US20050204984A1

US20050204984A1 - Carbon masts

Info

Publication number: US20050204984A1
Application number: US10/504,971
Authority: US
Inventors: Jean-Marie Finot
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-02-20
Filing date: 2003-02-18
Publication date: 2005-09-22
Also published as: EP1476349A1; AU2003222581A1; FR2836119A1; ES2244934T3; FR2836119B1; DE60300887D1; EP1476349B1; WO2003070558A1; DE60300887T2

Abstract

A carbon mast includes a tube which is made from, for example, a pre-impregnated material and which is produced by filament winding or pultrusion. The tube (1) remains sealed by gluing the pieces for attaching the different elements that equip the mast thereto, in particular, the mast head piece (15) , the fitting (16) for attaching the spinnaker, the fitting (17) for attaching the stay and shrouds, the fitting (18) for attaching the crosstrees, the fitting (19) for attaching the boom and the fittings (20, 21) for, respectively, the mast partner and the mast foot, the aforementioned fittings being made in such a way as to contribute to the sealing of the mast.

Description

The present invention relates to improvements made to laminated carbon masts intended for sailing boats. The invention applies particularly to masts produced from tubes of preimpregnated material which are manufactured by filament winding or by pultrusion.
The carbon masts produced at the present time make use of techniques employed with light-alloy masts for fastening the various fittings on which the attachment pieces equipping these masts are mounted. Thus, these fittings, generally produced from metal, are affixed with the aid of rivets to tubes previously manufactured.
On high-performance boats, that is to say those intended for competition, the attachment pieces, in particular crosstrees and shrouds, are produced from laminated material directly on the tube forming the mast, which is a craft difficult to carry out and very costly.
The present invention proposes to dispense with the disadvantages of the techniques currently employed for the manufacture of carbon masts, so as to obtain leaktight masts making it possible to increase the stability of the boat at large list angles and therefore the safety, while at the same time making manufacture and mounting easier. According to the technique afforded by the invention, the tube of the mast is not pierced, thus making it possible to avoid reducing the resistance of the mast (the holes made in the tube of the mast reduce the resistance of the composite material forming the tube by 25 to 50%), and the various pieces and fittings are designed and secured to the mast so as to contribute to ensuring the leaktightness of the mast.
Consequently, the present invention relates to a carbon mast produced from a tube, in particular consisting of preimpregnated material, manufactured by filament winding or by pultrusion, which is characterized in that the tube forming the mast is kept leaktight by securing to it, by adhesive bonding, the attachment pieces of the various elements equipping the mast and, in particular, the shrouding and the crosstree supports, and by producing the mast head, the mast hole piece and the mast support in a leaktight way, these various attachment pieces being produced so as to contribute to ensure the leaktightness of the mast.
According to one feature of the present invention, the various attachment pieces comprise a horseshoe-shaped fitting designed to be laid against the walls of the tube forming the mast, so as to fit snugly with these, this fitting being installed with the aid of a gripper and being secured to the profile by adhesive bonding.
According to the present invention, the adhesive bonding of the attachment pieces to the carbon tube forming the profile of the mast is carried out by the injection of glue via ducts provided in said pieces.
Other features and advantages of the present invention will become apparent from the following description, with reference to the accompanying drawings which illustrate some of its exemplary embodiments having no limiting character. In the drawings:
FIG. 1 a is a sectional view in a horizontal plane of a carbon mast tube to which the present invention applies;
FIGS. 1 b to 1 h are views intended for illustrating the installation in the tube of means provided for protecting the halyards;
FIG. 1 i is a view similar to FIG. 1 a, illustrating the mast with its rail on which the carriages of the mainsail travel and which, moreover, can receive the truss fitting;
FIG. 2 shows, in side elevation, a boat equipped with a mast on which the various fittings have been identified;
FIGS. 3 a to 3 d illustrate the manufacture of the attachment pieces;
FIG. 4 is a plan view illustrating the gripper employed according to the invention in order to position the attachment pieces on the tube forming the mast;
FIGS. 5 a to 5 d are partial views illustrating an embodiment of a system for attaching a stay or for the engagement of a spinnaker;
FIGS. 6 a and 6 b are respectively side elevation and plan views of the pieces produced according to the invention for attaching the stay and the shrouds;
FIGS. 7 a and 7 b are respectively side elevation and plan views of the pieces which, according to the invention, carry the shrouds and also the crosstree supports;
FIGS. 8 a to 8 c illustrate another exemplary embodiment of the piece which, according to the invention, supports the crosstrees and the shrouds;
FIGS. 9 a to 9 d illustrate an exemplary embodiment of the leaktight mast head equipping the mast according to the invention;
FIGS. 10 a and 10 b show an exemplary embodiment of a mast hole piece equipping the mast which is the subject of the invention;
FIGS. 11 a to 11 d illustrate a first exemplary embodiment of a mast support according to the invention, and
FIGS. 12 a to 12 c illustrate another exemplary embodiment of the mast support.
Reference is made in the first place to FIGS. 1 a-1 i and to FIG. 2.
FIG. 1 a illustrates, in horizontal section, a tube from which the mast according to the invention is produced. This carbon tube 1 can be manufactured, using the technique known as pultrusion. It consists of 65 to 75% of unidirectional fibers at 0°, surrounded by two layers of fibers at more or less 45°. Furthermore, a layer at 0° may be placed outside in order to assist friction. The profile thus produced comprises a rail 2 for the carriages equipping the mainsail. This rail 2 may be reinforced with respect to abrasion with the aid of a plate preformed from any material having sufficient hardness, such as, in particular, aluminum, stainless steel or titanium. This preformed plate can be held on the rail simply by pressure or else with the aid of adhesive bonding. This rail 2 may likewise receive the truss supporting the boom.
Onto the rear part of the profile of this tube 1 and inside the latter (FIG. 1 b), a polyvinyl chloride tube 3 is adhesively bonded, which is intended for receiving the halyards, such as 4, and this tube may be completed by two tubes of smaller diameter, such as 5, for the passage of the electrical wires 6 (supply for the lights, transmission of information from the various sensors, such as anenometers etc., to the instruments). In the variant illustrated in FIG. 1 c, these tubes are replaced by a partition 7 likewise adhesively bonded to the inner walls of the profile of the mast.
In the variant illustrated in FIG. 1 d, an external profile 8 is provided, which is affixed to the mast 1 in order to ensure the protection of the halyards 4 and of the electrical wires 6.
FIGS. 1 e to 1 h show an example of the installation and fastening of the tube 3 receiving the halyards 4. This tube 3 (FIG. 1 e) has placed on it discontinuously double-faced adhesive tapes or strips or spots of glue, such as 9. The tube 3 (FIG. 1 e) is placed on a support 10 provided with claws 11 forming a cradle so as to hold the tube 3, this support 10 (FIG. 1 f) is pushed into the profile of the mast 1, and, when this tube is in its correct location, the support 10 is rotated such that the tube 3 comes into position in the appropriate place in the profile of the mast 1, at the same time resting on the adhesive tapes or spots of glue 9 (FIG. 1 g). A weight 12 is then introduced into the tube 3 (FIG. 1 h). so as to ensure the pressure necessary for the setting of the adhesive bond of the tube 3. Alternatively or additionally, the adhesive bonding pressure may be ensured with the aid of an external weighting means 13.
The ball-mounted carriages 14 equipping the mainsail can travel on the rail 2 provided as a consequence of manufacture on the tube 1 of the mast (FIG. 1 i), and this rail 2 can likewise receive the truss fitting.
Reference is now made to FIG. 2 of the accompanying drawings which illustrate diagrammatically a boat equipped with a mast 1 according to the invention, the latter being provided with all its fittings and attachment pieces which contribute to ensuring leaktightness and which will be described later.
In this FIG. 2, therefore, the mast 1 comprises a mast head piece 15, a fitting 16 for attaching the spinnaker, a fitting 17 for attaching the stay and the shrouds, a fitting 18 for attaching the crosstrees, a fitting 19 for attaching the boom and fittings 20 and 21 for the mast hole and for the mast foot respectively.
All these pieces are prefabricated by hand either in male and female molds or on male molds with robotized winding, either from composite material or from cast stretch-leveled resin. According to the present invention, these various pieces are produced so as to contribute to ensuring the leaktightness of the mast on which they are held by adhesive bonding.
The manufacture of these attachment pieces and the way in which they are installed on the profile of the mast 1 will now be described.
Reference is made in the first place to FIGS. 3 a to 3 d which illustrate the various manufacturing steps and in which FIGS. 3 a and 3 c are views in horizontal section, FIG. 3 b is a view in vertical section of FIG. 3 c and FIG. 3 d is a diagrammatic plan view illustrating one of the steps.
According to the present invention, the starting point is to use a real or simulated profile intended for serving as a mold core 22, which core may be produced from carbon or from metal, for example from aluminum or from steel. A countermold 23, preferably consisting of silicone, is positioned on this mold 22. This countermold is reinforced with the aid of glass or carbon fibers, in order to preserve some rigidity. The mold thus obtained has stretch-leveled in it multidirectional external and internal fabrics, such as 24 (FIG. 3 d), between which are placed, around lost bushes 25, unidirectional threads intended for distributing the force around the piece. The assembly thus consisting of the external fabrics, the bushes and the internal fabrics is placed in the silicone mold 23 (FIGS. 3 b and 3 c). The whole is closed on the mold core 22, and the assembly is placed under vacuum and, if appropriate, placed in an oven or an autoclave. Before the countermold 23 is closed on the mold core 22, the core 22 may have placed around it a silicone film 26 ribbed so as to obtain ducts via which the adhesive bonding of the piece will be carried out after the latter is installed on the profile of the mast 1, as will be described below.
The attachment pieces produced as described above have inner dimensions slightly smaller than the outer profile of the mast 1. They are installed on this profile with the aid of tooling illustrated in FIG. 4, which takes the form of a gripper designated as a whole by the reference 27. This gripper 27 bears on the piece, such as 29, by means of a nose 28. The gripper thus makes it possible to keep the attachment piece open so as to make it easier to introduce the latter on the profile of the mast 1, and, when it is positioned in its intended location, it is sufficient to release the pressure on the handles of the gripper so that the piece 29 assumes its place on the mast exactly, without moving from it. After this installation, it is sufficient to inject glue via the holes 30 provided for this purpose (these holes being obtained, for example, by virtue of the installation of the ribbed silicone film 26 described above).
Reference is now made to FIGS. 5 a to 5 d which illustrate an embodiment of the piece for attaching a stay or for the engagement of the spinnaker 16 (see FIG. 2).
FIG. 5 a is a sectional view in a horizontal plane, FIG. 5 b is a side elevation view, FIG. 5 c is a sectional view in a vertical axial plane of FIG. 5 a, and FIG. 5 d illustrates a detail of FIG. 5 b on an enlarged scale.
As can be seen from these figures, this attachment piece 16 consists of a horseshoe-shaped fitting 31 designed so as to be positioned on the mast, at the same time fitting snugly with the external shape of its profile, as described above. This piece is adhesively bonded to the mast, using the technique described above, and receives a stirrup 32 for anchoring the stay and for .installing the halyard pulleys (.see FIG. 5 d). This stirrup 32 is held on the fitting 31 with the aid of a shaft, such as 33, a metal bush 34 being interposed between the shaft 33 and support bearings 35 forming an integral part of the fitting 31. This attachment piece 16 consists of unidirectional and multidirectional fibers which absorb the forces exerted on the stirrup 32 in order to transfer them to the mast 1. Ducts, such as 36, are provided for injecting the glue onto the mast, the glue being introduced into the ducts via the injection holes 37.
FIGS. 6 a and 6 b show the fitting 17 (see FIG. 2) serving for attaching the stay and the shrouds. This piece 17, like the piece 16 described above, consists of a horseshoe-shaped fitting 38, the wall of which fits snugly with the external profile of the mast 1 and which comprises two ribs, upper 39 and lower 39, respectively, which receive shroud carrier stirrups, such as 40 and 40′, these stirrups being held on the fitting 38 with the aid of articulation shafts, as seen clearly in FIGS. 6 a and 6 b. Installation is carried out with the aid of a gripper 27 (FIG. 4), and securing is carried out by adhesive bonding, as described above.
FIGS. 7 a and 7 b show an exemplary embodiment of the piece 18 which, according to the invention, makes it possible to support the crosstrees and likewise to carry the shrouds. This piece likewise consists of a horseshoe-shaped fitting 41 which is positioned on the external profile of the mast, at the same time fitting snugly with the shape. It comprises two ribs 41 and 41′, between which is interposed a shroud carrier stirrup 42 which bears on the reinforcing tube 43 making it possible to transfer the force of the shroud to the stirrup 42 in its lower and upper parts. The crosstrees (in this exemplary embodiment, they consist of two tubes 44, 44′) are supported.by an ovalized bush 45 by means of a threaded rod 46 which is welded to the bush and onto which is screwed another bush 47 receiving the end of the crosstree tube 44 or 44′. The installation of this fitting 18 on the mast 1 and its securing by adhesive bonding are carried out in the way described above.
Reference is now made to FIGS. 8 a to 8 c which illustrate another exemplary embodiment of the piece supporting the crosstrees and the shrouds. In these figures, FIG. 8 a is a side elevation view of this piece, FIG. 8 b is a sectional view in a horizontal plane and FIG. 8 c is a partial front elevation view. In this exemplary embodiment, this piece also consists of a horseshoe-shaped fitting composed of a corrugated and ribbed skin 48. On this skin 48 are screwed threaded rods, such as 49, at the end of which a sphere 50 is provided. A spherical bearing surface, such as 51, provided at the end of each crosstree, such as 52, comes to bear on this sphere 50. This spherical bearing surface 51 can be slipped onto the sphere 50 by means of what is known as a quarter-turn system. The spherical bearing surface 51 thus makes tit possible to hold the tubular crosstrees, such as 52.
Each shroud, such as 53 (FIG. 8 c), terminates in a hemispherical head 54 bearing on a carbon shoulder 55 by means of a friction cup 56 preferably consisting of stainless steel. The shoulder 55 is prolonged forward and rearward so as to receive the crosstree supports 57, as can be seen in FIG. 8 b, these supports forming part of the horseshoe-shaped fitting 48.
The installation of this fitting and its securing to the profile of the mast are carried out in the way described above.
Reference is now made to FIGS. 9 a to 9 d which illustrate an embodiment of the leaktight mast head (designated by the reference 15 in FIG. 2). FIG. 9 a is a section through this mast head in a horizontal plane, and FIGS. 9 b, 9 c and 9 d are respectively side elevation, plan and front elevation views.
As can be seen from these figures, the mast head comprises a molding 58 which is produced so as to ensure leaktightness and to engage onto the upper part of the profile of the mast 1. This molding has a general ‘hat’-shaped configuration, and it comprises inner and outer ribs so as to ensure its hold on the mast. It comprises a collar 60 surrounding the upper part of the mast in order to ensure engagement on the latter, and also a projecting part 59 for the passage of the halyards. The top of this leaktightness piece 58 is shaped so as to receive directly either a halyard pulley or a pulley support 61. This support may be produced in the form of a tube or of a tube portion receiving the shafts 62 of the pulleys and the pulleys, such as 63. The pulley support 61 is held in the leaktightness piece 58 by adhesive bonding.
A cover may be provided, making it possible to mask the pulley shafts and to house the position lights and the sensors provided at the mast head, while at the same time ensuring the aerodynamism of the mast head.
It can be seen that the halyards 4 redescend within the tube 3, as described above with reference to FIG. 1 b. FIG. 9 a likewise shows the tubes 5 which are provided for the passage of the electrical wires (supply for the lights, transmission of information from the various sensors, such as anenometers etc., to the instruments). As already mentioned above, the tubes, such as 5, adhesively bonded to the inside of the profile of the mast may be replaced by a partition 7, likewise adhesively bonded in this profile.
The mast hole piece (designated by the reference 20 in FIG. 2) will now be described, which equips the mast according to the invention and an exemplary embodiment of which has been illustrated in FIGS. 10 a and 10 b FIG. 10 a being a view in vertical axial section and FIG. 10 b being a plan view.
This mast hole piece consists of a circular element 64 which is cut in such a way as to receive the profile of the mast 1. It comes to bear on a bush 65, itself bolted to the deck 66 of the boat. On the profile of the mast, a collar 67 is provided, which is adhesively bonded to the profile in its part located above the deck 66, at the same time covering the bush 65, leaktightness between the collar 67 and the bush being ensured by a lip seal 68 being interposed.
It will be noted that, by virtue of this arrangement, the mast benefits from some freedom of upward displacement (of the order of a few centimeters), while at the same time the mast hole, leaktightness and bearing functions being maintained.
Reference is now made to FIGS. 11 a to 11 d in order to describe a first exemplary embodiment of a mast foot support according to the present invention, this support having been designated by the reference 21 in FIG. 2. In these figures, FIGS. 11 a and 11 b are respectively a view in vertical axial section, a side elevation view and a front view, and FIGS. 11 c and 11 d are respectively a plan view and a view in horizontal section.
In this first exemplary embodiment, the mast support consists of a carbon piece designated as a whole by the reference 69. This piece is designed so as to shut off the lower part of the profile of the mast 1, as can be seen clearly in FIGS. 11 a and 11 b, and also the lower part of the tube 3, said lower part being provided for the passage of the halyards. This piece has a general ‘hat’-shaped configuration, and it comprises inner and outer ribs so as to ensure its hold on the mast.
At the exit of the tube 3 for passage of the halyards, a cage 70 for housing the pulley wheels is provided, this cage making it possible to extract the halyards. The forces of the mast on the boat are transmitted by means of a support 71 comprising a spherical cavity dimensioned so as to house a sphere 72 mounted at the end of a threaded shaft 73 screwed into a support 64 bearing on the bottom of the boat. The vertical position of this sphere is therefore adjustable in this way. For this purpose, a flat is provided on the sphere 72, in order to rotate the latter and to make it possible to raise and lower the mast. The shutoff piece, 69 comprises ribs, such as 75 (FIG. 11 d), in order to ensure the stability of the profile.
FIGS. 12 a to 12 c illustrate an alternative embodiment of the mast hole piece. In this variant, the component elements of the mast hole piece described above with reference to FIGS. 11 a to 11 d are found again, but, here, the spherical support of the mast foot is replaced by a cylindrical tube 76 which can be produced from laminate or from cast aluminum and onto which the shutoff piece 69 is engaged, this tube supporting the mast and also the pulley wheel box 70.
It becomes apparent from the foregoing description that the invention makes it possible to produce carbon masts, all the fittings of which contribute to ensuring leaktightness, this manufacture being easy and economical to implement.
It goes without saying that the present invention is not limited to the exemplary embodiments described and illustrated above, but that it embraces all the variants of these.

Claims

1. A carbon mast produced from a tube, in particular consisting of preimpregnated material, manufactured by filament winding or by pultrusion, characterized in that said tube (1) is kept leaktight by securing to it by adhesive bonding the attachment pieces of the various elements equipping the mast and, in particular, the mast head piece (15), the fitting (16) for attaching the spinnaker, the fitting (17) for attaching the stay and shrouds, the fitting (18) for attaching the crosstrees, the fitting (19) for attaching the boom and the fittings (20, .21) for the mast hole and for the mast foot respectively, these various fittings being produced so as to contribute to ensure the leaktightness of the mast.

2. The mast as claimed in claim 1, characterized in that the various attachment pieces comprise a horseshoe-shaped fitting which is designed so as to be laid against the walls of the tube (1) forming the mast, at the same time fitting snugly with the profile of these, said horseshoe-shaped fitting having inner dimensions slightly smaller than the external profile of the mast, and its installation on this profile being ensured with the aid of a gripper (27) which comes to bear on the attachment piece (29) by means of a nose.

3. The mast as claimed in claim 1, characterized in that the adhesive bonding of the attachment pieces to the carbon tube (1) forming the profile of the mast is carried out by the injection of glue via ducts (36) provided in said pieces.

4. The mast as claimed in claim 1, characterized in that said attachment pieces are produced by molding, using a mold core (22), in which is positioned a countermold (23) consisting, in particular, of silicone reinforced with glass or carbon fibers, multidirectional external and internal fabrics (24), between which are installed unidirectional threads, being stretcher-leveled in the mold, the assembly subsequently being placed in the silicone mold (23) and then closed on the mold core (22), before being put under vacuum and then placed in an oven or in an autoclave.

5. The mast as claimed in claim 4, characterized in that, before the countermold (23) is closed on the mold core (22), a film (26) consisting, in particular, of ribbed silicone is placed around the core (22), in order to obtain the ducts by means of which injection of the glue ensuring the securing of the piece to the profile of the mast is carried out.

6. The mast as claimed in claim 1, characterized in that a plastic tube (3) intended for receiving the halyards (4) is adhesively bonded to the rear of the profile of the mast (1) and within the latter, and tubes of smaller diameter (5) may be provided for the passage of the electrical wires through the mast.

7. The mast as claimed in claim 6, characterized in that the installation and securing of the tube (3) receiving the halyards are carried out by adhesive bonding, by depositing adhesive tapes (9) on said tube and by placing the tube on a support (10) equipped with claws (11) forming a cradle on which said tube rests, this support being pushed into the profile of the mast and then driven in rotation in such a way that the tube comes into position at the appropriate location in the profile of the mast, at the same time resting on the adhesive tapes, a weight (12, 13) being provided in order to ensure the pressure necessary for the setting of the adhesive bond.

8. The mast as claimed in claim 1, characterized in that it comprises an external profile (8), fixed to the profile of the mast (1) in order to ensure the protection of the halyards (4) and of the electrical wires (6).

9. The mast as claimed in claim 1, characterized in that the piece for attaching the stay or for the engagement of, the spinnaker (16) consists of unidirectional and multidirectional fibers, and it is composed of a horseshoe-shaped fitting (31) coming into position on the mast, at the same time fitting snugly with the external shape of the profile of the latter, this piece adhesively bonded to the mast receiving a stirrup (32) for anchoring the stay and for installing the halyard pulleys, this stirrup being held on the fitting (31) with the aid of a shaft (33), a metal bush (34) being interposed between said shaft and support bearings (35) forming an integral part of the fitting (31).

10. The mast as claimed in claim 1, characterized in that the piece (17) serving for attaching the stay and shrouds consists of a horseshoe-shaped fitting (38), the role of which fits snugly with the external profile of the mast and which comprises two ribs (39, 39′) receiving shroud carrier stirrups (40, 40′) which are held on the fitting (38) with the aid of articulation shafts.

11. The mast as claimed in claim 1, characterized in that the piece (18) supporting the crosstrees and carrying the shrouds consists of a horseshoe-shaped fitting (41) which is positioned on the external profile of the mast, at the same time fitting snugly with the shape of said profile, this fitting comprising ribs (41, 41′) between which is interposed a shroud carrier stirrup (42) bearing on a reinforcing tube (43), the crosstrees (44, 44′) being supported with the aid of a bush (45) by means of a threaded rod (46), onto which is screwed a bush (47) receiving the respective end of the crosstrees.

12. The mast as claimed in claim 1, characterized in that the piece (18) supporting the crosstrees and carrying the shrouds consists of a horseshoe-shaped fitting (48) which is positioned on the external profile of the mast, at the same time fitting snugly with the shape of said profile, this fitting consisting of a corrugated and ribbed skin, to which are screwed threaded rods (49), at the end of which is provided a sphere (50) on which a spherical bearing surface provided at the end of each crosstree (52) comes to bear.

13. The mast as claimed in claim 11, characterized in that each shroud (53) terminates in a hemispherical head (54) which bears on a carbon shoulder (55) by means of a friction cup (56), this shoulder being prolonged forward and rearward in order to receive the crosstree supports (57), these supports forming part of said fitting (48).

14. The mast as claimed in claim 1, characterized in that it comprises a leaktight mast head (15) which is engaged onto the upper part of the profile of the mast (1), this mast head comprising a collar (60) surrounding the upper part of the mast and also a projecting part (59) for the passage of the halyards.

15. The mast as claimed in claim 1, characterized in that said mast hole piece (20) consists of a circular element (64) shaped so as to receive the profile of the mast 1, this piece bearing on a bush (65) secured to the deck of the boat, a collar (67) being adhesively bonded to the profile of the mast so as to cover the bush (65), a seal (68) ensuring leaktightness between said collar and said bush.

16. The mast as claimed in claim 1, characterized in that the mast foot support (21) consists of a carbon piece (69) designed so as, to shut off the lower part of the profile of the mast, a cage (70) being provided for housing the pulley wheels.

17. The mast as claimed in claim 16, characterized in that the forces of the mast on the boat are transmitted by means of a support (71) comprising a spherical cavity, in which is housed a sphere (72) mounted at the end of a threaded shaft (73) in engagement in a support (64) bearing on the bottom of the boat, the vertical position of said sphere being adjustable.

18. The mast as claimed in claim 16, characterized in that the forces of the mast on the boat are transmitted by means of a cylindrical tube (76) onto which the shutoff piece (69) is engaged, this tube supporting the mast and also the pulley wheel box.