Ocean-going ship with active stability

Abstract

The invention relates to a maritime structure with improved stability comprising manoeuvring and navigation means and comprising: - at least one elevated platform (1); - at least three masts (2) of adjustable height; - at least one underwater float (3) fitted with at least one lateral thruster (4) and with at least one longitudinal thruster (5), the platform being secured to the one or more floats by means of the masts; - static ballasting means inside the one or more floats; - controlled dynamic ballasting means located inside the masts; - position and attitude control means comprising at least one sensor and at least one means for controlling the dynamic ballasting means in order to control, in real time, the position and stability of the maritime structure depending on the swell and the wind.

Description

DESCRIPTION Title: Ocean-going vessel with active stability Technical field

[0001] The invention relates to the field of maritime mobility, in particular support vessels and offshore logistics bases, more particularly vessels dedicated to the maintenance and upkeep of floating supports, such as offshore wind farms. The invention is applicable in many maritime fields. Prior art

[0002] A SWATH (Small Waterplane Area Twin Hull) is a catamaran with a low waterline. This principle was invented by Canadian Frederick G. Creed in 1938. A SWATH is a motorized vessel with two hulls, each of which is deeply submerged. The central platform is connected to the hulls by thin junctions at the waterline. The aim is to improve seakeeping in bad weather, particularly compared to a conventional catamaran.

[0003] Ballasting is known to be used to stabilize ships, especially large ones. Ballasting generally involves loading seawater into tanks, also known as ballast tanks. This type of ballasting is referred to as slow or static ballasting in the following description.

[0004] Document DE10336547 describes a vessel comprising a SWATH type hull including a ballast system.

[0005] Patent EP2511168 describes a vessel with a so-called SWATH hull, with a static ballast system. Some maintenance vessel projects, for example of the "Windkeeper" type, feature ballast systems in the floats (without real-time control) to overcome the effects of swell, but the relative stability of this vessel is compromised as soon as the swell exceeds two or three meters in amplitude.

[0006] US Patent 8689720 describes a semi-submersible monohull vessel for recovering or deploying offshore equipment comprising a static ballast system in the form of water tanks in the lower part of the hull and in the columns connecting the hull to the platform.

[0007] However, the vessels described do not allow for real-time navigation and active stabilization, allowing them to be freed from the influence of wind and waves, in order to navigate and remain at sea in all weather while ensuring an optimal level of safety and comfort, particularly in the case of rough seas with waves that can reach heights of more than 8 meters.

[0008] There is therefore a need for ballasted floating maritime structures equipped with means of maneuvering and navigation, offering increased stability depending on sea conditions and conditions of use and allowing safe maintenance at sea. Summary of the invention

[0009] The invention makes it possible to overcome the drawbacks of the solutions of the prior art. The solution provided by the present invention is based in particular on a particular geometry of the maritime structure combined with a dual static and dynamic ballasting system making it possible to obtain virtual insensitivity to the state of the sea and increased stability of said structure.

[0010] The invention relates to this end to a maritime structure with improved stability comprising maneuvering and navigation means and comprising: - at least one aerial platform (1); - at least three masts (2) of adjustable height; - at least one underwater float (3) equipped with at least one lateral thruster (4) and at least one longitudinal thruster (5), said platform being secured to said float(s) by means of said masts; - static ballasting means inside said float(s); - controlled dynamic ballasting means located inside said masts; - means for controlling the position and the trim comprising at least one sensor and at least one means for controlling said dynamic ballasting means in order to control in real time the position and stability of said maritime structure as a function of the swell and the wind.

[0011] The maritime structure according to the invention may comprise at least two floats, preferably three floats, and at least one profiled crosspiece (6) connecting said floats transversely.

[0012] At least one sensor may allow at least one direct physical measurement of the trim, the height of the platform relative to the water surface or the absolute or relative position of the structure.

[0013] Said dynamic ballasting means may consist of at least one air-vacuum or air-filled cylinder (13) inside each mast, each of said cylinders being connected to water injection and ejection means (14).

[0014] Said static ballasting means may consist of at least one ballast tank (15) inside each float.

[0015] The maritime structure according to the invention may comprise at least one DP2 type servo means in position and heading, without anchoring, allowing the platform to maintain a fixed position and to free itself from the influence of wind and waves and a means of servo in altitude, pitch and roll allowing a substantially zero attitude to be maintained.

[0016] The maritime structure according to the invention may include electric motors providing propulsion as well as position and heading control.

[0017] The maritime structure according to the invention may comprise autonomous electricity production means chosen from wind turbines, photovoltaic panels, aeroturbines and energy storage means.

[0018] The maritime structure according to the invention may comprise means for generating electrical energy, making it possible to supply at least partly electrically the longitudinal and lateral thruster(s) of said float(s).

[0019] The maritime structure according to the invention may comprise at least one nuclear fuel generator.

[0020] The maritime structure according to the invention may further comprise sail propulsion means.

[0021] The aerial platform can be aerodynamically shaped to minimize the drag generated by absolute and relative wind, and of a thickness significantly less than its length to limit its frontal surface and its wind resistance.

[0022] The maritime structure according to the invention may include means for adjusting the height of the platform relative to the float(s).

[0023] The invention also relates to the use of the maritime structure according to any of the variants described for the handling or maintenance of equipment at sea. List of figures

[0024] Other characteristics and advantages of the device according to the invention will appear on reading the following description of non-limiting examples of embodiments, with reference to the figures appended and described below. - figure 1 represents a 3D view of a maritime structure according to the invention. - figure 2 represents a profile view of a maritime structure according to the invention. - Figure 3 represents a 3D view of an embodiment of a maritime structure according to the invention, of modular design and in which the base comprises three floats. Description of the embodiments

[0025] In the rest of the text, the term "draft" refers to the height of the submerged part of a ship or maritime structure, which varies according to the load carried. It corresponds to the vertical distance between the waterline and the lowest point of the hull.

[0026] The trim of a ship or marine structure is the quotient of the difference between the forward and aft drafts of a ship or marine structure and its length. Trim reflects the longitudinal inclination of the ship or marine structure and determines its smooth running. A ship has equal or no difference in draft when its draft is the same at the front and the rear: zero trim.

[0027] "Static ballast" means a slow ballast system in the form of seawater tanks distributed in the hull of the maritime structure, in the case of the present invention in the floats at the front and rear of each float

[0028] “Dynamic ballast” means a ballast system with almost instantaneous volume variation capable of compensating for movements generated by the sea, wind and load movements in real time.

[0029] The invention relates to a ballasted maritime structure comprising an aerial part, said structure being provided with navigation and maneuvering means. Said The maritime structure is similar in its movements to a ship. The maritime structure according to the invention can, in particular, navigate, maneuver and position itself precisely in the open sea (or high seas) in all types of weather, offering great stability, increased safety and comfort for its passengers.

[0030] The maritime structure according to the invention comprises both one or more submerged floats equipped with remote-controlled ballasts and an aerial superstructure or platform rigidly attached by profiled and robust watertight masts to said floats. The aerial superstructure (or upper aerial part) can take the form of a platform, structure or nacelle depending on the uses.

[0031] The design of the maritime structure according to the invention comprising one or more submerged floats therefore makes it possible firstly to extract the buoyancy and lift zone of the vessel from the turbulent zone of the surrounding elements (sea, wind) by immersing it in depth. The invention makes it possible in particular to dissociate the buoyancy zone from the living zone by separating them on either side of the surface turbulent zone.

[0032] In the remainder of the description, the maritime structure according to the invention is a structure comprising two floats (Figures 1 and 2), but it would not be outside the scope of the invention to increase or decrease the number of floats.

[0033] The present invention can be adapted with one or more floats. Figure 3 shows in particular a structure with three floats.

[0034] Since the vast majority of the upper aerial part (platform) is positioned several meters above the water surface, and the buoyancy equipment (floats) is positioned several meters below the surface, the entire maritime structure is inherently insensitive to sea surface movements. Furthermore, the emerged part of the masts advantageously represents 50% of their total length. For a platform resting on 20 m masts, the submerged length and the emerged length thus advantageously represent 10 m each relative to the average level of the water surface, making the aerial part relatively insensitive to waves of up to 10 meters from trough to crest.The height of the aerial part remains adjustable at any time using rapid ballasts (dynamic ballasts) whose equilibrium position can be controlled and configured in real time according to the navigation, safety or comfort conditions required.

[0035] The maritime structure according to the invention comprises static ballast means (also called static ballasts) distributed inside the float(s) and controlled dynamic ballast means (also called dynamic ballasts) distributed inside the masts.

[0036] In one embodiment, seawater tanks distributed in the floats at the front and rear of each float serve as static or slow ballast, while the dynamic ballasts arranged in the connecting masts make it possible to adjust the trim and altitude of the platform in real time, so as to compensate for movements generated by the sea, as well as load displacements on the structure, longitudinally and transversely.

[0037] The underwater floats are advantageously equipped at their ends with longitudinal and transverse thrusters providing the capacity to maneuver the vessel with great efficiency, longitudinally, transversely and in rotation.

[0038] The active stability of the entire maritime structure, provided in particular by the dynamic ballasts and the servo system, ensures great comfort of life on board and optimal safety for the personnel and equipment transported.

[0039] This ability to calmly face rough and heavy seas increases the range of use and intervention of the maritime structure according to the invention, whatever its final use.

[0040] Preferably, the aerodynamic shape of the aerial part also makes it possible to minimize the drag generated by the absolute and relative wind, and therefore the energy required to move it or maintain it in position during strong wind conditions. The geometry of the maritime structure according to the invention thus advantageously makes it possible to reduce the frontal surface area of ​​the aerial or emerged part (comprising the emerged part of the masts and the platform). By aerodynamic shape, it is meant in the present invention that the shape of the aerial part is such that the air only slightly opposes its movement, the platform having in particular a flattened and rounded shape at its ends making it possible to limit its frontal surface area and its wind resistance. The flow of air over its faces is thus optimized.

[0041] In one embodiment, the platform's supporting masts enable hybrid sail propulsion to be implemented.

[0042] The aerial platform rests via at least three masts (e.g. four masts) on a base comprising at least one submerged float (e.g. two floats). The immersion depth of the float(s), and therefore the height of the platform relative to the water surface, are adjustable depending on the sea conditions and the needs related, for example, to the docking or securing of the platform to the float or to the wind turbine tower in the case of use for offshore wind power.

[0043] To provide greater flexibility, for example to reduce draft and lower the center of gravity in port, the height of the platform may also be adjustable relative to the floats. The maritime structure according to the invention may include means for adjusting the height of the platform on the masts. These adjustment means allow the platform to move up or down relative to the floats.

[0044] In one embodiment, the adjustment means comprise a mechanism consisting of a vertical rack system on the masts. Apart from the phases of raising and lowering the platform on the racks, the mechanism can be completely locked in order to guarantee the rigidity and safety of the assembly.

[0045] The position and trim of the maritime structure according to the invention are continuously controlled by means of a servo-control system in order to guarantee the stability of the platform in all conditions, whether in rough sea conditions or to compensate for load transfers during handling or forces generated by the wind. The servo-control system ensures that it maintains its position and heading without anchoring, regardless of the wind direction relative to the platform's axis, as well as permanent stability in altitude, pitch and roll. The complete system is based on a passive safety approach: the platform is stable by design and returns to a stable state in the event of a total system failure. The servo-control system includes several degraded modes, ensuring safety at all levels.

[0046] The technology of dynamic ballasts controlled by immediate response allowing active stability of the maritime structure according to the invention makes it possible to envisage an application to maritime structures of all dimensions and all payloads. Applications

[0047] The invention can in particular be applied to all sectors requiring a stabilized means of movement and / or a stabilized platform at sea, such as scientific exploration and data collection platforms, or the transport of passengers in optimal conditions, or even aerial logistics deployment platforms (transport, maintenance, helicopter takeoff and landing or even takeoff and recovery of stratospheric and space vehicles).

[0048] Without limitation, the vessel according to the invention can be used and adapted for multiple uses, by adjusting the dimensions and on-board equipment: SOV (Service Operations Vessel) chosen from offshore service vessel, freight and personnel transport, offshore life base, surveillance and intervention vessel, autonomous vessel, heliport, diving and underwater exploration base, rescue vessel, pollution control vessel, vessel or base for deployment and recovery of drones and underwater robots known as ROVs), life base for marine aquaculture, maritime hospital, weather station, military building, solar eco-yacht, cruise ship, low-tide beachable habitation vessel, amphibious vessel, salvage crane boat, etc.

[0049] The ratio between the length and the width of the vessel according to the invention is not fixed and is not a limiting factor. Typically, the invention can be applied to vessels with lengths between 10 and 200 meters, and widths between 4 and 100 meters.

[0050] Likewise, the ratio between width and height of the vessel of the invention is not a limiting factor. Depending on the requirements and specifications specific to each possible use and destination, the height of the masts and the overall height of the vessel may be primarily defined with the objective of ensuring, on the one hand, reduced sensitivity to the state of the sea, and on the other hand, ensuring stability (in the sense of possible overturning) under all the conditions defined in the specifications. Typically, the invention relates to vessels for which the height of the masts may be between 2 and 40 meters. Small masts may be used on coastal vessels.

[0051] For certain applications of the invention, in particular those requiring increased movement speed, the shape of the submerged floats may vary depending on the movement speed of the vessel: in order to reduce drag, the specific design of the profiled submerged floats allows the piloting system to reduce the frontal surface floats by varying their volume. The resulting reduction in buoyancy is advantageously compensated in displacement by the lift generated by the horizontal control surfaces provided for this purpose.

[0052] The architecture of the maritime structure according to the invention, which is similar in principle and in its embodiment comprising two floats with a SWATH hull, offers good stability in difficult sea conditions.

[0053] The base of the maritime structure according to the invention advantageously comprises at least one, or even two profiled crosspieces connecting the floats. Compared to conventional hulls or architectures, the technique of the hull with reduced flotation surface makes it possible to reduce sensitivity to waves and offers good seakeeping. The solution provided by the present invention consists in particular of positioning the floats lower below the surface in a stable layer of water and this position is adjusted by ballasting and by orientation of the profiled crosspieces according to the state of the sea both during navigation and when the ship is stationary.

[0054] Preferably, two servo systems are implemented: - A DP2 type servo (in reference to the IMO circular: MSC.l / Circ.1580 - Guidelines for vessels and units with dynamic positioning (DP) systems) in position and heading, without anchoring, allowing the platform to maintain a fixed position and to free itself from the influence of wind and waves. In the case of a floating wind turbine, the servo allows the platform to follow the wind turbine in its movements around the anchors if necessary. - Altitude, pitch and roll control (trim and heel), allowing the intervention team to handle heavy loads on the platform or from the float of a floating wind turbine, and to ensure maintenance in the workshop in optimal safety conditions during difficult sea and wind conditions.

[0055] The operation of the system is therefore based on the implementation of two ballasting principles: - conventional technology static ballasts, which are implemented to compensate for slow load variations, such as those due to the reduction in fuel mass and the load of on-board equipment and personnel. - dynamic ballasts with almost instantaneous volume variation allowing an immediate response, arranged in such a way that they allow real-time compensation for load transfers at platform level due to the effects of waves, wind and the handling of heavy loads on the platform.

[0056] The system composed of dynamic ballasts with quasi-instantaneous volume variation and the associated control means constitute one of the technical specificities of the invention. These dynamic ballasts, due to their immediate response, make it possible to compensate in real time for the movements that would be generated by the variations in forces exerted on the system.

[0057] The system is based on a passive safety approach: in the event of a partial or total failure of the system, the platform returns to a stable position. Static ballasting is provided by the submerged float(s) filled mainly with air so as to passively ensure the buoyancy of the assembly. The controlled dynamic ballasting is carried out according to the chosen safety approach, either by adding mass (sea water) above the surface level, or by removing mass below the surface level. The volume used for said dynamic ballasting is a specifically dedicated volume in the masts. Each mast advantageously comprises at least one vertical cylinder, preferably two vertical cylinders whose base descends to the lower level of the floats. Two embodiments can be envisaged.

[0058] In a first embodiment, the cylinders are under partial vacuum, which naturally raises the water level above the waterline. The buoyancy equilibrium point of the vessel rests on this water level above the water surface in the cylinders. In the event of a total failure of the system, the passive safety naturally raises the floats to the water surface and floats the entire vessel.

[0059] In another embodiment, the cylinders are under positive air pressure, which naturally lowers the water level below the waterline in the dedicated cylinders. The buoyancy equilibrium point of the vessel rests on this water level above the waterline. In the event of a total failure of the system, passive safety naturally sink the floats, in order to lower the platform to the water surface. By design, the platform is advantageously buoyant.

[0060] The static ballasting means inside said float(s), as well as the controlled dynamic ballasting means located inside said masts, include means for filling and emptying water or air of the pump or solenoid valve type or vertical nozzle thrusters as well as means for controlling the air pressure of the compressor or vacuum pump type.

[0061] The servo-control is based on direct physical measurements: of the attitude (for example using an inertial unit providing the parameters of attitude, longitudinal and transverse inclinations and gyrocompass), of the height of the platform in relation to the water surface (for example the height is measured by an algorithm based on the signals received from water pressure sensors and / or proximity sensors such as LIDAR or ultrasound), of geolocation (GNSS: Global Navigation Satellite System), of other sensors (position, inclination, wind speed, temperature, etc.) if necessary.

[0062] The control means may include a computer controller equipped with navigation and position-keeping software, receiving information from the various sensors and controlling actuators. The control means may include a human-machine interface allowing some or all of the functions to be controlled on-site or remotely. In particular, the speed, position, heading, yaw angle, and height of the structure may be controlled manually or automatically.

[0063] The main actuators used can be the following: - longitudinal thrusters (for example one or two per float, fixed or on an adjustable pod depending on the applications) - lateral or transverse thrusters (e.g. a bow lateral thruster and a stern lateral thruster on each float) - pumps and solenoid valves for filling or emptying static ballasts - vertical nozzle thrusters allowing the water level in each dynamic ballast cylinder to be adjusted (typically two thrusters per mast) - front and rear horizontal rudders - a swivel pod or rudder on each float - a compressor and a vacuum pump to adjust the pressure levels in the static and dynamic ballast tanks.

[0064] The integration of degraded modes into the control system from its design phase makes it possible to ensure the level of safety required for any type of use by taking into account the failure(s) of sensors, actuators or the control means themselves. The first degraded modes include the failure(s) of a longitudinal thruster, one or more lateral thrusters, one or more ballast control pumps, the attitude sensor, one or more platform height measurement sensors, etc. The architecture of the controller is advantageously fail-safe; it is based, for example, on computer redundancy.

[0065] Dynamic ballasting means can operate: - in passive mode: the partial vacuum is adjusted in the cylinders, the water exchanges with the outside are done via calibrated pressure losses, located at the base of the cylinders (the system functions as a shock absorber) - in active mode: each cylinder is equipped with a pump which allows the water level to be dynamically controlled in real time.

[0066] The main advantage of this technical choice is to minimize energy consumption while ensuring optimal stabilization and safety. By design, the entire servo system automatically switches to safety mode in the event of one or more failures. The system includes several degraded modes, particularly if the buoyancy of the floats is compromised; the aerial superstructure is floating by design.

[0067] An example of an SOV vessel is depicted in Figure 1 without limitation. The vessel comprises a streamlined aerial platform (1) located 12 meters above the waves and sea spray.

[0068] This platform (1) is securely attached by four masts (2) to an underwater chassis comprising two floats (3), four lateral thrusters (4), longitudinal thrusters (5) with rotatable and steerable fairings (called "pods") and two profiled crosspieces (6) having hydrodynamic and aerodynamic profiles to facilitate the advancement of the vessel. In Figure 1, the platform (1) is equipped with a helipad (7).

[0069] The ship's propulsion is provided by the two electric pods (5) powered by containerized generators (8). The pods (in French, pod or capsule) are rotatable, steerable shrouded thrusters, allowing propulsion thrust to be provided in the desired direction, including forward if necessary, which allows it to beat backward without reversing the direction of rotation or the pitch of the propeller. The service energy on board is provided by LFP type battery packs stored in 20-foot containers in container locations (9) and are recharged by 1200 m 2 photovoltaic panels and 2 or 3 vertical axis wind turbines thanks to a structural axis supporting a crane or wind turbine (10).

[0070] Figure 2 is a side view of the structure according to the invention making it possible to describe an embodiment in which the platform (1) is equipped with a helipad (7) under which the command bridge (11) is located. The platform comprises a nacelle (12) with a living base, workshops and storage areas on three levels and a peripheral open walkway.

[0071] Figure 2 details the dual ballasting system, including: - the controlled dynamic ballasting means in the form of vertical dynamic ballasts of cylindrical shape (13) located inside the masts (2), which are filled and / or emptied by vertical thrusters (14); - static ballast means in the form of static ballast tanks (15) inside the floats (3).

[0072] Under the nacelle (12) there is a tilting gangway (16) for launching and recovering speedboats (2 semi-rigid 10m boats) and ROVs (Remotely Operated Underwater Vehicles).

[0073] At least one of the masts may include a structural axis (17) on the mast head for the attachment of a crane or a vertical axis wind turbine.

[0074] The rear deck of the nacelle offers 350 m 2 open surface for the lifting and handling of maintenance equipment and a retractable walkway (18) articulated for the transfer of personnel and materials to the wind turbines.

[0075] The general balance and height of the platform above the waves is adjustable using the static ballast tanks (15) distributed horizontally in the floats (3).

[0076] The position and trim control means comprising at least one sensor and at least one means of controlling said dynamic ballasting means make it possible to control in real time the position and stability of the maritime structure as a function of the swell and the wind.

[0077] The dynamic balancing which makes it possible to compensate for load movements and maintain a horizontal attitude is here controlled by an electronic device which controls vertical thrusters (14) which quickly fill and empty the vertical dynamic ballasts (13) distributed in the four masts (2). The means for filling / emptying the rapid ballasts are called "vertical thrusters" in the sense that they add a thrust component (by action / reaction) when they eject water from the ballasts, creating a vertical downward force adding punctually to the variation in buoyancy of the ballasts and allowing better reactivity of the system as a whole.

[0078] The steerable rotating shrouded longitudinal thrusters (5), the four lateral thrusters (4) and the dynamic ballasts (13) coupled with satellite navigation software ensure precise maneuvers and the possibility of maintaining a geostationary position without anchoring.

[0079] The design of the ship according to this type of architecture makes it possible to envisage large platforms with displaced masses lower than those displaced by conventional ships of the same size, allowing energy savings for the movement of the ship.

[0080] Advantageously, the ship's design is based on modularity and redundancy of construction elements, aiming to limit manufacturing costs (including for the transport of modules) while allowing a wide range of ship sizes to be covered. A construction method with modular elements can therefore be considered.

[0081] For example, as illustrated in Figure 3 for a maritime structure comprising three floats and six masts, the masts and floats can be composed of modular elements: modular float elements (19) and modular mast elements (20) allowing different ship concepts and architectures to be implemented. Modular elements are identical and repeatable elements of short length (compared to that of the ship, in general the length is imposed by the standard dimensions of the materials of construction) allowing, by assembling them together, to obtain a variable total length at a lower cost depending on the need. This approach makes it possible to optimize the purchase cost of certain materials such as sheets (6 or 12 meter modules for example) and to facilitate transport by land or sea. Example

[0082] A non-limiting example of the embodiment of a floating device (maintenance vessel for offshore equipment such as offshore wind turbines) according to the invention is described in the present example.

[0083] The proposed system is a maritime structure in the form of a stabilized platform (incorporating the control cell, the life base, the workshop, the store, the handling equipment, the electric power generation units) moving above the water surface, making it possible to go to and stay for extended periods in areas far from the coast (of the order of 100 km), the objective of which is to enable continuous maintenance of offshore wind turbines, whatever the sea conditions. The platform is equipped with the following means: - a storage capacity for equipment and spare parts (warehouse), - a maintenance workshop - heavy handling equipment (30t) - a wind turbine mooring system - a means of access to the wind turbine - a comfortable living cell allowing intervention teams to carry out operations 24 / 7 - launch / recovery and piloting cells for aerial and underwater drones

[0084] The platform in its basic configuration has a length of 48m, a width of 38m for a total height (draft plus air draft) of 30m. The draft is variable and can be temporarily reduced to 6m to allow access to areas requiring a shallow draft. The height of the platform in relation to the water surface is permanently adjustable according to needs (thanks to the ballast tanks), walk-to-work (pedestrian bridge, raised and deployed to the required height to provide access to the wind turbine), handling of loads between the wind turbine and the platform, docking, mooring, launching of ROVs or tenders and constraints (wave height). The platform can also be placed on the water to significantly increase handling capacities (in this case it is no longer stabilized and then behaves like a barge).

[0085] The volumes of the underwater floats (empty ballasts) are 500 m 3 each, giving the whole a maximum buoyancy of 1000 tonnes.

[0086] The platform offers an open working area of ​​350 m 2 A telescopic handling device allows heavy loads (up to 30 tonnes) to be handled without compromising the stability of the platform. This equipment also allows a load to be handled between the wind turbine and the platform.

[0087] The submerged underwater floats are equipped with electric motors to provide propulsion as well as position and heading control.

[0088] Electric motors can be powered by Diesel generators whose reliability is recognized. The generators are containerized (functional, modular and removable in their standard containers (20 feet or 40 feet), which makes them interchangeable depending on the technologies chosen. Thus, the power supply can be modified and entrusted to a hydrogen fuel cell generating electricity on board and powering the engines. This conversion from the Diesel generator to the fuel cell is done at a lower cost since the propulsion is already provided by electric motors.

[0089] The platform can deploy 1200 m 2of photovoltaic panels generating electrical energy stored in containerized MegaPack type batteries. In the embodiment including a power supply based on a fuel cell, the electrical energy generated by the photovoltaic panels is transformed into hydrogen to be stored and reused via said fuel cell. Advantages of the invention

[0090] The platform is capable of intervening at any time, in any type of weather, with autonomy in terms of energy, human resources and logistical means which guarantee the success of maintenance or repair operations of equipment at sea. The platform allows you to reach any offshore area at a reasonable speed (10 to 20 knots), to get as close as possible to the equipment, for example a floating wind turbine, and to follow its movement in position and heading, to transfer an intervention team onto the wind turbine float, to handle heavy loads and bring them back on board to be able to intervene in complete safety. The living cell allows the crew to be completely autonomous and installed in optimal comfort conditions for the entire duration of the mission.

[0091] In one embodiment, the maritime structure according to the invention is energy-autonomous, in that it comprises autonomous electricity production means chosen from wind turbines, photovoltaic panels, aeroturbines and energy storage means (including batteries and hydrogen storage for fuel cells). Electrical energy generation means make it possible to power at least partly electrically the longitudinal and transverse thrusters of said float(s), hybrid operation also being possible by further implementing sail propulsion means. In one embodiment, it may be envisaged to implement a nuclear fuel generator.

[0092] Of course, the invention is not limited to the examples which have just been described and which are given for illustration purposes only.

Claims

CLAIMS 1. Maritime structure with improved stability comprising means of maneuvering and navigation and comprising: - at least one aerial platform (1); - at least three masts (2) of adjustable height; - at least one underwater float (3) equipped with at least one lateral thruster (4) and at least one longitudinal thruster (5), said platform being secured to said float(s) by means of said masts; - static ballasting means inside said float(s); - controlled dynamic ballasting means located inside said masts - means for controlling the position and the trim comprising at least one sensor and at least one means for controlling said dynamic ballasting means in order to control in real time the position and stability of said maritime structure as a function of the swell and the wind.

2. Maritime structure according to claim 1 comprising at least two floats, preferably three floats, and at least one profiled crosspiece (6) connecting said floats transversely.

3. Maritime structure according to claim 1 or 2 wherein said at least one sensor allows at least one direct physical measurement of the trim, the height of the platform relative to the water surface or the absolute or relative position of the structure.

4. Maritime structure according to one of the preceding claims in which the dynamic ballasting means are constituted by at least one air-vacuum or air-filled cylinder (13) inside each mast, each of said cylinders being connected to water injection and ejection means (14).

5. Maritime structure according to one of the preceding claims in which the static ballasting means consist of at least one ballast tank (15) inside each float.

6. Maritime structure according to one of the preceding claims comprising at least one DP2 type servo means in position and heading, without anchoring, allowing the platform to remain in a fixed position and to free itself from the influence of wind and waves and a means of servo control in altitude, pitch and roll allowing a substantially zero attitude to be maintained.

7. Maritime structure according to claim 6 comprising electric motors providing propulsion as well as position and heading control.

8. Maritime structure according to one of the preceding claims comprising autonomous electricity production means chosen from wind turbines, photovoltaic panels, aeroturbines and energy storage means.

9. Maritime structure according to one of the preceding claims comprising means for generating electrical energy, making it possible to supply at least partly electrically the longitudinal and lateral thruster(s) of said float(s).

10. Maritime structure according to claim 9 comprising at least one nuclear fuel generator.

11. Maritime structure according to claim 9 or 10 further comprising sail propulsion means.

12. Maritime structure according to one of the preceding claims in which the aerial platform is of aerodynamic shape in order to minimize the drag generated by the absolute and relative wind, and of thickness very significantly less than its length in order to limit its frontal surface and its wind resistance.

13. Maritime structure according to one of the preceding claims comprising means for adjusting the height of the platform relative to the float(s).

14. Use of the maritime structure according to one of claims 1 to 13 for the handling or maintenance of equipment at sea.

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