Sail propulsion device

Abstract

A sail propulsion device (1) comprising: - first and second sails (3, 4), opposite each other and connected so as to share a trailing edge (BF); - an inflatable tubular envelope (5) extending along a longitudinal axis (Z'-Z), and comprising: a leading edge (BA), designed to face a wind (V), and defining with the trailing edge (BF) a camber line (L1); a joining zone (6), at which the first and second sails (3, 4) are joined, having an angular position (Ω) varying according to the camber line (L1); in which the tubular envelope (5) delimits a closed chamber filled with a fluid (F), preferably air, exerting pressure inside the tubular envelope (5), the pressure being different from atmospheric pressure and determined according to a wind speed (V) so that the leading edge (BA) is kept under tension. Figure 1

Description

Title of the invention: Sail propulsion device technical field

[0001] The invention relates to the technical field of sail propulsion devices.

[0002] The invention finds particular application in the sail propulsion of ships. State of the art

[0003] A sail propulsion device known from the prior art, in particular from documents WO 98 / 26982 A1 and US 3,391,668 A, comprises: - the first and second sails, opposite, and connected to each other in such a way as to share a trailing edge intended to be fixed to the clew of a ship; - a tubular, inflatable envelope extending along a longitudinal axis, and comprising: the first and second fixing zones opposite each other along the longitudinal axis, intended to be fixed respectively to the tack point and the halyard point of a ship; a leading edge, designed to face a wind, and defining with the trailing edge a line of camber which changes according to a wind direction.

[0004] Such a prior art wind propulsion device is not entirely satisfactory insofar as the tubular envelope, inflated by the dynamic pressure exerted by the wind, may not be high enough to maintain a stable leading edge shape under certain sailing conditions. Furthermore, the dynamic pressure exerted by the wind may be too high, so that certain areas near the trailing edge cannot maintain a stable shape under certain sailing conditions. Description of the invention

[0005] The invention aims to remedy, in whole or in part, the aforementioned drawbacks. To this end, the invention relates to a sail propulsion device for equipping a vessel having a halyard point, a tack point, and a clew point, the device comprising: - the first and second sails, opposite, and connected to each other in such a way as to share a trailing edge intended to be fixed at the clew; - a tubular, inflatable envelope extending along a longitudinal axis, and comprising: the first and second opposite attachment zones along the longitudinal axis, intended to be respectively attached to the tack point and the halyard point; a leading edge, designed to face a wind, and defining with the trailing edge a line of camber which changes according to a wind direction; a junction zone, on which the first and second sails are joined, presenting an angular position defined in relation to the leading edge and the longitudinal axis varying according to the line of camber; device in which the tubular envelope delimits a closed chamber filled with a fluid, preferably air, exerting pressure inside the tubular envelope, the pressure being different from atmospheric pressure and determined as a function of wind speed so that the leading edge is kept under tension.

[0006] Thus, such a sail propulsion device according to the invention makes it possible to maintain a stable shape of the leading edge thanks to the following characteristics: (i) the tubular envelope delimits a closed chamber (and not open compared to the prior art) filled with a fluid; (ii) the pressure exerted by the fluid inside the chamber is determined as a function of a wind speed (related to certain navigation conditions) so as to maintain tension on the leading edge (and not due to the dynamic pressure exerted directly by the wind during navigation, as in the prior art).

[0007] The sail propulsion device according to the invention may include one or more of the following characteristics.

[0008] According to one feature of the invention, the device includes a control circuit configured to regulate the pressure exerted by the fluid inside the tubular envelope as a function of wind speed.

[0009] Thus, one advantage provided is the ability to adjust the pressure exerted by the fluid inside the tubular envelope under real navigation conditions, in order to maintain tension on the leading edge.

[0010] According to one feature of the invention, the first and second sails are connected to each other in such a way as to delimit a volume open at their base with the tubular envelope, the open volume allowing an inlet of air at atmospheric pressure.

[0011] Thus, one advantage provided is simplicity of implementation. The fact that the volume is open at the base of the first and second sails prevents the atmospheric pressure of the air intake from being affected by the overpressure or underpressure exerted on the first and second sails depending on their position relative to the wind direction. The sail experiencing overpressure is called the lower surface (intrados), while the sail experiencing underpressure is called the upper surface (extrados). The lower surface is the sail closest to the prevailing wind. The upper surface is the sail furthest from the prevailing wind. The air flowing over the upper surface is accelerated, creating a low-pressure area through the Venturi effect, which is the primary cause of the lift propelling the vessel.

[0012] According to a feature of the invention: - the first and second sails are connected to each other in such a way as to delimit a closed enclosure with the tubular envelope; - the closed enclosure is filled with a fluid, preferably air, exerting a controlled pressure inside the closed enclosure so as to modulate a volume of the closed enclosure.

[0013] Thus, one advantage provided is the ability to control the volume between the first and second sails under real sailing conditions in order to optimize laminar wind flow. The fact that the sail junction zone has an angular position (defined relative to the leading edge and the longitudinal axis) that can vary depending on the camber line and the volume between the first and second sails makes it possible to improve the stability of the shape of areas near the trailing edge in the event of high dynamic pressure exerted by the wind on the sails, or in the event of a tack that reverses the camber line.

[0014] After navigation, the closed enclosure can be deflated to allow compact winding of the device.

[0015] According to one feature of the invention, the control circuit is configured to regulate the pressure exerted by the fluid inside the closed enclosure.

[0016] Thus, one advantage provided is to use a single control circuit to regulate both the fluid in the tubular envelope and the fluid in the closed enclosure.

[0017] According to a feature of the invention, the tubular envelope is free to rotate around the longitudinal axis.

[0018] Thus, one advantage provided is that it facilitates the modification of the angular position of the junction zone when the camber line varies in the event of a change in wind direction. In other words, the orientation of the sails can adjust to the change in wind direction without excessive stress.

[0019] According to one feature of the invention, the device includes drive means arranged to drive the tubular envelope in rotation around an axis of rotation passing through the first and second fixing zones.

[0020] Thus, one advantage provided is the ability to adjust the axis of rotation of the tubular envelope during navigation in order to adapt to specific conditions to improve the stability of the volume extending between the first and second sails.

[0021] According to one feature of the invention, the axis of rotation passing through the first and second fixing zones and the longitudinal axis are coincident, or parallel, or intersecting.

[0022] Thus, one advantage provided is the ability to modify the position of the axis of rotation which has an impact on the torque resulting from the tensions exerted by the first and second sails on the tubular envelope under navigation conditions.

[0023] According to one feature of the invention, the device includes adjustment means arranged to adjust the angular position of the junction zone.

[0024] Thus, one advantage provided is the ability to modify the volume between the first and second sails, for example by sliding them around the tubular envelope using a rope designed to twist the junction between the first and second sails. This makes it possible to adjust the variation in angle of attack to the wind according to the height of the junction area.

[0025] According to a feature of the invention, comprising a zipper arranged to connect the first and second sails together on the junction area or to connect the first and second sails together along the trailing edge.

[0026] Thus, one advantage provided is to obtain simplicity and speed in setting up the device on a ship, for example around a stay.

[0027] According to one feature of the invention, the device comprises a yard having first and second opposite ends, the first end being connected to the trailing edge, the second end being connected to the second attachment zone of the tubular casing.

[0028] Thus, one advantage provided is to improve the stability of the device by maintaining a sufficient area for the surface defined by the upper contour of the first and second sails.

[0029] The invention also relates to a vessel comprising: - a mast with a halyard point; - a tack point and a listening point; - a device according to the invention, the first and second fixing zones of the tubular envelope being respectively fixed to the tack point and the halyard point, the first and second sails being fixed to the clew point.

[0030] Definitions

[0031] - By "leading edge", we mean a forward part in the direction of the flow of the air, facing the wind.

[0032] - By "trailing edge", we mean a rear part in the direction of the flow of the air, opposite the leading edge.

[0033] - By "line of camber" is meant the curve passing between the first and The second sail (intrados and extrados, or vice versa) passes through points located midway between the intrados and extrados. The intrados is the sail closest to the prevailing wind. The extrados is the sail furthest from the prevailing wind.

[0034] - The expression "line of camber changing according to a wind direction" " does not mean that wind direction is the only parameter modifying the camber line.

[0035] - The term "tubular" should be understood as a tube shape in the sense of mathematical, not necessarily having a constant section along the longitudinal axis of the envelope, covering in particular a cylindrical shape, a conical shape, or a truncated conical shape.

[0036] - The term "fixed" should be understood as attached directly or indirectly (via an intercalary element) to the corresponding point (halyard, sheet, tack).

[0037] - The term "junction zone" designates a zone of the tubular casing where the The first and second walls are joined. In other words, the junction zone is the area of ​​the tubular envelope where the first and second walls are connected. This term does not necessarily imply that the first and second walls are permanently fixed to the tubular envelope at the junction zone. In other words, this term does not necessarily imply that the first and second walls are mechanically attached to the tubular envelope at the junction zone. Indeed, it is possible to design a connection between the walls and the tubular envelope that allows relative movement of the walls with respect to the tubular envelope at the junction zone.

[0038] - By "determined as a function of wind speed", it is meant that the pressure The pressure exerted by the fluid inside the tubular envelope can be calculated (estimated, simulated) based on a physical principle, experiments, or numerical simulations involving wind speed. One physical principle that can be used is the maximum dynamic wind pressure exerted on the external surface of the tubular envelope. The mathematical formulation of this physical principle is notably developed in NACA (National Advisory Committee for Aeronautics) report no. 563 by R.M. Pinkerton, entitled "Calculated and measured pressure distributions over the midspan section of the NACA 4412 airfoil," dated 1936. Besides wind speed, other parameters can be used to calculate the pressure exerted by the fluid inside the tubular envelope, such as the fluid velocity, fluid density, and the geometry of the device (tubular envelope and sails).The term "determined" does not necessarily mean that the pressure is fixed, i.e., constant over time. Indeed, with a regulating circuit, the pressure can be regulated during navigation and therefore varies while the device is in use. The term "determined" also covers the fact that the pressure can be predetermined (in this case, fixed), i.e., determined before the device is used for certain navigation conditions involving a typical wind speed. Brief description of the drawings

[0039] Other features and advantages will become apparent in the detailed description of different embodiments of the invention, the description being accompanied by examples and references to the accompanying drawings.

[0040] [Fig-1] is a schematic top view, illustrating a device according to the invention subjected to a first wind direction.

[0041] [Fig.2] is a partial schematic top view, enlarged to scale, illustrating a front part of the device according to the invention.

[0042] [Fig.3] is a schematic top view, illustrating a device according to the invention with zero wind incidence. The camber line is then a straight line coinciding with the chord line.

[0043] [Fig.4] is a schematic view analogous to [Fig.1], illustrating an inversion of the wind direction and a reversal of the camber line.

[0044] [Fig. 5] is a schematic top view of a device according to the invention, illustrating a zipper arranged to connect the first and second sails together at the junction area.

[0045] [Fig.6] is a schematic top view of a device according to the invention, illustrating a zipper arranged to connect the first and second sails together along the trailing edge.

[0046] [Fig.7] is a schematic top view, illustrating a pressure distribution dynamics acting at the periphery of a device according to the invention, the tubular envelope not being represented.

[0047] [Fig.8] is a schematic perspective view of a device according to the invention, illustrating an adjustment of the angular position of the junction zone.

[0048] [Fig.9] comprises three schematic top views of a device according to the invention, illustrating the influence of the angular position of the junction zone on the volume between the first and second sails for a given wind direction.

[0049] [Fig. 10] is a schematic perspective view of a device according to the invention equipping a ship, and fitted with a yard.

[0050] [Fig. 11] is a partial schematic perspective view, at an enlarged scale, of a device according to the invention equipping a ship, and fitted with a yard.

[0051] [Fig. 12] is a schematic perspective view of a device according to the invention.

[0052] It should be noted that the drawings described above are schematic, and are not not necessarily to scale for the sake of readability and to simplify their understanding. Detailed description of the implementation methods

[0053] Identical elements or elements performing the same function shall bear the same references for the different embodiments, for the sake of simplification.

[0054] An object of the invention is a sail propulsion device 1 for equipping a vessel 2 having a halyard point D, a tack point A and a sheet point E, the device 1 comprising: - the first and second sails 3, 4, opposite, and connected to each other in such a way as to share a trailing edge BF intended to be fixed to the clew point E; - a tubular envelope 5, inflatable, extending along a longitudinal axis Z'-Z, and comprising: first and second attachment zones opposite each other along the longitudinal axis Z'-Z, intended to be attached respectively to the tack point A and the halyard point D; a leading edge BA, intended to face a wind V, and defining with the trailing edge BF a camber line L1 which changes according to a wind direction V; a joining zone 6, on which the first and second sails 3, 4 are joined, having an angular position Q defined with respect to the leading edge BA and the longitudinal axis Z'-Z which varies according to the camber line L1; device 1 in which the tubular envelope 5 delimits a closed chamber filled with a fluid F, preferably air, exerting a pressure inside the tubular envelope 5, the pressure being different from atmospheric pressure and determined as a function of a wind speed V so that the leading edge BA is kept under tension.

[0055] First and second sails

[0056] The first and second sails 3, 4 are opposite. In other words, the first and second sails 3, 4 face each other. The first and second sails 3, 4 can be described as the lower and upper surfaces (and vice versa) depending on the wind direction V, by analogy with the surfaces of an airplane wing. The lower surface is the sail 3, 4 that is closest to the prevailing wind V. This sail 3, 4 is under higher relative pressure because the air flowing over it tends to slow down, creating a high-pressure area. The upper surface, conversely, is the sail 3, 4 that is furthest from the prevailing wind V. The air flowing over this sail 3, 4 is accelerated, creating a low-pressure area. The low-pressure area and the high-pressure area create a lift force that allows the propulsion of a ship 2.It should be noted that the low-pressure area on the upper surface contributes significantly more to lift than the high-pressure area on the lower surface.

[0057] The first and second sails 3, 4 are connected together so as to share a trailing edge BF intended to be fixed to a clew point E of a ship 2.

[0058] The first and second sails 3, 4 can be connected to each other so as to define a volume 7 open at their base with the tubular envelope, the open volume 7 allowing the entry of air at atmospheric pressure. Alternatively, the first and second sails 3, 4 are connected to each other so as to define a closed enclosure with tubular envelope. The closed enclosure is filled with a fluid, preferably air, exerting a controlled pressure inside the closed enclosure so as to modulate a volume 7 of the closed enclosure.

[0059] The first and second layers 3, 4 can be made of a material selected from a woven fabric (e.g., polyester) or a laminate (e.g., Mylar®). Aromatic polyamide (aramid), polyethylene (e.g., high molecular weight), and carbon fibers can also be used. The first and second layers 3, 4 can be manufactured by traditional methods: sewing, bi-radial / tri-radial assembly, welding, lamination, vacuum infusion of strip assembly, in-mold polymerization, etc. By way of non-limiting example, the first and second layers 3, 4 can be joined together by sewing, heat sealing, welding, etc.

[0060] Tubular casing

[0061] The tubular casing 5 is inflatable. In other words, the tubular casing 5 is made of a flexible material that can be filled with a fluid F, preferably air. The flexible material is designed to withstand the pressure exerted by the fluid F. By way of non-limiting examples, the flexible material can be a woven fabric (e.g., polyester) or a laminate (e.g., Mylar®). Aromatic polyamide (aramid), polyethylene (e.g., high molecular weight), and carbon fibers can also be used. The tubular casing 5 can be manufactured by traditional methods: sewing, bi-radial / tri-radial assembly, welding, lamination, vacuum infusion of strip assembly, in-mold polymerization, etc.

[0062] When the tubular envelope 5 is deflated, the winding of the first and second sails 3, 4 around the tubular envelope 5 is thus facilitated for their storage, and can be carried out using a sail winder.

[0063] The tubular casing 5 extends along a longitudinal axis Z'-Z, that is, taken along the length of the tubular casing 5. The tubular casing 5 has first and second attachment zones opposite each other along the longitudinal axis Z'-Z, intended to be attached respectively to the tack point A and the halyard point D. When the first and second attachment zones are attached directly to the tack point A and the halyard point D, the longitudinal axis Z'-Z corresponds to the axis defined by the tack point A and the halyard point D. According to a first geometric configuration (as in the case of a mainsail), the tack point A and the halyard point D can define a vertical axis. According to a second geometric configuration (as in the case of a jib), the tack point A and the halyard point D can define an oblique axis.

[0064] The tubular envelope 5 has a leading edge BA, designed to face a wind V. The trailing edge BF (shared by the first and second sails 3, 4) and the The leading edge BA defines a camber line L1 which changes according to a wind direction V. More precisely, the camber line L1 extends between the leading edge BA and the trailing edge BF, and the curvature of the camber line L1 is defined by the curve passing between the first and second sails 3, 4, that is to say passing through the points located halfway between the first and second sails 3, 4. The leading edge BA and the trailing edge BF also define a chord line L2 which is the straight line connecting the leading edge BA to the trailing edge BF.

[0065] The tubular shell 5 has a joining zone 6, to which the first and second sails 3, 4 are joined. The joining zone 6 has an angular position Q defined with respect to the leading edge BA and the longitudinal axis Z'-Z of the tubular shell 5. The angular position Q of the joining zone 5 varies according to the camber line LL. The first and second sails 3, 4 can be connected to the tubular shell 5 at the joining zone 6 by a textile membrane arranged on the tubular shell 5. Alternatively, the first and second sails 3, 4 can be connected to the tubular shell 5 at the joining zone 6 by a rope providing a floating connection between the first and second sails 3, 4 and the tubular shell 5.

[0066] The tubular casing 5 defines a closed chamber filled with a fluid F, preferably air, exerting pressure inside the tubular casing 5. The pressure exerted by the fluid F is different from atmospheric pressure and is determined as a function of a wind speed V such that the leading edge BA is kept under tension. The tubular casing 5 advantageously includes an air chamber arranged within it to retain the pressure exerted by the fluid F within the tubular casing 5. By way of non-limiting example, the air chamber may be made of thermoplastic polyurethane. The tubular casing 5 may be equipped with a zipper for inserting and removing the air chamber from the tubular casing 5. The tubular casing 5 may be inflated via a fitting 50, preferably equipped with a valve.

[0067] According to a first embodiment, the tubular casing 5 is free to rotate about the longitudinal axis Z'-Z. According to a second embodiment, the device includes drive means arranged to rotate the tubular casing 5 about an axis of rotation passing through the first and second mounting zones. The axis of rotation passing through the first and second mounting zones and the longitudinal axis Z'-Z may coincide, be parallel, or intersect. The second embodiment is not necessarily incompatible with the first embodiment. Indeed, it is possible to provide a mechanical transmission system (e.g., freewheel, clutch) configured to interrupt the rotational drive so that the tubular casing 5 is free to rotate about the longitudinal axis Z'-Z.

[0068] Regulation circuit

[0069] The device 1 advantageously includes a control circuit configured to regulate the pressure exerted by the fluid F inside the tubular casing 5 as a function of the wind speed V. For this purpose, the control circuit may include at least one pressure sensor (e.g., a strain gauge) arranged inside the tubular casing 5 to measure the pressure exerted by the fluid F. It is also possible to include at least one volume sensor. The control circuit may include at least one pump arranged to ensure the circulation of the fluid F within the control circuit.

[0070] When the first and second walls 3, 4 are connected to each other to define a closed enclosure with the tubular casing 5, the control circuit is advantageously configured to regulate the pressure exerted by the fluid inside the closed enclosure. For this purpose, the control circuit may include at least one pressure sensor (e.g., a strain gauge) arranged inside the closed enclosure to measure the pressure exerted by the fluid. A volume sensor may also be provided.

[0071] The control circuit may include at least one feedback loop configured to control the pressure value measured by the sensors against a setpoint value.

[0072] The control circuit may include at least one valve arranged to regulate the quantity of fluid F inside the tubular casing. Similarly, the control circuit may include at least one valve arranged to regulate the quantity of fluid inside the closed enclosure. The valve(s) may advantageously be remotely controlled (e.g., by radio) to inflate / deflate the tubular casing 5 and / or the closed enclosure.

[0073] Angular position adjustment

[0074] The device advantageously includes adjustment means arranged to adjust the angular position Q of the junction zone 6. The adjustment means are advantageously configured to slide the first and second sails 3, 4 around the tubular envelope 5.

[0075] According to one embodiment, the adjustment means comprise a rope system designed to twist the junction between the first and second sails 3, 4. It is also possible to provide an adjustable tension system (e.g. straps, pulleys, tensioners) designed to twist the junction between the first and second sails 3, 4.

[0076] A twist is applied along the junction between the first and second sails 3, 4 in order to twist the junction, for example by pulling the ends of the junction asymmetrically.

[0077] Zipper(s)

[0078] The device 1 advantageously includes a zipper 8a arranged to connect the first and second sails 3, 4 together on the junction area 6. The device 1 advantageously includes a zipper 8b arranged to connect the first and second sails 3, 4 together along the trailing edge BF.

[0079] Vergue

[0080] The device 1 advantageously comprises a spar 9 having opposing first and second ends 90, 91. The first end 90 of the spar 9 is connected to the trailing edge BF, more precisely to the upper part of the trailing edge BF. The second end 91 of the spar 9 is connected to the second attachment point of the tubular casing 5. The spar 9 is connected to the halyard point D of the vessel 2. More specifically, the spar 9 may include a connecting element 92 mounted to slide between the first and second ends 90, 91, so as to modify the distribution of tension between the tubular casing 5 and the trailing edge BF. The connecting element 92 is fixed to the halyard point D of the vessel 2. The spar 9 may be made in the form of a statically determinate beam having three ball-and-socket joints.

[0081] Ship

[0082] An object of the invention is a vessel 2 comprising:

[0083] - a mast 20 having a halyard point D;

[0084] - a tack point A and a listening point E;

[0085] - a device 1 according to the invention, the first and second fixing zones of the tubular envelope 5 being respectively fixed to the tack point A and to the halyard point D, the first and second sails 3, 4 being fixed to the clew point E.

[0086] According to one embodiment, the position of the tack point A can be modified so as to adjust the orientation of the longitudinal axis Z'-Z of the tubular envelope 5. Thus, it is possible to modify the value of the torques exerted by the first and second webs 2, 3 on the tubular envelope 5.

[0087] The invention is not limited to the embodiments described. A person skilled in the art is able to consider their technically operative combinations, and to substitute equivalents for them.

Claims

Demands

1. Sail propulsion device (1) for equipping a vessel (2) having a halyard point (D), a tack point (A) and a clew point (E), the device (1) comprising: - first and second sails (3, 4), opposite, and connected to each other so as to share a trailing edge (BF) intended to be attached to the clew point (E); - an inflatable tubular envelope (5), extending along a longitudinal axis (Z'-Z), and comprising: first and second attachment zones opposite along the longitudinal axis (Z'-Z), intended to be attached respectively to the tack point (A) and the halyard point (D); a leading edge (BA), intended to face a wind (V), and defining with the trailing edge (BF) a camber line (Ll) which changes according to a wind direction (V);a junction zone (6), on which the first and second sails (3, 4) are joined, having an angular position (Q) defined with respect to the leading edge (BA) and the longitudinal axis (Z'-Z) varying according to the camber line (Ll); device (1) in which the tubular envelope (5) delimits a closed chamber filled with a fluid (F), preferably air, exerting a pressure inside the tubular envelope (5), the pressure being different from atmospheric pressure and determined according to a wind speed (V) so that the leading edge (BA) is kept under tension.;

2. Device (1) according to claim 1, comprising a control circuit configured to regulate the pressure exerted by the fluid (F) inside the tubular envelope (5) as a function of the wind speed (V).

3. Device (1) according to claim 1 or 2, wherein the first and second sails (3, 4) are connected to each other so as to delimit a volume (7) open at their base with the tubular envelope, the open volume (7) allowing an inlet of air at atmospheric pressure.

4. Device (1) according to claim 1 or 2, wherein: - the first and second sails (3, 4) are connected together so as to delimit a closed enclosure with the tubular envelope (5); - the closed enclosure is filled with a fluid, preferably air, exerting a controlled pressure inside the closed enclosure so as to modulate a volume (7) of the closed enclosure.

5. Device (1) according to claim 4 in combination with claim 2, wherein the control circuit is configured to regulate the pressure exerted by the fluid inside the closed enclosure.

6. Device (1) according to any one of claims 1 to 5, wherein the tubular envelope (5) is free to rotate about the longitudinal axis (Z'-Z).

7. Device (1) according to any one of claims 1 to 6, comprising drive means arranged to drive the tubular envelope (5) in rotation around an axis of rotation passing through the first and second fixing zones.

8. Device (1) according to claim 7, wherein the axis of rotation passing through the first and second fixing zones and the longitudinal axis (Z'-Z) are coincident, or parallel, or intersecting.

9. Device (1) according to any one of claims 1 to 8, comprising adjustment means arranged to adjust the angular position (Q) of the junction zone (6).

10. Device (1) according to any one of claims 1 to 9, comprising a zipper (8a, 8b) arranged to connect the first and second sails (3, 4) together on the junction area (6) or to connect the first and second sails (3, 4) together along the trailing edge (BF).

11. Device (1) according to any one of claims 1 to 10, comprising a yard (9) having first and second ends (90, 91) opposite, the first end (90) being connected to the trailing edge (BF), the second end (91) being connected to the second attachment zone of the tubular casing (5).

12. Vessel (2) comprising: - a mast (20) having a halyard point (D); - a tack point (A) and a clew point (E); - a device (1) according to any one of claims 1 to 11, the first and second attachment zones of the tubular casing (5) being respectively fixed to the tack point (A) and the halyard point (D), the first and second sails (3, 4) being fixed to the clew point (E).