Background Art With the increasing popularity in recreational water activity the sit-on-top kayak has become increasingly popular due to its ease of use.

Typically, kayaks are of the conventional sit-in kayak construction where the operator sits in an enclosed cockpit within the shell of the kayak, entering through an opening in the upper deck of the kayak.

Sit-on-top kayaks, which include surf-skis and wave-skis, have become very popular for those people who do not enjoy being confined in a traditional kayak, preferring a floating platform that gives the operator easy access to board the craft, particularly after the craft has capsized.

Typically, a sit-on-top kayak is characterised by a watertight shell having an upper and lower skin, and an open cockpit area with seating and footrests moulded or provided on the upper skin of the shell.

Several types of sit-on-top kayaks are much wider across their beam and do not possess the narrow bow and streamlined hull dynamics found with surf skis and other similar watercraft, resulting in a more stable, user-friendly kayak for all to enjoy. However, such craft do not provide flexibility in their applications, and are only typically suited for use as a craft to travel from one place to the next.

Furthermore, these craft are relatively unstable for the novice, and often result in the operator falling off until they are able to balance the craft.

These type of craft also present a degree of difficulty for any one trying to mount the craft from a position in the water, as the craft has a tendency to move from a horizontal position as the operator attempts to board the craft.

The preceding discussion of the background to the invention is itnended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia as at the priority date of the application.

It is an object of this invention to provide a sit-on-top kayak having increased stability.

SUMMARY OF INVENTION The present invention provides a watercraft comprising: a shell having an upper skin adapted to support at least one operator, and a lower skin defining a hull for contact with the water, two floatation assemblies wherein each floatation assembly comprises an adjustable element such that each floatation assembly is adjustable between an extended position and a retracted position, allowing the operator to increase or decrease the degree of stability added to the shell, each floatation assembly being positioned sufficiently aftwardly on the shell so as not to interfere with the paddling motion.

Preferably the watercraft is in the form of a sit-on-top kayak.

The need exists for a sit-on-top watercraft designed to support one or more occupants where the occupant may be a novice or wishes to use the watercraft for other purposes such as a fishing or swimming platform. In these situations the watercraft is required to have a greater degree of stability to reduce the likelihood of the watercraft capsizing or rolling.

The floatation assemblies provide the watercraft with increased stability. As each floatation assembly is adjustable the operator is able to increase or decrease the stability of the watercraft depending on his/her skill level or the watercrafts particular application. For example, the operator may paddle to his/her destination with the floatation assemblies in a retracted condition. Upon reaching the destination the operator may wish to use the watercraft as a swimming or fishing platform. All that would then be required is to extend each floatation assembly. The watercraft then becomes a stable platform allowing the operator to stand or easily mount the watercraft from the water without it rolling.

Each floatation assembly may also comprise at least one support pontoon, known as an ama, attached to a support arm.

The support arm may incorporate the adjustable element.

The support arm may be telescopic, and may be lockable when in the extended or retracted positions. The support arm may be locked in positions therebetween.

The support arm, when in a retracted position, is partially contained within the hull.

Preferably the floatation assemblies are located in opposed relation with respect to each other such that they are symmetrical with respect to each other about a longitudinal axis of the watercraft.

Each floatation assembly may be releasably mounted with respect to the watercraft.

When fitted to the watercraft the floatation assemblies assist in transferring any unstable rolling action of the watercraft back to the amas to increase the stability of the overall craft. The degree of stability will depend on how far the operator has extended the floatation assemblies.

The shell may be adapted to releasably retain a propulsion means therein, the propulsion means being used for propelling the kayak.

The floatation assemblies may provide additional buoyancy to the kayak to provide full or partial compensation for the additional weight of the propulsion means.

Preferably the kayak is configured to maintain a watertight cavity within the shell such that the kayak may function practically when the propulsion means is removed.

Preferably the propulsion means is removably secured within an aperture in an aft portion of the kayak.

The aperture may extend through the upper and lower skin.

Preferably the aperture is defined by a sidewall enclosure between the lower skin and the upper skin such that the integrity of the shell is maintained.

Preferably the aperture is configured to provide easy positioning and securing of the propulsion means, Preferably the propulsion means is aft of the rearmost operator's position.

Preferably the propulsion means is adjacent the most rearward point of the stern.

The propulsion means may be easily released from the kayak to facilitate ease of handling when loading and unloading the kayak from storage and when at the waters edge.

Preferably the propulsion means has an inlet for receiving water and an outlet for discharging water.

The propulsion means may be positioned to ensure the inlet of the propulsion means has a continuous supply of water.

Preferably the propulsion means, when in place, is substantially flush with the lower skin, therefore having a low impact on the environment, particularly when passing across coral outcrops, weed banks and riverbanks.

When in position, the propulsion means may have its upper end positioned in a holding compartment integral with the upper skin. The holding compartment may incorporate a hood, lid or hatch cover to provide protection to, as well as from, the propulsion means.

The propulsion means may comprise a pump and a motor to drive the pump.

Preferably the motor is an electric motor. The electric motor may be mounted transverse to the longitudinal axis of the kayak.

In one aspect of the invention the pump may be an impeller type pump.

In another aspect of the invention the pump may be a centrifugal pump.

Preferably the water discharged from the propulsion means is propelled rearward, substantially parallel to the longitudinal axis of the kayak.

A shroud may be fitted over the propulsion means so as to cover the outlet.

Preferably the shroud directs the water discharged.

Preferably the shroud is rotatable in the horizontal plane, allowing angular redirection of the water discharged to facilitate steering of the kayak.

An inlet to the pump, through which water is drawn, may be flush with the lower skin or it may be protruding below the lower skin such that the water discharged is substantially below the water, the pump inlet provided the inlet for the propulsion means.

The kayak may be fitted with an activation means to allow the operator to activate and deactivate the propulsion means when required.

This clean, eco friendly form of propulsion is not intended to be of high speed but more inclined to appeal to the general populous of people enjoying the usage at beach side resorts, coral outcrops, ocean adventure tours, inland lakes and harbours, eco wilderness tours and general leisure activities.

The kayak may be fitted with a steering means for steering the craft when being propelled by the propulsion means.

Preferably the steering means comprises the shroud.

The hull may have a profile consisting of at least one keel or stepped hull formation. Preferably the at least one keel or stepped hull formation runs from the stern of the kayak towards the bow.

Preferably the hull has a recessed portion centrally located along the longitudinal axis towards the stern of the kayak, wherein the recessed portion induces and helps maintain the flow of water to the propulsion means, whilst reducing the drag upon the kayak.

The kayak may incorporate at least one storage compartment. Each storage compartment may be integral with the upper skin.

The upper skin may also provides a cockpit having a plurality of footrests and a seat for the at least one operator. The at least one operator's seat may be raised slightly above the cockpit floor so as to keep the operator above the lowest drain point.

The kayak may also incorporate an underwater viewing window for the viewing enjoyment of the at least one operator.

The cockpit floor may have an opening which may receive the viewing window.

The opening may have a raised rim extending around the entire perimeter. The raised rim aids in keeping the top of the viewing glass dry and clean for underwater viewing purposes.

To maintain a single shell type hull, and as an added safety feature in the event of damage to the transparent window, the window opening may be moulded to have side walls integral with the upper and lower skins so as maintain the integrity of the cavity of the shell.

Apertures may be provided in the shell. The apertures may be capable of accepting posts to aid in the transport of the kayak across land.

The present invention further provides a watercraft capable of being paddled by at least one operator, the watercraft comprising; a shell adapted to support the at least one operator; two floatation assemblies wherein each floatation assembly comprises an adjustable element such that each floatation assembly is variably adjustable between an extended position and a retracted position, allowing the operator to increase or decrease the degree of stability added to the shell ; whereby the floatation assemblies are located in an aft position of the shell so as not to interfere with the paddling motion, and are in an opposed relation such that they are symmetrical with respect to each other about the longitudinal axis of the watercraft.

The present invention further provides a watercraft comprising: a shell having an upper skin adapted to support at least one person, a lower skin defining a hull for contact with the water, two floatation assemblies wherein each floatation assembly comprises an adjustable element such that each floatation assembly is variably adjustable between an extended position and a retracted position, allowing the operator to increase or decrease the degree of stability added to the shell,

each floatation assembly being located in the aft position of the shell, on opposed sides of the kayak's longitudinal axis and symmetrical with respect to each other about said axis, and are located sufficiently aft so as not to interfere with the paddling motion.

The present invention further provides a watercraft comprising: a shell having an upper skin adapted to support at least one person, a lower skin defining a hull for contact with the water, the shell being adapted to releasably retain a propulsion means for assisting the propulsion of the watercraft, two floatation assemblies wherein each floatation assembly comprises an adjustable element such that each floatation assembly is variably adjustable between an extended position and a retracted position, allowing the operator to increase or decrease the degree of stability added to the shell, each floatation assembly being located in the aft position of the shell, on opposed sides of the watercrafts longitudinal axis and symmetrical with respect to each other about said axis, and are located sufficiently aft so as not to interfere with the paddling motion.

The present invention further provides a watercraft comprising: a shell having an upper skin adapted to support at least one person, a lower skin defining a hull for contact with the water, the shell being adapted to releasably retain a propulsion means for assisting the propulsion of the watercraft, at least one floatation assembly wherein the at least one assembly comprises an adjustable element such that the at least one assembly is variably adjustable between an extended position and a retracted position,

allowing the operator to increase or decrease the degree of stability added to the shell.

The present invention further provides a watercraft comprising: a shell adapted to support at least one operator, at least one floatation assembly wherein the at least one assembly comprises an adjustable element such that the at least one assembly is variably adjustable between an extended position and a retracted position, allowing the operator to increase or decrease the degree of stability added to the shell.

The shell may comprise an upper skin, and a lower skin defining a hull for contact with the water.

The watercraft may be the sit-on-top type. The upper skin may support the at least one operator.

The present invention further provides a watercraft formed by an upper skin and a lower skin whereby one or more operators are seated upon an open cockpit area formed as part of the upper skin with the shell capable of receiving and supporting at least one floatation assembly aft of the most rearward seating position and able to releasably retain a propulsion means aft of the most rearward seating position.

Typically, the watercraft is capable of functioning practically when the propulsion means is removed The rotational moulded kayak has many features that make the craft very user friendly and functional for the purpose of recreational usage. The upper skin cockpit area may have a shallow sidewall that forms the surround. The backrest may rise to a point higher than any deck portion forward of the most rearward seating position.

Description of the Drawings The invention will be better understood by reference to the following description of several specific embodiments thereof as shown in the accompanying drawings in which: Figure 1 is a plan view of the watercraft according to a first embodiment showing a first floatation assembly extended and a second floatation assembly retracted; Figure 2 is a side view of figure 1; Figure 3 is a perspective view of a rear portion of figure 1; Figure 4 is a rear view of the watercraft having both floatation assemblies extended and having a propulsion means in position according to a second embodiment Figure 5 is a perspective view of the watercraft shown in figure 4 Figure 6 is a perspective sectional view of the underside of the watercraft showing a propulsion means, without the floatation assemblies ; and Figure 7 is a bottom view of Figure 6.

Best Mode (s) for Carrying out the Invention Referring to figures 1 to 3, the invention according to the first embodiment is a watercraft in the form of a sit on top kayak 11 comprising an upper skin 13 and a lower skin 15 to define a sealed cavity.

The upper skin 13 provides a support area in the form of a cockpit 19 to support an operator (not shown). The lower skin 15 defines a hull 23 which contacts the water when the kayak 11 is in use.

The kayak 11 also comprises a first floatation assembly 36 and a second floatation assembly 37. Each floatation assembly 36,37 comprise a pontoon 39, known as an ama, and an adjustable element in the form of a support arm 41.

The support arm 41 is telescopic in nature, allowing the pontoon 39 to be moved between a first extended position, as indicated by the first floatation assembly 36, and a second retracted position, as indicated by the second floatation assembly 37.

Each floatation assembly 36,37 is secured to an aft region of the kayak 11 such that an operator can still use a paddle without interfering or knocking the floatation assemblies 36,37. The kayak 11 accommodates a portion of the support arm 41 of each floatation assembly 36,37 when in a fully or partially extended position.

The cockpit 19 incorporates footrests 57 and a seat 59, both being moulded into the upper skin 13. The seat 59 is raised above the floor 61 of the cockpit 19 so that the operator does not sit in a pool of water which may result from water splashing into the kayak 11.

The kayak 11 also incorporates compartments, not shown, which enable the operator to store items within.

When transporting the kayak 11, the floatation assemblies 36,37 are in a retracted position. When the operator wishes to use the kayak 11, he/she may position the kayak upon the waters edge and adjust the floatation assemblies 36, 37 to the desired position, dependent on the degree of stability required. The operator may then board the kayak 11 and paddle to his/her destination.

In figures 4 to 7 a second embodiment of the invention is shown. This embodiment differs from the first embodiment in that it is also fitted with a propulsion means 31. Please note that as the embodiments are similar, like annotations are used for like components.

In the second embodiment the kayak 11 has a stern region 25 aft of the cockpit 19. The stern region 25 incorporates an aperture, not shown, extending from the upper skin 13, through to the lower skin 15, with a sidewall, not shown, extending from the upper skin 13 to the lower skin 15.

The aperture is configured to releasably retain the propulsion means 31 such that the propulsion means 31 can be easily fitted to or removed from the kayak 11 by the operator.

The kayak 11 is configured such that, upon removal of the propulsion means 31, the kayak 11 can be used in a conventional manner.

The propulsion means 31 comprises a pump 33 and an electric motor (not shown) to assist in the propulsion of the kayak 11.

The pump 33 has an intake 49 for receiving water, and an outlet 51 for discharging water, to propel the kayak 11. The outlet 51 is positioned such that the water discharged therefrom is substantially aligned with the longitudinal axis of the kayak 11.

The pump also has a shroud 53 adapted to rotate in the horizontal plane and which is secured over the outlet 51. The shroud 53 has a nozzle 56 through which discharged water may accelerate therethrough as it is discharged from the shroud 53. The shroud 53 may be rotatably controlled by the operator to direct the water discharged from the pump, assisting the operator to manoeuvre and steer the kayak 11.

The propulsion means 31 is positioned such that it does not protrude below the hull 23 adjacent the propulsion means 31. This limits the damage that may be caused by underwater obstacles when the kayak 11 is in use.

The propulsion means 31 may be activated by an activation means in the form of an on/off switch located near the cockpit 19.

The hull 23 has a profile to induce water towards the pump 33 whilst protecting the pump from any underwater obstacles. For this purpose, the hull 23 has two keels 45 substantially parallel to the longitudinal axis of the kayak 11, and running along a rear portion of the kayak 11. The keels 45 define a recessed portion/channel 47 located in the stern region 25.

A hood 54 is supported on the upper skin 13 at the stern region 25, and is contoured with the shape of the kayak 11. The hood 54 is located over the propulsion means 31, providing protection from the elements.

The cockpit also provides a viewing window 26 allowing the occupants to view underwater.

In use the operator may position the kayak, minus the propulsion means 31, upon the waters edge and adjust the floatation assemblies 36,37 to the desired position, dependent on the degree of stability required. The operator may then retrieve and position the propulsion means 31 in the aperture at the rear of the kayak 11. Whilst paddling the operator may activate the propulsion means 31 using the on/off switch, and allow the propulsion means 31 to propel the kayak 11, or to assist the operator whilst the operator continues to paddle in a conventional mariner.

If the operator wishes to use the kayak 11 without the assistance of the propulsion means 31, the propulsion means 31 need not be fitted and the kayak 11 can still be used in a conventional manner.

It is believed that the introduction of this invention will provide recreational enjoyment for all type of people regardless of their level of skill, as it would greatly reduce their chances of rolling the kayak due to the floatation assemblies.

It will also provide enjoyment without any detriment to the environment in the form of noise, bank-wash erosion or pollution, whilst greatly reducing the chance of injuries to other people.

The kayak so described by this invention is primarily for recreational use in and around populated beaches and waterways. For reasons of safety and ease of use in recreational areas, it is envisaged that the speed range of the craft may be limited to 2-6 knots. At these low speeds, kayaks are equipped with a hand held paddle for the operator to enjoy the tranquil moments of kayaking without the engagement of the propulsion means. When the operator requires assistance or some relief from paddling, he or she simply engages the propulsion means through a simple on/off button or switch.

Modifications and variations such as would be apparent to the skilled addressee are considered to fall within the scope of the present invention.

Throughout the specification, unless the context requires otherwise, the word ; "comprise"or variations such as"comprises"or"comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.