WO2011021144A1

WO2011021144A1 - Rowing simulator motion-resistance unit

Info

Publication number: WO2011021144A1
Application number: PCT/IB2010/053694
Authority: WO
Inventors: David Eurig Evans
Original assignee: David Eurig Evans
Priority date: 2009-08-17
Filing date: 2010-08-16
Publication date: 2011-02-24
Also published as: GB0914403D0; GB2472795A

Abstract

Fixed installation rowing simulators are already known. The present invention provides a rowing simulator motion-resistance unit, comprising a first upwardly open container for holding a fluid and fluid directing means defining a path for movement of the fluid within the container, wherein the container comprises a flexible waterproof liner.

Description

Rowing simulator motion-resistance unit

The present invention relates generally to a rowing simulator motion-resistance unit used particularly, but not exclusively, in rowing training apparatus.

It is widely recognised that rowing is one of the healthiest forms of exercise, employing a large proportion (up to 82%) of the body's musculature in a low-impact movement which provides both aerobic and anaerobic exercise equally suitable for men and women.

A number of rowing machines are available for simulated rowing exercise on dry land. Existing rowing simulators offer resistance to the simulated rowing motion either by a rotating air paddle, in a housing with variable inlets and outlets which can be adjusted to vary the resistance, by a rotating water paddle arrangement or by magnetic resistance.

Each of these works by causing the resistance unit to rotate, this being achieved by the user drawing on a line or chain connected to a T-bar simulating the handles of the oars. This, of course, does not provide a simulation of the so-called "sweep" rowing motion which is that undertaken by an oarsman in a boat having a crew of several people, such as a four or an eight, and although attempts to provide such sweep motion on dry land have been made, they are complex and, ultimately, still use a rotating resistance unit.

The action of rowing itself, however, is far more complicated than can easily be simulated using a dry land simulator. First, the boat itself is unstable in that it might rock from side to side about its longitudinal axis; lateral balancing of the boat to secure the most efficient rowing action being an important skill. Secondly, the oars have to be feathered on the return stroke, and there is a distinct skill in positioning the oar at the end of the return stroke for the so-called "catch" where the oar is introduced into the water, after which the power stroke or "drive" is performed during which the boat is driven forward by the reaction of the oar being pulled through the water; then the oar is feathered again and removed from the water in a manner which does not cause additional resistance.

Although rowing clubs have attempted to provide dry land simulation using water tanks with a central row of seats for the oarsmen, this does not provide a comparable experience since the water in the tanks is simply churned about by the "oars" (in practice often simply oar handles without proper blades) and there is no simulation of a boat's instability nor of its "surge" movement as the oarsmen commence the drive phase of the rowing action. Further, because the water is not moving past the boat in the same way as it does when a boat is moving through the water, the required action for the catch cannot properly be practised.

One attempt to provide a more realistic training aid has been built in the form of a flume tank through which water can be pumped to simulate the motion of the boat through the water. This, however, is an extremely large, expensive and permanent installation, unlikely to be available to many, and suitable primarily for high level training of athletes at national level. Apparatus which can be used by beginners for practicing a full rowing motion prior to entering a boat on the water, and for training athletes of a wide range of abilities is, therefore, urgently needed. Such apparatus should preferably be portable, or at least transportable, small enough in size to be housed within existing buildings without requiring new installations, and sufficiently economical to be available to the majority of rowers at an affordable cost.

The present invention seeks to provide apparatus which overcomes the disadvantages of known dry land rowing machines, which is able to provide a full range of required movements for simulating rowing on water, and which will provide a full rowing experience with a complete range of all of the technical subtleties required to row on water and to increase general fitness.

According to a first aspect, the invention provides a rowing simulator motion- resistance unit, comprising a first upwardly open container for holding a fluid and fluid directing means defining a path for movement of the fluid within the container, wherein the container comprises a flexible waterproof liner.

The liner may be comprised of plastics, such as PVC. Other non-plastics material may be used such as waterproof material. The shape of the container may be adjustable. This may be effected by folding the liner and/or by means of altering the shape of a support means, discussed below.

The path may be a closed recirculating path. This motion-resistance unit can be used, as will be explained in more detail below, in combination with a support for a seat and an oar to provide a rowing motion simulator capable of providing both a scull (two oar) action, together with a motion-resistance unit on either side of the seat, and a sweep (single oar) motion, with a motion-resistance unit on only one side. The fluid directing means may be in the form of a dividing means for defining two communicating compartments within the first container. The dividing means defining such two compartments may comprise a generally horizontal septum, including apertures, separating the interior volume of the container into upper and lower compartments. Other compartment configurations are, however, possible. For example, a tube or pipe which feeds water around a loop and may produce a head of water.

Alternatively, the fluid directing means may comprise a duct in the form of a pipe the ends of which open into the interior of the container at spaced locations preferably (but not essentially) at or near the ends of the container. In use, therefore, water within the container can be driven, for example by the action of an oar, along the container, into the duct and returned from the other end of the duct into the container so that the oar itself can start the fluid moving in manner similar to that experienced by an oarsman on water.

In order to simulate the momentum of a boat through water it is possible to include means for causing forced circulation of the fluid within the container around the said recirculation path.

The said means for causing forced circulation may be a pump producing unidirectional fluid motion. Such forced circulation may be of adjustable speed and/or direction by varying the operation of the pump. This variation in speed and/or direction of the forced circulation may be related to the speed and/or direction of motion imparted, during use, by the movement of the oar(s), to the fluid in the upwardly open compartment of the container. Alternatively, of course, an additional component of relative speed between the water and the oars may be introduced by operation of the pump to simulate a current in a river.

The unit may further comprise a first controllable valve for controlling the flow rate of fluid within the first container. This may be located in the apertures in the septum and/or in the pipes or ducts discussed above. Alternatively, or additionally a membrane may be provided extending substantially across the entire container, in at least one compartment, with the first valve provided therein.

The flexible liner may be self-supporting. This may be effected by selected arrangement of the liner such that when filled with fluid the weight of the fluid pushes against the sides and holds them in place. The shape of the liner in plan, when substantially filled may be arcuate, rectangular, semi-circular, or any other shape, as required. It may have one or more substantially curved sides, in plan, when in use. The liner may be collapsible and foldable and relatively portable when not in use.

Alternatively, or additionally, the unit may comprise a framework for supporting the flexible liner.

The rowing simulator motion resistance unit may comprise a second upwardly open container within the first container and a weir plate extending between the upper edge of at least one side of the second container and at least one side of the first container forming a third container, such that, in use, any fluid spilling over the weir plate from the second container is prevented from flowing out of the third container into the first container. This may be useful for minimising back-wash created by the movement of the oars in the fluid within the second container.

The rowing simulator motion resistance unit may further comprise turbulence reducing means for creating a head of fluid in the first container, such that the surface of the fluid at least at one point in the first container is higher than the surface of the fluid in the second container.

The turbulence reducing means may include a second controllable valve connecting the third container to the first container to thereby control the flow of fluid from one to the other.

The turbulence reducing means may further include a third controllable valve connecting the second container to the first container to thereby control the flow of fluid from one to the other.

The turbulence reducing means may further include a fourth controllable valve connecting the first container to the second container to thereby control the flow of fluid from one to the other.

The third and fourth controllable valves may be located substantially opposite one another at either end of the second container.

The turbulence reducing means may further include a fluid movement means for moving fluid substantially from one end of the first container to substantially the other end of the first container. This may be a pump or impeller, which moves the fluid substantially from one end of the first container to substantially the other end of the first container to create, in use, a fluid level in the first container, substantially adjacent the second container, higher than a fluid level within the second container. This fluid level in the first container may also be higher at one end of the first container than at the opposite end.

The rowing simulator motion resistance unit may further comprise a damping means for damping surge flows within the first container. This means may be by provision of any one or more of a membrane, a valve, an impeller, a vane, a gill and a weir located in either, or both of the upper and lower chambers.

The rowing simulator may further comprise a housing for substantially enclosing the user in use, whereby the environmental conditions for said user may be varied. In this way the conditions, such as humidity or temperature, of the oarsman's environment can be controlled to allow simulation of conditions which may be experienced in other countries for training purposes.

The rowing simulator may comprise an oar, a support for the oar about which it can be angularly reciprocated, a seating arrangement for a user and a motion-resistance unit as defined herein into which a blade of the oar can be introduced in use of the simulator.

In a rowing simulator intended to provide exercise and/or training in sculling there may be provided two oars, two oar supports (one on either said of the said seat) and two said motion-resistance units, positionable one on each side of the seat.

Of course, the rowing simulator of the present invention need not be limited simply to one user, and there may be provided two or more seats provided by the seating arrangement, each having at least one associated oar support at least on one side thereof whereby to provide training for a crew of, for example, two, four or eight oarsmen.

Each seat may be carried on a fixed support which also carries the oar supports, although preferably the seat(s) are slidable along the fixed support to provide a simulation of the sliding seat arrangement common in most rowing boats. A seat which can be fixed in a single position is also possible.

In order to provide a more complete simulation of a boat on water the seat(s), or the support/ fixture on which they are carried, may be tiltable about a longitudinal and/or lateral axis of the simulator. This tilting action may be provided by suitable pivots which are adjustable so that the degree of instability of the seat(s) is adjustable.

It is normal to provide footrests for an oarsman in association with each seat and the simulator of the present invention may likewise be provided with a footrest which, in common with the existing simulators, may be provided with toe clips for restraining a foot or the feet of a user. Alternatively, in the case of the present invention, the seat may be resiliently or otherwise biased to one end of its range of movement, or there may be a prime mover capable of returning it to an original position after an excursion corresponding to the drive phase of the rowing stroke.

In order to adapt the rowing simulator of the present invention to oarsmen of different sizes, it is preferable that the lateral separation between each resistance unit and each seat is adjustable and although a generally linear trough-like container may be simplest to produce a container having a curved (or arcuate) outline matching the path of an oar blade in use, may be provided in order to minimise the amount of fluid which needs to be contained. In general, it is useful to minimise the amount of fluid because this makes it easier to control the flow speed.

The simulator may include a rowing fixture which is movable back and forth with respect to the motion resistance units and on which each seat is carried, either directly or indirectly, on or by the fixture. The rowing simulation is provided by a combination of the water flow in the units and movement of the fixture. During the stroke the fixture moves forward to simulate movement of a boat moving through water. At the end of stroke the fixture returns ready for the start of the next stroke.

In a second aspect, the invention provides a rowing simulator comprising a rowing simulator motion resistance unit according to the first aspect, and further comprising a flexible, fillable and enclosed bag for supporting one or more seats for a user, such as a rower, to occupy in use.

The bag may be collapsible and/or inflatable.

The bag may be arranged to substantially support a boat, the boat including one or more seats therein.

The bag may provide instability about the longitudinal axis (being parallel with the direction of movement of the "boat") and the lateral axis (perpendicular to the direction of the "boat") to more closely simulate a boat on water. Movement restriction means may be provided to limit the degree of instability. For instance springs may be attached at one end to the seat, or seat support structure/fixture, and at the other end to the ground or some other fixed anchor point.

The bag may be filled with any one or more of a liquid, a gas, a gel, a sponge or a foam. In a third aspect, the invention provides a method of rowing training comprising the steps of providing a rowing simulator motion-resistance unit according to the first aspect, providing a pivotable oar mountable on a support about which it is able to be angularly reciprocated, and causing the fluid in the container to move around a closed recirculation path by introducing and moving the oar in said container. The method may further comprise a step of providing a seat support according to the second aspect. The motion-resistance unit may include means for assisting the motion of the fluid once initiated by the movement of the oar.

Such motion-assisting means may be programmed or controllable to provide a variable (for example gradually decreasing) assistance to the motion of the fluid after each stroke of the oar, whereby to simulate the slowing motion of a boat through water. The fluid in the container as discussed herein may be water although for certain purposes a liquid having a greater viscosity may be appropriate and/or one having thixotropic properties in order to minimise spillage.

To simulate actual rowing conditions the flow of water through the trough/container and the variable resistance to the movement of the fixture need to be coordinated.

In normal rowing (with a boat travelling through water) if the oar is placed in the water at the normal catch position with minimum force applied the speed of the boat will reduce due to water resistance and the position of the blade in the water will remain substantially stationary in the water relative to the water. If the oar is placed in the water in the normal catch position and a normal rowing force applied then the speed of the boat will increase through the stroke with the blade in the water remaining relatively stationary. The rowing force is made up of two elements (a) maintaining the blade in a relatively stationary position (a negative value) as the blade is travelling in the opposite direction and (b) overcoming the resistance of the water to the movement of the boat (a positive value).

For a training aid (with the water travelling past the boat) if the oar is placed in the water in the normal catch position with minimum force applied (to maintain its position in the water) with the speed of the water remaining constant the position of the blade will remain relatively stationary in the water. If the oar is placed in the water in the normal catch position and a normal rowing force applied there will need to be a resistance to the movement of the fixture to simulate the resistance of the water to the movement of the boat through it. This resistance may need to be variable and the rowing fixture needs to return to a start position in time for the next stroke. In normal rowing the boat movement in a stroke can be up to 2 metres, this is made up of the distance the boat would travel with no force applied to the oar and the additional distance the boat travels when a normal rowing force is applied. In the case of the training aid the distance the boat travels with no force applied equates to approximately the rate of flow of water, but with no decay in speed of flow due to water resistance and the additional distance travelled when a normal rowing force is applied to the movement of the fixture against a variable force, so that the actual movement of the fixture is much smaller to enable it to return to the start position in time for the next stroke.

For maximum force the blade should be relatively stationary and equal in speed to the flow of water.

By co-ordinating the flow of water and fixture movement resistance, a range of training conditions can be achieved of varying intensity to suit different rowers. These conditions are reproducible and may be controlled by a computer programme to suit each individual training regime and/or to assess their performance. Some advantages of the present invention are:

1. Portable; relative low cost; can be set up in sport halls

2. Reproduces actual rowing conditions

3. Rowing in controlled environmental conditions

4. More accessible. Does not require river/lake for experience - sport for all

users/don't need to be close to river/lake

5. Can use own boat on system

6. Access for disabled: experience rowing

7. Water safety

8. With a smaller volume of water in each trough: easier to control flow

9. Force and physical measurements can be taken from a rower

10. Easier to instruct rower - the instructor can stand close and watch

11. Programmable and/or variable training conditions

In a fourth aspect, the invention provides a rowing training seat support comprising a flexible bag for supporting one or more seats for a user, such as a rower, to occupy in use. The bag may be collapsible and/or inflatable. The bag may be arranged to substantially support a boat, the boat including one or more seats therein. The bag may provide lateral instability about the longitudinal axis (being parallel with the direction of movement of the "boat") to more closely simulate a boat on water. The bag may be filled with any one or more of a liquid, a gas, a gel, a sponge or a foam.

The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. This description is given for the sake of example only, without limiting the scope of the invention. The reference figures quoted below refer to the attached drawings.

Figure 1 is a perspective view of one embodiment of the invention;

Figure 2 is a cross sectional view taken through the line II-II of Figure 1;

Figure 3 is an axial section taken on the line III-III of Figure 1;

Figure 4 is a plan view of a second embodiment of the invention;

Figure 5 is a side elevation of a rowing simulator formed according to an alternative embodiment; and

Figure 6 is a section of a motion resistance unit formed according to an alternative embodiment.

The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein.

It is to be noticed that the term "comprising", used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a device comprising means A and B" should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may refer to different embodiments. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

Similarly it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Furthermore, while some embodiments described herein include some features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form yet further embodiments, as will be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practised without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

The invention will now be described by a detailed description of several embodiments of the invention. It is clear that other embodiments of the invention can be configured according to the knowledge of persons skilled in the art without departing from the true spirit or technical teaching of the invention, the invention being limited only by the terms of the appended claims.

Referring first to Figures 1, 2 and 3, there is shown a rowing simulator generally indicated 10, comprising two separate components, namely a motion-resistance unit generally indicated 11 and a seating unit generally indicated 12. The motion-resistance unit 11 comprises an upwardly open trough-like container formed by a resiliently flexible membrane 13 secured in a generally u-shape configuration with rigid, approximately semi-circular, end panels 14 and carried on respective supporting frames 15, 16 each comprising an elongate rigid limb or rail 17, 18 to which the parallel edges of the flexible membrane, or liner, 13 are secured (by means not shown) held in place by respective triangular support frames 19, 20 of which only one is illustrated in Figure 1, although it will be appreciated that a plurality of such support frames will in practice be positioned along the length of the rails 17, 18. A connector or tie rod 21 joins the two support frames 19, 20 and, as mentioned above, although not illustrated, a number of similar such tie rods may be positioned along the length of the resistance unit 11. All of the individual support members 17, 18, 19, 20, 21 which compose the support frames 15, 16 are readily connectable together, by means not shown, so that the frames can be assembled and dismantled quickly and easily. The entire unit 11 thus forms an upwardly open trough-like container, which, as can be seen in Figure 1, can contain water. As can be seen in Figures 2 and 3, the membrane 13 has a flexible horizontal septum 22 attached, thereto, or integral with, separating the volume of the trough-like container formed by the membrane 13 into an upper compartment 23 and a lower compartment 24. The septum 22 has openings 25, 26 at each end so that the upper and lower compartments 23, 24 communicate with one another and, in effect, the two compartments form a closed loop path for the fluid (water) 27 within the trough-like enclosure formed by the membrane 13. Within the lower compartment 24 is housed a pump 28 and two flow sensors 29, 30 which are connected to an electronic control unit 31 the output 32 from which controls the energisation of the pump 28 in a manner which will be described in more detail below. A waterproof wall or membrane (not shown) may be provided adjacent the pump 28 extending from the underside of the septum 22 to the membrane 13 at the base of the container so that fluid flow is restricted to only being possible through the pump.

The seating unit 12 of the rowing simulator 10 comprises a flexible, inflatable cushion-like unit 5 on which is carried an upper platform 33 supporting two elongate rails 34, 35 which act as longitudinal guides for a seat 36. At one end of platform 33 are two footrests 37, 38 which, although not shown, may be equipped with toe clips or straps to retain the feet of a user, and projecting laterally from the platform 33 is a so- called "rigger" 39 in the form of a lateral support for a rowlock 40 which is pivotally mounted on a rowlock support 41 carried at the outboard end of the supporting framework 39 of the rigger. The rowlock 40 has central opening through which can pass the arm of an oar 42 allowing it to be angularly reciprocated and also turned about its longitudinal axis. The oar 42 has a blade 43 at its outboard end and a handle grip 44 at its inboard 25 end which can be grasped by a user sitting on the seat 36 with his or her feet on the footrests 37, 38.

Although described as a rigid supporting framework the frames 15, 16, which support the trough -like vessel, may in fact have any one or more of the following characteristics; hollow, flexible, tubular, Suable, inflatable, rigid and telescopic. They may be filled with a gas or liquid to provide the necessary strength to support the membrane 13 which forms the trough-like container. In this way the entire unit, once emptied of water, can be collapsed into a small space to allow it to be folded up and stored or transported easily.

In use of the apparatus described above, the user sits on the seat 36, grasps the oar 44 and introduces it into the water in the trough. Then, following the rowing stroke the oar blade 43 is caused to move along the trough 13 by pulling on the handle 44 and, at the same time, pushing with the legs to drive the seat 36 in the direction of the arrow A in Figure 1 along the rails 34, 35. In a boat on the water, once this "drive" phase of the rowing stroke is commenced the boat itself is driven to move through the water as the oar blade 43 is moved backwards through the water. Initially, with the boat stationary, the oar blade 43 moves in relation to water, but after several strokes when the boat has begun moving, the relative movement between the oar blade 43 and the water during the "drive" phase of the rowing stroke is markedly less. Indeed, ideally, it would be desirable for the blade 43 to be stationary with respect to the water and for all the energy imparted by the oarsman to go into moving the boat.

At the end of the drive stroke the oar blade 43 is lifted out of the water by depressing on the handle 44, and the blade feathered by turning the handle 44 to twist the oar 42 about its longitudinal axis, turning the blade through roughly 90°. The oar handle 44 is then pushed away from the user and the seat 36 caused to approach the footrests 37, 38 by flexing the legs. This motion may be assisted in embodiments (not shown) by a spring or other motion-assisting device. At the end of the recovery phase, when the user's shins are substantially vertical, the back straight and leaning forward and with the body closed up on the thighs with the arms fully extended, the hands are lifted slightly and rotated to introduce the blade into the water for the "catch". This motion must be accompanied by a synchronised commencement of the drive stroke so that the blade 43 is travelling at the same speed as the water (or slightly faster) since if it is not travelling fast enough the motion of the water against the back of the blade will cause the boat to slow. This is an important aspect of the training for accurate rowing, which is unavailable in other dry land rowing trainers. As the water in the upper compartment 23 of the trough 13 is caused to move longitudinally, in the direction of the arrow B of Figure 3, the water passes downwards through the opening 26 into the lower compartment 24 and commences to flow in the opposite direction past the flow sensors 29 and 30, returning upwardly through the opening 25 into the compartment 23. The flow sensors detect the speed of the water, and generate a signal which, processed by the control unit 31, energises the pump 28 to maintain the water flow at a rate suitable to simulate the motion of a boat through the water so that, at the end of the recovery phase the water is moving at a suitable speed to simulate the motion of a boat through the water and require accurate movements of the user to get the catch.

In order to simulate the weight of the boat for commencement of the rowing action, the pump 28 may initially be operated in the reverse direction so that the weight of water which has to be displaced by the blade of the oar during the first few strokes from "rest" is greater, giving the user a closer approximation of the real situation on a boat.

As will be appreciated, the embodiment of Figures 1, 2 and 3 provide suitable training for an oarsman with a "sweep" oar. The fluid-filled "cushion" 5 provides a degree of lateral and longitudinal movement, which, again, allows the user to obtain a more realistic simulation of a rowing boat by requiring lateral balance to be maintained as well as the exercise to be performed. The seat is stable on the platform but the platform is unstable on the bag to simulate a rocking motion, either or both of side-to- side and front- to-back..

The embodiment of Figure 4 is an example of a "scull" trainer with two motion- resistance units Ha, Hb, one on each side of the central base 12, and in this case there are left and right oar supports 39L, 39R for respective oars 42L, 42R, and in order to provide for synchronisation training of one oarsman with another, a second seat 50 and footrests 51, 52, together with a second pair of oar riggers 53, 54 are provided so that two users may train simultaneously not only to practice the rowing stroke, but also enabling them to practice synchronisation.

As can be seen in Figure 4, a further refinement is the convex curvature of the outer edge 55, 56 of the trough containers of the motion resistance units, which follow the curved path of the tips of the oars in use thereby minimising the required dimensions of these containers. The container on the right is large enough to accommodate the oar 42R on the right powered by the occupant of the first seat 36. The container on the left is large enough to accommodate the oar 42L on the left and another oar (not shown) powered by the occupant of the second seat 50 behind the first seat 36. This is an example of how the size and shape of the container(s) may be adjusted to whatever size is required so as to minimise water requirements.

Referring now to Figure 5 there is shown a simulator HO formed according to an alternative embodiment.

The simulator HO comprises a base 160 from which extend two support arms 162. The arms 162 carry a fixture 164 on a runner system which means that the fixture can move forwards and backwards. The inclination of the arms 162 with respect to the base 160 is variable to allow variation in the height of the fixture 164, but are fixed when the training aid is in use. The fixture 164 carries a fluid-filled flexible bag (in this case an air-filled bag)

105 or compliant foam pad which in turn supports a rowing (or seating) platform 133.

It is possible in some embodiments for the platform 133 to be substituted for a rowing craft, such as a boat. The fluid-filled bag may be of variable stiffness to adjust the stability of the rowing platform.

The platform carries a seat 136 which is slidable back and forth. The platform also carries a footrest 137.

It may be desirable to take force and physical readings off a rower in use of the simulator to assess their performance.

The simulator is used in combination with one or more oar-receiving fluid containers. The rowing simulation is provided by a combination of the water flow in the containers and movement of the fixture. During the stroke the rowing platform for rowing boat moves forward under a variable fore to simulate movement of a boat moving through water. At the end of stroke the fixture returns ready for the start of the next stroke. The fixture returns to the rearward start position at the beginning of each stroke. Control of the movement of the fixture and the fluid flow rate may be coordinated and under the control of a computer programme. The oar blade will remain relatively stationary relative to the flow of water in the fluid tank during the stroke due to movement of the fixture.

In use of the simulator there is a lot of energy generated, for example as the seat is moved back and forth and as the oar is pulled through the water. This energy could be used to generate electricity by the use of suitable conversion equipment such as a dynamo.

Referring now to Figure 6 there is shown a motion resistance unit 111 formed according to an alternative embodiment.

The until 111 comprises an upwardly open first container 113 comprising a U- shape central section 113a and front and rear end panels 114a, 114b. It has a water level at the left hand end referenced 130.

The first container 113 holds a second container 106 which extends across some of the width of the section 113a but which is smaller and which is located within and above the base of the first container. The second container 106 has a water level referenced 134. This is lower than the water level referenced 130 in the first container.

The top of the side of the second container adjacent the rear panel 114b is lower than the height of the top of the side of the second container adjacent the front panel 114a. An inclined weir plate 107 is provided between the top of the side of the second container having the lower height, adjacent the rear panel 114b, and to the rear panel 114b of the first container but at a height lower than the top of the second container where the weir plate is located. This forms a third "container" between the sides of the first and second containers and within the first container. It has a water level indicated by reference 135.

At the rear panel 114b end the second container has a non-return valve 120 allowing only water flow, as indicated by the arrow, from the second container to the first container. Similarly the weir 107 is also provided with a non-return valve 121, allowing water flow in the direction of the arrow shown from the third container to the first container. This effectively forms a sealed pipe under the second container which allows water to be sucked out and pumped under it towards the front panel 114a.

The pump 132 creates a head of water above a further, inward flow only (i.e. from the first container 113 to the second container 106) non-return valve 122 located at the front of the second container. The water is then pumped into the second container to complete the flow loop. The head of water above the front end valve 122 reduces turbulence of the water flowing into the second container. All of the valves are controllable to regulate flow-rate and adjust the height of the water in each container.

If there is any water surge in the second container it will pass over the weir 107 and into the third container from where it will be moved back into circulation through the valve 121 by pump 132. This pump 132 is provided within a membrane extending from the underside of the second container 106 to the base of the first container 113, although its presence is not mandatory and it and the pump 132 may be replaced by an impeller. The membrane may act to control fluid flow within the first container. The membrane may be flexible or inflexible and could be a wall.

Claims

1. A rowing simulator motion-resistance unit, comprising a first upwardly open container for holding a fluid and fluid directing means defining a path for movement of the fluid within the container, wherein the container comprises a flexible waterproof liner.

2. The rowing simulator of claim 1, wherein a shape of the container is adjustable.

3. The rowing simulator of either one of claims 1 and 2, further comprising a first controllable valve for controlling the flow rate of fluid within the first container.

4. The rowing simulator motion resistance unit according to any preceding claim, wherein the fluid directing means comprises dividing means for defining two communicating compartments within the first container.

5. The rowing simulator motion resistance unit according to any preceding claim, wherein the dividing means comprises a generally horizontal septum separating the interior volume of the first container into upper and lower compartments.

6. The rowing simulator motion resistance unit according to any preceding claim, wherein the flexible liner is self-supporting.

7. The rowing simulator motion resistance unit according to any one of claims 1 to 5, further comprising a framework for supporting the flexible liner.

8. The rowing simulator motion resistance unit according to any preceding claim, wherein the flexible liner is collapsible and/or foldable.

9. The rowing simulator motion resistance unit according to any preceding claim, wherein the container has a substantially curved side in plan.

10. The rowing simulator motion resistance unit according to claim 9, wherein the container has a substantially arcuate shape in plan.

11. The rowing simulator motion resistance unit according to any preceding claim, comprising a second upwardly open container within the first container and a weir plate extending between the upper edge of at least one side of the second container and at least one side of the first container forming a third container, such that, in use, any fluid spilling over the weir plate from the second container is prevented from flowing out of the third container into the first container.

12. The rowing simulator motion resistance unit according to claim 11, further comprising turbulence reducing means for creating a head of fluid in the first container, such that the surface of the fluid at least at one point in the first container is higher than the surface of the fluid in the second container.

13. The rowing simulator of claim 12, wherein the turbulence reducing means includes a second controllable valve connecting the third container to the first container to thereby control the flow of fluid from one to the other.

14. The rowing simulator motion resistance unit according to either one of claims 12 and 13, wherein the turbulence reducing means further includes a third controllable valve connecting the second container to the first container to thereby control the flow of fluid from one to the other.

15. The rowing simulator motion resistance unit according to any one of claims 12 to 14, wherein the turbulence reducing means further includes a fourth controllable valve connecting the first container to the second container to thereby control the flow of fluid from one to the other.

16. The rowing simulator motion resistance unit according to claim 15 when dependent on claim 14, wherein the third and fourth controllable valves are located substantially opposite one another at either end of the second container.

17. The rowing simulator motion resistance unit according to any one of claims 12 to 16, wherein the turbulence reducing means further includes a fluid movement means for moving fluid substantially from one end of the first container to substantially the other end of the first container.

18. The rowing simulator motion resistance unit according to any preceding claim, further comprising a damping means for damping surge flows within the first container.

19. A rowing simulator comprising a rowing simulator motion resistance unit according to any preceding claim, and further comprising a flexible, fillable and enclosed bag for supporting one or more seats for a user to occupy in use.

20. The rowing simulator of claim 19, wherein the bag is collapsible.

21. The rowing simulator of either one of claims 19 and 20, wherein bag is arranged to substantially support a boat, the boat including one or more seats.

22. The rowing simulator according to any one of claims 19 to 22, further comprising a housing for substantially enclosing the user in use, whereby the environmental conditions for said user may be varied.