SYSTEM AND METHOD FOR THE ACTIVE AND PASSIVE STABILIZATION OF A VESSEL

• US 20100275829A1
• Filed: 12/05/2008
• Published: 11/04/2010
• Est. Priority Date: 12/07/2007
• Status: Active Grant

• Current Assignee: Marine Roll & Pitch Control AS (Axess AS)
• Original Assignee: Marine Roll & Pitch Control AS (Axess AS)
• Inventors: Sporsheim, Ove Sigbjorn
• Granted Patent: US 8,479,674 B2
• Time in Patent Office: Days
• US Class Current: 114/125
• CPC Class Codes: B63B 39/03 by transferring liquids

Abstract

System for the active and passive stabilization of a vessel (10), such as ships, boats, rigs, barges, platforms and cranes operating in a maritime environment, which vessel (10) is provided with tanks (Ha-d) to provide buoyancy and/or ballast, which tanks (11a-d) are provided with openings (12a-d) in the bottom, which openings (12a-d) are facing the medium in which the vessel (10) is floating. The tanks (11a-d) are independent of each other and the openings (12a-d) are so large that a sufficient volume of fluid can pass without cavitation or other resistance, and the system includes means (13a-d) for supplying fluid to the tanks (11a-d), controlled to counteract the effects of external forces on the movements of the vessel (11). The invention further includes methods for the passive and active stabilization of the vessel by use of the system.

Claims

1. System for the active and passive stabilization of a vessel (10), such as ships, boats, rigs, barges, platforms and cranes operating in a maritime environment, which vessel (10) is provided with one or more tanks (11a-d) to provide buoyancy and/or ballast, which tanks (11a-d) are provided with openings (12a-d) in the bottom, which openings (12a-d) are facing the medium the vessel (10) is floating in, which tanks (11a-d) are independent of each other,

characterized in that:

the one or more tanks (11a-d) are arranged in such a way that they have an extension so that at least a substantial part of the tanks (11a-d) extends above a fluid level the vessel (10) is floating in, and at least a part of the tanks (11a-d) extends below the fluid level the vessel (10) is floating in, as the vessel (10) is floating in normal conditions without any loads,

the system includes means (13a-d) for providing positive or negative pressure in the tanks (11a-d) for the removal or supply of fluid, respectively, by directly adding positive or negative pressure to the interior of the tanks (11a-d) and which positive or negative pressure is acting directly on the surface of the fluid in the tanks (11a-d), which means (13a-d) are controlled to counteract the effects of external forces on the movements of the vessel (10).

2. System according to claim 1, characterized in that the system further includes means, such as pressure sensors/meters, floats, pressure pulses and/or similar, to provide information on the state in the tanks (11a-d).

3. System according to claim 1, characterized in that the system further includes means for finding information on the movements of the vessel, such as a MRU (Motion Reference Unit) and/or a VRU (Vertical Reference Unit) and/or a dynamic positioning system or similar means, which provides information on the movements of the vessel (10), mainly the vertical movements.

4. System according to claim 1, characterized in that the system further includes sensing means (14), such as pressure sensors and/or radar and/or laser and/or wave calibration or similar means, which means (14) preferably are arranged along the sides of the vessel to provide information on wave height and frequency.

5. System according to claim 3, characterized in that the system includes means for predicting the movements of the vessel based on information on the movements of the vessel and/or the sensing means (14) in order to counteract the wave movements before the vessel is affected by the wave.

6. System according to claim 1, characterized in that the system further includes a control system to control the fluid volume in the tanks (11a-d), by providing negative pressure in the thanks (11a-d) for ballast or positive pressure for buoyancy.

7. System according to claim 1, characterized in that the means (13a-d) for supplying fluid to the tanks (11a-d) are vacuum/pressure compressor and/or valves, where at least one of these means (13a-d) is arranged to each of the tanks (11a-d).

8. System according to claim 1, characterized in that the tanks (11a-d) are adapted to the vessel (10) as regards size and shape to available space in the vessel (10), and are arranged close to the front, rear and/or middle parts of the vessel (10) to provide the vessel (10) with the desired properties.

9. System according to claim 6, characterized in that the control system is arranged to calculate current ballast and/or buoyancy for the different tanks (11a-d), based on input from means for finding/predicting the movements of the vessel, and/or means for information on the state in the tanks (11a-d), and/or sensor means (14) for information on wave height and frequency, and/or given predefined parameters for the behaviour of the vessel, and provide means (13a-d) for supplying fluid to the tanks (11a-d) with settings.

10. System according to claim 1, characterized in that the system is manual or automatic.

11. System according to claim 1, characterized in that the system further includes means, such as valves, throttles, specially formed propellers (20, 21) or similar, arranged to the openings (12a-d) of the tanks (11a-d), to close the openings and/or supply fluid to the tanks (11a-d).

12. System according to claims 7, characterized in that the free capacity of the vacuum/pressure compressors (13a-d) is used to:

provide bottom tanks of a vessel with air supply, or

transport cooling water from a vessel'"'"'s sea chest and via the coolers of the vessel, or

evaporate water from contaminated bilge water and expel pure water vapour out in the atmosphere.

13. Method for active stabilization of a vessel (10), which vessel (10) is provided with a system according to claim 1, characterized in that it includes the following steps;

1. Acquiring information on the movements of the vessel,

2. Acquiring information on the state in the tanks of the system,

3. Based on information from the steps 1 and 2, calculating the ratio of filling for the tanks, i.e. if the pressure in the tank is to be positive or negative,

4. Providing means for controlling the pressure in the tanks with settings based on the calculation in step 3,

5. Increasing or decreasing the pressure in the tanks by means of means for controlling the fluid volume in the tanks, until means for the state in the tanks respond to the control system according to the invention that the desired positive or negative pressure is achieved,

6. Repeating the steps 1-5.

14. Method according to claim 13, characterized in that step 1 includes acquiring information from a MRU (Motion Reference Unit) and/or a VRU (Vertical Reference Unit) and/or a DP system or similar, which information includes information on the movements of the vessel.

15. Method according to claim 13, characterized in that step 2 includes acquiring information on the state in the tanks by suitable means for this, such as pressure sensors/meter, floats, pressure pulses or similar, which is a premise for the control system according to the invention to know if pressure or vacuum is to be supplied to the tanks.

16. Method according to claim 13, characterized in that step 1 and/or 2 also includes acquiring information on wave height and frequency by means of sensor means for this, which information makes it possible for the control system to form a picture of the wave frequency, direction of the wave and the total changing buoyancy provided by the wave.

17. Method according to claim 13, characterized in that step 4 and 5 include providing the means for controlling the fluid amount in the tanks with settings to achieve desired ballast or buoyancy in the tanks.

18. Method according to claim 17, characterized in that the pressure in the tanks is increased or decreased until means for the state in the tanks respond to the control system that the desired pressure is achieved.

19. Method according to claim 13, characterized in that the steps 1 to 5 are continuously repeated for the vessel to adapt to the continuously changing environment, which makes the system self correcting.

20. Method for passive stabilization of a vessel, which vessel is provided with the invention according to claim 1, characterized in that it includes the following steps:

1. Acquiring information on the movements of the vessel,

2. Acquiring information on the state in the tanks of the system,

3. Based on information from the steps 1 and 2, calculating if the tanks should have reduced and/or increased buoyancy,

4. Providing means for controlling the fluid amount in the tanks with settings to open a valve for supplying fluid to the tanks if reduced buoyancy in tanks is required and/or to close the valve if increased buoyancy in the tanks are required,

5. Continuously repeating the steps 1-4.

21. Method according to claim 20, characterized in that step 1 includes acquiring information from a MRU (Motion Reference Unit) and/or a VRU (Vertical Reference Unit) and/or a DP system or similar, which information includes information on the movements of the vessel.

22. Method according to claim 20, characterized in that step 2 includes acquiring information on the status of the tanks by suitable means for this, such as pressure sensors/meters, floats, pressure pulses or similar, which is a premise for the control system according to the invention to know if positive or negative pressure is to be provided in the tanks.

23. Method according to claim 20, characterized in that step 1 and/or 2 also include acquiring information on wave height and frequency by means of sensor means for this, which information makes it possible for the control system to form a picture of the wave frequency, direction of the wave and the total changing buoyancy provided by the wave.

24. Method for passive stabilization of a vessel according to claim 19, characterized in that if no information from step 1 and 2 is present, the valve can be manually adjusted for best possible effect by trial and experience.