Description

Title of Invention: Arrangement for adjusting the keel structure of a watercraft

Technical Field

[0001] The invention is aimed at controlling the keel structure of a watercraft, when in particular the aim is to control, with a movable keel structure, the vertical heeling perpendicular to the longitudinal direction of the watercraft by enabling, with the help of functional units, the rotation of the keel structure and to move the center of gravity laterally away from the centerline of the watercraft and by adjusting the angle of attack of the keel structure to obtain a righting force momentum to counteract the heeling and to cause a heaving force momentum affecting the watercraft hull by utilizing the water flow.

[0002] The pressure force applied to the sails has usually a lateral force component that not only tends to heel the boat but also moves the boat sideways. The lateral force component of the force affecting the sails is often considerably larger than the force component that moves the boat forward.

[0003] To prevent lateral movement of sailboats, a stabilizer is used, usually a keel fin, to which the pressure force acting against resists the lateral movement of the boat. The pressure force is generated by the passage of a conventional boat with a fixed keel laterally in the water, resulting in an angle of attack between the keel centerline and the direction of travel. The greater the keel fin angle of attack and the higher the speed of the boat, the greater the lateral force component of the pressure force. The keel fin angle is typically from zero to six degrees, but it can be up to ten degrees temporarily.

[0004] The adverse heeling caused by the lateral force component of the pressure force acting on the sails is opposed by the momentum effect generated by the lifting force and gravity acting on the hull of the boat. The more stable the hull shape of the boat is and the heavier the boat is, the greater the momentum effect and the lower the center of gravity of the boat are. As a result, monohull sailboats are usually equipped with a heavy keel fin, which increases the weight of the boat and shifts the center of gravity down. Ballast may account for more than 50% of the total weight of the boat and normally at least 25%. Often the weight is centered on the thickening of the keel fin and/or the bottom of it, the so-called bulb. Naturally, excess weight increases hydrodynamic drag. Therefore, the ballast has both its advantages and disadvantages in terms of the speed of the boat, so that the amount of ballast chosen is always a compromise between the different characteristics of the vessel.

[0005] Heeling can also be prevented, for example, by using a movable keel and/or a keel ballast bulb that allows the center of gravity to be shifted laterally. This will help to make more efficient use of the ballast and reduce its adverse effects. In practice, however, the moving of a large ballast may require considerable energy and strength, especially if the ballast is also to be moved in height and gravity itself resists the movement.

[0006] In sailboats, the movement of a ballast to reduce the heeling produces unquestionable benefits. However, the required equipment always generates costs and may also slow down the passage of the boat, which requires consideration of the benefits and disadvantages of the equipment. If the equipment increases the wetted surface area of the boat, it is clear that the equipment will also resist the passage of the boat. The wetted surface area of a vessel is the surface which is in contact with flowing water. The wetted surface area of a body advantageously designed for hydrodynamics is the determining factor for the hydrodynamic drag caused by the body. The larger the wetted surface area of the body is, the greater the hydrodynamic drag.

[0007] The aim of improving stability is therefore, firstly, to minimize the heeling and increase the speed of the boat. On the other hand, such improved stability will also contribute to the design and implementation of the boat in a way that it can be built significantly lighter than normal.

In addition, the purpose of the invention is to utilize a stabilization body, for example a keel fin, to more efficiently optimize the weight of the watercraft and the drag caused by water and thus to increase the speed.

Background Art

[0008] The basic solution for stabilizing the boat is a fixed keel and a centerboard derived from it, which is mainly intended to temporarily eliminate the disadvantages of a deep draft in terms of landing and road transport.

[0009] Solutions for stabilizing the boat and optimizing the keel structures can also be found, for example, by means of construction where the keel structure is arranged on the centerline of the sailing boat around a longitudinal axle, an example of such construction being represented by the canting keel. This type of solutions have a fixed turning direction of the keel axle and therefore the angle of attack cannot be adjusted, for example, according to the sailing conditions.

[0010] Implementation examples for the above-mentioned canting-keel solution are presented in patent publication EP 1 741 624.

[0011] A differing mechanism is described in patent publication FR 99 01 546, where the keel of a sailing boat, as described at the beginning of the document, is arranged to move laterally away from the centerline of the watercraft as a shifting movement essentially parallel to the centerline. This solution focuses on the location of the ballast and does not take advantage of the adjustment possibilities of the profile position in the water flow.

Summary of Invention

[0012] A heavy keel is useful in a monohull sailboat because it allows more use to be made of the pressure force effected on the sails by the wind. The heavy keel also prevents the sailboat from capsizing due to the wind effect. The heavy keel, on the other hand, also produces disadvantages to the performance of the boat in particular.

[0013] Since a heavy keel is not useful in all situations, for example in downwind, in which case the force on the sails does not have a lateral force component, it would be advantageous in these situations to strive to produce a required lifting force for the keel in each situation to compensate for the weight of the keel structure.

[0014] The invention is particularly well suited to those keels, where the center of gravity of the keel is shifted from side to side of the boat to maximize the righting effect for the boat and therefore the keel is rotated or canted away from the centerline of the boat. An example of a keel solution, in which the method could be utilized in particular, is the canting keel. When the keel is turned, for example 40 degrees, and the potential heel of the boat is taken into account, a large upward force component that effectively compensates for the weight of the keel is possible with a lifting force acting on the keel fin.

[0015] The lifting force on the keel can be considerably large. A typical keel could weigh 1000 kg and its side-projected surface area could be 1.4 m ² Already at 8 knots and with a 4° angle of attack, the lifting force acting on such a keel would be almost 5000 N.

[0016] The method has very high significance. A typical sailboat is slow because it cannot exceed the planing threshold. The planing threshold cannot be exceeded because there is too little usable power and too much weight. The weight problem can be solved by generating lift forces with different fins that compensate for the effect of gravity. It is particularly advantageous, hydrodynamically, structurally and economically, if that lifting force can be generated by the usually unavoidable and already existing ballast keel, which is already structurally strong and has a large surface area producing a large force, so that there is no need for new components inducing drag in the water.

[0017] The keel fin in the arrangement according to the invention is rotated with respect to the flow when required during sailing, making the fin asymmetrical with respect to the flow and a lift force is generated.

[0018] The lifting force can be produced and utilized either to compensate for the effect of gravity acting on the keel and boat with a force effect in the opposite direction or to enhance the righting effect of the keel weight on the boat by causing a force effect in the direction of gravity towards the keel. Brief Description of Drawings

[0019] Next, the attached drawings are described:

Fig. 1

[0020] [Fig. 1] shows a profile in a flow. The upper profile is aligned with the direction of the flow and the lower profile is shown with an angle of attack a, in the example of about four degrees.

Fig. 2

[0021] [Fig. 2] shows a standard canting-keel solution, where the keel can be pivoted from side to side to provide a righting moment, for example, from the middle position to a maximum of about 40 degrees to the side. The pivoting of the keel is used to counteract the opposite momentum effect caused by the wind and sails. The keel axle is positioned parallel to the boat's centerline, which means that the keel is essentially parallel to the flow when the boat is traveling in direction of its centerline.

[0022] The keel axle is supported by two bearing supports and the axle can only rotate around itself, but it cannot be canted or rotated in relation to the centerline of the boat. The keel can thus turn from one side of the boat to the other only when the axle rotates, but it cannot be actively canted or rotated in relation to the centerline of the boat.

[0023] In various sailing situations, such as when the boat is heeling or making leeway due to the wind, the boat might not travel parallel to its center line and thus creates a lift force on the keel. The keel axle can also be permanently mounted in a canted position, e.g., with the keel front bearing installed higher than the rear, allowing lifting force to be generated when the keel is turned to the side. Typically, in these situations, the lift forces are relatively small, and are generated passively in sailing situations and affected by other boat structures and cannot be actively influenced. Fig. 3

[0024] [Fig. 3] shows the standard canting-keel solution from the front. In the example, the boat heels about 10 degrees due to the momentum effect caused by the wind and sails and this heeling is countered by a momentum effect in the opposite direction, caused by canting the keel on its axle, at an angle of g , in the shown example approximately 40 degrees.

Fig. 4

[0025] [Fig. 4] shows a partial cross-section of a keel structure according to this invention, shown from the side, where the invention is applied to a canting keel structure. In this keel solution, the keel axle rests on spherical bearings. The illustration shows a situation where the keel axle is in the center position parallel to the centerline of the boat.

Fig. 5

[0026] [Fig. 5] shows a partial cross-section of a keel structure according to this invention, shown from the front, where the invention is applied to a canting keel structure. In this keel solution, the keel axle rests on spherical bearings. The illustration shows a situation where the keel axle is in the center position parallel to the centerline of the boat.

[0027] [Fig. 5] shows the same arrangement as [Fig. 4], but drawn from a different direction. In the solution, the front bearing is attached to an eccenterwith two roller bearings. The eccenter is rotated by using of a lever, for example, by means of pulleys or by hand, and locks into the desired position with pulleys, for example, or any other suitable locking mechanism.

[0028] The sideways movement of the front of the keel axle is prevented by a disc through which the axle passes. The disc has an elongated-shaped hole with a width equal to the thickness of the shaft, allowing the shaft to move in up-and- down in direction but not sideways. [0029] When the eccenter lever is turned, the eccenter forces the front of the keel shaft upwards or, alternatively, when turning in the other direction, allows the front of the shaft to lower by gravity. The change in the inclination angle of the keel axle requires that the keel axle uses spherical bearings as shown in the figures.

Fig. 6

[0030] [Fig. 6] shows a keel solution according to the invention corresponding to [Fig.

4] in a situation, where the eccenter is turned counterclockwise as per drawn view and the axle of the keel has deviated vertically by an angle of b from the centerline of the boat, in the shown example about 4 degrees.

Fig. 7

[0031] [Fig. 7] shows a keel solution according to the invention corresponding to [Fig.

5] in a situation, where the eccenter is turned counterclockwise as per drawn view and the axle of the keel has deviated vertically by an angle of b from the centerline of the boat, in the shown example about 4 degrees.

[0032] [Fig. 7] thus illustrates the same situation as [Fig. 6], but shown from a different direction.

Fig. 8

[0033] [Fig. 8] shows a keel solution according to the invention, applied to a keel that turns on a vertical hull-axle arrangement. The illustration shows the keel solution as a cross-section from the side.

Fig. 9

[0034] [Fig. 9] shows an example implementation of an orientation member (221) used for keel solutions according to [Fig. 8] and [Fig. 10] For easier illustration, the components that are connected to each other in use are presented separately and shown from two directions.

Fig. 10

[0035] [Fig. 10] shows a keel solution according to the invention, applied to a keel that turns on a vertical hull-axle arrangement. The figure shows the keel solution as seen from the side and when the keel is turned to the side and the keel-arm profile is oriented slightly upwards.

Fig. 11

[0036] [Fig. 11] shows the details of an arrangement according to the invention as shown in [Fig. 8] and [Fig. 10], based on auxiliary-power-operated alignment units, as viewed from above.

Fig. 12

[0037] [Fig. 12] shows the effect of the keel-axle inclination on the fin position in relation to the water flow when the keel is canted to the side. When the keel is in the middle position, there is no effect because the angle of attack of the profile is not changed. But when the keel is turned to the side, an angle of attack a begins to develop for the fin. If the keel were to be canted 90 degrees, the angle of attack of the fin would be the same as the axle inclination.

[0038] [Fig. 12] therefore shows the boat as seen from the front of in a situation where the eccenter has deviated the keel axle by approximately 6 degrees by raising the front bearing. The keel has been rotated about 40 degrees to the side. The figure shows a cross-section plane (x4) that cross-sects the keel at a right angle. The figure also shows the surface of the keel as cut by plane (x4), shown such that in the cross-section, the lower end of the profile corresponds to the front edge of the keel.

[0039] As shown, by deviating the keel axle by 6 degrees with an eccenter and rotating the keel 40 degrees with respect to its axle, an angle of attack of 4 degrees and a lifting force is formed for the keel.

Fig. 13

[0040] [Fig. 13] shows the lift forces forming on a keel according to the invention.

Fig. 14

[0041] [Fig. 14] shows a keel structure according to the invention, in which the ballast is incorporated into the keel arm. [0042] The detailed description of the figures is given in the following paragraphs.

Detailed description of the First Embodiment of the invention

[0043] The keel structure of an first embodiment according of the invention is shown in [Fig. 4] and [Fig. 5] (figures showing the principle in front and side orientation, keel axle in baseline position) and in [Fig. 6] and [Fig. 7] (figures showing the principle in front and side orientation, keel axle inclined 4 degrees).

[0044] The principle of the keel structure is given in [Fig. 4] and [Fig. 5] The apparatus consists of an elongated keel arm (103), shaped as a profile, suspended in a swivel mechanism, with a ballast bulb (105) attached to the bottom end. The suspension and rotation mechanism comprises shaft pins (410), attaching the upper end of the keel arm (103) to spherical bearings (409), such that the keel arm (103) and its ballast bulb (105) can be canted essentially laterally with respect to the centerline of the boat.

[0045] The force needed to cant the keel is provided by a canting member (405), for example a hydraulic cylinder, which is secured from one end to the hull of the boat in a suitable manner to a firmly anchored attachment mount (406), and from the other end to the top of the keel arm, thus forming a lever for rotation between the bearing pins (410) and the top of the keel arm.

[0046] The bearing (409) of at least one of the two bearing pins (410), in the side view example shown in [Fig. 4] the right one, is attached to a transfer member (403), which allows the bearing (409) attached to it to be transferred away from the centerline and advantageously for the bearing to be raised and/or lowered. For example, the transfer member (403) can be carried out as an eccenter plate with an adjustment arm (407) attached to it and by turning it, the hinge point is moved away from the center line, advantageously up or down. When using a adjustment arm (407) as a transfer unit, the force required to move it can be generated, for example, using a control rope, which can be routed to a suitable position to the operator by means of swivel blocks (404) fixed to the bottom of the boat (201) and which can be locked in a suitable manner, e.g., with a rope lock. As an alternative, the transfer member (403) can also be carried out hydraulically, e.g., by means of a hydraulic cylinder, with electrically operated equipment such as a rack drive or a spindle drive, mechanically with pulleys or by other suitable means.

[0047] [Fig. 6] and [Fig. 7] show the same keel structure according to the invention as a technical drawing in a front and side orientation, but unlike [Fig. 4] and [Fig. 5], the keel axle is inclined by 4 degrees. Like the side image of [Fig. 4], the side image of [Fig. 7] is also shown so that the right side is the front and the left side is the rear of the keel.

[0048] The keel axle can be tilted by lifting the right-hand bearing (409) on the side view shown in [Fig. 6] using a transfer member (403), e.g., an eccenter plate and an adjustment arm (407), from the base position, where the bearings of both bearing pins (410) are at the same level and the keel axle is horizontal from a side view, into a position where the right-hand bearing (409) in the side view is raised by such an amount that the keel axle will be positioned at an angle of four degrees above the horizontal plane.

[0049] When the adjusting arm (407) is turned, the eccenter forces the front of the keel axle upwards or, alternatively, when turning in the other direction, allows the front of the axle to lower by gravity. The change in the canting angle of the keel axle requires that the keel axle is attached to spherical bearings (409) as shown in the figures.

[0050] When the keel arm (103) and the ballast bulb (105) are in the centre position, tilting the keel axle has little effect, as the profile of the keel arm (401) is still practically perpendicular to the flow, but by turning the keel with the canting member (405) from the middle position toward the side, an angle of attack is formed on the profile which causes a lifting force. In this example, the direction of the lift force “lifts” the keel as shown in [Fig. 13] as the force FL. If the leading- edge bearing of the keel (409) is lowered and the keel axle is canted down four degrees instead of up, as shown in [Fig. 5], the direction of the lifting force would be opposite to the direction shown in [Fig. 13] for the force FL. [0051] The structure shown in [Fig. 4] and [Fig. 5], as well as [Fig. 6] and [Fig. 7], comprises an advantageously movable bearing (409) and, mounted in connection with it, a plate or other guide (408) with an elongated opening through which the bearing pin (410) passes. The width of the guide is equal to the thickness of the bearing pin, including the normal axial play required for rotation and the guide thus allows the shaft to move up and down in direction, but not sideways.

[0052] Although in the examples shown in [Fig. 4], [Fig. 5], [Fig. 6] and [Fig. 7], the right-hand bearing is moved (409) with respect to the side view, the invention can also be implemented by moving the left-hand bearing with respect to the side view or both bearings appropriately. The quantity affecting the flow characteristics of the keel is the keel-axle canting angle mentioned above.

[0053] In the structure shown in [Fig. 4], [Fig. 5], [Fig. 6] and [Fig. 7], the keel axle, which is the pivot axle of the keel arm (401 ), is implemented with two bearing pins (410), but it can also be realized by one axle passing through the keel arm.

In both cases, the fact must be taken appropriately to account that the distance between the bearings (409) increases slightly when canting the keel axle, for example by providing a some amount of additional length to the axle or to the axle pin.

Detailed description of the Second Embodiment of the invention

[0054] The keel structure according to a second embodiment of the invention is shown in [Fig. 8] and [Fig. 9]

[0055] As with the first embodiment, the second embodiment also aims to adjust the keel profile orientation in relation to the water-flow direction, thus making more efficient and versatile use of the keel structure.

[0056] Whereas in the first embodiment, the invention is applied to the basic concept of a canting keel, in the second embodiment, the invention is applied to a different keel structure, where the keel is essentially rotated around a vertical axle in relation to the plane of the hull of the boat. [0057] A drawing, illustrating principles of the second embodiment of the invention is presented in [Fig. 8] as a cross-section of the keel structure parallel to the longitudinal direction of the boat.

[0058] As shown in the keel structure of [Fig. 8], the keel arm (103) and the ballast bulb (105) can also be implemented in such a way that the keel arm (103) is equipped with a hydrodynamically advantageous profile and can be rotated around the axis (X1) with the help of bearings (302, 303) integrated into a hull- axle arrangement (202). Advantageously, the hull-axle arrangement (202) can be placed in a space between the cabin or hold floor (306) and the bottom of the watercraft (201). The hull-axle arrangement (202) is supported by bearings (307, 308) such that it can be rotated essentially around a vertical axis (X2) relative to the plane of the boat, thereby allowing the keel arm (103) to be turned and the ballast bulb (105) to be moved to the side in relation to the centerline of the boat.

[0059] In this case, auxiliary-power operated, such as electrical, hydraulic or pneumatic, internal-combustion engine and/or similarly operated the functional units (207) and/or orientation members (221) and (222) are advantageously arranged to be used to orient the keel arm (103) and/or the ballast bulb (105) with respect to the flow, for example to minimize the leading surface or produce a lifting force on the keel profile in the desired direction.

[0060] Advantageously, the functional units (207) can be realized as a hydraulic cylinder connected to the hull-axle arrangement (202) in a power-transmitting manner.

[0061] In this context, in an advantageous embodiment, the orientation units comprise a first orientation member (221) to rotate the keel arm (103) in relation to its longitudinal axis (X1) to minimize the leading surface of the keel arm (103) in terms of flow drag or to produce the desired directional lift force on the keel profile.

[0062] In this context, in a further advantageous embodiment, the orientation units comprise a second orientation member (222), turning the ballast bulb (105) in relation to the keel arm (103). The second orientation member (222) may be realized, for example, by an electric motor arranged to employ a spindle-drive principle to move the drive shaft (311) running inside the keel arm (103) longitudinally, i.e., in the direction of the axis (X1), in order to move the ballast bulb (105) in relation to articulation point (320) in view of the keel arm (103), by the angle (e) shown in [Fig. 8]

[0063] In an application as in [Fig. 8], the hydraulic cylinder used as the functional unit (207) turns the keel arm (103) in relation to the vertical axis (X2) and the ballast bulb (105) moves to the side. The first orientation member (221) in the application in question turns the keel arm (103) with respect to the axis (X1) so that the keel-arm profile is at the desired angle of attack with respect to the water flow direction. When the functional unit (207) turns the keel arm (103) at most typically less than 90 degrees, e.g., advantageously about +/- 76 degrees, the first orientation member (221) must turn the keel arm (103) with respect to the axis (X1) in order to keep the keel-arm profile substantially perpendicular to the direction of water flow in relation to or to set the desired angle of attack. One end of the orientation unit in question is attached with a suitable multi-directional moving joint (401 ), for example, a ball joint, to the adjusting member (313) attached to the hull of the boat.

[0064] For example, the orientation member (221) can be implemented as fork shaped, where a bar-like component (402) with attachment elements is able to move longitudinally inside a bushing (403) and is mounted such as to be able to rotate around its axis. Such an implementation example of the orientation unit is shown in [Fig. 9] as a principle-illustrating drawing from two directions, such that the fork-and-bar-like part, interconnected in use, is shown separately.

[0065] When the center of the joint (401 ) is on the keel axis (X3), the angle of attack of the keel arm (103) with respect to the water flow remains unchanged when the keel arm is turned. The keel axis (X3) passes through the intersection of the axes (X1), the longitudinal axis of the keel arm, and (X2), the vertical axis of rotation of the keel arm, and is parallel to the centerline of the boat. Joint (401) is attached to a variable length connecting piece (402), e.g., a pin that moves linearly inside a bushing and rotates freely. A fork (404), shown in detail from the front and side in [Fig. 9], is attached to the bushing and further connected to the keel arm by an axle pin passing through the keel arm. Joint (401), pin (402), bushing (403) and fork (404) are shown in detail from the front and side in [Fig. 9]

[0066] If the center of the joint (401) is raised or lowered by the adjusting member (313) in relation to the keel axis (X3) as described above, the angle of attack of the keel arm (103) and its profile in relation to the water flow changes. By adjusting the angle of attack, the lifting force acting on the profile can thus be adjusted.

[0067] The ballast bulb (105) is connected to the keel arm (103) by an axle pin (320), on which the ballast bulb (105) can be rotated in accordance with [Fig. 8] at an angle (e) on the cross-section plane of the of the keel arm, at a maximum angle of about 36 degrees in the example of the figure. As an implementation of a second orientation member (222), one can use, for example, an electric motor connected to a ball screw that moves a drive shaft (311) located inside the keel arm linearly, parallel to the axis (X1), as shown in [Fig. 8] When the drive shaft is moving linearly, it turns the bulb around the axle pin, to a maximum of 30-40 degrees, advantageously up to approximately 36 degrees, with the angle of rotation of the functional unit (207), e.g., implemented by a hydraulic cylinder, to the left and right being slightly less than 90 degrees, advantageously, e.g., +/- 76 degrees.

[0068] When the functional unit (207), for example, a hydraulic cylinder, turns the keel arm with respect to the axis (X2) and when the first orientation member (221 ) turns the keel arm with respect to the axis (X1 ), the angle of attack of the ballast bulb (105) with respect to the water flow changes. By simultaneously turning the ballast bulb (105) with second orientation member (222), for example by an electric motor, in a vertical plane as determined by the drive shaft (311), the direction of the ballast bulb (105) is kept as desired, for example, the leading surface in terms of the water flow is kept as small as possible and thus advantageous in terms of drag. Detailed description of the Third Embodiment of the invention

[0069] As an alternative embodiment to the above, with reference to [Fig. 14], the keel structure may also be implemented in such a way that the keel weight is integrated into the rotating keel arm (103), such that a separate ballast bulb (105), attached by means of a bearing, is not needed anymore.

[0070] Then, also the bulb-direction-related drive shaft (311) and second orientation member (222) are not needed.

[0071] Since, in this embodiment, the keel arm is also shaped as a profile, the principle of orientation of the profile is the same as in the second embodiment.

The first orientation member (221) turns the keel arm (103) with respect to the axis (X1 ), such that the angle of attack of the keel-arm profile with respect to the water flow is of the desired magnitude, for example either so that the leading surface against the water flow is as small as possible and the keel arm is in an optimal position for drag or so that the keel profile is at a desired angle of attack, thus allowing the lifting force acting on the keel to be adjusted.

[0072] As shown in [Fig. 14], the keel mass is advantageously placed as low as possible to ensure that the center of gravity of the boat is low as possible and the righting force is high.

[0073] It is clear that the invention is not limited to the applications shown, described or explained above, but can be modified in the context of the basic idea in accordance with given uses and applications. It is therefore clear, first of all, that the technical actuators and mechanisms used in the type of solution as described here can be implemented in a wide variety of ways, e.g., by combining mechanical and hydraulic functions or by using, e.g., battery-operated, singular operating actuators or control equipment.

[0074] It is also clear that by using, for example, measurement sensors, real-time or tabulated measurements, one can enhance and assist or automate the use of a keel structure consistent with the invention under different operating and sailing situations.