opening is still there, and its impact on the resistance is still great. Although the hydraulic door at the bottom of the moon pool has a good drag reduction effect, it is expensive, and the subsequent maintenance and repairs require the shipowner to pay a certain price. Summary of the invention

[0003] The object of the present invention is to provide a moon pool drag reduction device which does not require watertightness and can achieve low-cost and efficient moon pool drag reduction effect.

[0004] The present invention adopts the following technical solutions:

[0005] A moon pool drag reduction device comprises a bottom plate 2 shaped like a moon pool opening, the bottom plate 2 can be placed on a platform protruding inwardly provided at the bottom of the moon pool; symmetrically arranged notches are provided around the bottom plate 2 for allowing water pipes above and below the bottom plate to pass; at least one pressure balance hole device 4 is provided in the middle of the bottom plate 2, the pressure balance hole device 4 comprises a through hole 14 opened in the bottom plate, a pressure balance hole guide plate 8 with an upwardly tilted front portion is provided above the through hole 14, and a pressure balance hole 9 is formed between the front portion of the pressure balance hole guide plate 8 and the bottom plate 2.

[0006] Preferably, the notch is a chamfered portion provided at a corner of the bottom plate 2; the pressure balance hole 9 is in a long strip shape and is arranged along the longitudinal direction of the hull.

[0007] Furthermore, the chamfered portion is an arc chamfer, and a groove 12 is provided at the lower portion thereof. The groove 12 is used for installation and cooperation with the raised platform for lateral limitation.

[0008] Furthermore, it also includes a clamping device 7 and a transmission device 13; the clamping device 7 is installed at the bottom plate installation position in the moon pool, and after being adjusted by the transmission device 13, the bottom plate 2 can be pressed downward and fixed on the platform.

[0009] Furthermore, the transmission device 13 is a long straight rod, which is driven to rotate by a power component to drive the pressing device 7 to press down.

[0010] Furthermore, the clamping device 7 is a wedge, and the power component is a rocker arm or a connecting rod.

[0011] Preferably, a lifting lug 6 for lifting is fixed above the base plate 2 .

[0012] Furthermore, the upper part of the bottom plate 2 is fixed with crisscrossed stiffeners 5 , and the outer enclosure 3 is fixed around it; and the lifting lugs 6 are fixed on the stiffeners 5 .

[0013] Furthermore, the lifting lug 6 is in a pyramid shape.

[0014] Furthermore, the lower surface of the bottom plate 2 is smooth.

[0015] The beneficial effects of the present invention are:

[0016] 1) The design of non-watertight open steel plate beam structure cover plate with manual clamping device has simple structure, ingenious design and convenient implementation;

[0017] 2) The drag reduction effect of the moon pool is significant. By blocking the bottom opening of the moon pool, the bottom smoothness of the ship is close to that of the state without the moon pool, and the navigation resistance caused by the moon pool is basically eliminated.

[0018] 3) Low cost. The open plate beam structure cover is made of ordinary marine steel, which is extremely easy to manufacture. No hydraulic cylinders and control systems are used, which greatly saves construction costs and subsequent maintenance costs. Since ships with moon pools must be equipped with cranes, this cover device is hoisted by a marine crane and does not require additional opening and closing devices.

[0019] 4) There is no need to configure a watertight sealing device, and the pressure balance hole is set, which reduces the structural strength requirements and further reduces the manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the moon pool drag reduction device of the present invention;

[0021] Figure 2 This is an installation layout diagram of the moon pool drag reduction device of the present invention;

[0022] Figure 3 It is a schematic diagram of the pressure balance hole structure in the moon pool drag reduction device of the present invention.

[0023] In the figure: 1. clamped part, 2. bottom plate, 3. outer coaming, 4. pressure balance hole device, 5. stiffener, 6. lifting lug, 7. clamping device, 8. pressure balance hole guide plate, 9. pressure balance hole, 10. bow direction mark, 11. hull outer plate, 12. groove, 13. transmission device, 14. through hole. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0025] See also Figure 1-Figure 3 A moon pool drag reduction device comprises a bottom plate 2 shaped like a moon pool opening, the bottom plate 2 can be placed on a platform protruding inwardly provided at the bottom of the moon pool; symmetrically arranged notches are provided around the bottom plate 2 for passing water pipes above and below the bottom plate; at least one pressure balance hole device 4 is provided in the middle of the bottom plate 2, the pressure balance hole device 4 comprises a through hole 14 opened in the bottom plate, a pressure balance hole guide plate 8 with a front part tilted upward is provided above the through hole 14, and a pressure balance hole 9 is formed between the front part of the pressure balance hole guide plate 8 and the bottom plate 2.

[0026] In this embodiment, see Figure 1 The notch is arranged at the chamfered corner of the bottom plate 2; the pressure balance hole 9 is in a long strip shape and is arranged along the longitudinal direction of the hull.

[0027] In this embodiment, see Figure 1 The chamfered portion is an arc chamfer, and a groove 12 is provided at the lower portion thereof. The groove 12 is used to be installed and matched with the raised platform for lateral limitation.

[0028] In this embodiment, see Figure 1 , also includes a clamping device 7 and a transmission device 13; the clamping device 7 is installed at the bottom plate installation position in the moon pool, and after adjustment by the transmission device 13, the bottom plate 2 can be pressed downward and fixed on the platform.

[0029] In this embodiment, see Figure 1 The transmission device 13 is a long straight rod, which is driven by a power component to rotate and drive the clamping device 7 to press down.

[0030] In this embodiment, the clamping device 7 can be a wedge or a correspondingly designed pressure rod, and the power component is a rocker arm or a connecting rod. The rocker arm, connecting rod and other components are not shown in the accompanying drawings. It should be noted that the power component can be implemented in a variety of ways, as long as the clamping device 7 can be functionally rotated through the transmission device 13 through the thread to achieve up and down movement, and finally the bottom plate 2 can be pressed and fixed on the boss. Therefore, it will not be described in detail.

[0031] In this embodiment, see Figure 1 A lifting lug 6 for lifting is fixed above the base plate 2 .

[0032] In this embodiment, see Figure 1-Figure 2 The upper part of the bottom plate 2 is fixed with crisscross stiffeners 5 , and the outer enclosure 3 is fixed around it; the lifting lugs 6 are fixed on the stiffeners 5 .

[0033] In this embodiment, see Figure 1 , the lifting ear 6 is in a pyramid shape.

[0034] In this embodiment, the lower surface of the bottom plate 2 is smooth, which can reduce resistance.

[0035] Working principle:

[0036] The main structure of the moon pool drag reduction device is a "cover" installed at the bottom of the moon pool. The cover is hoisted to the bottom of the moon pool by the ship's own crane and placed on a platform protruding inwards at the bottom of the moon pool. The crew uses the transmission device 13 on the deck to control the clamping device 7 for clamping. The clamping device 7 is arranged at the bottom of the four corners of the moon pool and is driven by a connecting rod. It can be clamped by a rocker arm or a wedge. The connecting rod extends upward to the main deck and is provided with a nut structure, which is tightened by the crew using a wrench.

[0037] The "lid" at the bottom of the moon pool is a single-layer steel plate beam structure, which is not watertight. The smooth plate surface faces downward, consistent with the line shape of the hull, and keeps the bottom of the hull smooth when pressed. The beam structure is above the plate. A pyramid-shaped truss structure is welded above the beam structure, which is used for the hook to hook the truss when the line of sight is not clear in the water, so as to facilitate lifting. A pressure balance hole device 4 is set in the central position of the bottom cover of the moon pool. The pressure balance hole 9 is in the shape of a long strip and arranged longitudinally along the hull. An inclined pressure balance hole guide plate 8 is set above the pressure balance hole 9 to reduce the vortex generated when the ship is sailing. The pressure balance hole 9 does not need to be set too large, and is only used for pressure balance inside and outside the moon pool. When the bottom cover of the moon pool is hoisted, there is enough space between its four rounded corners and the four square corners of the inner wall of the moon pool for water flow balance. The structural design load of the entire bottom cover of the moon pool only needs to consider the vertical pressure of the seawater in the moon pool caused by the vertical acceleration at this location, and it does not need to be designed according to the watertight structure. When the moon pool is used for diving or drilling operations, the bottom cover of the moon pool in this device is lifted and placed in other areas of the deck and tied. Before the ship sails freely, the bottom cover of the moon pool in this device is hoisted in place and pressed. Under navigation, due to the effect of this device, the bottom of the hull is basically smooth, and the influence of the moon pool on resistance is basically eliminated. According to calculations, the resistance can be reduced by 10%-30%, which is basically equivalent to the situation without a moon pool. At the same time, the device has a simple structure and a very low manufacturing cost. It only has a single-layer plate beam structure of the size of the moon pool opening and manual clamping devices at the four corners. The hoisting can be operated by the working crane on the ship, which greatly improves the fuel economy of the ship during navigation at a very low cost.

[0038] The above are preferred embodiments of the present invention. A person skilled in the art may make various changes or improvements thereon. Without departing from the general concept of the present invention, these changes or improvements shall fall within the scope of protection claimed by the present invention.

Claims

1. A moon pool drag reduction device, characterized in that: It comprises a bottom plate (2) conforming to the shape of the opening of the moon pool, and the bottom plate (2) can be placed on a platform protruding inwardly provided at the bottom of the moon pool; The bottom plate (2) is provided with symmetrically arranged notches around it for allowing water bodies above and below the bottom plate to pass through; At least one pressure balancing hole device (4) is provided in the middle of the bottom plate (2), the pressure balancing hole device (4) comprising a through hole (14) opened on the bottom plate, a pressure balancing hole guide plate (8) with a front portion tilted upward is provided above the through hole (14), and a pressure balancing hole (9) is formed between the front portion of the pressure balancing hole guide plate (8) and the bottom plate (2); The notch is arranged at a chamfered corner of the bottom plate (2); the pressure balance hole (9) is in a long strip shape and is arranged along the longitudinal direction of the hull; The chamfered portion is an arc chamfer, and a groove (12) is provided at the lower portion thereof, and the groove (12) is used for mounting and cooperating with the raised platform for lateral positioning; It also includes a pressing device (7) and a transmission device (13); the pressing device (7) is installed at a bottom plate installation position in the moon pool, and after adjustment by the transmission device (13), the bottom plate (2) can be pressed downward and fixed on the platform; A lifting lug (6) for lifting is fixed above the bottom plate (2).

2. The moon pool drag reduction device according to claim 1, characterized in that: The transmission device (13) is a long straight rod, which is driven to rotate by a power component to drive the pressing device (7) to press downward.

3. The moon pool drag reduction device according to claim 2, characterized in that: The clamping device (7) is a wedge block, and the power component is a rocker arm or a connecting rod.

4. The moon pool drag reduction device according to claim 1, characterized in that: The base plate (2) is a plate-beam structure made of steel. A crisscrossing stiffener (5) is fixed to the upper part of the base plate (2), and an outer enclosure (3) is fixed around the base plate (2). The lifting lugs (6) are fixed on the stiffener (5).

5. The moon pool drag reduction device according to claim 4, characterized in that: The lifting lug (6) is in the shape of a pyramid.

6. The moon pool drag reduction device according to claim 4, characterized in that: The lower surface of the bottom plate (2) is smooth.

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