WO2009034595A1

WO2009034595A1 - Device and method for moving a drop keel of a boat

Info

Publication number: WO2009034595A1
Application number: PCT/IT2008/000468
Authority: WO
Inventors: Roberto Belardinelli
Original assignee: Roberto Belardinelli
Priority date: 2007-09-12
Filing date: 2008-07-11
Publication date: 2009-03-19
Also published as: ITMI20071752A1

Abstract

A device (10) for moving a drop keel (7) of a boat (1) floating or intended to float in un fluid medium (2) between an extended position and a withdrawn position comprises a moving member (11) mobile from an extended position to a withdrawn position according to a withdrawing movement and from the withdrawn position to the extended position according to an extending movement. The moving member (11) is connected to the drop keel (7) so that, when the moving member (11) is in the extended position, the drop keel (7) is in the extended position, and when the moving member (11) is in the withdrawn position, the drop keel (7) is in the withdrawn position. The device (10) also comprises a pressure chamber (12) able to be at least partially- filled with a working fluid at a working pressure, wherein such a working fluid is suitable for exerting a pressure force on the moving member (11) suitable for causing its withdrawing movement, and pressurisation means (13) suitable for keeping the working fluid in the pressure chamber (12) at the working pressure during the withdrawing movement of the moving member (11). The working fluid is at least partially provided by the fluid medium (2) in which the boat (1) floats or is intended to float.

Description

DESCRIPTION

DEVICE AND METHOD FOR MOVING A DROP KEEL OF A BOAT

The object of the present invention is a device for moving a drop keel of a boat. Another object of the present invention is a method for moving such a drop keel .

Numerous types of boat, in particular sailing boats, have a drop keel having a stabilising function during navigation. Drop keels comprise a main body that have a heavy bulb applied to its end. Such a heavy bulb has the main function of opposing the torques that are generated when the boat tilts to one side due to the effect of the wind acting on the sail, in this way avoiding it from flipping over. When the boat has to navigate in areas with shallow beds, for example in ports or near to the coast, the drop keel, which extends downwards from the hull, can constitute a hindrance too navigation since it can knock against the seabed with possible damage to the boat and therefore with possible risks to the well-being of the passengers .

In order to avoid this problem, it is known to equip boats with mobile drop keels, i.e. drop keels capable of projecting from the hull up to an extended position, suitable for navigation, and of at least partially withdrawing up to a withdrawn position when there is the risk of knocking against shallow beds.

The movement of such mobile drop keels takes place through moving devices that usually comprise one or more cylinder-piston groups connected to the drop keel through variously configured mechanical transmissions. Due to the great weights of drop keels, which are mainly due to the presence of the heavy bulbs, the piston of the cylinder- piston groups are moved through the pressure force on them of a working fluid at high pressure, which is reached by means of a suitable fluid treatment unit arranged on the boat . In order to ensure a correct operation of the moving device special working fluids are used, capable of working at the high working pressures required as well as of withstanding the increases in temperature as a consequence of the treatment in the pressurisation unit without boiling. The working fluids used in known devices are usually selected from the group of mineral oils . Such moving devices according to the prior art, however, are not without drawbacks.

Known devices, even when optimally assembled and maintained, are inevitably subject to small oil leaks, which can have an environmental impact upon the fluid medium in which the boat navigates, in particular on seas, lakes or rivers. Moreover, known devices have large bulks due to the presence of oil collection tanks as well as the transmissions^" arranged between the pistons and the drop keel . The purpose of the present invention is therefore to provide a device and a method for moving a drop keel of a boat that allows at least some of the quoted problems with reference to the prior art to be overcome.

In particular, the purpose of the present invention is to provide a device and a method for moving a drop keel of a boat that allow the pollution risks connected to them of seas, lakes or river (or similar) , in which the boat floats or is intended to float.

These and other purposes are accomplished through a device for moving a drop keel of a boat in accordance with claim 1, a boat in accordance with claim 35 and a method for moving a drop keel of a boat in accordance with claim 36.

In order to better understand the invention and appreciate its advantages some non-limiting example embodiments thereof shall be described hereafter, with reference to the attached figures, in which: figure 1 is a schematic side view of a boat equipped with a mobile drop keel; figure 2 is a schematic perspective view of a moving device of the drop keel of a boat according to an embodiment of the invention; figure 3 is an exploded schematic perspective view of the device^' in figure 2 ; figure 4 is a schematic side view, according to the arrow C, of the device in figure 2 in one particular condition of use; figure 5 is a schematic side view, from the same angle as the device in figure 4 in a further condition of use; figure 6 is a schematic section view, according to the plane D of the device in figure 2; figure 7 is a schematic section view, according to the plane D of the device in figure 2 in a further condition of use; figure 8 is a schematic section view, according to the plane E of the device in figure 2; figure 9 is a schematic section view of the device in figure 6 according to a further embodiment of the invention; figure 10 is a schematic section view of the device in figure 7 according to a further embodiment of the invention; figure 11 is a schematic side view according to the arrow F of a detail of the device in figure 2 according to a further embodiment of the invention.

With reference to the figures, a boat is indicated with reference numeral 1. The boat 1 floats or is intended to float, in normal conditions of use, in a fluid medium 2, for example a sea, a lake, a river or similar. The boat 1 is preferably shaped and sized to be able to float and navigate in water, in particular fresh water or sea water! The boat 1 comprises a hull 3 intended to be partially immersed in the fluid medium 2. In particular, the hull 3 comprises a submerged portion 4 intended to be submerged in the fluid medium 2 below a water line 5. Such a water line 5 can of course not have a fixed configuration and position during navigation, but can move and change shape. Consequently, the shape and size of the submerged portion 4 of the hull 3 can also vary. The boat 1 also comprises a steering rudder 6 and a drop keel 7 projecting from the hull 3. The drop keel 7 comprises a main body 8, for example having a wing-shaped profile, and preferably a bulb 9 with a heavy weight. The bulb 9 has the function of opposing the torques that are generated when the boat 1 is tilted to one side, for example due to the force of the wind on the sails, avoiding it from flipping over. The wing-shaped profile of the main body 8 ensures a low resistance to forward motion and ensures that the boat 1 has high stability during navigation.

The boat 1 is equipped with a device 10 for moving the drop keel 7 between an extended position and a withdrawn position. When it is in the extended position, the drop keel 7 has a configuration with high draft in the fluid medium 2 (see for example figure 4) and is therefore suitable for navigation of the boat 1, for example in open seas. When it is in the withdrawn position, the drop keel 7 has a configuration with lower draft compared to when it is in the extended position

(see for example figure 5) and is therefore suitable for crossing areas with shallow beds, like for example ports or coastal areas.

With reference for example to figures 4 and thereafter, the moving device 10 comprises a moving member 11 mobile from an extended position to a withdrawn position according to a withdrawing movement and from the withdrawn position to the extended position according to an extending movement . The moving member 11 is connected to the drop keel 7 so that:

- when the moving member 11 is in its extended position, the drop keel 7 is in its extended position

(see for example figure 6) ;

- when the moving member 11 is in its withdrawn position, the drop keel 7 is in its withdrawn position

(see for example figure 7) . The moving device 10 also comprises a pressure chamber 12 that can be at least partially filled with a working fluid at a working pressure. The working fluid is suitable for exerting a pressure force on the moving member 11 suitable for causing its aforementioned withdrawing movement. The working pressure of the working fluid in the pressure chamber 12 during the withdrawing movement of the moving member 11 is kept by suitable pressurisation means 13.

Advantageously, the working fluid is at least partially provided by the fluid medium 2 in which the boat 1 floats or is intended to float. In other words, the working fluid suitable for being used inside the moving device 10 to exert the pressure force on the moving member 11, once taken to and kept at the working pressure, can, at least partially, be taken from the fluid medium 2. For example, the working fluid (or part of it) can be taken directly from the seas, lakes or rivers (or similar) in which the boat 1 actually floats

(with reference for example to the normal conditions of use of the moving device installed on the boat 1 that has been launched or else in demonstration conditions in artificial tanks) or in which it is intended to float

(with reference to the condition of the boat 1 not yet launched into the fluid medium) . Consequently, the working fluid¹ itself will comprise (or will be entirely made up of) sea water, lake water, river water or similar and therefore possible losses thereof, for example due to leaks, in the fluid medium 2 will not of course have any- relevant environmental impact. The operation of the device with fresh water (for example from a river or lake) or salt water (for example from the sea) or treated water (for example for artificial tanks) , thus reduces the problems connected to the circulation of polluting working fluids (in particular mineral oils) , described previously with reference to the moving devices according to the prior art . The moving device 10 can be configured so as to be able to pick up the working fluid from a source outside of it. For example, the working fluid can be collected in suitable collection means (not shown in the figures) and picked up by the device 10 as needed. Alternatively, advantageously, the moving device is configured in such a way as to be able to take the working fluid from a source of working fluid outside the boat 1. In accordance with an embodiment, the source of working fluid comprises the same fluid medium 2 in which the boat is intended to float or in which it floats. In other words, the moving device 10, in conditions of use, is able to pick up the working fluid directly from the fluid medium 2 in which the boat floats, thus for example directly from the sea, from a lake or from a river. Consequently, it is not necessary to load the boat with bulky and heavy supplies of working fluid since it is always available outside of the boat 1 in its normal conditions of use.

According to a possible embodiment, the pressurisation means 13 are suitable for keeping the working pressure of the working fluid in the pressure chamber 12 at a value equal to or below 10 bars during the withdrawing movement of the moving member 11. It should be remembered that the pressure values indicated in the present description and in the subsequent claims should be taken in the sense of relative pressures. In other words, so that the moving member 11 can carry out its withdrawing movement, it is necessary for the working fluid in the pressure chamber to be at a suitable working pressure, the value of which is suitable for triggering such a movement depends upon the configuration of the moving member itself . The moving member 11 is preferably configured so that the suitable working pressure value is less than or equal to 10 bars. Such a working pressure value of the working fluid in the pressure chamber is advantageously maintained during the withdrawing movement by the pressurisation means.

In accordance with a further embodiment, the pressurisation means 13 are suitable for keeping the working pressure of the working fluid at a value equal to or below 3 bars, preferably at a value of between 2.6 and 2.7 bars. Such pressures are compatible with the physical properties of water and at the same time allow the moving device to undergo not excessively high stresses, which ensures a high reliability thereof .

Advantageously, the moving member 11 is mobile, preferably able to slide, in the pressure chamber 12 and, with further advantageousness, the drop keel 7 is firmly connected to the moving member 11. This allows the overall bulk of the device 10 to be further reduced since it is not required to have mechanical transmission arranged between the moving member 10 and the drop keel 7. Even more advantageously, the drop keel 7 is at least partially received and preferably able to slide in the pressure chamber 12. In this way, in the passage from its withdrawn position to its extended position, the drop keel 7 partially comes out from the pressure chamber 12 , and in the passage from its' extended position to its withdrawn position, it goes partially back into the pressure chamber 12. In other words, the pressure chamber 12 not only has the function of being at least partially filled with the working fluid at the working pressure necessary to bias and move the moving member 11 in its withdrawing movement, but it also has the function of partially housing the mobile drop keel 7, in particular a sliding portion 29 of its main body 8, when it is in its withdrawn position. This means a further reduction in overall bulk, since the drop keel 7 does not have to be housed in a special seat but can be housed directly inside the pressure chamber 12.

In accordance with an embodiment, the pressure chamber 12 is defined by a cylindrical body 14 of a cylinder-piston group 15 (figures 2-10) . Preferably, the cylindrical body 14 and the pressure chamber 12 in cross section have a substantially rectangular shape. Moreover, the moving member 11 advantageously comprises a piston 16 of the cylinder-piston group 15, preferably connected so that it can slide as a unit with the drop keel 7. The piston 16 is able to slide in the pressure chamber 12 between a lowered position and a raised position. The lowered position of the piston 16 corresponds to the extended position of the moving member 11 (figure 6) and the raised position of the piston 16 corresponds to the withdrawn position of the moving member 11 (figure 7) . Consequently, the lowered position of the piston 16 corresponds to the extended position of the drop keel 7 and the raised position of the piston 16 corresponds to the withdrawn position of the drop keel 7. According to this configuration, if, in accordance with a possible embodiment, the cylindrical body 14 and the pressure chamber 12 defined by it extend along rectilinear axes, the sliding of the piston 16 in the pressure chamber are also rectilinear, as are the movements of the drop keel 7 with respect to and in the pressure chamber 12. In this way, advantageously, the drop keel 7 forms a stem of the cylinder-piston group 15. Preferably, the piston 16 has a substantially rectangular outer profile, so as to avoid rotations with respect to the pressure chamber.

From now on, the movement of the piston 16 from the lowered position to the raised position shall be indicated with the expression "raising movement" , whereas the movement of the piston 16 from the raised position to the lowered position shall be indicated with the expression "lowering movement" . The same expressions can also be used for the movements of the drop keel 7, preferably connected so as to slide as a unit with the piston 16, as stated.

Advantageously, the piston 16 divides the pressure chamber 12 into a thrusting portion 17 that is intended to receive the working fluid kept at the working pressure and into a free portion 18 opposite the thrusting portion 17. The volumes of the thrusting portion 17 and of the free portion 18 of the pressure chamber 12 vary following the sliding of the piston 16 in the pressure chamber 12. In particular, when the piston 16 is in its raised position (figure 7) , the thrusting portion 17 reaches its maximum volume and the free portion 18 it minimum volume, whereas when the piston 16 is in its lowered position

(figure 6) the thrusting portion 17 reaches its minimum volume and the free portion 18 its maximum volume.

Advantageously, the piston 16 comprises a thrusting surface 19 facing towards the thrusting portion 17 of the pressure chamber 12. Such a thrusting surface 19 is suitable for ' cooperating with the working fluid at the working pressure so that the action of the latter in the thrusting portion 17 biases the raising movement of the piston 16. In other words, the thrusting surface 19 is of shape, orientation and size suitable for ensuring that the pressure force of the fluid at the working pressure equal to or less than 10 bars is suitable for triggering the raising movement of the piston 16. With further advantageousness, the thrusting surface 19 of the piston 16 is oriented so that the pressure force exerted on it by the working fluid kept at the working pressure opposes the force of gravity in normal conditions of use . Consequently, the raising movement of the piston 16 is opposed or has a component opposed to the direction of the force of gravity.

Advantageously, the drop keel 7, in particular its main body 8, is connected to the piston 16 at the thrusting surface 19. With further advantageousness, the piston 16 and the drop keel 7 are shaped so that the outer perimeter of the thrusting surface 19 defines a closed curve 20 that at least partially encloses inside of it the curves 21 defined by the outer perimeters of the drop keel 7 at each cross section of the sliding portion 29 thereof, intended, as stated, to be received in the pressure chamber 12 (see, for example, figure 11) . Preferably, the piston 16 and the drop keel 7, in particular it^'s main body 8, are substantially coaxial to one another. In accordance with an embodiment, the piston 16 comprises a frusto-conical element 22 on the outside at least partially defined by an outer surface 26 (figures 3, 6-8) . Such a frusto-conical element 22 is suitable for inserting in a corresponding frusto-conical seat 23, preferably formed inside the pressure chamber 12, when the piston 16 is in its lowered position. The coupling of the frusto-conical element 22 and of the frusto-conical seat 23 ensures the correct positioning of the drop keel- piston group when the piston 16 is in its lowered position. Moreover, such a coupling avoids undesired movements, in particular oscillations, of such a drop keel-piston unit with respect to the hull 3 through the effect of the friction between the walls of the frusto- conical element 22 and of the frusto-conical seat 23. Advantageously, the frusto-conical element 22 comprises a through opening 24 suitable for receiving the sliding portion 29 of the main body 8 of the mobile drop keel 7 at an end 25 thereof facing towards the piston 16.

According to a possible embodiment, the frusto- conical element 22, in particular its outer surface 26, at least partially forms the thrusting surface 19. For this purpose, the frusto-conical element 22 is advantageously tapered according to the direction of the lowering movement of the piston 16, so that the pressure force of the working fluid at the working pressure is suitable for biasing the raising movement of the piston 16.

Advantageously, the moving device 10 comprises guide means suitable for guiding the piston 16 in its sliding in the pressure chamber 12 (see for example figures 3, 6, 7) . In accordance with an embodiment, such guide means comprise a first guide plate 27 provided with a through opening 28 having a profile substantially matching the outer profile of the sliding portion 29 of the main body 8 of the drop keel 7. Preferably, the first guide plate 27 is fixed onto the bottom of the hull 3, outside of it. The guide means can also comprise a second guide plate 30, preferably connected to the piston 16, having an outer profile substantially matching the inner profile of the pressure chamber 12, so as to be able to slide inside Of it.

Advantageously, the moving device 10 comprises sealing means suitable for limiting leaks of the working fluid between the thrusting portion 17 and the free portion 18 of the pressure chamber 12 and/or between the pressure chamber 12 and the space outside of it, for example the inside of the hull or the fluid medium 2 in which the boat 1 floats. According to a possible embodiment, the sealing means comprise a first gasket 31 preferably housed in a first sealing seat 32 formed in the first guide plate 27 and oriented so that the first gasket 31 is arranged between the guide plate 27 and the bottom of the hull 3. The sealing means can also comprise a second sealing gasket 33, preferably housed in a second sealing seat 34 formed by the piston 16. For example, the second sealing seat 34 can be defined by the frusto- conical element 22 and by a sealing plate 35 arranged between the frusto-conical element 22 itself and the second guide plate 30.

Advantageously, the moving device 10 comprises means for locking the piston 16 in its lowered position and/or in its raised position. According to a possible embodiment, such locking means comprise one or more, preferably two locking rods 36 that comprise a low threaded portion 37 and a high threaded portion 38

(figures 9 and 10) . Such low and high threaded portions 37, 38 are both suitable for being screwed into a corresponding threaded seat 39 of the drop keel 7 or of the piston 16 and are arranged so as to lock them when they are in the lowered position and in the raised position, respectively. In this way, when the piston 16 is in its raised position (figure 10) , it is possible to empty the thrusting portion 17 of the pressure chamber 12 008/000468

from working fluid since the weight of the drop keel- piston group is opposed by the forces deriving from the threaded connection of the high threaded portion 38 of each of the locking rods 36 with each of the threaded seats 39. When the piston 16 is in its lowered position

(figure 9) , the thrusts of the fluid medium 2 on the drop keel 7, which would tend to make it carry out a raising movement, are opposed by the forces deriving from the connection of the low threaded portion 37 of each of the locking rods 36 with each of the threaded seats 39. The threaded seats 39 are preferably formed in a locking plate 40 able to be inserted and locked in a cavity 41 of the main body 8 of the drop keel 7, at its end 25. Such a cavity 41 has the further function of receiving inside of it the locking rods 36 when the piston 16 is in its raised position (as can be seen for example in figure 10) .

Each of the locking rods 36 can be manoeuvred manually or through the help of suitable actuators (not shown in the figures) . According to a possible embodiment, each of the locking rods 36 comprises a portion 42 projecting outside of the cylindrical body 14, so as to allow screwing and unscrewing, from outside of the cylindrical body 14. According to such an embodiment, upper through openings 43 of the cylindrical body 14 are provided, suitable for allowing the passage towards the outside of each of the locking rods 36, in particular of their projecting portions 42. Such upper through openings 43 are preferably formed in a removable plate 44 of the cylindrical body 14 and are configured so as to allow the arrangement between the removable plate 44 and the locking rods 36 of further sealing means 45, for example gaskets, so as to avoid leaks of working fluid between the free portion 18 of the pressure chamber 12 and the inside of the hull 3. In order to allow the sliding of the locking rods 36, corresponding through openings 43' and 43" may be provided also in the sealing plate 35 and in the second guide plate 30, respectively. It should be noted that the threaded seats 39 are also of a size such as to allow the sliding inside them of the locking rods 36 when neither the low threaded portions 37, nor the high threaded portions 38 engage the threaded seats 39. In this way, the locking means do not impede the raising and lowering movements of the piston 16 and of the drop keel 7. Advantageously, the moving device 10 comprises a hydraulic circuit 46 for the distribution and pressurisation of the working fluid (figures 6 and 7) . Such a hydraulic circuit 46 preferably includes the pressurisation means 13, for example a pump 47 suitable for taking and keeping the working fluid at the working pressure. Moreover, the hydraulic circuit 46 is suitable for conveying the working fluid towards the pressure chamber 12 and for picking it up from it.

The hydraulic circuit 46 is configured in such a way as to allow the working fluid to be picked up and/or discharged, in particular from and into the fluid medium 2. For this purpose, the hydraulic circuit 46 advantageously comprises one or more openings intended to be arranged in the hull 3 of the boat 1 below the water line 5 thereof . In order to control the distribution of the working fluid inside of it, the hydraulic circuit 46 can comprise suitable distribution means, like for example check valves, recirculation pumps, taps, adjustable opening valves or gate valves, as well as a plurality of interconnected ducts. In this way, it is possible to convey the working fluid into the various parts of the hydraulic circuit 46 according to the required operations .

Hereafter, a description of the configuration and operation of the hydraulic circuit 46 according to a possible embodiment of the invention is provided. According to such a possible embodiment, the hydraulic circuit 46 comprises a discharge and intake opening 48 arranged below the water line 5 of the hull 3, having the dual function of picking up working fluid and of discharging it into the fluid medium 2 in which the boat 1 floats in normal conditions of use. Preferably, the discharge and intake opening 48 is arranged on the bottom of the hull 3^".

With reference to the direction of the working fluid when it is picked up from the fluid medium 2 and conveyed towards the pressure chamber 12, downstream of the discharge and intake opening 48 an adjustable inlet valve 49 can be provided suitable for modifying the flow rate of working fluid inside the hydraulic circuit 46. In particular, such an inlet valve 49 can be opened when it is necessary to take working fluid to the hydraulic circuit 46 and it can be closed when this is no longer necessary and it is wished to avoid that the circulating working fluid be discharged into the fluid medium 2.. Downstream of the inlet valve 49 there can be a pressure line 50 suitable for conveying the working fluid up to the pressure chamber 12. The pressurisation means 13, in particular the pump 47, are preferably arranged along the pressure line 50. Moreover, along the pressure line 50 there can be at least one check valve 51 suitable for preventing the working fluid from crossing the pump 47 in the opposite direction to that necessary for the pressurisation of the working fluid. The pressure line 50 opens out into the pressure chamber 12 through an opening 55, preferably at the thrusting portion 17 in a position such as to strike the frusto-conical element 22 when the piston 16 is in its lowered position. In this way, the working fluid, kept at the suitable working pressure by the pump 47", striking the frusto-conical element 22 exerts a thrust on it, in particular on the thrusting surface 19, sufficient to bias the piston 16 away from its lowered position towards its raised position.

When the piston 16 has reached its raised position, the thrusting portion 17 of the pressure chamber 12 is filled with working fluid kept at the working pressure by the pump 47. As described earlier, the piston 16 can be locked in its raised position for example through the locking rod 46. In this condition, the pressure force of the working fluid is no longer necessary to keep the piston 16 in the raised position and therefore it is preferable to discharge the working fluid, so as not to keep a heavy weight loaded on the boat 1. For this purpose, in the hydraulic circuit 46 it is possible to foresee a discharge line 52 suitable for evacuating the working fluid from the thrusting portion 17 of the pressure chamber and discharging it into the fluid medium 2. The discharge line 52 is preferably arranged in parallel to the pressure line 50 and, even more preferably, it shares with it the opening 55, which places it in fluid communication with the thrusting portion 17 of the pressure chamber. When the working fluid is discharged through the discharge line 52, the check valve 51 prevents it from crossing the pump 47 in the opposite direction to that suitable for pressurisatioh. In the discharge line 52 an adjustable distribution valve 53 is preferably provided, which can be opened when it is required to discharge the working fluid and which is preferably kept closed when the working fluid is sent to the thrusting portion 17 of the pressure chamber 12 and kept at the working pressure. The working fluid thus picked up can be discharged from the hydraulic circuit 46 through the discharge and intake opening 48 following the at least partial opening of the adjustable inlet valve 49.

The hydraulic circuit 46 can also foresee an auxiliary distribution line 54 suitable for placing the free portion 18 of the pressure chamber 12 in fluid communication with the discharge and intake opening 48, and therefore with the fluid medium 2 in which the boat 1 floats. Preferably, such an auxiliary distribution line 54 is in fluid communication with the pressure line 50 and the discharge line 52. The auxiliary distribution line 54 has the function of allowing the discharge of the air and of the working fluid present in the free portion 18 of the pressure chamber during the raising movement towards the raised position of the piston 16. The working fluid can, indeed, collect inside the free portion 18 of the pressure chamber 12 through dripping from the thrusting portion 17 or through sucking due to depressions that can be created in the free portion 18 following the lowering movement of the piston 16.

Hereafter a method for moving the mobile drop keel 7 from the extended position to the withdrawn position with reference to the embodiments described above is described.

In accordance with the present invention, the method for moving a drop keel 7 of a boat 1 floating or intended to float in a fluid medium 2 from an extended position to a withdrawn position, in which the drop keel 7 is connected to a moving member 11 that is mobile from an extended position to a withdrawn position according to a withdrawing movement and from such a withdrawn position to such an extended position according to an extending movement so that, when the moving member 11 is in the extended position, the drop keel is in the extended position, and when the moving member 11 is in the withdrawn position, the drop keel is in the withdrawn position, comprises the steps of:

- providing a working fluid;

- at least partially filling a pressure chamber 12 with the working fluid at a working pressure, so as to exert a pressure force on the moving member suitable for causing its withdrawing movement;

- keeping the working fluid in the pressure chamber 12 at such a working pressure during the withdrawing movement of the moving member, in which the working fluid is at least partially provided by the fluid medium 2 in which the boat 1 floats or is intended to float .

According to a possible embodiment, during the withdrawing movement of the moving member 11 the working pressure of the working fluid in the pressure chamber is kept at a value equal to or less than 10 bars. According to a further possible embodiment, during the withdrawing movement of the moving member 11 the working pressure of the working fluid in the pressure chamber is kept at a value equal to or less than 3 bar, preferably at a value of between 2.6 and 2.7 bar . According to a possible embodiment, the method comprises a further step of picking up the working fluid necessary for the pressure force on the moving member 11 from a fluid source outside of the boat 1.

Advantageously, such a fluid source comprises the fluid medium 2 in which the boat is suitable for floating or floats, preferably sea water, lake water or river water (or similar) .

In accordance with an embodiment, the method also comprises a locking step of the moving member in the withdrawn position.

According to a further embodiment, the method also comprises a step of discharging the working fluid from the pressure chamber following the locking step of the moving member in the withdrawn position.

From the description that has been given above, the man skilled in the art can appreciate how the device and method for moving a drop keel of a boat according to the invention solve at least some of the quoted problems with reference to the prior art .

In particular, the man skilled in the art will understand how the device and method according to the invention, being able to work with a working fluid that is at least partially provided by the fluid medium in which the boat floats or in which it is intended to float, wipe out the problems of pollution connected to possible leaks of the working fluid itself.

The possibility of keeping the working fluid at low pressures, preferably below 10 bars, means low stresses on the device and therefore an overall increased reliability of the device. Moreover, the man skilled in the art can appreciate how the device and method according to the invention allow low overall bulks. Indeed, the working fluid does not necessarily have to be collected permanently, but can be picked up, at least partially, as necessary directly from the fluid medium. The bulks can also be further reduced thanks to the housing of the drop keel directly inside the pressure chamber.

Of course, variants and/or additions to what has been described and illustrated above can be foreseen.

For example, according to a possible variant, the drop keel could be rotatably mobile with respect to the hull and the moving member could comprise rotary blades that can be actuated following the pressure force of the working fluid at the working pressure.

According to a further variant, the piston and the drop keel could slide in two distinct chambers, for example arranged next to one another or else one on top of the other .

According to a further variant, the drop keel could be arranged outside of the volume cleared by the piston in its raising and lowering movements.

According to a further variant, it is possible to add additives of various types to the working fluid at least partially provided by the fluid medium in which the boat floats or is intended to float. Of course, the man skilled in the art can make numerous changes, modifications or replacements of elements with others that are functionally equivalent to the embodiments described above of the device and of the method for moving a drop keel of a boat, in order to satisfy contingent and specific requirements, without however departing from the scope of the following claims. *** * ***

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Claims

DEVICE AND METHOD FOR MOVING A DROP KEEL OF A BOAT 1. Device (10) for moving a drop keel (7) of a boat (1) floating or intended to float in a fluid medium (2) between an extended position and a withdrawn position, comprising:

- a moving member (11) mobile from an extended position to a withdrawn position according to a withdrawing movement and from said withdrawn position to said extended position according to an extending movement, said moving member (11) being connected to said drop keel (7) so that, when the moving member (11) is in said extended position, the drop keel (7) is in said extended position, and when the moving member (11) is in said withdrawn position, the drop keel (7) is in said withdrawn position;

- a pressure chamber (12) able to be at least partially filled with a working fluid at a working pressure, said working fluid being suitable for exerting a pressure force on said moving member (11) suitable for causing it to make a withdrawing movement;

- pressurisation means (13) suitable for keeping said working fluid in the pressure chamber (12) at said working pressure during said withdrawing movement of the moving member (11) , characterised in that said working fluid is at least partially provided by said fluid medium (2) in which said boat (1) floats or is intended to float.

2. Device (10) according to the previous claim, wherein said working fluid comprises sea water, lake water or river water.

3. Device (10) according to any one of the previous claims, configured in such a way as to be able to take said working fluid from a fluid source outside of said moving device (10) .

4. Device (10) according to any one of the previous claims, configured in such a way as to be able to take said working fluid from a fluid source outside of said boat (1) .

5. Device (10) according to claim 3 or 4, wherein said fluid source comprises said fluid medium (2) in which said boat (1) floats or is intended to float.

6. Device according to any one of the previous claims, wherein said pressurisation means (13) are suitable for keeping said working pressure of the working fluid in the pressure chamber (12) at a value equal to or below 10 bars during said withdrawing movement of the moving member (11) .

7. Device (10) according to the previous claim, wherein said pressurisation means (13) are suitable for keeping said working pressure of the working fluid in the pressure chamber (12) at a value equal to or less than 3 bars during said withdrawing movement of the . moving member (11) .

8. Device (10) according to the previous claim, wherein said pressurisation means (13) are suitable for keeping said working pressure of the working fluid in the pressure chamber (12) at a value of between 2.6 and 2.7 bars during said withdrawing movement of the moving member (11) .

9. Device (10) according to any one of the previous claims, wherein said drop keel (7) is at least partially- received in said pressure chamber (12) .

10. Device (10) according to any one of the previous claims, wherein said drop keel (7) is at least partially mobile in said pressure chamber (12) .

11. Device (10) according to any one of the previous claims, wherein said moving member (11) is mobile in said pressure chamber (12) .

12. Device (10) according to any one of the previous claims, wherein said drop keel (7) is fixedly connected to said moving member (11) .

13. Device (10) according to any one of the previous claims, wherein said pressure chamber (12) is defined by a cylindrical body (14) of a cylinder-piston group (15) .

14. Device (10) according to the previous claim, wherein said moving member (11) comprises a piston (16) of said cylinder-piston group (15) , said piston (16) being able 008/000468

to move by sliding in said pressure chamber (12) between a lowered position, corresponding to said extended position of the moving member (11) , and a raised position, corresponding to said withdrawn position of the moving member (11) .

15. Device (10) according to the previous claim, wherein said piston (16) divides the pressure chamber (12) into a thrusting portion (17) intended to receive the working fluid at the working pressure and into a free portion (18) opposite the thrusting portion (17) , said thrusting and free portions (17, 18) having variable volumes following said sliding of the piston (16) in the pressure chamber (12) .

16. Device (10) according to the previous claim, wherein said piston (16) comprises a thrusting surface (19) facing towards said thrusting portion (17) of the pressure chamber (12) and suitable for cooperating with the working fluid at the working pressure so that the pressure force exerted on the thrusting surface (19) by the working fluid at the working pressure in the thrusting portion (17) biases the piston (16) away from said lowered position towards said raised position.

17. Device (10) according to the previous claim, wherein said thrusting surface (19) is oriented so that said pressure force on the thrusting surface (19) by the working fluid at the working pressure opposes the force of gravity .

18. Device (10) according to any one of claims 13 to 17, wherein said drop keel (7) forms a stem of said cylinder-piston group (15) .

19. Device (10) according to any one of claims 14 to 18, wherein said drop keel (7) and said piston (16) are connected so as to be able to slide as a unit.

20. Device (10) according to any one of claims 16 to 19, wherein said drop keel (7) and said piston (16) are connected at said thrusting surface (19) .

21. Device (10) according to any one of claims 16 to 20, wherein the outer perimeter of said thrusting surface

(19) defines a closed curve that at least partially encloses inside of it the curves defined by the outer perimeters of the drop keel (7) at each cross section of a sliding portion (29) of the latter intended to be received in the pressure chamber (12) .

22. Device (10) according to any one of claims 14 to 21, wherein said piston (16) and said drop keel (7) are substantially coaxial.

23. Device (10) according to any one of claims 14 to 22, wherein said piston (16) comprises a frusto-conical element (22) suitable for inserting into a corresponding frusto-conical seat (23) of the pressure chamber (12) when the piston is in the lowered position, said frusto- conical element (22) tapering in the direction that goes from the raised position to the lowered position of said piston (16) , so as to avoid relative movements between said frusto-conical element (22) and said frusto-conical seat (23) .

24. Device (10) according to the previous claim, when dependent upon claim 16, wherein said frusto-conical element (22) at least partially forms said thrusting surface (19) .

25. Device (10) according to any one of claims 14 to 24, comprising guide means (27,30) suitable for guiding the piston (16) in said pressure chamber (12) .

26. Device (10) according to any one of claims 15 to 25, comprising sealing means (31, 33, 45) suitable for limiting leaks of the working fluid between said thrusting portion (17) and said free portion (18) of the pressure chamber (12) and/or between said pressure chamber (12) and the space outside of it.

27. Device (10) according to any one of claims 14 to 26, comprising means (36,37,38,39) for locking said piston (16) in said lowered position and/or in said raised position.

28. Device (10) according to any one of the previous claims, wherein said pressurisation means (13) comprise a pump (47) .

29. Device (10) according to any one of the previous claims, comprising a hydraulic circuit (46) for the distribution and pressurisation of said working fluid.

30. Device (10) according to the previous claim, wherein said hydraulic circuit (46) is configured in such a way as to allow said working fluid to be picked up and/or discharged.

31. Device (10) according to claim 29 or 30, wherein said hydraulic circuit (46) comprises one or more openings (48) intended to be arranged in a hull (3) of said boat (1) below a water line (5) of the latter in said fluid medium (2) , so as to discharge and/or pick up the working fluid directly into/from said fluid medium (2) .

32. Device (10) according to any one of claims 29 to 31, wherein said hydraulic circuit (46) is suitable for conveying the working fluid towards and for discharging it away from said pressure chamber (12) .

33. Device (10) according to any one of claims 29 to 32, wherein said hydraulic circuit (46) includes said pressurisation means (13) suitable for keeping the working fluid in the pressure chamber (12) at said working pressure.

34. Device (10) according to any one of claims 29 to 33, wherein said hydraulic circuit (46) comprises distribution means (49, 47, 51, 53) of the working fluid suitable for adjustably distributing the working fluid in said moving device (10) and outside of it. 000468

35. Boat (1) comprising a drop keel (7) able to be moved between an extended position and a withdrawn position and a device (10) for moving said drop keel (7) according to any one of the previous claims.

36. Method for moving a drop keel (7) of a boat (1) floating or intended to float in a fluid medium (2) from an extended position to a withdrawn position, wherein said drop keel (7) is connected to a moving member (11) mobile from an extended position to a withdrawn position according to a withdrawing movement and from said withdrawn position to said extended position according to an extending movement so that, when the moving member

(11) is in said extended position, the drop keel (7) is in said extended position, and when the moving member (11) is in said withdrawn position, the drop keel (7) is in said withdrawn position, said method comprising the steps of :

- providing a working fluid;

- at least partially filling a pressure chamber (12) with said working fluid at a working pressure, so as to exert upon said moving member (11) a pressure force suitable for causing its withdrawing movement;

- keeping the working fluid in the pressure chamber at said working pressure during said withdrawing movement of the moving member (11) , characterised in that said working fluid is at least partially provided by said fluid medium (2) in which said boat (1) floats or is intended to float.

37. Method according to the previous claim, wherein during said withdrawing movement of the moving member (11) the working pressure of the working fluid in the pressure chamber (12) is kept at a value equal to or below 10 bars.

38. Method according to the previous claim, wherein during said withdrawing movement of the moving member (11) the working pressure of the working fluid in the pressure chamber (12) is kept at a value equal to or below 3 bars .

39. Method according to the previous claim, wherein during said withdrawing movement of the moving member (11) the working pressure of the working fluid in the pressure chamber (12) is kept at a value between 2.6 and 2.7 bars .

40. Method according to any one of claims 36 to 39, comprising the step of picking up the working fluid suitable for exerting said pressure force upon the moving member (11) from a fluid source outside of said boat (1) .

41. Method according to the previous claim, wherein said fluid source comprises said fluid medium (2) in which said boat (1) floats or is intended to float.

42. Method according to any one of claims 36 to 41, wherein said working fluid comprises sea water, lake water or river water.

43. Method according to any one of claims 36 to 42, also comprising a step of locking the moving member (11) in said withdrawn position.

44. Method according to the previous claim, also comprising a discharging step of the working fluid from the pressure chamber (12) following said locking step of the moving member (11) in the withdrawn position.