Patent Application
20050183654
The present invention relates to a foot brace system for use in a kayak, canoe, or similar water craft.
In order for a kayaker to maintain the stability of, and control over, a kayak, it is important that they are able to brace themselves in a snug, comfortable position. A footrest assists in this by enabling the kayaker to brace themselves with their feet on the footrest. Various foot brace systems have been disclosed for this purpose.
One such system employs a stationary footrest, fixed in a permanent position relative to the kayak seat (which is typically fixed). The most important limitation of this system is that it renders the kayak unsuitable for kayakers with different leg lengths. It also does not allow a kayaker to adjust the position of the footrest for comfort.
In order to overcome these problems, a variety of foot brace systems have been disclosed in which the footrest is moveable fore and aft. As the sides (gunwales) of a kayak taper inward toward the bow, if a connector is used between the footrest and the gunwales the system must accommodate variation in the beam of the kayak. A conventional solution to this problem is to attach a support for each foot to a rail on each side of the kayak and to build a taper into the rails which counteracts the taper of the hull. A problem with this solution is that the increased rail thickness introduces additional weight to the kayak and occupies a considerable part of the already limited space. It is also specific to each kayak.
The load applied to the footrest can be via the kayaker's heel or ball of their foot and these forces must be transferred to the hull via suitable connectors.
The loads applied to the footrest are:
An object of this invention is to provide an improved foot brace system, or at least to provide a useful alternative.
A first aspect of the invention provides a foot brace system for use in a kayak or similar water craft, the system including a footrest for engaging both feet of a user; a first connector for connecting the footrest to a first side of the craft; and a second connector for connecting the footrest to a second side of the craft; wherein the first and second connectors can retract and extend laterally so as to permit the system to account for variations in the beam of the craft when the footrest is moved fore or aft.
The connectors may retract and extend in a linear fashion (for instance by a telescoping action) but preferably each connector includes a connection member and the relative angle between the footrest and the connection member moves when the connector retracts or extends. This lends itself to a more simple construction.
Each connector may comprise a pair of rigid telescoping connection members. However, preferably each connector includes a flexible connection member which flexes when the connector is moved between its retracted and extended positions.
The flexible connection members are typically resiliently flexible so as to provide a resilient biasing force which biases the member towards its extended position.
The first and second connectors may be rigidly connected to the footrest. However a problem with a rigid connection is that it can result in the transmission of certain undesirable forces which are not aligned with the axis of the connectors. Therefore preferably the first and second connectors are rotatably connected to the footrest. This tends to result in forces being transmitted as tensile or compressive forces along the length of the connectors.
The fore/aft position can be achieved by simple lengthening/shortening of the connector, or by fixing the connector at a selected point along a rail.
The first and second connectors may be formed separately, or as a single piece for ease of manufacture.
In order to easily adjust the footrest fore and aft the system typically includes a first rail for mounting the first connector to the first side of the craft; and a second rail for mounting the second connector to the second side of the craft, wherein the connectors can be moved along an axis of their respective rails to move the footrest for or aft. The connectors may be movable between discrete positions along the rail, or may be continuously movable along the rail.
In on embodiment the rails have rail axes which lie in a common plane, and each connector includes a connection member which extends between a first connection point adjacent to the footrest and a second connection point adjacent to a respective one of the rails, and wherein a line between the first and second connection points lies in the common plane of the rails. This arrangement provides resistance against side to side of the footrest in the common plane (which will in most cases be approximately horizontal).
A second aspect of the invention provides a foot brace system for a kayak or similar water craft, the system including a footrest for engaging both feet of a user; a first connector for connecting the footrest to a first side of the craft; and a second connector for connecting the footrest to a second side of the craft, wherein the first and second connectors can be adjusted between a first configuration in which the footrest is oriented at a first fore/aft tilt angle; and a second configuration in which the footrest is oriented at a second fore/aft tilt angle.
In a preferred example each connector includes a pair of struts, and the tilt angle is adjusted by altering the strut locations relative to the hull. This can be achieved by altering the length of one of the struts, or altering position at which the strut is fastened to the hull. In an alternative example (not shown) the variation in tilt may be achieved by altering the connection point between the struts and the footrest.
A third aspect of the invention provides a foot brace system for a kayak or similar water craft, the system including a footrest for engaging both feet of a user; a first connector for connecting the footrest to a first side of the craft; and a second connector for connecting the footrest to a second side of the craft, wherein the first and second connectors can be adjusted between a first configuration in which the footrest is positioned at a first height with respect to the floor of the craft; and a second configuration in which the footrest is positioned at a second height with respect to the floor of the craft.
The third aspect enables the height of the footrest to be adjusted so that the foot brace system can be fitted into a variety of different kayaks and/or the height can be adjusted to suit different users.
The connectors may expand and contract in a linear fashion (for instance by a telescoping action) but preferably each connector includes a connection member and the relative angle between the footrest and the connection member moves when the connector moves between its configurations. This lends itself to a more simple construction.
Each connector may be formed by only a single connection member, but preferably each connector includes a pair of connection members, and the relative angle between the pair of connection members changes when the connector moves between its first and second configurations.
A fourth aspect of the invention provides a foot brace system for a kayak or similar water craft, the system including a footrest for engaging one or both feet of a user; a rail; a connector having a first part connected to the footrest and a second part mounted to the rail such that it can slide along the rail; and a locking device for locking the connector at a desired position along the rail.
The fourth aspect uses a slidable connection which transfers forces applied to the footrest to the locking device. The locking device can then be designed to transfer the forces in turn to the hull without risking buckling of the hull wall. In order to minimise such buckling forces, the locking device typically includes a first locking member which applies a shear force to a second locking member in order to lock the connector at the desired position along the rail. One suitable locking device is a rope/cleat device, which enables the footrest to be locked at any position.
In a preferred embodiment the rail has an elongate rail channel running along all or part of the length of the rail, the second part of the connector being slidably mounted in the rail channel. Alternatively the connector may contain a channel which receives the rail.
A fifth aspect of the invention provides a foot brace system for a kayak, the system including a footrest for engaging one or both feet of a user; and an adjuster for adjusting the fore/aft position of the footrest, wherein the adjuster includes a rope coupled to the footrest, and a cleat for locking off the rope at a desired position.
As kayak hulls are generally thin shell structures they are not well equipped to withstand buckling forces typically present in conventional systems where the hull fastening is adjacent to the footrest.
A sixth aspect of the invention provides a foot brace system for a kayak or similar water craft, the system including a footrest for engaging both feet of a user, a pair of rails; and a pair of connectors each connecting the footrest to a respective one of the rails at a connection point positioned fore or aft of the footrest.
Positioning the connection point fore or aft of the footrest tends to reduce the application of buckling forces to the hull of the craft.
Typically each connector includes a connection member which extends between a first connection point adjacent to the footrest and a second connection point adjacent to the respective one of the rails, and a line between the first and second connection points subtends an angle with the respective rail which is less than 45 degrees. The angle with the hull axis, and the side of the hull is also typically less than 45 degrees.
The following comments are applicable to all of the above aspects of the invention.
Typically the pair of connectors suspend the footrest between the first and second sides of the craft with a gap between the footrest and the floor of the kayak. This avoids stress damage when the kayak is grounded—a common event in river kayaks.
The connectors may be employ relatively broad connection members (such as a triangular sheet or plate) but preferably the connection members are relatively elongate. These elongate members may be in the form of solid struts or ropes (which can generally only transmit tensile forces) or hollow tubes (which are more rigid in compression). The cross section of the connection members may be circular, or may be elongate (which gives greater bending strength).
In the preferred examples, the connectors are adjusted by changing the point at which the connectors attach to the rail (which is in turn attached to the side of the hull). However, various other mechanisms might be used: for instance the length of the connectors may be adjusted telescopically, or the connectors may be ropes, each rope running through a fairlead which may or may not be common with another fairlead.
A strap may be employed to hold the kayaker's foot to the footrest. In this case, the connectors must be designed to accommodate loading due to pulling forces.
The connectors may fasten the footrest directly to the hull walls, or may be fitted to rails which extend fore and aft.
A seventh aspect of the invention provides a method of locking the fore/aft position of a kayak foot brace by actuating a locking device (such as a rope/cleat) while seated in a cockpit of the kayak.
Two examples of the invention will now be described with reference to the accompanying Figures, in which:
Rails (1) and (2) are formed from extruded Aluminium and fastened to the inside of the kayak hull (using nuts and bolts or adhesive) near to the gunwale line parallel with the kayak floor. The rails comprise a cylindrical channel. The channel is semi-enclosed with a slot running the length of the channel facing toward the centre of the kayak.
The plate (6) is supported by three stays (3), (4) and (5) formed from drawn stainless steel. These stays provide the connection between the footrest and the hull. Each stay is connected to the rails (1) and (2) via pairs of sliding blocks (15), (16) and (17). The sliding blocks (15), (16) and (17) are cylindrical and fit into the cylindrical channel in the rails (1) and (2). The attachment of the stays (3), (4) and (5) to the sliding blocks is made possible through the slot in the rail which provides an opening from the channel to the interior of the kayak. The relative diameters of the cylindrical channel in the rails and the sliding blocks are such that the sliding blocks can freely move along the length of the channel. The size of the slot in the rails relative to the diameter of the sliding blocks is such that the sliding blocks are held securely in the channel and are not able to move through the slot.
The stays connect to the sliding blocks by extending through the slot in the rails. The stays are fastened into the sliding blocks by means of a thread. There are threaded holes in the sliding blocks to receive the ends of the stays, and the ends of each stay are threaded.
Each stay has a lateral portion 3-3, two stay legs 3-2 at an angle to the lateral portion 3-3, and two end legs 3-1 approximately parallel with the lateral portion 3-3. The stays (3), (4) and (5) are flexible, so that the angle between the stay legs 3-2 and the lateral portion can vary. This enables the stays to retract and extend laterally so as to adjust to the variable widths that occurs between the rails (1) and (2) as the rails converge towards the bow.
As shown most clearly in
The lateral portions 3-3 of stays (3) and (4) are in contact and can be considered to be one axis. As shown in the side views of FIGS. 3 to 6, three corner nodes of a triangle are defined by the axis formed by the lateral portions 3-3 of stays (3) and (4), and the end legs 3-1 of the same stays where they attach to the sliding blocks (15)(16). This triangle has two fixed sides (the two stay legs 3-2) and one variable side (the distance between the sliding blocks (15) and (16)). By controlling the distance between the two blocks the distance of the lateral stay portions 3-3 running across the plate to the kayak floor can be controlled. Thus the distance between the blocks can be adjusted to set the height of the plate from the kayak floor.
The distance between the sliding blocks (15) and (16) is controlled by a height adjustment tie rod (19). One end of the rod (19) is fastened into the forward slide block (15) by a thread identical to those used to connect the stays to the sliding blocks. The other end is not threaded and lies inside a clearance hole in sliding block (16). The distance between the sliding blocks (15) and (16) can be altered by moving the non threaded end of the rod (19) out of one of the holes (as shown in 4-1
The fore/aft inclination of the plate (6) from the vertical can also be adjusted by adjusting the position on the aft sliding block (17) to which stay (5) is connected (Stay (5), as follows. The stay (5) is threaded into aft sliding Block (17) into a selected one of a row of threaded holes in the aft sliding block. In order to adjust the fore/aft inclination, the stay (5) is first removed from aft sliding block (17) by sliding the block out of the rail in which it is held (1) or (2). The aft sliding block is then unthreaded from the stay, and rethreaded onto the desired hole. The aft sliding block is then inserted back into the rail.
Once adjusted for height clearance from the kayak floor and tilt as desired, the footrest can be positioned and anchored at a position best suited for the intended kayaker. The sliding blocks are all free to move fore and aft in the rails. Forward movement of the sliding blocks is fixed by a position adjust rope (23) that is held by a rope cleat (18). One method to find the correct position for the plate is to pull on the position adjust rope (23) on both sides and locate the footrest as far aft as possible while still retaining the sliding blocks in the rails. With the position adjust rope (23) removed from the cleats (18) the kayaker can then enter the kayak and push the footrest forward with their feet stopping at the position that suits their seating and leg extension preference. It is then possible for the kayaker to fix the position adjust rope (23) into the respective cleats on each side while still seated in the kayak; or if preferred, to exit the kayak and then set the rope into the cleat on both sides. This sets the footrest positioning fore and aft.
As kayak hulls are generally thin shell structures they are not well equipped to withstand buckling forces typically present in other systems where the hull fastening is adjacent to the footrest. Ideally the force would be in complete shear across the surface of the hull. In this invention the forces applied to the plate by the kayaker's foot are transferred to the hull via the stays. This method of transfer provides an advantageous loading case on the hull as the flexible or hinged nature of the stay connections to the plate and slide blocks ensure the stay is in tension. The connections are not capable of transferring any significant load other than in the axis of the stay due to their flexible or hinged nature. With the stay axis set at an acute angle to the hull surface the major force is in shear with the hull. The force component normal to the hull surface is transferred via the rail.
In contrast with the system of
The action of spring 37 tends to bias the hinge 41 towards the rail. When acting together with the spring (not shown) on the port side of the kayak this tends to move the footrest forward due to the steadily narrowing beam. This forward bias may be overcome by frictional forces between the bars 31, 32 and the rail 30, but the footrest is also prevented moving forward by a suitable locking device such as a rope (not shown) attached to stay 34 or bar 32 and made fast by a cleat (not shown) on the rail 30.
When the footrest is locked in this manner, the spring action resists movement of the hinge 41 side-to-side, as explained below. For the footrest to move sideways a sideways force has to make hinge 41 move. For this to happen, stay 33 has to apply a force along the rail axis to the bar 31. This can only be done as a component of the force acting along the stay 33. Due to the angle between stay 33 and a line normal to the rail 30 being acute, the transverse force acting to push or pull the bar 31 against the rail will be greater than the axial force acting to push or pull the bar 31 along the rail. Also, on one side of the kayak the bar 31 will need to be moved opposite to the spring force, adding further to the resistance. Due to the acute angle of stay 33, any sideways force it at a mechanical disadvantage to these resisting forces.
The stiffness of the connector between the footrest and the rail is also greater than the embodiment of
When the footplate is to be moved aft, force can be applied to the stay 34 or bar 32 (by pulling on the rope). This force will have a major component along the axis of the rail and therefore will not face much resistance. Due to the difference in stiffness between the stay 34 and spring 37 this force will tend to move the hinge 41 inboard thus expanding the linkage to account for the increase in beam as the footrest is moved aft.
The arrangement provides a resisting force (thanks to friction and the spring and the mechanical disadvantage through the linkage) to sideways movement that is higher than the typical load in this direction and therefore ‘holds’ it in place ‘locked’ but in contrast the force resisting the movement along the rail is lower than the typical force expected to make this adjustment. Therefore the adjustment fore and aft can be made without the need to release a clamp or lock mechanism for sideways movement yet still provide an effective ‘lock’ to sideways movement at any position along the rail.
In contrast to the circular cross-section stays in
In an alternative further embodiment (not shown), the coil spring 37 may be omitted. In this case, the bar 31 has a groove which slidably receives an end of the bar 32. After the linkage has been adjusted to its desired position, the bar 32 can be locked in the groove by a wing-nut.
While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus and method, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of the Applicant's general inventive concept.
| Number | Date | Country | Kind |
|---|---|---|---|
| 530917 | Jan 2004 | NZ | national |
