Lowerable platform with float for a watercraft

The invention relates to a lowerable platform (1) for a water craft (10), which can be also horizontally extended and to which a float (2) is fastened that comprises a closed hollow space (43) or an open hollow space (43), a buoyancy (A) acting upon the float (2) being generated by the air volume (L). As a result, the water craft's proper weight or the payload (N) of e.g. a tender boar (27) on the lowerable platform (1) can be compensated by the buoyancy (A). A hydrodynamic design of the float (2) additionally generates a hydrodynamic buoyancy (D1) which can be varied in terms of its height in relation to the current (S) by means (4, 37, 38, 39), depending on the float (2).

TECHNICAL FIELD

The invention is directed to a lowerable platform with an integrated float for watercrafts, according to the preamble of the first claim.

Lowerable platforms, in particular for swimmers, divers and tenders, are known in the art and described, for example, in the patents DE 196 02 331, US 2001/0027740 A1, or partially lowerable swimming pools with walkable surfaces, as described in the patent EP 0253745.

Also known are spacer-type fastening means with height adjustment for outboard motors on the stern of watercrafts, in order to attain by the height adjustment speed advantages, and to not take up space in the cockpit of the watercraft when the outboard motor is tilted upward, as described in the U.S. Pat. No. 3,075,490 or U.S. Pat. No. 4,657,513.

DESCRIPTION OF THE INVENTION

It is an object of the invention to attach on the stern of a watercraft a lowerable platform, also for applications with outboard motors, which also has buoyancy means for keeping the lowerable platform unaided above the water line, whereby the buoyancy means provide, at a corresponding speed of the watercraft, also hydrodynamic support, or can form a container for various technical means.

Lowerable platforms have a considerable tare weight and essentially include the deformation-resistant lowerable platform itself, pivoting arms, articulated joints, hydraulic cylinders and fastening components on the stern of the watercraft. A lowerable platform can be used to enhance the comfort for swimmers, divers, to get in and out of the water, or to relax on the platform and to just sit at the same level as the water line and be splashed by the water and/or for putting a tender or jet ski in the water, which can be parked and secured in dry condition on the lowerable platform when not in use.

Persons and the tender vehicle can weigh many times the tare weight of the lowerable platform, thus representing a large load for the stern structure of a watercraft. Such weight can also substantially change the trim of a watercraft, even at low speed, and many even cause the propeller of the bow thruster to partially rise above the surface, so that port maneuvers can no longer be effectively performed. The dynamic stresses in the stern region of a watercraft are also considerably greater when the watercraft is moving through waves and when at the same time a tender or jet ski is attached on the lowerable platform. The hydraulics must also be able to permanently absorb the full weight and the impact from the waves of the lowerable platform, possibly supported only by hooks and bolts which help to prevent the lowerable platform from becoming detached from the secured position.

The invention solves these problems by providing the lowerable platform with buoyancy means which help to absorb the tare weight or the weight of the useful load by way of the floats, thereby additionally improving the safety of the moving watercraft, supporting the trim of the watercraft and ensuring that the lowerable platform cannot be uncontrollably lowered, and that the fluid cylinders need not move large loads. The pivot arms can then have a much thinner and lighter shape.

Because the platform is lowered by about 0.6 to about 1.5 m below the water line, it is technically not difficult to provide the buoyancy means with technical means, such as trim flaps, steering rudder, underwater lights, exhaust gas piping, extendable stilts, transverse jet rudder and the like, and to route the hydraulic and electric lines accordingly. The buoyancy means can have openings, so that pivot levers can freely move therein and are protected from environmental harm, within the protection is provided also to the swimmers, because they cannot get caught in the mechanism of the pivot arms.

The buoyancy means can be constructed as one unit or made of modules and are suitably attached to the lowerable platform. To provide optimal buoyancy with respect to the tare weight and the weight of the useful load, variable hollow bodies can be provided in the buoyancy means, so that depending on the size of a hollow body, this can produce more or less buoyancy, so that positive weight balancing can be performed easily and accurately.

The height of the contact position of the platform on the stern can be limited, on one hand, by the mechanical properties of the pivot arm or the fluid cylinders or, on the other hand, with a mechanical limit stop placed between the platform and the rear wall of the watercraft. This limiting feature can be implemented by aligning the buoyancy means with the bottom of the watercraft hull so that they are subjected to the same flow, or by forming a corresponding step. Alternatively, limit stop on the platform or on the buoyancy means can be varied, while the watercraft is moving, depending on the speed of the watercraft, so that the buoyancy means are more or less wetted by the water flow.

In a particular application, the lowerable platform can be attached to a watercraft having an outboard motor. Such watercraft leave very little space behind the motors, because the motor must be pivoted upward when the propeller hits bottom or in the rest position, so that according to the invention a means, on which the lowerable platform is located, is interposed between the watercraft and the outboard motor, so that the lowerable platform can be lowered laterally. Such an embodiment would not be realistic without a float, because the watercraft could tilt strongly to the side when someone walks on the lowerable platform, in particular with the solution having an additional horizontal extension, which would compromise the safety and would be detrimental for a substantially tilt-free lowering of the platform.

This is attained with the invention with the features of the first claim.

The core idea of the invention is to reduce loading of a lowerable platform with respect to the stern of a watercraft, to safely maintain the position of the lowerable platform, to guarantee the trim and roll stability of the watercraft, in particular when applying a lowerable platform in conjunction with outboard motors, and to use the lowerable platform as means for simultaneously attaching various technical means in the stern region, as well as to improve the hydrodynamic properties of the watercraft, without requiring additional installation work on the stern of the watercraft.

Additional advantageous embodiments of the invention are recited in the dependent claims.

Only the elements required for a fundamental understanding of the invention are schematically illustrated.

APPROACH FOR IMPLEMENTING THE INVENTION

FIG. 1shows schematically a side view of the lowerable platform1with the float2attached thereto, which is a watertight hollow body43illustrated with an air volume L and partially submerged, as illustrated by the waterline WL. However, the watertight hollow body43may also contain a water-repellent light foam with an equivalent air volume L. The lifting mechanism3, consisting of a working cylinder4as well as a lower pivot arm5and an upper pivot arm6—representing a parallelogram, whereby at least two parallelograms are mounted for each lowerable platform1—and are attached accordingly on the lowerable platform1or on the float2and are connected on the opposite side to the stern8of the watercraft10by way of an articulated joint mount7with the screw connection9.

The float2can also include various technical means13, for example trim flaps13a, underwater lighting, rudder elements and the like, wherein the technical means13are separated from the float2to prevent water from entering the hollow body43of the float2. This is effectively accomplished by filling the hollow body43with foam.

The lift limiting means11have a large a surface as possible to avoid localized pressure exerted on to the stern8, while simultaneously allowing adjustment of the upper contact position of the lowerable platform1. The lowerable platform1is lowered, optionally below the water line WL, as indicated by the lifting/pivoting line HS, by activating the working cylinder4on the lifting mechanism3.

Due to the buoyancy force A generated in the float2, which is produced by the air volume L and corresponds to the static buoyancy D2, the lowerable platform1is not lowered by gravity, but is instead pushed into the lowering direction by the thrust force K1of the working cylinder4. This has the advantage that in the event of a failure of the hydraulic, the lowerable platform1is automatically raised by the buoyancy force A, so that the working cylinder4therefore never has to push the entire tare weight of the lowerable platform1and of the lifting mechanism3. A self-lock12is attached on the stern8, so that when the lowerable platform1is raised by the buoyancy force A to the lift limiting means11, the platform1is automatically secured with the self-lock12in the contact position and the float2also smoothly fits the hull10afor optimal flow S during travel. The self-lock12is released by activating the locking cylinder41. The self-lock12is constructed to hold the position of the lowerable platform1even when the watercraft is moved to a dry dock.

If a tender boat27or people are on the platform1and if the useful load N is greater than the buoyancy force A, then the working cylinder4brakes the lowering of the platform and supports lifting the platform1with the useful load N by applying the pulling force K2.

The float2can also have a hydrodynamic shape, from which the watercraft10can benefit with respect to the stability, fuel consumption and the like. The float2can also have a float lock12a, so that the lifting mechanism3is not subjected to uncontrolled forces from large hydrodynamic forces caused by the flow S; instead, the forces are already absorbed on the float2, preferably in the lower region thereof. The float lock12acan be passive, in that when the platform1contacts the stern8, a formfitting coupling12b,12cof the float2with the stern8is produced, or active where a second self-lock12is used in conjunction with a locking cylinder41that can be unlocked.

Of course, the hydraulics which may be double-acting, can also be implemented pneumatically or with an electric spindle drive, and a linear rail system can be substituted for a parallelogram of the lifting/pivoting region HS.

FIG. 2shows schematically a side view of the lowerable platform1, with the float2attached thereto, in the horizontally extended position P, indicated by the arrow X, which is achieved with a sliding mechanism14located under a second fixed upper platform1a. The sliding mechanism14can be a slide rail or a rail/roller combination, so that the lowerable platform1can be moved back and forth horizontally on the lifting support15. The horizontal displacement is performed either manually or with a horizontal working cylinder31. The lifting support15can simultaneously also form a mount for the pivot arms5,6. When the lowerable platform1slides horizontally, the attached float2is moved by the buoyancy force A and therefore only slightly changes the trim of the watercraft10, even when a tender boat is attached, as compared to a variant without floats2.

The lifting support15can also be raised so that the lowerable platform1attains a position above a shortened upper platform1a, and the lowerable platform1is moved, by way of un-illustrated openings in the floats2, horizontally according to the arrow X to an upper lift limiting means11a, where it can be placed on the upper platform1a.

FIG. 3shows schematically a side view of the lowerable platform1with the float2attached thereto in the horizontally extended and additionally raised lifting position P1, as indicated by the vertical arrow Z. By completely extending the lowerable platform1beyond the region of the upper platform1a, the lift on the working cylinder4can be additionally raised, so that the lowerable platform1forms a plane with the upper platform1a. In this way, a very large flat platform surface is attained, which can be used as an additional standing surface for persons and goods and which can provide sufficient buoyancy due to the float2, so that the watercraft can does not become submerged in the stern region. To protect the persons and goods, insertion element16, for example holes, are provided in the lowerable platforms1,1afor insertion of barrier elements17, such as posts17awith rope barriers17b.

FIG. 4shows schematically a top view onto a watercraft10with an outboard motor19with laterally extendable and lowerable swim platform1having a float2attached thereto. One or more supports20which support a cross brace21and a freestanding transverse platform1bare located on the stern8, with the articulated joint mount7and the lifting mechanism3attached to one support20, wherein the lifting mechanism3allows the lowerable platform1to be pivoted out transversal to the travel direction of the watercraft10. The lowerable platform1can be positioned above or below the transverse platform1b, or the transverse platform1bcovers only one half of the area between the cross brace21and the stern8, indicated by the measure M, so that the lowerable platform1can operate without horizontal lift X and rotated directly into or out of the water. The cross brace21supports the outboard motor19, or several, as well as the cover22, so that a safe separation exists between the swimmer on the lowerable platform1, the lifting mechanism3and the outboard motor19, in particular the propeller of the outboard motor, also during high waves.

Damping means18for damping the vibrations from the outboard motor19can be interposed in the screw connection9between the support20and the stern8, to prevent to the greatest extent possible a transmission of vibrations from the motor to the watercraft10.

FIG. 5shows schematically a side view of the lowerable platform1, with the float2attached thereto, in the horizontally extended position P, wherein the lowerable platform1have a tender mount23, which is at one end fixedly connected with the lowerable platform1by way of an articulated joint24and which has at the other end a movable roller pair25. The tender mount23can have a sensor26which informs the operator of the watercraft or the controller38if a tender boat29is located on the tender mount23, or if it is properly positioned. The tender mount23can also have corresponding un-illustrated mounting devices for securely holding the tender boat27on the watercraft10, as indicated by the mounting device sensor58. If the tender boat27rests on the tender mount23and the lowerable platform is in the position P, then the buoyancy force A produced by the float2preferably fully compensates the useful load N on the lowerable platform. If the lowerable platform1is oriented horizontally with respect to the stern8, then the tender mount23secured to the articulated joint24moves up the ramp28of the upper platform1aon its roller pair25, continues until shortly before the end of the horizontal movement, descends the second ramp29into the opening30having a corresponding hole dimension, so that the tender mount23, or the roller pair25, now again rests directly on the lowerable platform1, thereby unloading the upper platform1a.

FIG. 6shows schematically a stern view onto a stern8with a lowerable platform1with attached modular floats2aand integrated lifting mechanisms3. If an obstacle34is located on the stern10, such as a Z-drive or an exit opening of a jet drive or the like, then it makes little sense to use a continuous float2, but rather corresponding modules which can be quickly and easily installed individually on the lowerable platform1. These modules can also perform hydrodynamic tasks and can also include technical means13. Advantageously, watercrafts10can also have different widths, while the slope of the ship's bottom is mostly the same. For example, a certain modular float2awith a slope of 19° can advantageously be attached to a watercraft10having a width of 3 m or 4 m, together with a suitable dimensioned lowerable platform1.

Besides lowering the platform1below the water line (WL) and then raising it, it may be desirable to leave the platform1, e.g., in a submerged position and have the swimmers instead use a swim ladder. For this purpose, a telescopable swim ladder33is provided which, on one hand, is rotatably attached to the stern8or the platform1aand, on the other hand, is attached to the float2, with the swim ladder33being shortened or extended according to the lift/pivot line.

FIG. 7shows schematically a side view of the lowerable platform1with an attached float2, wherein the lifting height of the float2is limited by a variable limiting means11b, so that the bottom edge U of the float2is located in the water flow S, or alternatively is only partially wetted or can be completely moved out of the flow. The lift may also be limited by the working cylinder4. The length of the watercraft can then be changed and, if desired, the submerged length of the hull10aof the watercraft10can be shortened or lengthened the watercraft10by submerging the float2arranged on the lowerable platform1. Tests on hydro-gliding watercrafts10have shown that it is advantageous up to a certain speed to have an additional hull length exposed to the water flow, because the additional hull length produces additional hydrodynamic buoyancy D1, whereas after further increase in speed, the friction on the additional hull length adversely affects efficiency. A measurement transducer37which records the rotation speed and the travel speed37, respectively, can transmit a command to the hydraulic units39via a controller38, to retract or extend the working cylinder4, wherein the effective position is acknowledged by the position measuring sensor40. When the working cylinder4is operated, the locking cylinder41is first unlocked to release the lock42, which can be a toothed gear, allowing the float2to move freely. The lock42allows various fixed positions, so that the float2can be locked at each full lift position H, so that a watercraft can with the lowerable platform1can safely jump over waves.

A simpler way to affect the hull length of a sliding watercraft10as a function of speed is to install one or more step edges U1, U2on the lower edge U of the float2, because the faster a hydro-gliding watercraft10with V-shaped hull travels, the higher it lifts out of the water, so that it is desirable to further shorten or decrease the friction surface at the hull end.

Also contemplated is a solution wherein the lowerable platform1is not moved when adjusting the float (2), and wherein instead the variable lifting limit11bis located between the platform1and the float2, with un-illustrated variable spacers allowing a correct adjustment of the float2. The height can also be varied manually or with hydraulic or electrical means.

Accordingly, there is always a buoyancy A on the float2. When the watercraft8is at rest, the float2produces a static buoyancy D2. When the speed of the watercraft8increases, then the static buoyancy D2is reduced and dynamic buoyancy D1is created. The two types of buoyancy, either the first or the second type or the combination, are combined here to form the buoyancy A.

FIG. 8shows schematically a side view on a lowerable platform1with an attached float2having a basic fill level35integrated in a hollow space43, as well as stackable hollow bodies44each having an air volume L1, which are secured on the bottom section47of the float2by using, for example, a threaded rod45and a nut46. Instead of using air in the hollow bodies44, these can also be filled with foam. The opening48allows the hollow body43to be filled with water or to be drained, as illustrated by the arrow E. The boatyard or the ship's owner can thereby balance the buoyancy A on the float2and accurately set a positive, neutral or negative total buoyancy with respect to the tare weight or with respect to the additional useful load, and accurately adjust the desired value.

FIG. 9shows schematically a side view on a float2with an adjustable hollow body49integrated in the hollow space43, for example in form of a bellow, wherein the air volume L2in the bellow can be varied manually or automatically with a pressure sensor50or a tender sensor51. The volume is increased or decreased through the line52using an air pump53. Automatic filling or venting is triggered by a pressure sensor50which measures the forces at the pivot arm4or5, wherein the measured pressure value is transmitted to the controller38, which in turn transmits the command to the air pump53and changes the volume in the adjustable hollow body49until the pressure sensor50indicates the desired value. The same applies to the tender sensor51, which measures a predetermined weight of a tender boat27via the sensor26and thereby controls the effective useful load N by blowing into or venting from the adjustable hollow body49a corresponding air volume L. By increasing or decreasing the volume of the adjustable hollow body49, the hollow space43is filled through the opening48with more or less water, thereby varying the buoyancy, while always maintaining a basic fill level35, and hence a basic buoyancy A.

Instead of air, any medium lighter than water can be selected.

FIG. 10is a schematic diagram of the control of the working cylinder4with the controller38based on the various sensors32,40,54,55,56,57,58, such as the horizontal lift measurement sensors32of the horizontal working cylinder31, travel position40of the working cylinder4, rotation speed level54, gear position55, Z-drive position56,57, with the latter subdivided in turn position56and excursion position57, as well as mounting device sensor58and travel position sensor32of the horizontal working cylinder31. For safety reasons, the watercraft10should not be operated with the platform1lowered, so that the transmission is locked when the engine is operating, so as to prevent travel, or only slow travel is permitted by limiting the rotation speed of the engine. If the tender boat27is still mounted on the tender mount23, or on the lowerable platform1, as indicated by the mounting device sensor58, then the lowerable platform1cannot be lowered past a predetermined lift value. The lowerable platform1should also not be extended beyond a predetermined value, as long as to the obstacle34, for example the trim position56and the excursion position57of the Z-drive, are not with in a predetermined position field, because the housing of the Z-drive could otherwise damage the lowerable platform1.

It will be understood that the invention is not limited to the illustrated and described exemplary embodiments.

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