STABILIZED FLOATING PLATFORM

PRIORITY STATEMENT

[0001] This application claims the priority of U.S. Patent Application No.

60/663,736, filed on March 22, 2005, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND

[0002] Typical floating platforms acquire their floatation forces by directly displacing the water with their hulls. A pneumatic floating platform utilizes indirect displacement, in which the platform rests on trapped air that displaces the water. The primary buoyancy force is provided by air pressure acting on the underside of the deck.

[0003] A pneumatically stabilized platform (PSP) is a type of pneumatic platform that includes cylindrically shaped cells packed together in a rectangular pattern to form a module. Each cylinder is sealed at the top, open to the ocean at its base, and contains air at a pressure slightly above atmospheric pressure.

[0004] As needed, air is allowed to flow from a cylinder to its neighbors through a manifold or connecting orifices. The airflow provides a mechanism to help reduce the peaks in the pressure distribution beneath the structure and provide platform stability as well as a mechanism for dissipating wave energy.

[0005] An assembly of cylinders results in enclosed interstitial regions between cylinders, which may be filled with air, foam or other material. These regions are isolated from the air pockets within the cylinders to provide additional buoyancy and righting moment. As long as design loads are not exceeded, this feature can enable the PSP to endure catastrophic air pressure loss. The distribution of the flotation force in a PSP can be modified as needed to minimize the hogging moment or in response to large concentrated loads on the deck. Further, it is possible, for a given sea state, to tune the oscillation of the water columns inside the cylinders to minimize the overall hydrodynamic loading to which the platform is subjected.

SUMMARY

[0006] An embodiment of the present invention provides a floating structure floatable in a body of liquid and stabilized with respect to at least one of roll and pitch. Such a structure can include: a hull including compartments, each compartment being open at the bottom thereof relative to a horizontal plane, and being adapted to accommodate ingress by the body of liquid; a negative pressure source to negatively pressure a volume above a level of the liquid in at least one of the compartments; and one or more arrangements by which at least one or more other of the compartments can be made to exhibit a positive buoyancy.

[0007] An embodiment of the present invention provides a floating structure floatable in a body of liquid and stabilized with respect to at least one of roll and pitch. Such a structure can include: a hull including a plurality of compartments, each compartment being open at the bottom thereof relative to a horizontal plane, and being adapted to accommodate ingress by the body of liquid; a negative pressure source to induce a negative buoyancy, relative to a net positive buoyancy of the structure as a whole, in at least one of the compartments; and one or more arrangements by which at least one or more other of the compartments can be made to exhibit a positive buoyancy, relative to the net positive buoyancy of the structure as a whole.

[0008] An embodiment of the present invention provides a method of stabilizing, with respect to at least one of roll and pitch, a structure that floats in a body of liquid, the method comprising: providing a hull; configuring the hull to include a plurality of compartments, each compartment being open at the bottom thereof relative to a horizontal plane, and being adapted to accommodate ingress by the body of liquid; negatively pressuring a volume above a level of the liquid in at least one of the compartments; and inducing a positive buoyancy in at least one other of the compartments.

[0009] An embodiment of the present invention provides a method of stabilizing, with respect to at least one of roll and pitch, a structure that floats in a body of liquid, the method comprising: providing a hull; configuring the hull to include a plurality of compartments, each compartment being open at the bottom thereof relative to a horizontal plane, and being adapted to accommodate ingress by the body of liquid; inducing a negative buoyancy, relative to a net positive buoyancy of the structure as a whole, in at least one of the compartments; and inducing a positive buoyancy, relative to the net positive buoyancy of the structure as a whole, in at least one other of the compartments.

[0010] Additional features and advantages of the present invention will be more fully apparent from the following detailed description of example embodiments, the accompanying drawings and the associated claims.

BRIEF DESCRIPTION OF DRAWINGS

[0011] The accompanying drawings are intended to depict example embodiments of the present invention and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted.

[0012] Fig. 1 is a top view of a stabilized floating platform according to an example embodiment of the present invention.

[0013] Fig. 2 is a side cross-section of a stabilized floating platform according to an example embodiment of the present invention, wherein Fig. 2 corresponds to view line II- IP depicted in Fig. 1.

[0014] Fig. 3 is a side cross-section of another stabilized floating platform according to an example embodiment of the present invention.

[0015] The accompanying drawings are intended to depict example embodiments of the present invention and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0016] It will be understood that if an element or layer is referred to as being "on,"

"against," "connected to" or "coupled to" another element or layer, then it can be directly on, against connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, if an element is referred to as being "directly on", "directly connected to" or "directly coupled to" another element or layer, then there are no intervening elements or layers present. Like numbers refer to like elements throughout. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

[0017] Spatially relative terms, such as "beneath", "below", "lower", "above",

"upper" and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different

orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, term such as "below" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0018] Although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers and/or sections, it should be understood that these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.

[0019] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "includes" and/or "including", when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

[0020] Fig. 1 is a top view of a stabilized floating platform 100 according to an example embodiment of the present invention. Fig. 2 is a side cross-section of a stabilized floating platform 100 in the context of restraining in location relative to latitude and longitude, according to an example embodiment of the present invention, wherein Fig. 2 corresponds to view line H-Il' depicted in Fig. 1.

[0021] In Figs. 1-2, the floating structure 100 is: floatable in a body of liquid 102

(e.g., a majority component of which is water); and stabilized with respect to at least one of roll and pitch is disclosed. The stabilized floating structure 100 includes: a hull 104 that itself includes a plurality of compartments 106, each compartment 106 being open at the bottom thereof relative to a horizontal plane, and being adapted to accommodate ingress by the body of liquid; a negative pressure (or, in other words, a vacuum) source 108 to induce negative pressure in a volume 110N above a level 112 of the liquid in at least one of the compartments; and a positive pressure source 114 to positively pressure a volume 110P above the level 118 of the liquid in at least one other of the compartments.

[0022] In Fig. 1 , it can be observed that the plurality of compartments 106, from the perspective of a top view, is arranged as a matrix. Typically, the stabilized floating structure 100 will include multiple respectively negatively-pressurized 110N compartments 106 and multiple respectively positively-pressurized 110P compartments 106. For example, the matrix can be arranged so that the negatively-pressurized 110N compartments 106 are distributed relatively more towards the periphery of the matrix and the positively-pressurized 110P compartments 106 are distributed relatively more towards a central region of the matrix. Doing so increases the effective lever arm of the negatively-pressurized 110N compartments 106 relative to an assumed centrally located center of mass of the stabilized floating structure 100. As another example, the matrix can be rectangular, and all of some of the negatively-pressurized 110N compartments 106 are located at corner positions of the matrix.

[0023] In Fig. 2, it can be seen that the stabilized floating structure further includes a deck 120 on the hull 104. Also, in Fig. 2, it can be seen that the level 112 of the liquid in a negatively-pressurized 110N compartment 106 can rise above a median level 112 for the body of liquid 102 considered as a whole (or, in other words, the liquid level 112 in a negatively-pressurized 110N compartment 106 is raised). Correspondingly, it can be seen in Fig. 2 that the level 118 of the liquid in a positively-pressurized 110P compartment 106 can drop below the median level 122 for the body of liquid 142 considered as a whole (or, in other words, the liquid level 118 in a positively-pressurized 110P compartment 106 is depressed).

[0024] Operation of the stabilized floating platform of Figs. 1-2 will now be described. The negative pressure source 108 creates suction in the one or more compartments 106, i.e., it reduces the pressure of the gaseous and/or vaporous mixture (e.g., humid air) in the volume 110N located above the level of liquid that has ingressed into the compartment. Such a suction effect in the negatively-pressurized 110N compartment 106 is somewhat familiar to many people who have had the experience, e.g., when playing as a child, of capsizing an inflatable raft and then trying to right it by pushing it from underneath. The suction makes it very difficult to right the capsized inflatable raft. But if the seal is broken between the capsized raft and the waterline so that air is allowed to enter the volume previously enclosed by the surface of the water and the capsized raft, then righting the capsized raft becomes much easier.

[0025] Relative to an overall buoyancy of the stabilized floating structure 100, each negatively-pressured 110N compartment 106 represents a negative buoyancy contribution to the overall buoyancy. Depending upon the number of such negatively- pressurized 110N compartments 106, their proportions and the magnitude of the negative pressure applied to them, they collectively could make the overall buoyancy of the stabilized

platform 100 negative, causing the platform 100 to sink. To counterbalance the negative buoyancy of the negatively-pressurized 110N compartments 106, one or more positively- pressurized 110P compartments 106 are provided, each of which represents a respective positive buoyancy contribution to the overall buoyancy. Alternatively, other arrangements for introducing positive buoyancy (e.g., sealed compartments filled with a gas such as air, compartments that may or may not be sealed and that are filled with foam, etc.) could be used instead of, or in addition to, the respectively positively-pressurized 110P compartments 106.

[0026] In Figs. 1-2, it is assumed that each compartment 106 is configured as one of: a prism, a bottom end of which is not present (and so is fictional); and a cylinder, a bottom end of which is not present (and so is fictional). It should be understood that such conformations of the compartments are not limiting, but rather are merely examples. Similarly, the number of such compartments has been shown as six for ease of illustration. It should be understood that the depicted number of compartments is not limiting, but rather is merely an example. Also similarly, one source of negative pressure and one source of positive pressure are depicted. Again, it should be understood that the depicted number of pressure sources is not limiting, but rather is merely an example.

[0027] Also, for simplicity of illustration in Fig. 2 (and Fig. 3, discussed below), the level 112 of the liquid in the two negatively-pressurized 110N compartments 106 has been shown as being substantially the same. While this can be true, it does not necessarily have to be. Alternatively, pressure (and with it liquid level) in the various compartments (irrespective of whether each is positively pressurized or negatively pressurized) can be controlled on an individual basis, on the basis of various sub-groupings, etc.

[0028] Further as to Fig. 2, the stabilized floating platform 100 is shown as being restrained by a tether 124, e.g., by a chain and anchor, to a floor 126 of the body of liquid 142 in which it is floating. This can achieve a relatively fixed location of the stabilized floating platform 100 in terms of latitude and longitude.

[0029] Fig. 3 is a side cross-section of another stabilized floating platform 300 according to an example embodiment of the present invention.

[0030] The stabilized floating platform 300 has many similarities with respect to

Figs. 1-2. For brevity, such similarities will not be discussed. In contrast to Figs. 1-2, a greater number of compartments 106' are depicted in the hull 104' of Fig. 3, and a load 302, e.g., a crane (attached to the hull 104', e.g., via a turntable 304), is depicted as being disposed towards one side of the deck so as to induce a first roll moment upon the floating platform. In Fig. 3, the matrix of compartments 106' of the hull 104' is arranged so that the respectively negatively-pressurized 110N' compartments 106' are distributed relatively more

towards a side of the matrix opposite the load 302 so as to induce a second roll moment that opposes the first roll moment, thereby stabilizing the floating platform 300 against roll and/or pitch.

[0031] Other such pitch/roll inducing loads are contemplated. For example, consider the load as being a ramp (not shown) from one side of the floating platform 304 to a dock (not shown) in a circumstance in which the floating platform 300 is a ferry. Such a ferry 300 would make use of the matrix of compartments 106' to stabilize against pitch and/or roll while at the ^" dock while loading/offloading vehicles, etc. In contrast, while the ferry 300 is under way (or, in other words, not loading/offloading at the dock, then pressurization of the matrix of compartments 106 could be disabled, or each of the compartments 106' could be sealed by closing a lid thereof so as to reduce drag.

[0032] Furthermore, in the circumstance of Fig. 3, an adaptive control system (not shown) can be provided whose functions include doing the following: monitoring the changing nature of the roll moment induced by a moving load (e.g., a cargo container of fixed weight albeit variable position as it travels from deck to shore or vice-versa, a vehicle drive across the ramp from the dock and then to its parking place on the ferry and vice-versa, etc.); and dynamically varying the magnitudes to which compartments 106' are positively- pressurized 110P' or negatively-pressurized 110N', respectively. As a further variation, not only could the control system adaptively vary pressurization magnitudes, it could adaptively establish which compartments 106 are positively-pressurized 110P' and which compartments 106 are negatively-pressurized 110N'. In the further variation, a source 108' of negative pressure and a source (not shown) of positive pressure and appropriate controllable valves (not shown) would be connected to each compartment 106' that is desired to be variably controllable as either negatively-pressurized 110N' or positively- pressurized 110P'.

[0033] With some example embodiments of the present invention having thus been described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications are intended to be included within the scope of the present invention.