ROWLOCK

DESCRIPTION

Field of the invention

The present invention relates to an improved rowlock, in particular for use in watercrafts for sports activities.

Technical front - Technical problem

A rowlock is a device for connecting an oar with a watercraft. The rowlock positions and keeps the oar when rowing, and assists the rotation movement of the oar, in particular during the back and forth movements of each rowing stroke.

Rowlocks normally comprise an annular or fork-shaped oar-engagement portion, which is configured for receiving the an oar shaft with a minimum clearance. The engagement portion comprises a support surface, perpendicularly to which a reaction force is exerted by the engagement portion to the oar, during the rowing power phase. A means is also provided to let the rowlock rotate with respect to the watercraft, so that the rowlock can be oriented with respect to the watercraft during the rowing stroke, in order to assist the movement of the oar. The rotation means can comprise a pin and a hole configured for receiving the pin, respectively of the rowlock and of the watercraft, or vice-versa, where the pin defines a relative rotation axis.

The need is felt of adjusting the inclination angle, i.e. the angle between the rotation axis and a direction perpendicular to the support surface of the engagement portion, in order to take into account the rower's build, in particular his/her height, as well as other rower's features, so that an ergonomic position can _. be allowed while rowing. This would improve the comfort and the efficiency of rowing, by taking into account the rower's features.

This need is particularly felt in the case of watercrafts that are used in turn by rowers whose height and/or build is very different, which is the case of watercrafts used by athletes of different age and/or experience.

In order to solve this problem, a rowlock 10 has been proposed as shown in Fig. 1 , which has a side housing 11 , typically a cylindrical hole that can receive demountable hollow elements, like bushings 12 shown in Fig. 2. Bushings 12 have a hole 13 configured for receiving a pivot 4 integral to the watercraft. Hole 13 is made in such a way that, once bushing 12 has been inserted into housing 1 1 , the axis 14 of hole 13 is at a predetermined angle a with respect to the axis 15 of housing 1 1 . In particular, in the case of the cylindrical bushings 12, axis 14 of hole 13 is at an angle a with respect to the axis of bushing 12. In the embodiment of Fig. 1 , two bushings 12 with the same inclination a of hole 13 are provided, which are configured to be housed in two end portions 1 1 ', 1 1 " of housing 1 1 .

Rowlock 10 is equipped with a set of bushings 12, typically four couples of bushings that can be distinguished from one another by the inclination of axis 14 of hole 13 with respect to the axis of the cylinder that defines bushing 12. If a couple of bushings 12 is replaced with another couple of the set of bushings 12 in housing 1 1 , a change is obtained in the inclination angle a of rotation axis 14' of rowlock 10 with respect to the support surface 10' for oar 2, which coincides with axis 14 of hole 13 of bushing 12.

However, such rowlocks have some drawbacks.

Firstly, whenever one wants to change said inclination, the rowlocks must be removed from the watercraft, then the bushings replaced and the rowlocks mounted again.

Secondly, the solution described above requires keeping all the set of bushings 12 (Fig. 2), which can fit with the rowlock, along with the rowlock, preferably on board of the watercraft.

Thirdly, housing 1 1 must have a large diameter and it is therefore relatively cumbersome in order to house bushings 12, in such a way that axis 14 of hole 13 can reach a wide angle with respect to the axis of bushing 12.

From AU2009 01026 a rowlock is known comprising a connection pin configured to be pivotally housed in a hole of the watercraft, and also comprising an oar-engagement portion that is connected to the pin by a hinge having a horizontal axis. The hinge allows adjusting the angle between the engagement portion and the pin. The rowlock also comprises a device for causing the engagement portion to rotate about the hinge when the rowlock rotates about the connection pin with respect to watercraft, while rowing. This device is used for synchronizing the rotation of the pin-engagement portion of the rowlock with the rotation of the whole rowlock, comprising the pin, with respect to the watercraft. In an embodiment, the rotation synchronization device comprises a cam connected to the rotation pin and a cam follower connected to the engagement portion. Therefore, the rowlock according to AU2009101026 is intended for adjusting the inclination of the engagement portion responsive to the position of the oar about the pin, following a predetermined pitch profile, so as to maximize the rowing efficiency. In order to change the pitch profile, the cam and/or the cam follower must be changed.

GB 637.861 relates to a rowlock configured for obtaining a longer effective oar stroke for a given movements of a rower's hands, without reducing the distance of the rowlock from the longitudinal axis of the watercraft. Adjustment means are depicted for adjusting the position of the rowlock in a vertical plane, comprising a hinge and a couple of adjustment nuts that are screwed on a screw-threaded rod and that abut on the two faces of a flat connection element integral to a rotation pin of the rowlock, where the rod abuts against the oar- engagement portion.

FR 964.586 and US 1 ,656,534 describe rowlocks comprising a bracket for engaging an oar, a base configured for being mounted on an outrigger plate and a support that rises from the base. The bracket is connected through a lower spherical joint and an upper spherical joint with the base and with the upper end of the support, respectively, in order to allow it rotate about an axis that passes through the two spherical joints. In US 1 ,656,534, the base has a first guide oriented according to the watercraft forward-aft direction, on which a first slide element is arranged. The first slide element has in turn a second guide oriented according to the watercraft inward-outward direction. On the second guide a second slide element is arranged whose upper face houses a portion of the spherical joint. The slide elements are normally locked on their respective guides through respective bolts, which can be loosened and then tightened to displace the lower spherical joint according to the respective above described directions, thus changing the direction of the rotation axis of the bracket with respect to the base. A similar device, comprising two nuts for loosening/tightening the bracket at lower and upper spherical joints is provided in FR 964.586, in order to change the inclination of the rotation axis of the bracket with respect to the support.

The above described adjustments compensate any slight deviation from verticality of the support, and/or any manufacturing defects of an oar which cause the blade to be not exactly aligned with the flat face of the shaft, pushing on the rowlock, so that the blade can enter the water at a right angle, in each stroke.

In these devices, if the inclination of the oar-engagement portion is modified, the direction of the rotation axis of the engagement portion also changes. Therefore, the opening angle of the two rowlocks cannot be kept fixed, as it is presently required by most athletes, in order to improve the stroke efficiency.

US 540,580 describes a rowlock comprising an outrigger plate configured for being fixed to a watercraft, a support having an extended base to be mounted to the outrigger plate, and a rotatable oar-engagement portion, whose lower portion is hinged to the outrigger plate and whose upper portion is hinged to an end of the support. The outrigger plate has a through hole. A screw- threaded pin extends from the lower face of the extended base and is arranged with clearance in the hole of the outrigger plate. A fixing nut is screwed to the portion of the screw-threaded pin protruding from the outrigger plate, and is normally tightened against the lower face thereof. A bolt is screwed in a threaded through hole of the extended base, and abuts against the outrigger plate. The angle between the support and the outrigger plate can be adjusted by loosening the nut, by moving the screw, and by tightening again the nut, in order to fix the new inclination.

Also in this case, the inclination adjustment serves for compensating construction and accidental imperfections of the rows, and the inclination cannot be changed as it would be required to take into account any possible features (build, height) and preferences of the rower.

In any case, in the prior art devices, briefly described above, the inclination of the oar-engagement portion is a relatively complicated operation, which can hardly be carried out on board of the watercraft. Firstly, the prior art rowlocks require tools such as multiple spanners, screw drivers and so on, which cannot be comfortably kept on board of watercrafts such as racing shells and the like. Secondly, a fine angle adjustment of these rowlocks is very hard to be carried out from on board of the watercraft, due to the movement of the watercraft in the water. For these reasons, the inclination must necessarily be changed ashore, which makes it difficult to carry out subsequent slight adjustments of the angle onboard. Summarv of the invention

It is therefore a feature of the present invention to provide a rowlock where the inclination angle between the rotation axis and a direction normal to the support surface of the oar-engagement portion can be changed easily and quickly, to allow to each rower who in turn uses a watercraft to get easily the inclination angle according to the own features and preferences.

It is a particular feature of the invention to provide a rowlock where said inclination angle is changed by the rower directly on board of the watercraft, typically on board of a racing shell, and remains in water.

It is another particular feature of the invention to provide such a rowlock that does not require keeping on board of the watercraft spare parts and/or tools for changing said inclination angle.

These and other objects are achieved by a rowlock comprising:

an oar-engagement portion configured to receive a linear portion or shaft of an oar, the engagement portion having a support surface for the oar and arranged to rotate about a pivot having a first fixed rotation axis;

said support surface having an inclination angle with respect to the first fixed rotation axis;

an inclination-adjustment means for adjusting the inclination angle with respect to the first fixed rotation axis;

a manoeuvre element configured to be operated by an operator for enabling the engagement portion to carry out a rotation about a second rotation axis that is substantially orthogonal to the first fixed rotation axis, and for manually displacing the inclination-adjustment means from a first inclination to a second inclination of the support surface with respect to the first fixed rotation axis;

a blocking means of the inclination-adjustment means, where the blocking means is configured to keep the inclination angle fixed while rowing, wherein a connection portion is provided for rotatably mounting said engagement portion to the pivot, the connection portion configured to rotate about the first rotation axis,

wherein the engagement portion is configured to rotate with respect to the connection portion about the second rotation axis;

wherein the manoeuvre element is arranged for causing the engagement portion to rotate about the connection portion with respect to the second rotation axis,

and wherein the manoeuvre element is arranged on the engagement portion.

This way, the inclination angle of the rowlock can be adjusted without replacing such parts as bushings, which requires disassembling the rowlocks.

This adjustment can be carried out without using such tools as keys, screw drivers and the like.

Therefore, a rower can carry out the adjustment operation alone, staying in water on board of the watercraft, in particular, by only one hand. In particular, it is no longer necessary to move the watercraft out and then again into the water as many times as required for obtaining the best adjustment, nor support boats or quays are necessary any longer, which saves time and energy. For this reason, the invention enables a fine and easy adjustment of the oar- engagement portion with respect to the watercraft.

Moreover, the connection portion allows adjusting the inclination angle of the oar-engagement portion, with respect to the watercraft, without changing the inclination of the axis of the rowlocks. For this reason, the adjustment can be done without opening the rowlocks, i.e. without changing the relative distance therefrom. This condition is presently considered necessary by most rowers, in order to obtain the best performances.

The above mentioned first and the second inclinations of the support surface with respect to the first rotation axis can be inclinations preferred by two rowers that use in turn the watercraft, to obtain a customized comfortable rowing position.

By the expression "support surface", a surface is meant on which the oar rests during the power phase of the rowing stroke, through which the rower supplies a driving force to the watercraft, and through which the oar receives a reaction force in response to this driving force.

The pivot is arranged integral to the watercraft, for instance, it is arranged integral on an outboard support or an "outrigger plate" of the watercraft. As an alternative, the pivot can be integral to the connection portion, and the device can comprise an element provided with a hole configured to pivotally couple with the pin.

Preferably, in order to keep the axis of the hole coincident with the axis of the pin, guide bushings are provided in the hole, in order to define a first rotation axis of the rowlock with respect to the watercraft.

In particular the rowlock has a two-part structure, where the connection portion and the engagement portion are two distinct parts, and the inclination- adjustment means comprises a hinge element in which the engagement portion and the connection portion engage with each other in the relative rotation about the second rotation axis. More in detail, the hinge allows a relative rotation of the engagement portion with respect to the connection portion, in a plane ideally passing through the first rotation axis and perpendicular to the second rotation axis.

In an exemplary embodiment, the manoeuvre element comprises a rod member arranged at a predetermined distance from the second rotation axis, the rod member configured to carry out a translation movement along the engagement portion, and the connection portion comprises an abutment member integral to it,

where the rod member comprises:

a head portion configured to abut against the abutment member integral to the connection portion;

a knob portion configured to be operated by an operator for translating the rod member with respect to the engagement portion, so that the engagement portion carries out said rotation about the second rotation axis, thus changing its mutual inclination angle.

Preferably, the rod member comprises a screw-threaded portion, and a nut, i.e. an internally screw-threaded ring element is provided that is integral to the engagement portion and configured to engage with the screw-threaded portion of the rod member. In this case, the knob portion can be pivotally engaged by the operator in such a way that, by rotating the rod member in a screw-in direction, a mutual slide movement of the screw and of the nut takes place, and the head portion pushes against the abutment member and causes a rotation of the engagement portion with respect to the connection portion, in particular a relative rotation of the connection portion with respect to the engagement portion about the hinge, i.e. about the second rotation axis, so as to decrease the inclination angle between the engagement portion and the connection portion. The screw-threaded connection allows a fine and precisely reproducible adjustment of the inclination angle between the engagement portion and the connection portion. In particular the rod member is at least in part arranged in a longitudinal recess within the engagement portion. In this case, a nut element can also be arranged in this recess.

For example, the knob portion can be selected between a knob integral to the screw and a head knob portion for a screwing/unscrewing tool.

In an exemplary embodiment, the abutment member is bilaterally constrained with respect to the head portion of the rod member or the screw such that, by rotating the rod member in a screw-out direction, opposite to the screw-in direction, the rod member drags the nut element to cause a rotation of the engagement portion with respect to the connection portion, to increase the inclination angle between the engagement portion and the connection portion. In this exemplary embodiment, the inclination angle can both increased and decreased by operating the screw in a screw-in direction or in a screw-out direction, respectively.

Advantageously, a single screw is provided that is arranged substantially orthogonally to the second axis, i.e. to the axis of the hinge, at a predetermined distance from the second axis.

In an exemplary embodiment, the abutment member is rotatably arranged about a third rotation axis integral to the connection portion. More in detail, the abutment member can comprise a housing where the screw head portion of the rod member is inserted. This way, the screw and the connection portion exchange forces that have substantially the same direction of the axis of the screw.

In an exemplary embodiment, not shown, the abutment member can be fixed to the engagement portion, while the head portion of the rod member or the screw and the abutment member, in particular its housing, can be arranged to form a rotatable coupling about an axis oriented as the third axis, for example the head portion and the housing can be configured to form a cylindrical joint or a spherical joint.

In an exemplary embodiment, the rod member is a first rod member, and the inclination-adjustment means comprises a second rod member, the first rod member and the second rod member arranged substantially orthogonally to the second axis at a respective predetermined distance from the axis and at opposite sides with respect to the second axis, where the first and the second rod member comprise respective end portions or head portions that unilaterally abuts against a respective abutment member, so that operating the first/second rod member in a screw-in direction, a translation movement occurs of the first/second rod member with respect to the nut element, or nut, and the head portion pushes against the respective abutment member and causes a rotation of the engagement portion with respept to the connection portion about the second rotation axis, where the inclination angle increases/decreases, respectively.

Each rod member is advantageously equipped with an own end portion opposite to the head, with a manoeuvre element configured to be operated by an operator, in this case a head knob portion for a screwing/unscrewing tool.

By operating the manoeuvre element of the screw in a screw-off direction, the screw head portion moves away from the respective abutment portion enabling a relative rotation between the connection portion and the engagement portion. This rotation corresponds to an increase of the inclination angle between the engagement portion and the connection portion. The rotation can be actuated by directly moving the engagement portion of the rowlock, or by operating the manoeuvre element of the screw in a screw-in direction of the screw into the respective nut. The new inclination angle is predetermined by the previous rotation of the screw, in other words the rotation takes place until the screw head portion abuts again against the respective abutment member.

In an exemplary embodiment, the manoeuvre element comprises a rod member arranged for carrying out a translation movement along the engagement portion, and

the blocking means comprises mutual slide surfaces arranged to slide along each other, the mutual slide surfaces integral to the engagement portion and to the connection portion, respectively,

where the rod member comprises a screw-threaded portion, and a nut element, i.e. an internally screw-threaded ring element is provided that is integral to the engagement portion, and is arranged for engaging with the screw-threaded portion of the rod member such that, by rotating the rod member in a screw-in direction, a mutual translation movement of the rod member occurs with respect to the nut element, and such that the rod member pushes against the connection portion to cause a relative translation movement of the engagement portion with respect to the connection portion and frictionally engages with the mutual slide surfaces, in order to mutually block the engagement portion and the connection portion at a predetermined relative inclination.

In particular, the nut element, which is integral to the engagement portion, is arranged to engage with the screw-threaded portion of the rod member so that, by rotating the rod member in a screw-out direction, a mutual translation movement of the rod member occurs with respect to the nut element, and the rod member pushes against the connection portion to cause a relative translation movement of the engagement portion with respect to the connection portion disengaging the mutual slide surface from each other, in order to allow a relative rotation of the engagement portion and of the connection portion.

In an advantageous exemplary embodiment, the engagement surfaces have a friction engagement means, in particular comprising teeth, which provides further blocking means, besides the threaded portion of the screw and of the nut, and are associated with the inclination-adjusting blocking means in order to block the engagement portion at a predetermined inclination angle with respect to the connection portion.

In an exemplary embodiment, the blocking means is a friction blocking means for blocking the rod member, said friction blocking means comprising respective friction surfaces of the rod member and of a housing of the engagement portion, where the friction blocking means is configured to allow a displacement of the rod member by exerting a force or a torque exceeding a predetermined limit value to the knob portion of the rod member higher than a predetermined limit.

In particular the respective friction surfaces are mutually engaging screw- threaded surfaces of the rod member and of the housing of the engagement portion. In other words, the screw-threaded portion and the nut element can be configured to provide the friction blocking means.

As an alternative, or in addition to the above, the blocking means comprises

a block key that is slidingly arranged along a slide housing of the engagement portion adjacent to rod member, the block key having a projection oriented towards the rod member;

a block engagement surface of the rod member, where the block surface is configured to engage with the projection, in order to resist to a translation movement of the rod member along the engagement portion, and the block key has a retaining means for securing said block key in an engagement position of the projection with respect to the block surface the rod member.

Brief description of the drawings

The invention will be now shown with the description of exemplary embodiments of the rowlock according to the invention, exemplifying but not limitative, with reference to the attached drawings, in which like reference characters designate the same or similar parts, throughout the figures of which:

— Fig. 1 shows a prior art rowlock, whose inclination can be changed according to the prior art;

— Fig. 2 shows a plurality of bushings for changing the inclination angle between the rotation axis and a direction normal to the support surface of the engagement portion of the rowlock of Fig. 1 ;

— Figs. 3 and 4 are diagrammatical side views of a rowlock according to the invention, in two different configurations;

— Fig. 5 is a diagrammatical rear view of the rowlock of Figs. 3 and 4 in the configuration of Fig. 4;

— Fig. 6 is a perspective view of a rowlock according to a first exemplary embodiment of the invention;

— Fig. 7 is a cross sectional view of the rowlock of Fig. 6;

— Fig. 8 is a perspective view of a rowlock according to a second exemplary embodiment of the invention;

— Fig. 9 is a cross sectional view of the rowlock of Fig. 8;

— Fig. 10 is an exploded perspective view of the rowlock of Fig. 8;

— Fig. 1 1 is a perspective view of a rowlock according to a third exemplary embodiment of the invention;

— Fig. 12 is a cross sectional view of the rowlock of Fig. 1 1 ;

— Fig. 13 is a perspective view of a rowlock according to a fourth exemplary embodiment of the invention;

— Fig. 14 is a cross sectional view of the rowlock of Fig. 13.

Description of preferred exemplary embodiments

Figs. 3-5 show two side views and a rear view of a rowlock 20 according to the invention. Rowlock 20 also comprises an oar-engagement portion 21 configured to receive an oar 2, which is shown in the cross sectional views of Figs. 3 and 4. Rowlock 20 also comprises a connection portion 23 for rotatably mounting oar-engagement portion 21 to a pivot 4, of axis 19, which is configured to be fixed to the watercraft, not shown, for example on an outboard support, i.e. an outrigger. In this exemplary embodiment, connection portion 23 has a cylindrical hole 29 configured to couple with a cylindrical pivot 4. In an exemplary embodiment, not shown, the pivot can be integral to the connection portion and the device can comprise an element provided with a hole suitable for pivotally coupling with pivot 4.

During the power phase of the rowing stroke, a surface 22 of oar- engagement portion 21 produces a reaction force R in response to the driving force that a rower, through oar 2 and rowlock 20, exerts on pivot 4 and, therefore, on the watercraft. This surface is indicated as support surface 22. Support surface 22 forms an inclination angle a with the direction of first rotation axis 19.

Inclination angle a between support surface 22 and the direction of first rotation axis 19 may range between two extreme angles, for example it may range between 0° and 8° with respect to first rotation axis 19 of the rowlock, as shown in the attached figures. This operating range corresponds to a range between -4° and +4° with respect to canoeing conventional reference inclination, which is an inclination of 4° with respect to first rotation axis 19 of the rowlock.

In order to adjust inclination angle a, rowlock 20 comprises a means 25 for causing connection portion 23 and oar-engagement portion 21 to rotate respect to each other about a second rotation axis 18, which is substantially orthogonal to axis 19 of hole 29, i.e. of pivot 4.

Rowlock 20 of Figs. 3-5 has a two-part structure, in which connection portion 23 and oar-engagement portion 21 are two distinct parts. In this case, inclination-adjustment means 25 advantageously comprise a hinge 17 that defines second rotation axis 18.

Hinge 17 allows a relative rotation of engagement portion 21 and of connection portion 23, in a plane that passes through first rotation axis 19 and is perpendicular to second rotation axis 29.

In an exemplary embodiment, not shown, connection portion 23 and oar- engagement portion 21 can be made in one piece that has a rotatably compliant region between portions 21 and 23, to allow a relative rotation between portions 21 and 23.

Inclination adjustment means 25 for angle a comprises a manoeuvre element 24, configured to be operated by an operator, in order to bring oar- engagement portion 21 from a first inclination cti (Fig. 3) to a second inclination 02 (Fig. 4), with respect to connection portion 23. For instance, inclination ai is an inclination to ensure an ergonomic posture to a first rower, while inclination a ₂ is an inclination to ensure an ergonomic posture to a second rower.

In the exemplary embodiment of Figs. 3-5, the manoeuvre element has the shape of a rod member 24 slidingly arranged along oar-engagement portion 21. Rod member 24 has a head portion 24' that is arranged for abutting against an abutment member 16 of connection portion 23, and has also a knob portion 24" that is configured to be gripped by an operator's hand, in order to cause a translation movement of rod member 24 with respect to oar-engagement portion 21 , so that oar-engagement portion 21 rotates about hinge 17 thus changing inclination angle a with respect to connection portion 23.

Preferably, rod member 24 comprises at least one screw-threaded portion 27, so that it can be indicated as a screw 24, and a female threaded element 28 is provided, i.e. a nut element 28 arranged for engaging with screw-threaded portion 27 of rod member 24. in this case, knob portion 24" can be rotatably engaged by the operator such that, by rotating rod member 24 in the screw-in direction, head portion 24' pushes against abutment member 16 and causes oar-engagement portion 21 to rotate with respect to connection portion 23, while inclination angle a decreases.

For example, the rod member or screw 24 can be arranged along an edge 21 ' of oar-engagement portion 21 and preferably in a recess 21" of edge 21 ', as shown in Figs. 3 and 4.

According to the invention, inclination adjustment means 25 for angle a, in particular manoeuvre element 24, are made so that inclination angle a do not change during a rowing stroke. More in detail, a blocking means is provided for keeping manoeuvre element 24 at a position that corresponds to a predetermined inclination angle a, during a rowing stroke.

For instance, the blocking means can be a friction blocking means, which comprises a friction surface between rod member 24 and a housing 26,28 of oar-engagement portion 21.

In this case, friction blocking means 26,28 can be configured to allow a displacement of rod member 24 by applying a force or a torque to knob portion 24" of rod member 24, higher than a predetermined force or torque limit value, depending upon the friction coefficient of the surface of rod member 21 and of housing 26.

In an advantageous exemplary embodiment, described with reference also to Fig. 7, screw-threaded portion 27 and nut element 28 (44,45 in Fig.7) can be selected in such a way that they themselves can work as the blocking means.

Figs. 6 to 14 show rowlocks 30,50,70,90 according to further specific exemplary embodiments of the invention. Rowlocks 30,50,70,90 comprise an oar-engagement portion 21 and a connection portion 23 with a cylindrical pivot 4. Rotatable portion 23 has a cylindrical hole 29 of axis 19 that is configured to couple with cylindrical pivot 4 (Figs. 8-10), so as to rotatably mount oar- engagement portion 21 to pivot 4, about axis 19. In order to keep the axis of hole 29 coincident with the axis of pivot 4, bushing guides 31 are provided that define axis 19 of pivot 4 as first rotation axis of rowlock 30,50,70,90, with respect to the watercraft.

Moreover, rowlocks 30,50,70,90 comprise annular oar-engagement portion 21. Oar-engagement portion 21 comprises a substantially U-shaped frame 32 that has two arms 33,34 and a base 32' from opposite end portions of which arms 33,34 extend. The arms have has respective heads 33' and 34', and a closure member 37,97 like a rod member 37 (Figs. 6-7 and 1 1-14) or a door 97 (Figs. 8-10), to prevent oar 2 (Figs. 3,4) from leaving oar-engagement portion 21. Closure member 37,97 has one end hinged at head 34' of frame 32, and is arranged to rotate in a middle plane of frame 32. In an own opposite end, closure member 37,97 has a lock means 38,98 configured to engage with a lock seat 39,99 of head 33' of frame 32. For instance (Figs. 6-7 and 1 1 -14), the lock means comprises a knob 38' equipped with an inner ring abutment recess 38" configured to engage with a protrusion 33" of head 33'. Lock seat 39 has an opening 39' for receiving an end portion 37' of rod member 37. Opening 39' and end portion 37' of rod member 37 can be configured to provide a snap engagement of rod member 37 within lock seat 39.

As shown in Figs. 8-10, oar-engagement portion 21 can comprise a removable surface element 36, connected to one of the arms of frame 33 through conventional fixing means 36', 36", in order to establish the inner size of oar-engagement portion 21. In the exemplary embodiment of Figs. 8-10, the lock means of closure member 97 to engage with frame 32 comprises a key element 98 comprising knob 98' and at least one radial tooth 98" configured to engage with an undercut portion 99' at head 33' of frame 32, by rotating key element 98.

Even if in the drawings ring engagement portions 21 are shown comprising a substantially quadrangular or U-shaped frame 32 and a closure member 37,97 at the open portion of the "U", the scope of the invention also includes rowlocks equipped with engagement portions of different type and shape, for example fork-shaped engagement portions, ring portions having a different shape, which may have or not have closure member 37,97.

Rowlocks 30,50,70,90 also comprise an inclination adjustment means 35 for adjusting inclination angle a between support surface 22, as above defined, and first rotation axis 19. As in the case of rowlock 20 of Figs. 3-5, inclination adjustment means 35 comprises a hinge 17 that allows the rotation of oar- engagement portion 21 with respect to connection portion 23 about a second rotation axis 18.

In rowlocks 30,50,70,90, according to the exemplary embodiments shown in Figs. 6-14, inclination adjustment means 35 also comprises a rod member, in particular a screw 41 , 41 ',41 " that has an end portion, i.e. a head portion, 42,42',42" that engages with an abutment member 43,43',43" integral to connection portion 23 of rowlock 30,50,70,90, and that has a screw-threaded portion 44 that engages with a nut element 45 integral to oar-engagement portion 21 of rowlock 30,50,70,90. Screw 41 , 41 ',41 " has a manoeuvre element 47,47',47" at an own end portion 46, opposite to the head portion 42, which is configured to be operated by an operator, for example a knob 47 integral to screw 41 or a head knob portion AT, AT for a screwing/unscrewing tool.

This way, by operating manoeuvre element 47,47',47" in a screw-in direction of screw 41 into nut element 45, a mutual slide movement of screw 41 occurs with respect to nut element 45, where, in particular, nut element 45 slides integrally with oar-engagement portion 21 along screw 41 . In rowlocks 30,90 (Figs. 6-10), this mutual slide movement causes a rotation movement of connection portion 23 with respect to oar-engagement portion 21 about hinge 17, i.e. about second rotation axis 18. In this case, nut element 45 moves back integrally to oar-engagement portion 21 along screw 41 with respect to connection portion 23, and causes inclination angle a to decrease. This is also possible in an operation mode of two-screw rowlock 50 (Figs. 1 1 ,12).

In rowlocks 30,90, according to exemplary embodiments shown in Figs. 6- 10, a single screw 41 is provided that is arranged substantially orthogonally and at a distance D with respect to axis 18 of hinge 17. By rotating knob 47 in a screw-in direction of screw 41 into nut element 45, oar-engagement portion 21 moves away rotationally from connection portion 23, i.e. inclination angle a decreases.

In rowlocks 30,90, head portion 42 and abutment member 43 are configured to bilaterally engage with respect to each other, in other words head portion 42 has at least one bilateral translation constraint with respect to abutment member 43, so that the distance between head portion 42 of screw 41 and abutment member 43 cannot change.

This way, by operating manoeuvre element 47 in a screw-off direction of screw 41 from nut element 45, a mutual slide movement of screw 41 occurs with respect to nut element 45, which moves forward integrally with oar- engagement portion 21 with respect to connection portion 23 and, accordingly, a rotation movement of connection portion 23 occurs with respect to oar- engagement portion 21 about hinge 17, i.e. about second rotation axis 18, in which connection portion 23 rotationally moves toward oar-engagement portion 21 , i.e. inclination angle a increases.

Therefore, in rowlocks 30,90, inclination angle a can be both increased and decreased by rotating screw 41 through manoeuvre element 47, respectively in the screw-off direction and in the screw-in direction of screw 41 with respect to nut element 45.

In the exemplary embodiments of Figs. 6-10, abutment member 43 is rotatably arranged about a third rotation axis 49 that is integral to connection portion 23. More in detail, abutment member 43 comprises a housing 55 in which the head portion 42 of screw 41 is inserted and is retained by pins 55'. This way, screw 41 and connection portion 42 exchange forces that have substantially the same direction as the axis 40 of screw 41 . In an exemplary embodiment, not shown, abutment member 43 can be fixed to the engagement portion 23, while head portion 42 of screw 41 and abutment member 43, in particular its housing 55, can be configured to form a rotatable coupling about an axis that has the same direction as axis 49, for example head portion 42 and the housing 55 can be configured to form a cylindrical or spherical joint. Still with reference to the exemplary embodiment of Figs. 6-10, screw 41 and nut element 45 are arranged within a longitudinal recess 32" within base 32' of frame 32. End portion 46 of screw 41 protrudes along with knob 47 from recess 32" through an end opening of recess 32", in which a guide element 47' (Fig. 7) is preferably present. Knob 47 and end portion 46 of screw 41 are connected to each other in a fixed joint.

A resilient element 57 can be arranged in arm 34 of frame 32 to provide a blocking means to nut element 45, which can be demounted from recess 32" of frame 32.

In the exemplary embodiment of Figs. 8-10, a blocking means 51 is provided in addition to, or instead of, the thread portion of screw 41 and of nut element 45. In particular, further blocking means 51 comprises a block key 52 that is slidingly arranged along arm 33 of frame 32, in this case it is housed within a slide housing 53. Moreover, block key 52 has a tooth 54. Blocking means 51 also comprises a block surface 56 of screw 41 , configured to engage with tooth 54 to contrast the translation movement of screw 41. Block key 52 has a blocking means 52' (Fig. 9) for blocking its own translation movement in a block engagement position of tooth 54 with block surface 56.

More in detail, block surface 56 is made on an element 56' (Fig. 10) that has a first longitudinal recess 58' (Fig. 9) for fixedly receiving a joint portion of screw 41 , and a second longitudinal recess 58" (Figs. 9 and 10) for fixedly receiving a connection pin 59 that is in turn fixed to knob 47.

With reference to Figs. 11 and 12, a rowlock 50 is described according to an alternative exemplary embodiment of the invention, in which the inclination- adjustment means 35 comprises/besides hinge 17, two screws 41 ',41 " that are arranged substantially orthogonally to axis 18 of hinge 17, at a predetermined distance from axis 18 and at opposite sides with respect to hinge 17, preferably the two screws 41 ',41" are at a same distance E. Each screw 41 ',41" has one end portion or head portion 42', 42" that abuts against an abutment member 43', 43" that, in this case, has the shape of a plate and is integral to connection portion 23 of rowlock 50. Each screw 41 ',41" is also equipped with a screw- threaded portion 44 that engages with a respective nut element 45 integral to oar-engagement portion 21 of rowlock 50. Each screw 41 ',41 " has a manoeuvre element 47',47" configured to be operated by an operator at an own end 46 opposite to head portion 42. In this case, the manoeuvre element is a head knob portion 47',47" for a screwing/unscrewing tool, not shown.

In rowlock 50, according to the exemplary embodiment of Figs. 1 1 , 12, head portion 42',42" and abutment member 43',43" are configured to abut against each other, in other words each head portion 42',42" can push against the respective abutment member 43',43".

More in detail, for instance, by operating manoeuvre element 47' of screw 41 ' in a screw-off direction, head portion 42' of screw 41 ' moves away from the respective abutment portion 43' in order to enable a relative rotation 61 ' of oar- engagement portion 21 with respect to connection portion 23, where said rotation has clockwise direction from the point of view of Fig. 12. Rotation 61 ' causes inclination angle a to decrease. Rotation 61 ' can be actuated by directly moving oar-engagement portion 21 , after grasping frame 32, i.e. by using frame 32 as a manoeuvre element, and then / alternatively, operating manoeuvre element 47" of screw 41" in a screw-in direction between screw 41 " and the respective nut element 45. The new inclination angle a is predetermined by previous rotation 61 ' of screw 41 ', in other words rotation 61 ' continues until head portion 42' of screw 41 ' abuts again against the respective abutment member 43'.

Similarly, by operating manoeuvre element 47" of screw 41 " in a screw-off direction, head portion 42" of screw 41 " moves away from the respective abutment portion 43" in order to enable a relative rotation 61 " of oar- engagement portion 21 with respect to connection portion 23, which has a counter clockwise direction from the point of view of Fig. 12. Rotation 61 " causes inclination angle a to increase. Rotation 61 " can be actuated by directly moving oar-engagement portion 21 , after grasping frame 32, i.e. by using frame 32 as a manoeuvre element, and then / alternatively, operating manoeuvre element 47' of screw 41 ' in a screw-in direction between screw 41 ' and the respective nut element 45.

In the latter case, the screws 41 ',41 " are used as a manoeuvre means that enables and causes the rotation of oar-engagement portion 21 with respect to connection portion 23. The inclination angle a is predetermined by previous rotation 61 " of screw 41 ", in other words rotation 61 " continues until head portion 42" of screw 41 " abuts again against the respective abutment member 43".

Preferably, oar-engagement portion 21 and connection portion 23 comprise respective mutual slide surfaces 63,64, in particular cylindrical slide surfaces. Mutual slide surfaces 63,64 are arranged in such a way that, during relative rotation 61 ',61 ", oar-engagement portion 21 and connection portion 23 mutually slide along surfaces 63,64.

With reference to Figs. 13 and 14, a rowlock 70 is described according to a further exemplary embodiment of the invention. Oar-engagement portion 21 comprises, in a portion of its own frame 32 opposite with respect to connection portion 23, a housing 73 and a screw 41 slidingly housed in housing 73 along its own axis 40. In this case, screw 41 engages housing 73 through an own screw- threaded portion 44 and a nut element 45 integral to housing 73 of oar- engagement portion 21 .

In an exemplary embodiment, screw 41 is pivotally connected with connection portion 23 at its own head portion 42. This connection can be provided by a hinge 17, whose axis 18 is substantially orthogonal to axis 19 of hole 29, i.e. to first rotation axis 19 of rowlock 70.

In this exemplary embodiment, oar-engagement portion 21 and connection portion 23 comprise respective engagement surfaces 63', 64', in particular surfaces having a substantially cylindrical profile. Mutual slide surfaces 63',64' are configured in such a way that, if they are mutually arranged with predetermined clearance therebetween, they can slide with respect to each other in order to allow a relative rotation between oar-engagement portion 21 and connection portion 23.

Engagement surfaces 63',64' are preferably provided with a friction engagement means, which allows blocking the relative rotation between oar- engagement portion 21 and of connection portion 23. In the case shown, the friction engagement means of engagement surfaces 63',64' comprises respective pluralities of teeth protruding from respective surfaces 63',64'.

Moreover, screw 41 has a manoeuvre element 47 at an own end opposite to head portion 42 and protruding from oar-engagement portion 21 , said manoeuvre element configured to be operated by an operator, in this case a knob 47. This way, by operating manoeuvre element 47, screw 41 translates integrally to connection portion 23 with respect to the remainder of oar- engagement portion 21 . More in detail, by rotating screw 41 in the screw-in direction or in the screw-out direction, engagement surface 63' of oar- engagement portion 21 moves towards or away from engagement surface 64' of connection portion 23, respectively. Therefore, by rotating screw 41 in the screw-in direction engagement surfaces 63' ,64' can be fixed to each other, i.e. they can be brought into a mutual engagement condition, in which the relative rotation of oar-engagement portion 21 with respect to connection portion 23 is blocked, and inclination angle a of portions 21 ,23 of rowlock 70 is fixed at a predetermined value.

The engagement condition can be a friction engagement condition. In the case of engagement surfaces 63', 64' provided with teeth, the engagement condition determined by the relative engagement of the teeth.

On the other hand, by rotating screw 41 in the screw-off direction, engagement surfaces 63', 64' can be released from each other, in order to unlock their relative rotation, so that inclination angle a of portions 21 ,23 of rowlock 70 can be brought to a new value, by a relative rotation 61 ' or 61 ", i.e. a decrease or an increase of inclination angle a, before mutually blocking again portions 21 ,23 at the new relative inclination, by rotating screw 41 in the screw- in direction.

Relative rotation 61 ',61 " can be provided by directly moving oar- engagement portion 21 , after grasping frame 32, i.e. by using frame 32 as a further manoeuvre element, in which the rotation of oar-engagement portion 21 with respect to connection portion 23 is allowed by the previous rotation of screw 41.

The foregoing description exemplary embodiments of the invention will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt in various applications the specific exemplary embodiments without further research and without parting from the invention, and, accordingly, it is meant that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology that is employed herein is for the purpose of description and not of limitation.