Title of Invention: Arrangement for the stabilization of a watercraft

Technical Field

[0001] The invention aims to stabilize the watercraft, in particular to control the vertical inclination perpendicular to the longitudinal direction of the watercraft with a movable keel structure by enabling the functional components to turn the keel structure and to move the center of gravity laterally away from the centerline of the craft in order to obtain a righting force moment.

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

[0003] To prevent lateral movement, sailboats are fitted with a keel, which is subject to an effective pressure force to resist the lateral drift of the boat. The pressure force is generated by the sideways movement of a conventional fixed-keel boat in the water, resulting in an angle of attack between the keel centerline and the direction of travel. The higher the keel angle of attack and the higher the speed of the boat, the greater the lateral force component of the pressure force. The keel angle of attack is typically zero to six degrees, but it can be up to ten degrees for a moment.

[0004] The adverse heeling caused by the lateral force component of the thrust acting on the sails is countered by the righting-moment effect resulting from the lifting force acting on the hull of the boat. The more stable the hull shape of the boat, the lower the center of gravity of the boat, and the heavier the boat, the greater the effect of the righting moment. As a result, monohull sailboats are usually equipped with a heavy keel, which increases the weight of the boat and shifts the center of gravity down. The ballast may account for more than 50% of the total weight of the boat and normally not less than 25%. In many cases, the keel weight is concentrated in a thick lower component part, the so-called bulb. Naturally, excess weight increases the friction of the water. 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 boat.

[0005] The heeling can also be prevented, for example, by using a movable keel fin and/or a ballast-filled 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 shift of position of a large ballast may require considerable energy and force, especially if the ballast is also moved vertically and the gravity itself resists the shift.

[0006] In sailboats, the shift of position of a ballast to reduce heeling is unquestionably beneficial. However, the equipment required always generates costs and may also slow down the forward motion of the boat, which requires careful 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 forward motion of the boat. The wetted-surface area of a body is the surface which is in contact with flowing water. The wetted-surface area of an advantageously designed body is the determining factor for fluid friction. The greater the wetted-surface area of a body, the greater the fluid friction of the body.

[0007] The aim for 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 building of the boat in a way that is significantly lighter and/or simpler than normal, for example in terms of the required equipment or machinery.

Background Art

[0008] Examplary solutions related to the above-mentioned purpose can be found in constructions where the keel structure is arranged, for example, on the centerline of a sailboat, turning around a longitudinal axis, as represented by the so-called canting keel. However, these types of solutions do not provide sufficient stability to reduce the boat's heeling without the boat having a significantly greater draft than normal. In addition, very complex and costly mechanisms are required, which also require constant monitoring and maintenance, so that these solutions, particularly when used in humid conditions, can function reliably. The current commercial arrangements require a separate source of power in the case of anything larger than a minor boat.

[0009] Some implementation methods for the above-mentioned canting keel-back solution are described in patent publication EP 1 741 624.

[0010] A different mechanism is described in patent publication FR 99 01 546, where the keel structure of the sailing boat, as described in the beginning of the document, is arranged to move laterally away from the centerline of the boat as a shift essentially parallel to the centerline. This solution is quite complex in terms of practical application because it moves the keel structure on two inline articulating arms on the centerline of the sailboat, which is why this construction is also very heavy.

[0011] On the other hand, it is a fact that it is advantageous to have as low a ballast as possible. In this solution, the articulating arms are horizontal and inside the boat hull. If the ballast is to be brought down, the structure also requires vertical structures, for example two keel fins, where the structures have a large wetted- surface area compared to one articulating arm. Due to the heavy stress caused by the ballast, these vertical structures must also be very strong.

[0012] The solution in the international publication WO 87/00812 is based essentially on the fact that the mast of the sailboat is arranged to heel in relation to the hull of the sailing boat. To compensate for this heeling motion, the solution includes mechanisms following the heeling of the mast, which shift the counterweight arrangement at the bottom of the boat, which can be either inside the boat or outside the boat, combined with the keel. This solution consists of many hydraulic cylinders on different areas of the boat, some of which are fully at the mercy of environmental conditions such as rain and sea water and therefore require very careful and continuous monitoring and maintenance. Summary of Invention

[0013] The purpose of the arrangement under consideration is to achieve a decisive improvement to the above-mentioned problems, thereby substantially raising the level of technology influencing the sector.

[0014] The main advantages of the arrangement consistent with the invention are the simplicity and effectiveness of the equipment and their application, enabling, with extremely simple mechanisms, functional units using minimal power to rotate or move the keel structure in such a way that it can maintain the heeling of the boat within the desired limits.

[0015] One way of implementing an invention is, therefore, the transfer of the keel structure with a small external power source, but the invention can also be implemented with very simple principles, by means of completely self-powered solutions, for example by dividing the keel resisting the transfer into two keel fins. The arrangement consistent with the invention does not have higher maintenance and service requirements than usual, nor does it require special monitoring, due to its operation with minimal force.

[0016] Unlike the solution in the case of the patent publication FR 99 01 546, the invention now under discussion consists of only one keel-arm, which can be combined with the ballast and/or the ballast can be placed in the lower ballast bulb. Due to the trigonometric laws, this single keel arm is only less than 15% longer than the above-mentioned single articulating arm of the forementioned French solution with the same lateral reach of the arms.

[0017] With the trigonometric functions of the sine and cosine a horizontal keel arm can be compared with a keel arm, which is at some angle a to the horizontal keel arm. The length of the horizontal keel arm is L. When the keel arm is canted, the angle a increases. The vertical shift of the lower end of the keel arm and the ballast bulb that may be attached to it is defined by the function sine (a) x L.

When the angle is relatively small, then as the angle a increases the ballast bulb shifts relatively much downward. At an angle a of, say, 30 degrees, the ballast bulb has already shifted down the distance of 0,5 x L. The horizontal extent of the keel arm is defined by the function cosine (a) x L. When the angle a is relatively small, the extent of the keel arm decreases only slightly as the angle a increases. At an angle a of e.g., 30 degrees, the lateral extent of the keel arm is approximately 0,866 x L. In other words, only about 14% less than when the keel arm is in a horizontal position.

[0018] Thus, when the angle a is advantageous, for example, 30 to 40 degrees, only a small loss of the keel-arm extent is incurred, but the center of gravity has shifted sufficiently downward, whereas in comparison, the solution of the patent publication FR 99 01 546 requires two arm joints and, in addition, vertical structures to reach the same distance down and to the side with its ballast bulb.

[0019] An embodiment of the invention equipped with self-powered and self functioning functional units differs from, for example, the solution presented in international publication WO 87/00812, first of all, by the two-fin arrangement, which is used in an advantageous embodiment in the present invention by transferring the keel structure from the centerline of the watercraft with a power effect that is essentially transmitted from the water instead of the force of the heeling of the mast. Further, the solution in the above-mentioned international publication does not have the same principle as the present invention for the movable keel either, because it also states that the control of the movable keel, which acts as a counterweight, is still based on a hydraulic system, which in turn is based on the heeling of the mast, as explained above.

[0020] In an advantageous embodiment, the length of the keel arm (103) is 25-150%, advantageously 50-80% of the maximum width of the craft (101).

[0021] In reference to Figures 3, 4 and 10, in an advantageous embodiment, the keel arm (103) is further arranged into a lateral slope position, as viewed from the side, e.g., at a 30-70°, advantageously a 40° angle to the horizontal plane and to rotate (w) around the essentially vertical axis in opposite directions. [0022] Figure 2 shows the effect of gravity on the boat as two forces. Force (g) is the effect of gravity on the ballast bulb of the boat and the movable keel structures. Force (G) is the effect of gravity on all other boat structures (gi) is a force component of (g) perpendicular to the vertical axis of the boat. In such a construction consistent with the invention, the sideways movement (d2) of the ballast bulb is not dependent on the draft of the boat. Therefore, the ballast bulb of a shallow-draft monohull sailboat can achieve a long sideways distance when shifted. Also, when moving the ballast bulb, the center of gravity of the boat is not raised and (di) remains constant. When the keel structure and ballast bulb are moved around a vertical axis, the ballast bulb will not move in a vertical direction except when the boat is heeling. Therefore, there is no need for a large amount of force to move the ballast bulb (cf. the canting keel, where the mass is raised vertically when the keel is turned to the side).

[0023] The following is an explanation of the operation and benefits of the arrangement consistent with the invention compared to the existing commercial canting keels and the standard fin keel.

[0024] Conventional canting keels have difficulty reaching a heeling angle of more than 35°, which produces unfavorable cylinder angles, requires large forces and high structures inside the boat and in practice also likely extra cylinders.

[0025] The canting keel requires large cylinders, great forces and a lot of energy. Large cylinders across the hull of the boat cause sills/thresholds and make it difficult or impossible for the crew to move and use space inside the boat. In the arrangement according to the invention, in embodiments using hydraulics, the cylinders are small, they are located close to the bottom of the boat and the cylinder forces are a fraction of the forces compared to a canting keel mechanism.

[0026] Prior art technology solutions require a deep fin, which for the canting reel means a very deep draft. This invention permits a normal draft.

[0027] A watercraft arranged according to the invention reacts also “softer” when running aground. If the keel arm is in the side position, it will flex back a very long way, while the overload valve releases pressure when, for example, an underwater rock is struck. However, the worst situation is when the boat is stuck on the shoals, when the sea is heaving the boat and slamming it against the bottom. In this case, the traditional fin keel will eventually push through the bottom. In the invention, the keel arm axle is flexible and primarily bends, but the boat remains afloat.

[0028] With canting keels, the keel is always upright, perpendicular to the flow. The keel arm in an arrangement consistent with the invention is only perpendicular to the flow when maximum righting moment is required. At other times, the keel arm is inclined backwards, which means that the effective leading surface is smaller and the water-induced drag is also lower.

[0029] Further advantageous embodiments of the invention arrangement are presented in the detailed description and in the respective dependent patent claims.

Brief Description of Drawings

[0030] Next, follows a description of the included drawings.

Fig.1

[0031] [Fig.1 ] shows a cross-sectional view of a sailboat equipped with a particular arrangement according to the invention.

Fig.2

[0032] [Fig.2] is a cross-sectional view of the principle of the effects of the forces related to a sailboat equipped with a particular arrangement consistent with the invention as presented in [Fig.1 ].

Fig.3

[0033] [Fig.3] illustrates a particular advantageous arrangement consistent with the invention, based on mechanical orientation members, presented here as a side view.

Fig.4 [0034] [Fig.4] shows a particular advantageous arrangement according to the invention, based on orientation members with auxiliary power sources, presented here as a side view.

Fig.5

[0035] [Fig.5] shows a particular advantageous arrangement according to the invention, based on orientation members with auxiliary power sources, presented here as a view from above.

Fig.6

[0036] [Fig.6] illustrates a particular advantageous arrangement according to the invention, based on orientation members with auxiliary power sources, presented here as a side view, with the keel turned to the side.

Fig.7

[0037] [Fig.7] shows details of a particular advantageous arrangement according to the invention, using orientation members with auxiliary power sources, as presented in [Fig.4], [Fig.5] and [Fig.6], the details presented here separately in order to aid in understanding said arrangement.

Fig.8

[0038] [Fig.8] presents a particular advantageous arrangement according to the invention, based on orientation members with auxiliary power sources, here presented as a side view.

Fig.9

[0039] [Fig.9] shows a particular advantageous arrangement according to the invention, based on orientation members with auxiliary power sources, here presented as a side view.

Fig.10

[0040] [Fig.10] presents a side view of a sailboat with an arrangement of the type as shown in [Fig.3] Fig.11

[0041 ] [Fig.11 ] presents a sailboat equipped with a particular arrangement according to the invention, shown here as a view from below.

Fig.12

[0042] [Fig.12] illustrates force effects on a sailboat equipped with a particular arrangement according to the invention as per [Fig.11]

Fig.13

[0043] [Fig.13] illustrates a movable keel structure according to a particular arrangement according to the invention, shown from above.

Fig.14

[0044] [Fig.14] shows force effects on the particular arrangement according to the invention as presented in [Fig.13]

Detailed description of the First Embodiment

[0045] The arrangement for the stabilization of a watercraft according to the first embodiment is presented in [Fig.1 ] (cross-sectional view of the principle), [Fig.2] (illustration of the principle of [Fig.1] with illustrated force effects), [Fig.11] (from- below view of the functional principle), [Fig.12] (principle illustration as per [Fig.11 ] with illustrated angles of attack and force effects), [Fig.13] (principle illustration of the keel structure) and [Fig.14] (principle as per [Fig.13] with the illustrated force effects).

[0046] The purpose of the arrangement is the control of a vertically perpendicular-to- the-centerline heel (a) with the help of a movable keel structure, particularly a rotating keel arm (103), equipped with a ballast bulb (105), on a at least partially self-propelled watercraft (101), such as a sailboat or equivalent, by enabling the operational members (207), such as a rope pulleys, threaded rods, rack bars or hydraulics to rotate the keel arm (103), supported by a frame-shaft arrangement (202) and shift the ballast bulb (105) laterally away from the centerline of the watercraft, advantageously as a essentially parallel shift to the centerline of the boat, so as to provide a righting moment to counteract the heeling. The arrangement involves a single rotating keel arm (103) fixed to the hull of a watercraft (101), advantageously to the bottom of a watercraft (201), with a ballast bulb connected to the lower end of the keel arm (105) and arranged in a power-transmitting connection with the operational members (207).

[0047] Advantageously, with reference to the side view shown in [Fig.10], for example, a solid keel fin (102) has been arranged to the bottom of the watercraft (201), and an essentially vertical additional fin (104) to the ballast bulb (105).

[0048] Further, advantageously, mechanical orientation members (204, 205, 211), such as based on a belt, chain, articulated members or similar, have been arranged in connection to the keel structure and keel arm (103) to hold the ballast bulb (105) and/or the additional fin (104) longitudinally essentially parallel to the centerline of the watercraft.

[0049] For example, orientation members can be implemented by means of a joint arm (211) running inside the keel arm (103) and attached to the ballast bulb (105) such that the ballast bulb (105), rotating by the ballast bulb bearing (215), can be directed at will, preferably such that the longitudinal direction of the ballast bulb (105) is kept essentially parallel to the centerline of the watercraft. The orientation is performed, for example, with a control crank (204), which can be locked in the desired position by means of a locking mechanism (205).

[0050] Referring to [Fig.3] and [Fig.11], the arrangement according to the invention, implemented with mechanical orientation members, is based on a single hull-axle arrangement (202) installed on the bottom of the boat and a keel arm (103) connected to that hull-axle arrangement (202) such that the keel arm can be rotated essentially around the vertical axle. To the keel arm (103), preferably to its upper end, e.g., a pivot wheel (203) may be connected to turn the keel arm. Further, functional members (207) may be connected to the pivot wheel (203), e.g., one or more rope pulleys, a threaded rod, gear rack or hydraulic cylinder, in order to adjust or lock the position of the keel arm (103). The keel arm (103) may be horizontal or at an angle in relation to the horizontal plane. In view of the hydrodynamic factors and the advantages of achieving the lowest possible center of gravity, it is advantageous to arrange it, with reference to [Fig.3], at an angle of about 30 to 70 degrees, or advantageously at a 40° angle (b) in relation to the horizontal plane. A bearing arrangement has also been implemented at the other end of the keel arm (103), for example by shaping or attaching another vertical axle, by which the ballast bulb (105) is supported on a bearing (215). A guide fin or profile (212), which turns freely with the flow, may be advantageously placed around the keel arm (103) to minimize the drag. It is, of course, possible to equip it with, for example, a locking pin that keeps it parallel to the centerline of the boat and from which position it can be turned if necessary, the effect being the same as the fin (104) attached to the ballast bulb. In addition, in the example solution shown in [Fig.13], [Fig.14] and [Fig.3], the turning of the keel arm (103) has been prevented with two pulleys functioning as functional members (207), with the pulley ropes led around the turning wheel (203). The ends of the ropes are then advantageously attached to the turning wheel (203). Alternatively, the rotation of the keel arm (103) may also be carried out by other arrangements, e.g., with electrical, pneumatic, hydraulic members or mechnisms using internal combustion engine operation or equivalent.

[0051] As the keel arm (103), as shown in [Fig.3], turns from the center position to both directions, the ballast bulb (105) attached to the end of the keel moves in relation to the center line of the boat, while also the center of gravity of the boat shifts sideways. The angle of rotation of the keel arm (103) from the center to the sides could be 0-90 degrees, or advantageously up to 76 degrees per side, with the entire angle of rotation from one side to the other side (w) being the double number of degrees.

[0052] Since the ballast bulb (105) turns with the keel arm (103) on an essentially vertical hull-shaft-bearing arrangement (202), arranged in the boat hull, the keel arm (103) and ballast bulb (105) move horizontally in relation to the boat. However, as the boat heels, the keel arm (103) and the ballast bulb (105) must be moved up on an incline, which is typically 30 degrees maximum in a normal operating range, but in most cases considerably less. Moving the ballast bulb as horizontally as possible is beneficial, because it requires little power and energy. In this case, the equipment needed for the functional members (207) can be small and light and the boat will be less dependent on additional power sources.

A further benefit of moving the ballast bulb on the vertical axle horizontally in relation to the boat is that this allows it to be moved a long distance sideways, without the boat's draft being a critical factor. Further, when the center of gravity is moved on a horizontal plane, it will always stay down, unlike in the previously mentioned canting-reel arrangement, which has an axle that is longitudinal in relation to the boat and the keel is swung from one side to the other. When the keel is canted, the center of gravity of the boat is also raised, which means that the self-righting requirements for offshore sailboats require an increase in weight.

[0053] In particular, the arrangement in [Fig.3] has further advantageously orientation members (204, 205, 211), with an appropriate adjustment capability, e.g., via a transmission method with a steering crank, such as a cardan-shaft arrangement, inside the above-described hull-shaft arrangement (202) and keel arm (103). The other end of the orientation member (211) is fixed to the ballast bulb (105). The purpose of the orientation members (204, 205, 211) is to maintain the ballast bulb (105) in the desired orientation relative to the centerline of the boat. When the keel arm (103) turns from side to side, the orientation members always maintain the ballast bulb in the same orientation as the centerline of the boat and the steering crank orientation member (204) is kept stationary relative to the hull of the boat. By turning the steering crank (204), the ballast bulb (105) can be turned in relation to the centerline of the boat. The steering crank (204) can be equipped with a locking mechanism (205), such as a locking pin and a knob that releases the lock and allows the steering crank (204) to be turned. Turning such a crank does not require heavy forces or much energy.

Detailed description of the Second Embodiment

[0054] As an alternative application to the above, with reference to [Fig.8], the ballast bulb (105) can also be implemented without an additional fin (104). Detailed description of the Third Embodiment

[0055] As an alternative application to the above, with reference to [Fig.1 ], [Fig.10], [Fig.11 ] and [Fig.12], the stabilization mechanism can also be implemented in an essentially self-powered manner, using two keel fins (102) and (104).

[0056] [Fig.12] shows the wind direction as an arrow (WD). In the pictured situation, the fins (104) and (102) move through the water such that the center line of the fins is not parallel to the direction of travel. The fins have angles of attack (a) and (r), with the pressure forces (F _a ) and (F _r ) exerted on the fins. In a normal operating range, the pressure force exerted on the fin increases as the angle of attack increases.

[0057] In the situation shown in [Fig.12], fin (104) is turned five degrees clockwise in relation to the boat centerline, which means that the lateral movement of the boat is resisted by the force F _a + F _r . The lateral movement of the boat is balanced when the lateral movement is constant, not accelerating. [Fig.12] shows the lateral movement of the boat as being in balance of motion and the angle of attack of the fin (102) at the bottom of the boat being three degrees and the angle of attack of the other fin (104) located at the end of the keel arm (103) on the ballast bulb (105) being eight degrees.

[0058] The lateral motion balance could also be obtained by turning the fin (104) five degrees counterclockwise. In this case, the course of the boat in relation to the centerline would be different from the picture and could be assumed to be seven degrees, for example. In both cases, the sum of the forces F _a + F _r would be equal. By rotating the second fin (104) of the arrangement consistent with the invention, the mutual force distribution of the fins and consequently the pressure force applied to the second fin can be influenced (similarly, the first fin (102) could also be constructed such as to be rotatable).

[0059] As shown in [Fig.2] and [Fig.14], the vertical-axle momentum balance is determined by the equation F _h x = l_2 x F _r - l_3 x gi. The force gi is therefore a horizontal force component relative to the boat of the gravity force of the bulb, the center of gravity of which is illustrated in these figures by a circular symbol. If you define the rotation effect as positive clockwise, the situation in the image is F _r x L2 < 0 and gi x L ₃ > 0. If one wants to move the ballast bulb further away, i.e., rotate the axle counterclockwise, it would be beneficial if F _r x L2 + gi x l_ ₃ < 0. In this case, the pulleys used to lock the keel arm would not need to produce force to turn the keel arm. It would be sufficient to release rope from the pulley under tension. Similarly, if one would like to move the ballast bulb towards the center line of the boat, it would be beneficial if F _r x L2 + gi x L ₃ > 0.

[0060] The direction and magnitude of the momentum effect of gi x l_ ₃ depends on the sailing situation and can be influenced, for example, by changing the course of the boat, which is not always possible or at least not appropriate. The direction and quantity of the momentum effect F _r x L2 can therefore be changed in a simpler way by turning the second fin (104), which, instead, can easily and simply affect the force F _r and thus the vertical-axle momentum balance.

[0061] In addition to the mobile fin (104) installed in the ballast bulb (105), a fixed keel fin (102) is attached advantageously to the bottom of the boat. The combined lateral force-effects of the pressure forces exerted on the fins resist the lateral travel of the boat. In a balance of motion, the combined lateral force-effect of these fins is equal to the opposite force-effect of the pressure forces acting on the sails. In continuous sailing, where there is no need to change the position of the ballast bulb, it may be advantageous to keep the attached fins slightly turned, e.g., two degrees in either direction. This allows the total drag of the fins to be adjusted to an optimum.

[0062] If, in some state of balance of motion, the angle of attack of either of the two fins is changed, the pressure exerted on that fin and its lateral force component will change. In order for the boat to reach its balance of motion again, the angle of attack of the second fin needs to be changed such that the lateral effect of the pressure force applied to this other fin changes by the same amount of absolute value, but in the opposite direction.

[0063] For example, when the steering crank is turned in such a way that the angle of attack of the fin (104) attached to the ballast bulb (105) increases, the pressure force applied to this fin increases almost linearly as a function of the angle of attack. This reduces the lateral movement of the boat, reducing the angle of attack and the lateral force-effect of the fixed fin (102). In a motion equilibrium, the combined lateral force effect of the pressure forces on the fins is more or less equal than before turning the fin attached to the bulb. However, the pressure force exerted on the fixed fin has decreased and the pressure exerted on the fin attached to the bulb has increased. The corresponding chain of events occurs with opposite consequences, when turning of the steering crank reduces the angle of attack of the fin (104) attached to the bulb.

[0064] There may be further fins and the fins may also be rotatable. Thus, for example, in a two-fin solution, the fixed fin could be rotatable, thus eliminating the need to rotate the ballast bulb.

[0065] In particular, the arrangement in [Fig.3] is therefore intended to turn the keel arm (103) and move the ballast bulb (105) laterally using the arrangement’s self generated forces as much as possible without much need for energy generated by machinery or human power, in which case the operation of the sailing boat is mainly based on wind power exploitation.

[0066] The most significant forces affecting the ballast bulb (105) and the fin (104) attached to it, which affect the momentum equilibrium, are the gravity force acting on the ballast bulb (105) and the pressure force acting on the fin (104), in particular its lateral force component.

[0067] The gravity magnitude depends first of all on the boat's degree of heel. The boat crew can have a certain effect on the boat's heeling angle and thus on the magnitude of gravity’s force-effect, for example by adjusting the sails and changing the course of the boat. However, the required measures are relatively large and time-consuming and the boat will not sail optimally in the selected direction. In addition, the acting direction and magnitude of gravity with respect to the momentum equilibrium of the hull-axle arrangement (202) are limited. The pressure force magnitude depends on the angle of attack of the fin (104) attached to the ballast bulb and the speed of the boat. The orientation member steering crank (211) can be rotated to turn the ballast bulb (105) and the other fin attached to it (104) as easily as the rudder. When the fin in question is turned, its angle of attack changes, which also changes the magnitude and direction of the pressure force that affects it and changes the momentum equilibrium of the hull- shaft arrangement.

[0068] The momentum equilibrium is suitable for the self-propelling rotation of the hull-axle arrangement when the aggregate moment effect of gravity and pressure force is in the desired direction, i.e., in the direction that the ballast bulb is desired to be turned to in each case. In this case, the force required for the turning wheel may be 0 N and the ballast bulb will move in the desired direction when releasing the pulley.

[0069] For example, a normal sailing situation is one where the boat heels and the ballast is affected by gravity. There would be a need to reduce the heel by shifting the ballast bulb to the side. However, the momentum effect of gravity is counter to the desired direction of rotation. A prerequisite for the arrangement consistent with the invention to be effective is that the fin (104) attached to the ballast bulb is subjected to a pressure force of sufficient magnitude and correct direction in order to turn the keel arm (103) in the desired direction. The point to achieve is that the momentum effect of the pressure force on the hull-shaft arrangement (202) is made greater than the momentum effect of gravity.

[0070] In practice, the arrangement in [Fig.3] is thus feasible for a very lightweight operation, and the transfer of the ballast bulb (105) does not require much energy, for example, hydraulic or electrical energy, but rather, in typical sailing situations, the ballast bulb can be moved simply, e.g., by turning the fin (104), for example, when at the most 20% of the weight of a boat with a relatively stable hull is placed at the end of a turning keel arm, the boat is traveling at speed and the boat has an angle of heel less than 25 degrees. There exist also sailing situations where self-powering does not always occur. For example, after a turn, the boat may be moving so slowly that sufficient pressure force is not generated on the fin. If the ballast bulb (105) is then to be moved, it requires the use of external energy, e.g., that produced by the crew, or produced electrically or hydraulically. But what is essential is that when used correctly and by using the right sailing technique, almost all sailing situations can be dealt with by only turning the fin. [0071] The following is a brief example presentation of the operation of an alternative arrangement consistent with the invention.

[0072] The boat sails on a beam reach with desired five degrees of heel. The keel arm (103) is turned 20 degrees into the wind and both fins (104), (102) and the boat centerline are parallel. In this case, for example, if the wind shifts more towards headwind and strengthens, the boat may heel 15 degrees instead. The aim is to reduce the heeling by moving the ballast bulb (105). In this case, the angle of attack of the second fin (104) attached to the ballast bulb (105) can be increased by turning the fin, e.g., four degrees, with a pressure force acting on it so high that the lateral force component of the pressure force exceeds the gravity force effect in the opposite direction. The momentum equilibrium on the keel arm (103) is then such that the keel arm rotates in the desired direction when the rotation wheel (203) is unlocked. The keel arm is then allowed to turn, for example, to a 60-degree deviation, with the boat angle of heel then being again, e.g., the desired five degrees, after which the rotation wheel (203) can be locked and the fin (104) rotated back to its central position.

[0073] For example, when the wind force decreases and returns to its original direction, the boat heels windward “to the wrong side”, e.g., 5 degrees. In this case, it is necessary to turn the keel arm (103) to the original deviation of, e.g., 20 degrees. In this case, the second fin (104) is turned, e.g., 8 degrees into the other direction, thus changing the direction of the force effect of the pressure force acting on it. Since the boat is then due to leeway drifting about 2 degrees and the fin (104) is turned “in the opposite direction,” e.g., 8 degrees, the angle of attack of the fin (104) is, e.g., 6 degrees. The momentum equilibrium acting on the keel arm (103) is such that the arm turns in the desired direction when the turning wheel (203) is unlocked. Then keel arm (103) is allowed to turn, e.g., to a 20- degree deviation, which means that the boat has a desired degree of heel 5 degrees again, then the turning wheel (203) is locked and the fin (104) is turned back to the center position. Detailed description of the Fourth Embodiment

[0074] As an alternative application with reference to [Fig.4], the keel arm (103) and ballast bulb (105) can also be implemented so that the keel arm (103) is rotatable with bearings (302, 303) integrated into the hull-axle arrangement (202) around the axis (X1). The hull-axle arrangement (202) can be advantageously placed essentially between the cabin or hold floor (306) and the bottom of the craft (201). The hull-axle arrangement (202) in turn is supported by bearings (307, 309) so that it can be turned around the axis (X2), thus allowing the keel arm (103) to be turned and the ballast bulb (105) to be moved sideways in relation to the boat centerline.

[0075] In this case, auxiliary-power-operated, such as electric, pneumatic/hydraulic, internal combustion and/or equivalent functional units and the first orientation member (221) and the second orientation member (222) are advantageously arranged in connection with the keel arm (103) and the hull-shaft arrangement (202), to be used to rotate the keel arm (103) and/or ballast bulb (105) in relation to the direction of water flow, e.g., in order to minimize for example, the leading surface. An advantageous realization for the functional members (207) is by utilizing one or more hydraulic cylinders connected to the hull-axle arrangement (202).

[0076] In this context, in an advantageous application, the orientation members comprise a first orientation member (221) for rotating the keel arm (103) with respect to its longitudinal axis (X1), for example, to minimize the leading surface of the keel arm (103) with respect to waterflow drag.

[0077] In this context, in a further advantageous application, the orientation members comprise a second orientation member (222), rotating the ballast bulb (105) with respect to the keel arm (103). The second orientation member (222) can be implemented, for example, with an electric motor arranged according to a rack drive principle to move the drive shaft (311) running within the keel arm (103) longitudinally, i.e., in the direction of the axis (X1) to move the ballast bulb (105) with respect to the articulation point (320), in relation to the keel arm (103), in the amount of the angle (a1 ) shown in [Fig.4] [0078] With the above-mentioned structures in accordance with [Fig.4], the trajectories of the keel arm (103) and ballast bulb (105) are corresponding to those of the solution in [Fig.3]

[0079] Specifically, referring to the arrangement as shown in [Fig.4], when compared to the structure consistent with [Fig.3], it lacks a fin (104) attached to the ballast bulb (105), which receives drift-force at large angles of keel deviation. The arrangement in [Fig.3] can also, of course, include a fin, in which case the self- powered feature can be carried out by means of the force of drift.

[0080] The application shown in [Fig.4] has, compared, for example, to the application shown in [Fig.3], the advantage that the keel arm (103) in [Fig.4] can be of solid steel. The bending stiffness of a steel keel-arm is much greater than that of a tube of the same strength. This will allow for even a flatter design and a more favorable shape for water flow, thereby allowing for smaller wetted surface area and leading surface and thus lower drag.

[0081] The drag is influenced not only by the wetted-surface area of the body but also by the angle of alignment of the body in relation to the water flow. The angle of alignment of the fin, ballast bulb or other streamlined body is favorable and the drag is usually low when the leading surface of the body against the flow is minimized.

[0082] In an arrangement as shown in [Fig.4], the hydraulic cylinder used as functional member (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) turns the keel arm (103) with respect to the axis (X1), so that the leading surface of the keel arm perpendicular to the flow is as small as possible and the keel arm is thus in the optimal position for drag. As the orientation member (207) turns the keel arm (103) at a maximum of +/- 90 degrees, the first orientation member (221) must rotate the keel arm (103) in relation to the axis (X1) +/- 90 degrees. Advantageously, the orientation member (207) turns the keel arm (103) at a maximum of approximately +/- 76 degrees. The other end of the orientation member (221) is fixed with a suitable multi-directional moving joint (401), for example, a ball joint, to the bracket (312) attached to the boat hull. The center of the joint (401 ) must be on the keel axis (X3) to maintain the angle of attack of the keel arm unchanged with respect to the water flow. The keel axis (X3) passes through the intersection of the axis (X1), the longitudinal axle 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 the joint component (402), for example a pin that moves linearly inside a bushing so that the length of the orientation member (221) can change if necessary. The bushing is fitted with a fork (404), shown from the front and side in detail [Fig.7], which is further connected to the keel arm by means of 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 from the side in [Fig.7]

[0083] The ballast bulb (105) is connected to the keel arm (103) with an axle pin (320), on which the ballast bulb (105) can be rotated according to the angle (a1) in [Fig.4], with a maximum of approximately 25-45 degrees, advantageously at an angle of approximately 36 degrees, as shown in [Fig.4], at an intersecting plane of the keel arm. An electric motor, as the first orientation member (221), with a ball screw connected to it, moves the drive shaft (311) positioned inside the keel arm linearly in the direction of the shaft (X1) as shown in [Fig.4] As the drive shaft (311) moves linearly, it rotates the bulb on an axle pin, up to approx. 36 degrees, with an angle of rotation of a functional member (207), for example, the keel arm (103) powered by a hydraulic cylinder, being, e.g., +/- 76 degrees.

[0084] When a functional member (207), for example a hydraulic cylinder, turns the keel arm in relation to the axis (X2) and the first orientation member (221) turns the keel arm in relation to the axis (X1), the angle of attack of the ballast bulb (105) in relation to the water flow changes. By simultaneously turning the ballast bulb (105), for example, by means of an electric motor through the drive shaft (311) in relation to the keel arm, in a vertical plane determined by the keel arm (103), the ballast bulb (105) is directionally adjusted such that its leading surface is as small as possible with respect to the water flow and thus advantageous in terms of drag. Detailed description of the Fifth Embodiment

[0085] As an alternative arrangement to the above, with reference to [Fig.9], the keel structure may also be implemented with the keel weight being integrated into a rotatable keel arm (103), thus eliminating the need for a separate ballast bulb (105), e.g., attached with a bearing. There is then also no need for a bulb orientation drive shaft (311) and a second orientation member (222). As the keel arm’s shape is also streamlined in this application, for example as a profile, the first orientation member (221) rotates the keel arm (103) in relation to the axis (X1) so that the keel-arm leading surface perpendicular to the flow is as small as possible and the keel arm is thus in an optimal position for drag. As shown in [Fig.9], the keel mass is best placed as low as possible to ensure that the center of gravity of the boat is as low as possible and the righting moment force is as strong as possible.

[0086] It is clear that the invention is not limited to the arrangements 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 above 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 actuators or control equipment. It is also clear that by using, for example, measurement sensors and 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.