SAIL PROPULSION ELEMENT, SAIL-POWERED VEHICLE

Description

[0001] The invention relates to an inflatable sail and is in the field of sail propulsion or hybrid sail propulsion.

[0002] Below are some definitions used in the following: Reefing: consists of reducing the surface area of ​​a sail by folding it partially from the bottom, in order to adapt the surface area of ​​the sail to the strength of the wind. Reefing can be done manually or automatically. Reefing bands: horizontal areas with reinforced sections allowing the reefing lines to be attached, for example with eyelets or pulleys. These reefing strips are placed on the sail at the rib at each height where a reefing is planned. There are as many reefing strips as there are possibilities for reducing the sail area. Lazy jacks : device for guiding the sail during reefing and lowering maneuvers. Boom: horizontal spar, articulated near the base of the mast, which allows certain sails to be held and oriented. The boom can also accommodate the sail when it is lowered. Faseyer : a sail that flutters is an insufficiently trimmed sail that partially deflates. A well-trimmed sail should be at the limit of fluttering. With a fully inflated sail, there is no fluttering, which allows you to stay facing the wind. Leading edge : front part of an aerodynamic profile (wing, propeller, etc.) where a fluid will separate in two. Trailing edge : characteristic part of any profile (wing, keel, rudder, etc.) subjected to a flow of a fluid (air, water, etc.) on either side. It designates the part opposite the direction of the steering, or in other words, the rear part considered in the direction of the flow. Headrest : upper end of the sail which follows the upper contour of the inflatable sail. Lowering : consists of lowering the sail. Hoisting: consists of raising the sail. Rigging : set of fixed and moving parts of a boat, such as a sailboat, enabling its propulsion and maneuvers by the force of the wind. Sail receptacle : in addition to receiving the lowered sail, it can integrate other functions, such as taking up the tension forces provided by the sail or housing other actuators, energy storage sensors and control module used to operate the sail. Hydrodynamic drag : friction force between the boat and the water. The higher the drag, the more the boat is braked. Aerodynamic drag : component of the force experienced by a body in motion in a fluid which is exerted in the direction opposite to the direction of movement. According to the invention, the sail generates aerodynamic drag. Aerodynamic lift : component of the force experienced by a body in motion in a fluid which is exerted perpendicular to the direction of movement. According to the invention, the sail generates aerodynamic lift. Relative wind or apparent wind: vector sum of the wind created by the boat's own speed and the actual wind speed. Aerodynamic resultant : vector sum of aerodynamic lift and aerodynamic drag. Prior art

[0003] Document WO 2017 / 221117A1 already discloses a sail propulsion element comprising an inflatable sail with a symmetrical profile. This propulsion element comprises an inflatable sail consisting essentially of two adjacent surfaces, substantially sealed and connected to each other around their periphery, thus forming at least one closed cavity. The element further comprises a conduit arranged between the inside and the outside of the cavity and means for injecting air into the cavity. This sail, once inflated, has a profile which remains permanently symmetrical, regardless of the movement of the element, the direction or intensity of the wind. The sail of this document is constantly inflated during its use in navigation.

[0004] Unfortunately, such a soft sail has the disadvantage of not having an inflation adapted to the different stages of its use, and in particular during the lowering and hoisting phases. Indeed, unlike a rigid sail, a soft sail does not have a well-defined position during these handling stages (hoisting and lowering). During these stages it is important to keep the sail close to the axis of symmetry of the sail profile, so as to avoid the sail falling into the water or catching on an element close to it, or not stacking properly to be able to be stored compactly. Furthermore, it is important to maintain a low pressure inside the sail during the lowering or reefing phase to avoid it flapping, which could reduce its lifespan.

[0005] Also known from document US2006174810A1 is a device for lowering and hoisting a conventional sail of a sailing boat with a guidance solution external to the sail. This manipulation can be carried out easily with one hand, and can be controlled, in its lowering or hoisting, continuously at any intermediate position, allowing rapid adaptation of the sail to different wind conditions.

[0006] Unfortunately, such a sail management device is located outside the sail, which increases drag. Furthermore, since such a device is attached to the boom and mast, it cannot be fitted to a telescopic mast.

[0007] Document GB2151199A describes an inflatable boat sail comprising in its internal cavity a system of flexible mechanical connections, of the lacing type, connecting the two walls constituting the sail. This system is arranged over the entire height of the sail, and is fixed in the lower part of the mast. Its function is to allow optimal operation of the sail from an aerodynamic point of view in these different uses.

[0008] Unfortunately, such a system is not suitable for managing the repeated lowering and hoisting of an inflated sail, and remains complex. Document US2006 / 118020 A1 discloses a sail propulsion element with an inflatable sail, but without a permanently symmetrical profile and without means for injecting air into the sail cavity.

[0009] Finally, the skilled person is also aware of the use of devices for external ropes on a conventional sail, fixed to the boom and intended for its maneuverability during lowering and hoisting maneuvers.

[0010] But such devices increase the drag of the sailboat, therefore penalizing its speed, and are not adaptable to telescopic masts. Summary of the invention

[0011] There is also a need for an inflatable sail which, when lowered, remains correctly on its axis of symmetry along the mast, without flapping or risking damage, and which can be deployed repeatedly, manually or automatically.

[0012] The invention relates to a sail propulsion element comprising a mast, an inflatable sail consisting essentially of two adjacent surfaces which are substantially sealed and connected to each other around their periphery, thereby forming between them at least one closed cavity, said sail comprising an upper part, a lower part, a leading edge and a trailing edge, the sail comprising different curves forming bulges over the entire length, at least one air duct arranged between the inside and the outside of the cavity of the sail, at least one means for injecting air into said cavity, the sail once inflated having a profile which remains permanently symmetrical, regardless of the movement of said propulsion element, the direction or intensity of the wind, a head arranged on the upper part of the sail, a sail receptacle arranged between the leading edge and the trailing edge on the lower part of the sail.

[0013] The propulsion element according to the invention is characterized in that it comprises at least one guide line arranged in the closed cavity of said sail, for the hoisting and lowering maneuvers of the sail, said guide line extending from the leading edge to the trailing edge of said sail, passing through the head and the sail receptacle.

[0014] More precisely, the guide line is a device made through a rope to ensure the correct geometric positioning of the sail during operation and during the hoisting or lowering phases. The inflatable sail (or wing) comprises several curves (or boxes) separated from each other by ribs, one rib being located between two neighboring curves. A rib of the sail, for example considered at the mid-height of the sail, is constrained in its position by the fact that it allows the mast to pass through an orifice made for this purpose in the rib, but apart from the rigidity of the sail (which is low), nothing prevents it from rotating around the mast under the effect of the pressures exerted on the sail. Such a rotation would cause the sail to twist and therefore poor performance. To avoid this twisting, each rib is crossed by the guide line at a point sufficiently far from the mast.When lowering or hoisting, the rib slides along the mast and along this guide line. This is also true for all the ribs of the sail's curves, as they are all crossed by the guide line.

[0015] In other words, the invention proposes at least one guide line arranged in the closed cavity of said sail intended to assist the hoisting and lowering maneuvers of the sail and making it possible to ensure good geometry of the inflated sail (or wing) in all operating conditions thereof.

[0016] This guide line is not intended to hoist the sail. It is also slightly under tension during the hoisting phase and therefore opposes the raising of the sail. In the context of the invention, the sail is hoisted by the telescopic mast which supports the head, which pulls the sail upwards while it is inflated. In the variant of the invention in which the mast is not telescopic, the sail is hoisted by moving the head along the mast.

[0017] The propulsion element according to the invention has the following various advantages. The guide line present in the cavity of the sail avoids generating unnecessary additional drag, unlike conventional rigging. The guide line according to the invention makes it possible to correctly guide the descent and ascent of the sail (meaning without twisting) towards its storage location located on the sail receptacle. The guide line according to the invention makes it possible to have a low tension (approximately 50N for a sail of approximately 100m 2 < ) in the sail.

[0018] Finally, the element according to the invention allows reefing without having to stop the boat. Only the sail faces the wind, unlike the device known until now, which requires the entire boat to face the wind.

[0019] Preferably, the guide line is in one part, and is fixedly attached to the sail receptacle on the trailing edge and furling-movable on the leading edge, or, furling-movable to the sail receptacle on the trailing edge and fixed on the leading edge and in that the guide line is arranged along the headboard in a movably manner on at least one pulley between the trailing edge and the leading edge.

[0020] Preferably, the guide line is in two parts, the first part on the trailing edge side being fixed or movable with a pulley on the head and movable by a winder on the receptacle, the second part on the leading edge side being fixed or movable with a pulley on the head and movable by a winder on the receptacle.

[0021] Preferably, a pulley helps limit friction compared to an eyelet.

[0022] Preferably, at least two guide lines can improve the accuracy of the guidance. The presence of several guide lines allows for preferential distribution of forces, and thus increases the accuracy of the guidance. Reefing can also help with guidance.

[0023] Preferably, the guide line has a length ranging from about 2 to 150m for a sail ranging from 10 to 1000m 2< , and preferably about 50m for a sail of 100m 2< .

[0024] Preferably, the guide line has a tension of between 5 and 500N for a sail ranging from 10 to 1000m 2< , and preferably approximately 50 to 250N for a sail of 100m 2< .

[0025] Preferably, the sail includes at least one reefing bulkhead, and more particularly from 0 to 10 reefing bulkheads. Cargo ships may have no reefing, and more than 3 on the main sails of sailing ships.

[0026] Preferably, each reefing bulkhead includes a reinforced rib.

[0027] Preferably, the mast is fixed or telescopic.

[0028] Preferably, the guide line is made of ultra-strong polyethylene fibers.

[0029] Another object of the present invention is a sail-powered or hybrid-powered vehicle comprising at least one sail-powered element as mentioned above, a hull and a mast secured to said hull, but still free to rotate. This vehicle is characterized in that the mast is arranged inside the inflatable sail cavity mentioned above.

[0030] By hybrid propulsion vehicle according to the invention, we mean sail propulsion coupled to another source of propulsion such as for example propulsion by a propeller, driven by an electric or combustion engine, with energy storage of batteries, hydrogen (with a fuel cell), natural gas, ammonia or fuel.

[0031] By vehicle we mean land yachts, ice yachts, boats, cars.

[0032] Preferably, the sail is oriented according to the direction of the wind, and the direction of travel of the vehicle manually or automatically to optimize the thrust in the axis of the boat or to achieve the desired thrust while limiting the efforts, pressures and heeling to acceptable values. Description of the drawings

[0033] The invention will be described using the following figures, schematic and not necessarily to scale, and in which: There Figure 1 represents a reminder of the different physical forces which are applied to a ship, for example a sailboat with an engine and in particular the projection of the resulting aerodynamic force; The Figure 2 represents a schematic sectional view of a sail propulsion element according to the invention, arranged on a boat hull; The Figure 3 represents a schematic sectional view of a sail propulsion element according to another variant of the invention, arranged on a boat hull. Figures 4A, 4B and 4C each represent a schematic top view of the position of the propulsion element according to the invention, as a function of different relative wind angles.

[0034] Before explaining in more detail the sail propulsion element, the subject of the present invention, using the figures cited, a reminder of some definitions of hydrodynamics and aerodynamics is set out below.

[0035] A sail-powered vehicle, hereinafter referred to as a sailboat or ship, is in contact with both air and water. From a physical point of view, the predominant factors are the hydrodynamic and aerodynamic forces acting on the hull, sails and appendages (daggerboards, keel, rudder, propeller).

[0036] As shown la Figure 1 , the force aerodynamic(or sail thrust) results from the deflection of air by at least one sail. The aerodynamic force is relative to the position and surface of the sail and to the position and strength of the relative wind. The drag force is in the direction of the relative wind, the lift force is in the perpendicular direction of the relative wind, it is not always perpendicular to the sail. For example, at 0°, a symmetrical profile has no lift due to the fact that the air travels exactly the same distance on the upper and lower surfaces. At this point, it only generates drag.

[0037] The aerodynamic force generated by the sail can also be decomposed in the frame of reference of the boat, and not in that of the sail, to be composed of the sail propulsive force (which is in the axis of movement of the boat) and a drift force (perpendicular to the axis of the boat) which can induce heeling (transverse inclination of a boat caused by an external phenomenon such as the wind).

[0038] The force hydrodynamicresults from the friction of the water on the hull and the centerboard or keel and the various submerged appendages. Its direction depends on the aerodynamic force it opposes, the propulsive force in hybrid mode, the state of the sea and the ocean currents. The longitudinal component is called hydrodynamic drag, and the transverse component is called the drift lift or anti-drift force or hydrodynamic lift. The direction and intensity of the hydrodynamic force does not depend only on the aerodynamic force. For a vessel (boat) operating in hybrid mode (wind and other energy), the hydrodynamic force will depend strongly on the speed of the vessel generated by thermal or electric propulsion for example, the state of the sea and ocean currents.

[0039] When the wind force is greater than the hydrodynamic force, the boat accelerates. When the wind force is less than the hydrodynamic force, the boat slows down. Furthermore, if the aerodynamic force is greater but directed toward the rear of the boat, the latter will slow down. If the hydrodynamic force is in the direction of travel of the boat (due to a strong current, for example), the boat (sailboat) will accelerate.

[0040] It is by optimizing the sail trim that the boat (sailboat) will achieve its maximum performance in terms of sail thrust in the direction of travel. Indeed, it is the optimization of the angle of the sail in relation to the relative wind and the direction of the boat, as well as the adjustment of the sail surface that will allow the boat to achieve the maximum of its sail propulsion in the axis of the boat. There may be an additional adjustment parameter by playing on the internal pressure of the sail. This thus makes it possible to increase the speed of the boat or on the contrary to maintain the same speed while reducing the consumption of other energies, through the sail propulsion.

[0041] There Figure 1 includes each of the preceding names with a reference specific to it listed below: a: Lift force b: Drag force c: Aerodynamic resultant force d: Aerodynamic thrust force (along the ship's axis) e: Aerodynamic drift force f: Relative wind g: Relative angle between wing and ship's axis (e.g. 15°) h: Relative wind angle and ship's axis (e.g. 30°) i: Propeller propulsive force j: Hull k: Sail l: Mast m: Aerodynamic center of thrust n: Propeller o: Sensor on fixed part (hull frame of reference) p: Sensor on moving part (sail frame of reference)

[0042] The information given by the Figure 1 allow switching from data sensors coming from the hull reference frame to data sensors coming from the sail reference frame, and vice versa.

[0043] There Figure 2represents the sail propulsion element according to the invention, mounted on a boat, sailboat type, in operating position. This element comprises a general reference sail 1 mounted on the hull 2 ​​of a boat. The element comprises a mast 3 whose base 4 is fixed to the hull 2 ​​while allowing the rotational movement of the mast 3. The mast 3 is self-supporting. The connection of the mast 3 with the hull 2 ​​is carried out using a support (not shown) intended to take up the forces of the physical forces and leave the degree of freedom in rotation. The forces are measured at the level of the support(s). The sail 1 comprises two adjacent surfaces 5 (only one is shown in the figure) connected together so as to form a closed cavity. The material used for the two adjacent surfaces 5 must limit permeation so as to reduce air consumption, and allow the recovery and transmission of the various forces present.In some cases, it may be necessary to add different treatments to the material in order to ensure, for example, a certain UV resistance, or antistatic behavior.

[0044] Sail 1 comprises several curves (not shown) regularly distributed over the height (the curves are larger in the lower part of the sail, and smaller in the upper part). The height of the curve is often linked to the length of the profile chord. Preferably, the curves are separated by ribs which allow air to pass from one curve to the other and which each have an opening allowing the mast to pass through.

[0045] The curves give it the external appearance of a bellows. The sail 1 comprises an upper part 6, a lower part 7, a leading edge 8 and a trailing edge 9. At least one air inlet 18 is arranged, for example, at the lower part 7 of the sail 1. Other air inlets 30 may also be arranged on the surface of the leading edge 8. At least one active means for injecting air 7a into the cavity of the sail is arranged in the extension of the air duct so as to be able to inject air into the cavity of the sail. The sail further comprises a head 10 arranged on its upper part 6, and a sail receptacle 11 arranged on its lower part 7 between the leading edge 8 and the trailing edge 9. This receptacle 11 is intended to receive all or part of the sail when it is lowered.This receptacle 11 may include different actuators and sensors facilitating manual or automatic maneuvering when hoisting or lowering the sail 1.

[0046] The sail propulsion element according to the invention comprises a guide line 12 arranged in the cavity of the sail 1. This guide line is intended for guiding the sail during the hoisting and lowering maneuvers, and for reefing the sail 1. This line 12 comprises a rope which extends substantially around the perimeter of the sail 1. The guide line 12 is fixed in a removable or non-removable, but non-movable manner, to an end 13 located close to the intersection of the trailing edge 9 and the sail receptacle 11. It then extends towards the upper part 6 of the sail 1, to run along the headboard 10 between the trailing edge 9 and the leading edge 8. The guide line 12 is movable along the headboard 10 using at least two pulleys or other possible return systems (not shown) each arranged on either side of the mast 3.This guide line 12 is adjacent to the leading edge 8, towards the sail receptacle 11 to then be fixed using a winder 19 on the sail receptacle 11 substantially at the level of the leading edge 8. The guide line 12 can be mounted towards a locking cleat if it is operated manually. On the other hand, it is wound onto an automatic winder for the automated version.

[0047] More specifically, the guide line rope runs through all the ribs separating the different curves that form the inflatable sail. In order to prevent the different ribs from rotating around the mast, each rib has an oblong slot that allows the guide line rope to pass through on the leading edge side and another oblong slot that allows the guide line rope to pass through on the leech edge side. The oblong slot allows the rope to pass through the ribs in all the positions that these ribs take along the mast when lowering and hoisting the sail. This prevents the ribs from rotating around the mast, despite the fact that the ribs, as well as the sail, are made of a flexible material, which allows the sail to maintain its profile during operation and especially during hoisting and lowering maneuvers.

[0048] Unlike a lazy-jack type system of the state of the art, lazy-jack which is outside the sail and is permanently fixed, the rope of the guide line of the invention is inside the sail and its length is adjusted to ensure a low tension keeping the inflatable sail (or wing) in the correct position. This rope will move with the head located at the top of the sail so as to always guarantee a low tension in the rope of the guide line.

[0049] The guide line 12 has a length of approximately 50 meters for a sail having a total surface area of ​​approximately 100m 2< , and a tension of between approximately 50 and 250N depending on the uses made of it during the various lowering or hoisting maneuvers.

[0050] Mast 3 can be telescopic or fixed. When mast 3 is telescopic, head 10 is integral with the last element of the telescopic mast 3, being able to maintain a degree of freedom in rotation, either relative to the mast, or by having the last element of the telescopic mast which can rotate. When mast 3 is telescopic, it is made up of different elements which slide successively against each other to deploy or retract. It is also possible to deploy all the elements at the same time, if intermediate positions of the sail are not necessary.

[0051] When the mast 3 is fixed, only the head 10 is movable along the mast 3. The sail 1, being fixed to the head 10, descends or rises with the latter.

[0052] It is also possible to combine a telescopic mast 3 and a head 10 which slides along the mast 3.

[0053] The head 10 has sufficient rigidity to communicate the physical forces existing between the different ropes and the mast 3, but also to support the weight of the sail when it is not inflated. According to the different embodiments of the invention, the head 10 can be, as desired, freely rotating around the mast 3, locked in rotation around the mast 3, locked in rotation around the mast 3 up to a torque limit value to limit the forces to an acceptable value or even controlled so as to control the twisting of the sail.

[0054] Mast 3 is attached to hull 2 ​​using a mast support 14 whose role is to take up the different physical forces existing between the sail and the boat while leaving mast 3 a degree of freedom in rotation so that it can position itself at the right angle in relation to the relative wind.

[0055] At the base of the mast 3, at the level of the hull 2, there is a system 15 for adjusting the angle of incidence which makes it possible to control the rotation of the sail 1 by rotating the mast 3 and all the operating parts fixed to said mast 3. This system 15 can consist, among other things, of a brake motor. This system 15 allows the sail 1 to be able to rotate around the axis of rotation of the mast 3, and consequently to control the desired angle of incidence of the sail 1. This system for adjusting the angle of incidence can also be mounted integrally with the mast 3, for example on the "nest" (or sail receptacle) with a brake motor driving via a pinion a crown integral with the hull.

[0056] It is recalled that measuring the angle of incidence allows us to know the angular positioning of sail 1 in relation to the axis of the boat. Such a device makes it possible to put sail 1, hull 2 ​​and the relative wind in the same frame of reference, regardless of where the wind measurement is taken on sail 1 or on hull 2. Such an on-board system simplifies navigation in automatic mode.

[0057] The propulsion element according to the invention arranged on the hull of a boat can further be combined with a torque limiter, arranged at the base of the mast 3, and known to limit the maximum torque transmissible by the sail 1 to the hull 2.

[0058] The propulsion element according to the invention arranged on the hull of a boat may further comprise an electronic control system 16 arranged in the sail receptacle 11, also called a "nest". An electrical rotating joint 17 may also be added in the hull at the lower base of the mast 3. This joint 17 makes it possible to transmit the electrical power and the electrical controls between the hull 2 ​​and the lower part 7 of the sail 1. The joint 17 may also be replaced by a suitable conventional cable chain. When the energy used to operate the sail element according to the invention is, for example, hydraulic or pneumatic, the same solution may be used with a hydraulic or pneumatic rotating joint.

[0059] Among the various measuring sensors, we can find the sensors for measuring the force transmitted from the sail 1 to the hull 2, the sensors for measuring the force in the transverse axis of the hull 2, the sensors for measuring the force in the longitudinal axis of the hull 2, the pressure sensor in the internal cavity of the sail 1, and the sensor for measuring the speed and angle of the relative wind. This last measurement can be carried out on both the sail 1 and the hull 2. In the case where the sensors are arranged on the part secured to the mast 3, they measure the forces in the longitudinal axis and the transverse axis of the sail 1.

[0060] There Figure 3 is distinguished from the Figure 2by the additional presence of a reefing line system consisting of a reefing bulkhead (or racket) 20, a reefing line 21 and a reefing winch 22 (the reefing winch can be replaced by a cleat and muscle power in manual mode).

[0061] The propulsion element according to the invention may comprise several reefing bulkheads 20, for example up to 3. The number of these bulkheads 20 depends on the boat, the use and the user. The reefing bulkheads 20 are arranged at each reefing band.

[0062] The reefing line is connected to the reefing bulkhead 20 and allows the sail 1 to be brought back and compacted in the receptacle 11. The racket has sufficient rigidity so that the point force at the pulley, fixed on the racket, can be transmitted to the entire reefing bulkhead 20.

[0063] Each reefing line intended to reduce the sail area to a certain level is associated with a reefing bulkhead 20 and a reefing line. The reefing line can be made either in one go with returns or with separate lines.

[0064] On conventional sails of the prior art, each reef line includes eyelets, added pulleys, allowing the reefing line to pass through for reefing, or lines (small ropes which allow the folded sail to be attached by passing under the bollard from each side).

[0065] For the inflated sail according to the invention, the eyelets (or other passage point) are not arranged on the vertical part of the sail as in a conventional sail, but on the horizontal part of the reefing bulkhead 20, which must not be watertight.

[0066] Therefore, the reefing bulkhead 20 (or racket) in the propulsion element of the invention is fixed to the external wall of the sail 1. This bulkhead 20 allows, in addition to the reefing, to approach the guide line 12 to the trailing edge 9 and the leading edge 8, especially for sails which are not substantially triangular. In addition, the guide line 12 combined with the bulkhead 20 makes it possible to partially balance the forces exerted on the headboard 6 because it simultaneously exerts a downward thrust, on either side of the mast 3, on the headboard 6.

[0067] The reefing bulkhead 20 allows, in addition to reefing, to bring the guide line 12 of the leading edge 8 closer to the trailing edge 9, especially for sails which are not substantially triangular in shape.

[0068] When hoisting the sail, the following steps are performed: Place the sail in the axis of the relative wind, Put an initial tension in the guide line and the reefing lines, Inflate the sail to a low pressure, and control this pressure, Raise the sail at a defined speed with a speed limiter if the internal pressure cannot be maintained, After a certain height of rise, slightly increase the pressure in the sail, When the reefs are reached, release them successively if the surface must be used, Stop raising the sail when the surface of the sail is reached; this rise corresponds either to the sail fully deployed, or to a height corresponding to a reefing in place, Raise the cavity of the sail to the nominal pressure (which depends on the strength of the wind, the state of the sea, the desired point of sail). It is not necessary to constantly blow air into the sail. Indeed, it is possible to have an acceptable pressure adjustment range, thus allowing the air blowing means to be used only when necessary.

[0069] When lowering the sail, the following steps are performed: Put the sail in the direction of the relative wind (facing the wind), Reduce the internal pressure of the cavity Regulate the tensions of the guide line and the reefs, Lower the sail with a speed limiter if the internal pressure cannot be maintained, Each time a reef is folded, block the relative reef line, 2m from the end of the mast folding, set the internal pressure to zero to create a slight vacuum in the sail in order to compact it.

[0070] These different stages of maneuvers are preferably automated, especially when the sail reaches a surface area of ​​500m 2 or more. Manual maneuvers are easily achievable with surfaces of around 40m 2, with a sufficient number of individuals.

[0071] THE Figures 4A, 4B and 4C are distinguished from each other by a different angle of incidence of the sail.

[0072] On the Figure 4A , the relative wind is in the axis of the sail. On the Figure 4B , the axis of the sail presents an angle substantially equal to 15° with respect to the direction of the relative wind, and on the Figure 4C , the axis of the sail has an angle symmetrical and equal to that represented on the Figure 4B relative to the relative wind direction.

[0073] On the Figures 4A, 4B and 4C , sail 1 has a roughly symmetrical profile. Mast 3 is symbolized by a circle. The relative wind is symbolized by arrow 23.

[0074] There Figure 4A represents a sail 1 in a stabilized state, facing the wind 23. The different forces are balanced; the aerodynamic lift is zero because it is identical on both sides of the sail due to its symmetrical profile. The aerodynamic lift is zero, only the drag 24 exists and maintains the sail 1 along an axis parallel to the axis of the relative wind.

[0075] There Figure 4B represents a sail 1 whose axis has an angle of approximately 15° to the direction of the relative wind. The axis of rotation of the mast 3 is offset towards the front of the profile relative to the center of thrust 25 of the aerodynamic forces along the axis of symmetry of the profile. The Figure 4B shows that the torque generated by the aerodynamic force at a certain distance from the center of rotation of mast 3 tends to bring the sail back to its position facing the wind, where it can remain stable thanks to the symmetrical profile of the sail.

[0076] The offset existing between the attachment point of the mast 3 and the center of thrust 25 allows the propulsion element of the invention to guarantee that the sail 1 is held in place both in situations of large deviation in angle with the wind direction and in those of small deviation. Such an offset between this point of rotation of the mast 3 and the center 25 allows the sail 1 to be returned to the neutral position of the sail, that is to say facing the wind when it deviates from it. Such an offset makes it possible to reinforce the safety of navigation since the sail returns by itself to a suitable and optimal position in relation to the direction of the relative wind, which minimizes the forces and maintains the sail in a position facing the wind. This distance must however be minimized so as not to excessively increase the forces necessary for the rotation of the sail.

[0077] There Figure 4C is the figure symmetrical to that of the Figure 4B relative to the relative wind axis. The same remarks as those of the Figure 4B apply. Example

[0078] The following example is given for illustration purposes only and is not intended to be exhaustive. The following table lists various possible situations. Sailboat Cargo Boat length (meter) 13 140 Number of sails 1 4 Inner layer of polyester sail (g / m 2 < ) 220 240 Outer layer of coated polyester sail 110 160 Sail height (meter) 17 40 Longest sail length (meter) 8 17 Largest sail width (meter) 1,8 4 Sail area (m 2 < ) 100 500 Number of partitions 30 35

[0079] The outer layer of the sail, also called the body, is made of a fabric comprising an external part in contact with the outside air, and an internal part. This fabric can be made of a polyester woven fabric coated with polyurethane. The weight of this fabric can be 180g / m 2 for a sail area of ​​approximately 100m 2 .

[0080] The upper part of the sail can be attached using Velcro-type self-gripping strips. The connections between the outer parts of the sail and the ribs (internal connections), as well as the connections between the components of the outer part, can be made by welding or gluing or any other means of connection (zipper for example) to ensure both a sufficiently low level of permeation compatible with the existing inflation system and also to guarantee the transmission of forces.

Claims

1. Sail propulsion element, comprising: a. a mast (3), b. an inflatable sail (1) consisting essentially of two substantially fluidtight adjacent surfaces (5) joined together along their periphery, thus forming at least one closed cavity between them, said sail comprising an upper part (6), a lower part (7), a leading edge (8) and a trailing edge (9), the sail comprising various cambers forming bulges along its entire length, c. at least one air conduit positioned between the inside and the outside of the cavity of the sail, d. at least one means for injecting air into said cavity, the sail once inflated having a profile that remains permanently symmetrical, irrespective of the movement of said propulsion element, or of the direction or strength of the wind, e. a headboard (10) positioned on the upper part (6) of the sail (1), f. a sail receptacle (11) positioned between the leading edge (8) and the trailing edge (9) on the lower part (7) of the sail, characterized in that it comprises at least one guide line (12) positioned in the closed cavity of said sail, for the manoeuvres of hoisting and dropping the sail (1), said guide line (12) extending from the leading edge (8) to the trailing edge (9) of said sail, passing through the headboard (10) and the sail receptacle (11).

2. Element according to Claim 1, wherein the guide line (12) is made in one part and is attached fixedly to the sail receptacle (11) on the trailing edge (9) and able to be moved by a roller on the leading edge (8) or else is able to be moved by a roller in the sail receptacle (11) on the trailing edge (9) and fixedly attached to the leading edge (8), and in that the guide line (12) is positioned along the headboard (10) such as to be able to move over at least one pulley between the trailing edge (9) and the leading edge (8).

3. Element according to Claim 1, wherein the guide line (12) is made in two parts, the first part on the side of the trailing edge (9) being fixed or else able to be moved with a pulley on the headboard (10) and able to be moved by a roller in the receptacle (11), the second part on the side of the leading edge (8) being fixed or else able to be moved with a pulley on the headboard (10) and able to be moved by a roller in the receptacle (11).

4. Element according to one of the preceding claims, wherein a pulley limits friction by comparison with a grommet.

5. Element according to one of the preceding claims, wherein at least two guide lines make it possible to improve the precision of the guidance.

6. Element according to one of the preceding claims, wherein the guide line has a length ranging from around 2 to 150m for a sail ranging from 10 to 1000m2, and preferably of around 50m for a 100m2 sail.

7. Element according to one of the preceding claims, wherein the guide line (12) has a tension ranging between 5 and 500N for a sail ranging from 10 to 1000m2, and preferably of around 50 to 250N for a 100m2 sail.

8. Element according to one of the preceding claims, wherein the sail comprises at least one reefing panel.

9. Element according to one of Claims 1 to 7, wherein the sail comprises from 0 to 10 reefing panels (20).

10. Element according to one of Claims 8 or 9, wherein each reefing panel (20) comprises a reinforced rib.

11. Element according to any one of the preceding claims, wherein the mast (3) is fixed or telescopic.

12. Vehicle with sail propulsion or hybrid propulsion comprising at least one element according to one of the preceding claims, a hull and a mast secured to said hull but still free to rotate, characterized in that the mast (3) is positioned inside the cavity of said inflatable sail.

13. Vehicle according to Claim 12, wherein the sail (1) is oriented according to the wind direction and according to the direction of running of the vehicle either manually or automatically.