Title:
MECHANICAL FLUID DYNAMIC DEVICE FOR THE PROPULSION AND FLOW CONTROL IN THE WATER-JET PROPELLED BOATS
Kind Code:
A1


Abstract:
The device includes conveying ducts of the fluid (2, 9), a tubular mean (1) with variable internal volume (1′), a tapered onion-shaped body (17) centred (18) inside the tubular mean, a nozzle (16) for the ejection of the fluid adjustable in position and opening for the variation of said internal volume (11), one or more gas injectors (21), and means to change the direction of the jet (6). In this way a fluid with variable characteristics can be obtained which allows the adjustment of the intensity, flow, direction and slant of the jet (6), moreover releasable also above the water surface (10), in view of the optimisation of the increased performances and consumption reduction. Unlike the devices of the known technique suitable only to convey the fluid and give the flow a single direction, the jet (6) is not diverted by other members, but is oriented through the joint (8) which allows its displacement in all the directions, in fact thanks to this said jet (6) can be directed without damping. It finds peculiar application in the propulsion and control of the hydrodynamic flow in the water-jet propelled boats or craft, besides as retrofit of easy embodiment to be installed also on the boats that have a traditional water-jet.



Inventors:
Erriu, Fernando (Cagliari, IT)
Application Number:
12/374314
Publication Date:
12/31/2009
Filing Date:
07/19/2006
Primary Class:
International Classes:
B63H11/107
View Patent Images:
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Primary Examiner:
AVILA, STEPHEN P
Attorney, Agent or Firm:
JOHN ALEXANDER GALBREATH (REISTERSTOWN, MD, US)
Claims:
1. Mechanical fluid dynamic jet device for the propulsion and control of the hydrodynamic flow in the water-jet propelled boats, including conveying ducts of the fluid (2, 9), a tubular mean (1) with variable geometry and variable internal volume, a body (17) centred inside said tubular mean by means of a wing-shaped ring or support nut (18) with spokes or fluid dynamic blades, an adjustable nozzle (16) to eject the fluid, one or more gas injectors (21), and means (8, 22) to change the direction and the slant of the jet (6), characterised by the fact that the change of the volume of the chamber (1′) inside the tubular mean (1) for the control of the flow is obtained by displacement and opening of the adjustable nozzle (16) to change said internal volume (1′), without the need to change the shape and geometry of said nozzle (16) (FIG. 3).

2. Mechanical fluid dynamic jet device for the propulsion and control of the hydrodynamic flow in the water-jet propelled boats, according the claim 1, characterised by the fact that the movement of the nozzle (16) for the adjustment of the volume of the chamber (1′) inside the tubular mean (1) is carried out by a motorised system including a motor (12, 14, 24), like an electrical stepper motor, and by a gearbox, pinion and cogwheel (13, 15), suitable to displace, adjust and restrict said nozzle (16) from a minimum to a maximum opening position for the variation of the kinetic energy of the jet (6) itself. (FIG. 3).

3. Mechanical fluid dynamic jet device for the propulsion and control of the hydrodynamic flow in the water-jet propelled boats, according to claim 1 or 2, characterised by the fact that the tapered pinecone or onion-shaped body (17) to drive and control the flow is made of deformable plastic material and has a hole (17′) linked to a hydraulic circuit (17″) to be filled by a fluid to change its volume and obtain a further adjustable element to control the hydrodynamic flow (FIG. 4).

4. Mechanical fluid dynamic jet device for the propulsion and control of the hydrodynamic flow in the water-jet propelled boats, according to any one of the previous claims, characterised by the fact the ring or nut (18), on which the pinecone or onion-shaped body is mounted and centred (19, 20, 23) for guidance and control of the hydrodynamic flow inside the tubular mean (1), has a wing section or an aerodynamic profile (18″) and can move (18′) along the axis of the said body (17) from a minimum to a maximum point, to guarantee a depression at its centre and to direct the gas or air on the said onion-shaped tubular element, to determine a further adjustable element to change the parameters of the flow (FIG. 5).

5. Mechanical fluid dynamic jet device for the propulsion and control of the hydrodynamic flow in the water-jet propelled boats, according to any one of the previous claims, characterised by the fact that the injectors (21) are placed and arranged at the centre of the ring (18) with wing section (18″) to force the gas to lap only on the surface of the pinecone (17) without disperse on the chamber (1′).

6. Mechanical fluid dynamic jet device for the propulsion and control of the hydrodynamic flow in the water-jet propelled boats, according to any one of the previous claims, characterised by the fact that the jet (6), besides the possibility of a release underwater like the traditional water-jets, can be also released outside the water above the water surface (10), like a jet engine or water-jet, said option resulting more effective and more appreciable in terms of better performances.

7. Use of the mechanical fluid dynamic jet device for the propulsion and control of the hydrodynamic flow in the water-jet propelled boats, according to any one of the previous claims, characterised by the fact that it (1) is symmetrically arranged in a determined number of couples on the lateral walls of the hull to optimise the auxiliary manoeuvres in harbour, said water-jets (1) being fed by hydraulic pumps (29, 29′) through ducts (30, 30′) and shutters (27, 27′) driven by electrovalves (28, 28′) and controlled by joystick (FIGS. 6, 7).

8. Use of the mechanical fluid dynamic jet device, according to any one of the previous claims, for the control of the hydrodynamic flow in the propulsion and in the manoeuvre of the water-jet propelled boats or crafts.

9. Use of the mechanical fluid dynamic jet device for the propulsion and control of the hydrodynamic flow in the water-jet propelled boats, according to any one of the previous claims, for the control of the hydrodynamic flow in the propulsion and in the manoeuvre of the water-jet propelled boats or crafts, as a retrofit of easy embodiment to be installed also on the boats that have a water-jet or manoeuvring propellers of traditional type.

Description:

The subject of this invention is an integrated mechanical fluid dynamic device or unit to be coupled to a traditional boat water-jet, able to interact with the some jet and to modify all the characteristics of the said hydraulic flow, obtaining a water-jet controlled and adjusted in thrust and direction, with advantage to the best speed and consumption performances.

Currently and usually the water-jet propulsion units are not able or are not intended to control and adjust the parameters of the flow which determines the thrust, in fact, they are suitable only to convey the fluid and give the flow a single direction, according to the amount of pumped water, furthermore all the traditional water-jets utilise the pumping system with underwater release of the hydraulic flow under the surface of the water or at a level that from the start until the phase of planning remains immersed and disturbed by the ebb of the wake, contrary to this invention where the jet is expelled still at the beginning outside of the surface of the water.

Some water-jet propulsion devices have tried to intervene on the flux parameters through variation of volume, shape and direction of the nozzle by means of mobile surfaces or creating a poly-phase fluid, water-gas, but at expense of complicated mechanism mostly of complex carrying out and mostly expensive.

The propulsion unit, subject of this invention, unlike those of the known technique, allows essentially to adjust and control the characteristics of the flow and the pumped water jet, like density, speed, angle of incidence, direction, by variation of the motion among its internal components or movement of the whole unit, while in the traditional water-jets nothing of that happens, in fact they convey and eject the pumped water by variation of the shape of the walls or their rotation.

As far as the applicant knows in fact up to today the devices of the known technique do not allow the variation of the characteristics of the jet in this way.

In fact making reference of the next State-of-the-Art, the U.S. Pat. No. 5,692,371 shows a ram-jet engine where the change of the internal volume of the chamber and the orientation of the jet occur by variation of the relative position of the mobile foldable walls of the nozzle, kinematical adjustable bodies in its interior and rotation of a part of its walls, and neither by displacement of the nozzle or of the hydrodynamic body in the chamber nor by its rotation, all methods and devices that are detrimental to the efficiency of the jet.

The USA Patent Application 2003/0013356 presents a propulsion device with morphological characteristics similar to the above mentioned patent for the control of the flow and to operate it needs a three-phased system of liquid, that is it is based on a working principle fully different from that of this invention.

In fact the intake of the gas is in our case only functional to the variation and control of the characteristics of the jet, to increase its performance and complementary to its power, no to produce the main power of the jet.

In both cases the injection of the gas into the tubular chamber that generates the power occurs in a chaotic and aleatory way with reduced efficiency because of the increase of the pressure drops of the nozzle, while in our case the injection of the gas drawn from the internal combustion engine driving the hydro pump, that creates ad feeds the jet, has on the contrary the aim of complement to increase the efficiency and further control the flow. In fact it is released in a precise point at the middle of the ring element so that it laps against the whole surface of the onion or pinecone-shaped body, said gas, or alternatively compressed air, having a density lower than that of the water and a higher speed, reduces decidedly the friction between water and surface of the tubular onion or pinecone-shaped body so that it favours the fluency and increase at the same time the speed of the flow, lowering at the same time the pressure drops.

On the contrary the subject of this invention, by the adoption of the device as described and depicted in the following, allows through a variable volume directional chamber to increase the jet speed besides its angle of incidence, while the density is changed by the introduction of gas, for example the exhaust of the engine, into the same chamber, finally the kinetic energy of the jet is increased by the jet ejection above the surface of the water, and also by the effect of the said gas injection that in our case is not chaotic but circumscribed around the tubular body centred inside the chamber, with an adjustable slant which characterises the boat attitude.

That is the main difference from the methods of the known State of the Art, the subject device or unit bringing instead a considerable increase of the performance, both about speed and agility/handling. Especially in the phase of start and acceleration, in fact such system is able to make up for the drawbacks of the traditional water-jets, that in the start phase until the attainment of the plane, or at low speeds when the craft does not plane, give cause to an excessive consumption, caused mainly by the fact that the thrust energy given by the mass times the speed squared is higher in our system as consequence of the fact that we could increase the speed of the flow first allowing it to flux to open air, which has a noticeably lower density, and secondly imposing by a limited control an easier downflow of the fluid on the internal tubular body with injection of gas or compressed air.

In any case the jet results already by itself exceptional and efficient, also without the injection of gas or compressed air, because of the variation of its flow and direction.

More in detail, unlike the devices of the known technique, the present invention refers precisely to a mechanical fluid dynamic jet device for the propulsion and control of the hydrodynamic flow in the water-jet propelled boats, including conveying ducts of the fluid, a tubular mean with variable geometry and variable internal volumes, a body centred inside said tubular mean by means of a ring of wing aerodynamic section or a ring nut carrying spokes or fluid dynamic blades, an adjustable nozzle to eject the fluid, one or more gas injectors, and means to change the direction and the slant of the jet, characterised by the fact that the variation of volume of the internal chamber of the tubular mean for the flow control is obtained by displacement and opening of the adjustable nozzle to change said internal volume, without the need of variation of the shape and geometry of said nozzle.

Said mechanical fluid dynamic jet device for the propulsion and control of the hydrodynamic flow in the water-jet propelled boats, is furthermore characterised by the fact that the variation of the volume of the chamber inside the tubular mean for the control of the flow is obtained by displacement of the adjustable nozzle from a position of minimum opening to one of maximum opening.

Said mechanical fluid dynamic jet device for the propulsion and control of the hydrodynamic flow in the water-jet propelled boats, is furthermore characterised by the fact that the movement of the nozzle for the adjustment of the volume of the chamber inside the tubular mean is carried out by a motorised system including an electrical stepper motor and by a gearbox, pinion and cogwheel, or by a hydraulic actuation device, suitable to displacement, adjustment and restriction of the said nozzle from a minimum to a maximum opening position for the variation of the kinetic energy of the jet itself.

The device of the invention characterises itself also by including a hydrodynamic body for the guidance and the control of the flow inside the tapered onion-shaped chamber and by the fact that it is centred fixed inside the said tubular mean a wing-shaped ring or a ring nut carrying spokes or fluid dynamic blades.

In the mechanical fluid dynamic jet device for the propulsion and the control of the hydrodynamic flow in the water-jet propelled boats the tapered pinecone or onion-shaped body for guidance and control of the flow is of elastic deformable material and includes a hole connected to an hydraulic circuit to be filled with fluid to change its volume to obtain a further adjustable element to control the hydrodynamic flow.

So that the flow can be controlled also by the hydraulic swelling of the tapered onion of elastic polymeric material without resort to mobile surfaces or complex mechanisms, drawback from the point of view of their carrying out, cost and reliability.

Furthermore in the mechanical fluid dynamic jet device for the propulsion and control of the hydrodynamic flow in the water-jet propelled boats, the ring or nut, on which the hydrodynamic pinecone or onion-shaped body is mounted and centred to drive and control the hydrodynamic flow inside the tubular mean, is a wing section or aerodynamic profile, and is mobile translating along the axis of the said body from a point of minimum to a point of maximum to determine a further adjustable element to change the flow parameters. Said element is able to create with its wing profile, concentric to the aerodynamic body, a depression centred in the chamber on the said onion-shaped tubular body and is essential to arrange for the air or the gas being driven by this depression to lap only on said tubular body, in order to assure an increase of the speed of the jet which is determined by the better fluency due to the lower sliding friction of the water on the onion.

The mechanical fluid dynamic jet device for the propulsion and control of the hydrodynamic flow in the water-jet propelled boats includes also injectors that are placed and arranged in the middle of the wing-shaped ring to force the gas to lap only on the surface of the pinecone without disperse in the chamber, so that reduces the frictions between water and surface of the pinecone and at the same time increases the speed of the jet.

This, while the gas injection is carried out by means of injectors communicating with the interior of the tubular mean, in order to change the main characteristics of the jet, like speed and density, besides the performances, power and angle of incidence, of said jet together with the adjustment of the volume of the chamber, with the consequential variation of the kinetic energy of the jet itself, said gas could be composed by the exhaust extracted from the engine or by a compressed air coming from a tank with release and control valve, connected to a turbocharger, driven by the same engine of the boat.

The device of the invention allows in addition the variation of the direction and the slant of the jet, course and attitude of the boat, through means formed by a jointed system, suitable to orient said tubular body mounted on said joint in direction and slant, which allows the displacement of the device in all the directions, without the need of displacement of mobile surfaces in the manner of rudders that damp the jet.

By means of this device the jet, besides the possibility of a release underwater like the traditional water-jet, can be also released outside the water above the water surface, like a jet engine or water-jet, said option resulting more effective and more appreciable in terms of better performances. Particularly the response at low speeds must be noted, while by the traditional water-jets at low speeds, that is when the boat is not yet about to plane, the engine consumes as much as at high speeds, this defect which remains still a handicap in the traditional boats is instead remarkably solved by this invention.

The mechanical fluid dynamic jet device for the propulsion and control of the hydrodynamic flow in the water-jet propelled boats finds also use in the hydrodynamic guidance and control of the boats when it is symmetrically arranged in a given number of couples on the lateral walls of the hull to optimise the auxiliary manoeuvres in harbour, said nozzles fed by hydraulic pumps by means of shutters driven by electrovalves and controlled by joystick.

The mechanical fluid dynamic jet device finds particular use to control the hydrodynamic flow in the propulsion and in the manoeuvre of water-jet propelled boats or crafts.

In addition said device, besides the installation “ex novo” on the boats or craft intended for the water-jet propulsion, allows retrofit actions on the boats of the known technique, because it can be easily installed also on the boats which have a traditional water-jet.

The unique innovative element which justifies our patent application consists of having a water-jet with nozzle adjustable through a mechanism driven by a stepper motor, guaranteeing in this way the possibility to change the volume of the chamber for the control of the power of the jet without modification of the geometry and shape of the nozzle with multiplied hydrodynamic efficiency and high construction reliability avoiding mobile surfaces.

Carefully studying the above mentioned documents of the previous State of the Art, it is evident that in none of them, unlike this invention, the fact appears that said water-jet is purposely built and designed to operate outside the water surface, as well as the fact that in this invention, unlike the others, to make the boat turning rudder or mobile surfaces are not needed to deviate the jet, configurations that damp the flow deviating it, but it is able to rotate the whole jet without taking power out.

It is to be added that in this invention we adopt an hydrodynamic body inside the variable chamber shaped as deformable tapered pinecone or onion, to change its shape and volume, which determines in the interaction with the flows new characteristics that cause an increment of kinetic energy of the flow, higher incisiveness, better performance for the boat, being a further adjustable element of control.

Similarly the nut supporting said hydrodynamic body is shaped like a ring with wing section able to create a depression at the centre just around the hydrodynamic body, causing an increase of the speed of the flow, allowing to use a very tapered pinecone shape instead a more pronounced onion shape as usual, therefore without inducing excessive restriction of the flow which would loose more energy, obtaining a better result without restriction of the chamber, but utilising the said element.

Currently in the traditional systems quoted before the speed of the pumped fluid is increased by means of the onion or pinecone-shaped element at the centre of the duct where the fluid flows, in all these cases to obtain a satisfactory result restrictions are practically carried out that in any cause take power away the flow with pressure drops, in our case, even noticeably reducing the restrictions imposed by the onion which results more slender with the application of the special ring which support it around itself, we obtain better results in terms of power essentially because we have reduced the pressure drops.

Furthermore bear in mind that the ring can be mobile, transferring longitudinally, becoming a further adjustable element of control to improve the propulsion device and to refine the efficiency.

Said ring sliding along the axis of the pinecone, remaining centred against it, bring by this effect a change of the flow inside the chamber causing an element of further implementation in the control.

About the carrying out of the jet by a bi-phase flow liquid-gas, the double flow air or gas plus water, pre-eminent to give power to the jet in the previous technique, in our case drawn from the power generator, internal combustion engine or turbine, it is only complementary to increase the power, increasing on the contrary the efficiency and the possibility of control of the flow. The injection occurs at the centre of the wing-shaped ring, which is able through the depression creative at its centre to force the gas to lap the surface of the pinecone avoiding actually that the same gas flows freely in the whole chamber, this element because of its deployment in that specific position and with that particular section in fact succeeds to drive, concentrate and make the gas lapping only on the pinecone.

The fluid dynamic mechanical jet device subject of this invention finds further use for the control of the aerodynamic flow in the propulsion and the manoeuvre of the water-jet propelled boats and craft and as retrofit of easy embodiment to be applied also on the boats that have a water-jet or manoeuvre propellers of traditional type.

We give now in the following a description of a particular non-limiting form of carrying out of the invention without depriving of anything the generality of the invention itself and without limiting the field of implementation, with reference to the explanatory drawings of the attached tables.

FIG. 1 shows a view of the device as applied to a water-jet propelled boat.

FIG. 2 shows a view more in detail of the table 1 indicating also the flows and the movements of the device.

FIG. 3 shows a cross section of the body and the tubular chamber, the nozzle and the joint of the device of the invention.

FIG. 4 shows the pinecone or onion-shaped hydrodynamic body installed inside the chamber, provided with internal hole to change its shape and volume.

FIG. 5 shows the mobile wing-shaped ring element acting as support and centring nut of the pinecone or onion-shaped hydrodynamic body.

FIG. 6 shows an installation arrangement of a couple of water-jets with auxiliary manoeuvre function at the boat prow.

FIG. 7 shows an installation arrangement of the water-jets, with auxiliary manoeuvre function, on the hull of the boat, prow and stern, for its guidance in the manoeuvres in harbour, of sailing and docking.

A motor or pump 4 through the intake 3, 25 of a boat 5, 11 takes and conveys the fluid in the duct 2 and in the subsequent duct 9 up to the inside 1′ of the tubular chamber 1, where the flow is managed, controlled and adjusted and subsequently ejected and transformed in jet 6 through the nozzle 16, preferably above the water surface 10 (FIGS. 1, 2).

The flexible or rigid ducts 2, 9, can be made of any material compliant to the requirement of watertight and mechanical resistance, suitable to connect the pump 25, 3 to the control and propulsion device 21, 8, 1, 16 (FIG. 2).

The pumped fluid can be altered as one likes in its characteristics by the concomitant introduction of gas taken from the engine exhaust 4 through the duct 2a or alternatively from a compressed air tank and injected through the control valve 26 by means of one or more injectors 21 into the duct 2 (table 2) in a preferred form of manufacture of this invention or into the chamber 1′ of the tubular body 1 (FIG. 3) in a second preferred form of manufacture.

Said fluid comes into the internal chamber 1′ of the tubular body 1, driven and regularised by a tapered onion-shaped hydrodynamic body 17 intended to regularise the flow, centred inside said chamber 1′ by means of a ring or clamp 18 carrying the onion-shaped body with fluid dynamic blades and ledges 19, 20 (FIG. 3).

Similarly a nozzle 16, actuated and adjusted from a minimum to a maximum opening position by means of a cogwheel 15 and a pinion 13, driven by an electrical stepper motor 12, 24, 14, allows the variation of the internal volume 1′ of the tubular chamber 1 (FIG. 3).

Said device works like a hydro-jet, including a tubular body 1, with an internal variable geometry and volume chamber 1′, a tapered onion-shaped element 17, arranged longitudinally to the flow, fixed 23, 19, 20 and maintained centred inside the tubular body by a clamp with fluid dynamic spoke 18, an outlet nozzle adjustable in position and opening 16, a motorised system 12, 14, 24 (e.g. an electrical stepper motor) suitable to allow the displacement and the adjustment of said outlet nozzle 16 by means of the pinion 13 and the cogwheel 15, a system with cables or levers or pistons or telescopic arms (not shown) suitable to orient the direction and the slant of the device by means of the guide of the tubular chamber 1, 1′ mounted on the joint 22, 8, then of the jet 6, to drive the changes of course and attitude of the boat (FIG. 3).

The new polymer body hydrodynamic shaped as tapered pinecone or onion 17 has shape and volume variable through an internal hole 17″ which swells out by means of a pneumatic or hydraulic circuit 17″, able to swell or contract changing its shape and volume to obtain a further control element together or without the need of a restrictor (FIG. 4).

Similarly the support ring nut 18 can be carried out as wing section or aerodynamic profile 18″ and be mobile in translation 18′ from a point of maximum excursion to a point of minimum excursion inside the chamber 1′, its displacement 18′ determining the change and the control of a number of parameters, like for instance shape and dimension of the flow sections, speed, pressure drops by friction, density of the fluid and so on, that contribute to the further, alternatively or concurrently, control and optimisation of the jet (FIG. 5).

The jet 6 of the pumped 3 and conveyed 2, 9, 1′ fluid is in this way controlled by the device of the invention which allows to change its characteristics of speed and density as one likes, to alter the fluid with the injection of another fluid into the duct 2 or into the chamber 1′, that precede the mobile nozzle 16 which releases said jet, suitable to change the flow characteristics and to allow the mix of the fluid with a gas, which in this case is the exhaust of the internal combustion engine which drives the pump 4, or alternatively compressed air, and finally the undoubted innovation which breaks definitely with tradition, the fact that the substantially elaborated flow is ejected above the water surface 10 with slant and direction controlled and adjusted as one likes 8. To come to the point this invention can replace or succeed all the traditional water-jets for boat propulsion, because it allows for the first time to change the jet characteristics, to alter the flow, to obtain more effectiveness in the propulsion, to obtain considerable increase of speed for the same used power.

Interacting through the nozzles injecting the engine exhaust or compressed air and adjusting the geometry of the chamber 1′ by means of the electrical stepper motor 12, 13, it results not only the variation of the main characteristics of the jet 6 like speed and density, but also power and angle of incidence, with increase of the kinetic energy of the jet itself.

The device subject of this invention ensures the boat besides the best performances already mentioned, a neutral progress of the movement always in horizontal position, more comfort, more angle of incidence by the changes of direction, saving of power, saving of fuel, all advantages that of course were up to now not found in the previous state of the technique because in the traditional water-jet it is not possible to intervene neither to control nor to alter the hydraulic jet. All these things are on the contrary achievable by the device subject of this invention. The subject of the invention conceived and tested by the applicant at first sight characterises itself mainly because the jet 6 happens above the water surface 10 few centimetres above the water-line 10 of the boat 5, 11, and precisely it happens from the top downwards in diagonal with an adjustable slant 8 at will. Further analysing the achieved results we can mention the fact that utilising this device the wake of the boat is cleaner and the turbulent foamy part is no longer tied to the stem but it is at a distance of a few metres, in fact, by the implementation of the invention it is possible to noticeably improve also the fluid dynamics of the boat. Many further advantages and improvements can be achieved by the use of the invention; the device can be carried out of any metal or plastic or composite provided that it is suitable and complies with the technical mechanic requirements peculiar to the intended use.

The water-jet control device described above is finally characterised by the fact that by means of it, veers more precise, cleaner und sharper can be achieved with less wasted power; in fact by the traditional water-jets to do a veer the rudder damp the jet 6 taking power and incisiveness from the jet itself, inducing a noticeable loss of speed, while by the device, subject of this invention, the veer is always carried out with the full jet 6 available, without the need of an additional rudder and without damping, without taking or wasting power and incisiveness, simply because the jet is not diverted by other members, but it is oriented by the joint 8 by means of dedicated telescopic arms (here not shown in the tables), that allow the displacement in all the direction of the tubular body 1 of the device, in fact thanks to this the jet can be fully directed without being damped.

The mechanical fluid dynamic jet device for the propulsion and the control of the hydrodynamic flow in the water-jet propelled boats finds also used in the hydrodynamic guidance and control in the boats when it is symmetrically arranged in a given number of couples on the lateral walls of the hull to optimise the auxiliary manoeuvres in harbour, said nozzles being fed by hydraulic pumps through shutters driven by electrovalves and controlled by joystick.

The device of the invention finds also use to optimise the traditional system of prow propellers and auxiliary propellers for the manoeuvres in harbour, sailing and docking of the boats. (FIGS. 6, 7).

An installation with four water-jets, one port and one starboard prow, likewise two stern water-jets, results much more easy and functional than any system with traditional electric motor, because it makes use of four holes made on the hull, one for each device, positioned on the water surface, avoiding the complex and expensive work to install electric motors with auxiliary propeller.

The system configured in this way beside the water-jets that are linked through ducts to a single hydraulic pump with intake from the sea (also this extremely simple) adopts four electrically driven valves one for each jet controlled by a joystick.

By the installation with one couple, two couples or more couples of water-jets 1, they are linked through ducts 30, 30′, with interposed shutters 27, 27′ driven by electrovalves 28, 28′, to a single hydraulic pump for each couple 29, 29′ with intake from the sea (also this extremely simple) and adopt electrically driven valves 28, 28′, one for each jet, controlled by a joystick, for the differential control of the flow of the said water-jets (FIGS. 6,7).

The system is very reliable, assures perfect manoeuvring with immediate and precise response, but above all it will be promoted because of its installation simplicity, reliability and cost on the new boats as well as on the second-hand ones.

The carrying out of the installation with four water-jets (with the device of the invention) was satisfactory tested on a 24-meter super-yacht.

The mechanical fluid dynamic jet device for the propulsion and the control of the hydrodynamic flow in the water-jet propelled boats finds also used in the hydrodynamic guidance and control in the boats when it is symmetrically arranged in a given number of couples on the lateral walls of the hull to optimise the auxiliary manoeuvres in harbour, said nozzles being fed by hydraulic pumps through shutters driven by electrovalves and controlled by joystick.

The mechanical fluid dynamic jet device find particularly use for the control of the hydrodynamic flow in the propulsion and the manoeuvre of the water-jet propelled boats or crafts.

The system finds also use to optimise the traditional system of prow propellers and auxiliary propellers for the manoeuvres in harbour, sailing and docking.

The device subject of this invention can have many forms and variations relevant to the geometry, the fluid dynamics, the materials, the details or particulars here not described but not for this excluded by the ambit of protection of such invention.

It finds particular use by the propulsion and control of the hydrodynamic flow in the water-jet propelled boats or crafts.

Furthermore said device allows retrofit actions in the boats of the known technique, because can be easily embodied also on the boats that have a traditional water-jet.