Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
  • B63B1/16—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces
  • B63B1/24—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces of hydrofoil type
  • B63B1/248—Shape, hydrodynamic features, construction of the foil
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
  • B63B1/16—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces

Definitions

• the present invention generally relates to the nautical field and more precisely it relates to a device applicable to a watercraft, in particular a fully planing or semi-planing watercraft, to increase the hydrodynamic lift on the bottom thereof. Description of the prior art
• figure 1 the dynamic equilibrium that balances the navigation of a watercraft of this kind is diagrammatically shown: the weight (1) in fully planing or semi-planing watercrafts is not balanced by the sole hydrostatic lift but by the involvement of two forces, one of which is a fraction of the hydrostatic lift (2) that would balance the motionless floating boat, and the other is the hydrodynamic lift (3) as generated by the dynamic action of the water on the bottom • of the watercraft.
• the equilibrium between the combination of these two forces and the weight force (1) is dynamical, since: - the point of application of the hydrodynamic lift (3) changes as varies the wetted surface of the bottom, whereas its absolute value depends on the speed (4); - the fraction of hydrostatic lift (2) , corresponding to the water displaced by the wetted part of the bottom, changes in intensity and point of application as the dipping of the aft bottom varies, in a way responsive to the moment of the hydrodynamic lift (3) with respect to the barycentre (5) for achieving a balanced position.
• the waterline 8 When the watercraft navigates in a fully planing way the waterline 8 is inclined at an angle with respect to the waterline 9 of the watercraft that navigates in a displacing way, owing to the water mass that is continually displaced for hydrostatic lift, which is a passive work that causes a great power absorption.
• the hydrodynamic lift (3) bears the maximum part of weight of the watercraft and the hydrostatic lift (2) is used only to assure the equilibrium.
• the flaps are horizontal sheets, adjustable in height in order to change their incidence, and deflect the flow that has left the aft bottom.
• the trimming surfaces instead, are fixed and deflect the flow under the aft bottom part.
• the forces thus generated have a moment with respect to the barycentre that changes the longitudinal trim. They are used when, for defective design or for high load, the barycentre is shifted towards the aft bottom from its ideal point, in order to correct the longitudinal trim.
• the lifting device for watercrafts in particular of the type with fully planing or semi-planing bottom, whose main feature is to provide at least a transversal element constrained to the watercraft at a predetermined distance from the bottom and suitable to increase the hydrodynamic lift on the bottom.
• the or each transversal element is arranged selected from the group of: substantially parallel to the bottom of the watercraft, or inclined with respect to the bottom of the watercraft.
• means are provided for adjusting the inclination of the or of each transversal element with respect to the surface of the bottom and, therefore, with respect to the water flow.
• the means for adjusting the inclination of the or of each transversal element are selected from the group of mechanical, manual, hydraulic, pneumatic or electromechanical means. More in detail, the adjustment can be obtained both changing the incidence of the entire planar surface, both changing the incidence of the sole rear part with respect to the water flow.
• the transversal element in use has an upper surface that faces the bottom of the watercraft and a lower surface opposite to the upper surface, said transversal element being subject to a lifting force perpendicular to the lower surface owing to the difference of pressure between the two surfaces when navigating. Therefore, the transversal element is a lifting element capable of increasing the hydrodynamic lift that balances the weight of the watercraft during navigation.
• the transversal element is arranged below the bottom at the barycentre of the watercraft.
• the transversal element is arranged shifted with respect to the barycentre for correcting the trim of the watercraft.
• the or each transversal element is bridged to the surface of the bottom.
• the or each transversal element is constrained below the bottom of the watercraft by at least two support elements substantially orthogonal to the waterline.
• a support element is provided at each end of the transversal element.
• the or each support element is a shaped plate with an opening, for not affecting the trim when steering the watercraft, said plate being arranged substantially orthogonal to the waterline.
• the transversal element is made of a substantially V-shaped single part arranged transversally to the bottom of the watercraft. In particular, this single part crosses transversally the bottom of the watercraft for substantially all its width and more. In this case, support elements can be provided also near the vertex of the "V" to provide a steadier fastening to the bottom.
• a lifting device comprises at least a first and a second transversal element of the type above described fixed in different points of the bottom symmetrically to its longitudinal midplane.
• a further exemplary embodiment of the device provides at least a first and a second transversal element as above described arranged with the respective surfaces on planes substantially parallel to each other. This way, an effect of additional hydrodynamic lift is obtained on two parallel surfaces .
• the or each transversal element as above described is located at a distance from the bottom to work always dipped in the mass water. This way, the positive effect of the transversal element on the overall hydrodynamic lift on the watercraft is optimised and also the condition of equilibrium for navigating is not affected. More in detail, the minimum distance of the or of each transversal element from the bottom must not affect the water flowing thereon.
• a bottom for watercrafts in particular of the fully planing or semi-planing type has the feature of having at least one lifting device as above described.
• FIG. 1 shows diagrammatically the dynamic equilibrium during navigation of a fully planing or semi-planing of prior art watercraft as above described;
• FIG. 2 shows diagrammatically the dynamic equilibrium during navigation of a watercraft on which a device to increase the hydrodynamic lift acting on the bottom of the watercraft in planing navigation, according to the invention, is installed;
• - figure 3 shows a perspective view of a possible exemplary embodiment for a device to increase the hydrodynamic lift on the bottom of the watercraft in planing navigation
• - figures 4 and 5 show the device of figure 3 respectively in a perspective elevational front view and an oblique perspective view installed on a planing watercraft;
• FIG. 6 and 7 show an alternative exemplary embodiment of the device of figure 3 installed on a planing watercraft in a perspective elevational front view and an oblique perspective view respectively;
• - figure 8 shows a perspective view of a further alternative exemplary embodiment of the device of figure 3 "castle-like" provided by the present invention
• - figure 9 shows a perspective view of the possibility of equipping the device of figure 3 or 6 with means for changing its inclination with respect to the surface of the bottom and then the incidence with respect to the flow in which it is dipped
• - figure 10 shows diagrammatically the correction of the dynamic equilibrium when using the device of figure 3 on a watercraft with a forwardly shifted barycentre;
• figure 11 shows diagrammatically how the dynamic equilibrium changes , on watercrafts that have the barycentre too close to the point of application of the hydrodynamic lift, using the device of figure 3.
• a lifting device 10 for watercrafts of the fully planing or semiplaning type provides at least a transversal element 15 constrained to bottom 25 by means of supports orthogonal to the waterline 8 and suitable to increase the hydrodynamic lift acting on the bottom 25.
• the position indicated in figure 2 of the device 10 is under barycentre 5, and generates, when in navigation at a sufficient speed 4, an additional hydrodynamic lift 6, indicated as resultant applied to barycentre 5, which adds to hydrodynamic lift 3 on the bottom and to the hydrostatic lift 2 for balancing the weight of the watercraft.
• the transversal element 15 is arranged substantially parallel to the watercraft bottom 25, so that in fully planing or semi-planing conditions it is inclined with respect to the speed 4 of the watercraft. Therefore, the addition of the lifting surface 15, adding the surplus of hydrodynamic lift ⁇ , serves to support much more weight decreasing the dipped part of the watercraft that provides the hydrostatic lift 2. This way it is possible to reduce the amount of water displaced thus approaching the minimum value necessary to obtain an optimal planing.
• transversal surface 15 is very effective with respect to the planing part of bottom 25 because it is always dipped in the water flow, without exiting from the water surface when the watercraft is pitching or "pumping", thus supplying a substantially steady hydrodynamic lift, directly proportional to its surface and to the square speed value. From a physical viewpoint, using the formula of the hydrodynamic lift
• a hydrodynamic lift coefficient of 0,25 is easily obtainable with a surface without any design of its profile aimed at increasing its profile hydrodynamic efficiency.
• a hydrodynamic force P is obtained of about 700 Kg that has to be broken down into ' the two components vertical 6 (P-cos ⁇ ) and horizontal P-sen ⁇ , with angle of incidence.
• the braking component P-sen ⁇ is normally less than one tenth of the lifting component.
• lifting surface 15 of figure 2 gives an additional contribution to the lift of the watercraft, decreasing the displaced mass of water during navigation of the watercraft and decreasing the power absorption at a same speed, without changing the typical position of equilibrium.
• the part of weight 1 balanced by the additional hydrodynamic lift 6, under a same hydrodynamic lift 3 generated by the bottom requires a much lower hydrostatic lift 2.
• the lower value of hydrostatic lift 2 requires that less water be moved during navigation.
• the equilibrium of figure 2 causes a lower overall resistance, consequently increasing the speed.
• the limit balance conditions occur when the hydrodynamic lift, consisting of the sum of the contribution 3 due to bottom 25 and of the contribution 6 due to surface 15, is less than the value of the weight force 1 of an amount that corresponds to a minimum water mass 2 capable of generating the hydrostatic lift to reach the equilibrium. According to the invention it is therefore possible to improve the operative conditions of fully planing or semiplaning watercrafts without that the bottom looses contact with the water at speeds that are normally less than those of hydrofoil boats. A skilled person for maximising effectiveness, depending on the design features of the watercraft, chooses the size of surface 15 easily.
• Device 10 in addition to increasing the hydrodynamic lift on watercraft 25, allows also improving the comfort of the watercraft in navigation with rough sea.
• the bottom 25 transmits to the watercraft noisy and violent hits.
• the front part of bottom 25 of the watercraft falls downwards in the gap between two waves splashing on the water owing to speed and weight.
• the presence of lifting surfaces 15 under the bottom would reduce the hit on the water causing it to be more gradual.
• the device 10 can be located at a distance from bottom 25 of about 20-40 cm, in such a way to work always dipped in water. This allows to optimize the positive effect of transversal element 10 on the overall hydrodynamic lift acting on the watercraft and not to affect the balance of the watercraft during navigation.
• lifting surface 15 not only gives minimum additional resistance in water of the watercraft in planing navigation, with respect to the lifting force generated, but also in case of displacing navigation the additional resistance is minimum and steering of the watercraft is not affected.
• the device according to the present invention can be mounted on existing watercrafts in a very simple way, improving the performances both if centred under the barycentre and if shifted to correct defects.
• device 10 is completely external to the bottom and can be fixed to all watercrafts, with easy operations for fixing the lifting surfaces in suitably strengthened points.
• the transversal element 15 is bridged to bottom 25 by means of support elements 11, flanged and connected substantially orthogonal to the bottom same.
• support elements 11 are plates having an opening 12, for not affecting the trim when steering the watercraft.
• transversal element 15 is made of a substantially V- shaped flat element arranged transversally to watercraft bottom 25. This way, this single part transversal element 15 crosses transversally watercraft bottom 25 for substantially all its width, and support elements 11 are provided also near the vertex of the "V" to provide a steadier connection to the bottom near the keel.
• Surface 15 can also having a width larger than bottom 25, in case a great additional hydrodynamic lift is required by the design of the watercraft.
• two surfaces 15 are provided at opposite sides with respect to the keel, each with support elements 11 at the ends.
• a first and a second surface 15 and 15' are provided, arranged in planes substantially parallel to each other. This way, a doubled additional hydrodynamic lift is obtained on two parallel surfaces .

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• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Ocean & Marine Engineering (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Navigation (AREA)
• Cleaning Of Streets, Tracks, Or Beaches (AREA)
• Load-Engaging Elements For Cranes (AREA)
• Optical Integrated Circuits (AREA)
• Preparation Of Compounds By Using Micro-Organisms (AREA)
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• 2003
  • 2003-01-10 IT IT2003LU000002U patent/ITLU20030002U1/it unknown
• 2004
  • 2004-01-12 WO PCT/IB2004/000035 patent/WO2004062999A1/fr not_active Ceased
  • 2004-01-12 DE DE602004020732T patent/DE602004020732D1/de not_active Expired - Fee Related
  • 2004-01-12 EP EP04701401A patent/EP1590232B1/fr not_active Expired - Lifetime
  • 2004-01-12 AT AT04701401T patent/ATE429380T1/de not_active IP Right Cessation
  • 2004-01-12 US US10/541,941 patent/US20060150885A1/en not_active Abandoned

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