AU2020237554B2

AU2020237554B2 - Rigid-hulled inflatable boat

Info

Publication number: AU2020237554B2
Application number: AU2020237554A
Authority: AU
Inventors: Fraser Yule
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-03-14
Filing date: 2020-03-12
Publication date: 2022-09-01
Anticipated expiration: 2040-03-12
Also published as: WO2020181327A1; AU2020237554A1

Abstract

An inflatable boat comprising a rigid hull and a sponson assembly slidably attached to the rigid hull. The sponson assembly comprising a plurality of elongate inflatable modular units, each of the modular units having at least one chamber inflatable by air, and the modular units are engagable to each other in an end-to-end relationship. The sponson assembly also comprises an inflatable bow sponson is also slidably attached to the rigid hull, and engagable with two of the modular units.

Description

RIGID-HULLED INFLATABLE BOAT

TECHNICAL FIELD

This invention relates to a rigid-hulled inflatable boat. In particular, the present invention is described with reference to rigid-hulled inflatable boat, which has a sponson assembly comprising an inflatable bow sponson and a plurality modular sponson units removably connected to each other and the rigid hull.

BACKGROUND

A rigid-hulled inflatable boat (RHIB), also known as a rigid-inflatable boat (RIB), is a lightweight boat made from a solid hull and a sponson of inflatable flexible tube, at the bow end and along the gunnels. The design of an RHIB is stable and seaworthy. The sponson allows the vessel to remain buoyant if a large quantity of water is shipped aboard due to bad sea conditions. RHIBs have many uses including but not limited to use as tenders for yachts and larger boats, as work boats in trades that operate on water, military craft, rescue boats, lifeboats and as recreational boats.

Some widely known RHIBs are those sold under the brand names ZODIAC™, AVON™ and AB™. Many of the RHIBs sold under these brands, comprise a single inflatable tubular sponson which when viewed in plan, looks like an elongate U-shape, with the closed end being at the bow (fore) end of the RHIB.

The hull of an RHIB may be made of wood, steel, fibreglass or a combination of wood and fibreglass. However, a widely used material for the hull of commercially available RHIBs is aluminium.

The inflatable sponsons (flexible tubes) are typically made from PVC for the less expensive line of RHIBs, and polyethylene synthetic rubber marketed under Hypalon™ together with Neoprene, for the more expensive boats such as those used for military purposes. The sponsons are usually constructed to have internal separate chambers (sections) to reduce the effect of a puncture, each with a valve to add or remove air. Larger boats (those greater than seven metres in length) have six or more chambers in each tube, with a valve for each chamber. The more chambers a boat has the more redundancy the boat is considered to have. This is because if only one chamber is damaged then the impact the damage has on the boat is much less. Dark colored tubes often have pressure relief valves as the air inside them expands when exposed to sunlight. This prevents the tubes bursting from overpressure.

Typically, the seams of the tubes are glued or thermo-bonded (welded). Also, a sponson is typically bonded to the hull, however some RHIBs have sponsons mechanically and slidably attached to the hull.

The life expectancy of an RHIB will vary considerably, and typically it is failure of the inflatable sponson either by snags, punctures, UV damage, adhesive failure and/or seam leaks that cause the end of their usable life.

It is quite common for RHIBs with sponsons glued to their hulls, which are being used commercially on a daily basis, to only have a life of about two to three years, before the maintenance required causes them to no longer be cost effective to maintain, and replacement is necessary. Whilst it is possible for owners to make minor repairs with repair kits, serious damage to RHIBs are usually entrusted to specialised workshops who are set-up for adhesive/glue repairing of the sponsons. A problem associated with RHIBs is that certain adhesives used in their manufacture do not hold up well in areas of high humidity. Also, the amount of humidity in the air is critical when repairing RHIBs. Humidity must be minimised whilst the adhesive/glue is applied and curing. As such, most professional RHIB repair workshops have air-conditioned rooms or enclosures just for this purpose. THE RHIB is usually placed in such room or enclosure for at least twenty-four hours before gluing to dry out. It stays there until the adhesive is cured. This makes the repair of an RHIB, and more particular the inflatable sponson, quite costly in both time and the labour necessary. This is a disadvantage to operators who use RHIBs on a commercial basis.

For recreational users, it is usually incorrect usage, poor maintenance and storage, UV exposure and incorrect pressurisation of the sponson that leads to problems affecting the serviceable life of RHIBs.

Many RHIBs are retired due to failure of the sponson or its separation from the hull, when the aluminium hull is still usable. In many instances it is more cost effective to replace the whole RHIB rather than to attempt to repair or replace the sponson. Since the manufacture of aluminium has a significant environmental impact, discarding an RHIB with aluminium hull after a short life has a significant environmental footprint. RHIBs which have sponsons (tubes) slidably attached to the hull, go some way to making sponson replacement and repair easier. There is a“slide on tube” design used on certain boats marketed by ZODIAC™, which makes re-tubing a straightforward process. It relies on an elongate rail projection disposed on a gunnel, slidably and removably engaged with an elongate groove along the sponson. However, the sponson attached to the hull is the full U- shaped sponson. Whilst this arrangement means that a sponson can be removed for repair or replacement, it is a complete one-piece flexible tube that runs the full length of the hull. As such it is still a costly and lengthy exercise to repair or replace the full-length U-shaped sponson.

There are other“slide on rail” designs for joining an inflatable sponson (tube) to a hull that have been proposed, such as those described in US5584260 (Hemphill) and W02008/010731 (Mapua Limited).

The present invention seeks to ameliorate at least some of the problems associated with the prior art.

SUMMARY OF INVENTION

In a first aspect the present invention consists of an inflatable boat comprising a rigid hull and a sponson assembly slidably attached to said rigid hull, wherein said sponson assembly comprising a plurality of elongate inflatable modular units, each of said modular units having at least one chamber inflatable by air, said modular units are engagable to each other in an end-to-end relationship.

Preferably each of said modular units has a male member at one end and a female receiving portion at the opposed end, and when two modular units are engaged to each other said male member of one of said two modular units is insertably engaged into said female receiving portion of the other of two said modular units.

Preferably said male member of each of said modular unit is inflatable and fluidally connected to its respective chamber, and when said male member of one of said two modular units is insertably engaged into the female receiving portion of the other of two said modular units, it is done so when at least partially deflated, and both of said two modular units are fully inflated to cause said engagement there between.

Preferably when two modular units are engaged in end-to-end relationship, they are at least partially deflated in order to for the modular units to disengage from one another. Preferably each of said modular units has two spaced apart elongate rails projecting there from, each rail extending axially there along, and wherein said rails slidably engage with two respective elongate channels axially disposed on a gunnel of said rigid hull.

Preferably each said modular sponson has an axially extending first substantially flat face that abuts against an axially extending second substantially flat face on said gunnel, said first substantially flat face disposed between said two rails, and said second substantially flat face disposed between two said channels.

Preferably said sponson assembly further comprising an inflatable bow sponson slidably attached to said rigid hull, and said bow sponson has two space apart trailing portions with free ends disposed on opposite sides of said rigid hull, and each of said free ends has a female receiving portion similar to that of each said modular units, each free end of said bow sponson is capable of engaging with said male member of a respective modular sponson.

Preferably said bow sponson and said modular units include attachment means and/or handles.

Preferably said attachment means is for attaching rope.

Preferably at least one of said modular units can also be used independently of said inflatable boat as a fender for a different water vessel.

Preferably said modular units and said bow sponson each have at least one valve through which said unit and bow sponson is inflated and deflated.

Preferably each modular unit has an axially extending upper flap and an opposed axially extending lower flap, with said upper flap and said lower flap each having an elongate axially extending bead at its free end.

Preferably said respective beads of said upper flap and said lower flap are slidably engagable with respective channels disposed on the hull of a boat.

Preferably said respective channels are disposed on respective upper and lower rails secured to or integral with said hull, said upper rail disposed internal of the gunnel of said boat, and said lower rail disposed external of said hull.

Preferably said upper flap flexibly bends over and abuts against the gunnel of said boat.

In a second aspect the present invention consists of a modular sponson unit for attachment to a rigid hulled boat, said unit having at least one chamber inflatable by air, said unit having a male member at one end and a female receiving portion at the opposed end, said unit engagable to a like unit in an end-to-end relationship, wherein said male member of said unit engages with said female engaging portion of said like unit, and both said unit and like unit are slidably attachable to said rigid hull.

Preferably said male member of said modular sponson unit is inflatable and fluidally connected to said chamber, and when said male member is insertably engaged into said female receiving portion of said like modular sponson unit, it is done so when at least partially deflated, and both of said modular sponson unit and said like modular sponson unit are fully inflated to cause said engagement there between.

Preferably said modular sponson unit has two spaced apart elongate rails projecting there from, each rail extending axially there along, and wherein said rails slidably engage with two respective elongate channels axially disposed on a gunnel of said rigid hull, and said unit has an axially extending first substantially flat face that abuts against an axially extending second substantially flat face on said gunnel, said first substantially flat face disposed between said two rails, and said second substantially flat face disposed between two said channels.

Preferably an inflatable bow sponson having two spaced apart free ends each of which has a female receiving portion similar to that of said modular sponson unit, said free ends capable of engaging with said male member of said modular unit, said inflatable bow sponson is slidably attached to the bow end of said rigid hull.

Preferably said modular unit includes attachment means for attaching rope.

Preferably said modular sponson unit can also be used independently of said inflatable boat as a fender for a different water vessel.

Preferably a valve is disposed thereon, through which said modular sponson unit is inflated and deflated.

Preferably said modular sponson unit has two spaced apart flaps projecting there from, each flap extending axially there along, and wherein each of said flaps has an axially extending bead that slidably engages with a respective elongate channel axially disposed on the hull of said boat

Preferably said respective elongate channels are disposed on respective upper and lower rails secured to or integral with said hull, said upper rail disposed internal of the gunnel of said boat, and said lower rail disposed external of said hull. Preferably said upper flap flexibly bends over and abuts against the gunnel of said boat.

In a third aspect the present invention consists of a modular sponson assembly for attachment to a rigid hull of an inflatable boat, said assembly comprising:

(i) a plurality of elongate inflatable sponson modular units, each unit having at least one first chamber inflatable by air, and a male member at one end and a female receiving portion at the opposed end, said unit engagable to a like unit in an end-to-end relationship, and said male member of said unit sponson engages with said female engaging portion of the like unit, said unit slidably attachable to said rigid hull; and

(ii) an inflatable bow sponson having at least one second chamber inflatable by air and two spaced apart free ends each of which has a female receiving portion similar to that of said unit, and each of said free ends is capable of engaging with said male member of said unit, said inflatable bow sponson is slidably attached to the bow end of said rigid hull.

Preferably each said unit has two spaced apart elongate rails projecting there from, each rail extending axially there along, and wherein said rails slidably engage with two respective elongate channels axially disposed on a gunnel of said rigid hull, and said unit has an axially extending first substantially flat face that abuts against an axially extending second substantially flat face on said gunnel, said first substantially flat face disposed between said two rails, and said second substantially flat face disposed between two said channels.

Preferably said male member of each said unit is inflatable and fluidally connected to said chamber, and when said male member is insertably engaged into the female receiving portion of said like unit, it is done so when at least partially deflated, and both of said modular sponson and said like modular sponson are fully inflated to cause said engagement there between.

Preferably each said unit has two spaced apart flaps projecting there from, each flap extending axially there along, and wherein each of said flaps has an axially extending bead that slidably engages with two respective elongate channels axially disposed on the hull of said boat.

Preferably said respective elongate channels are disposed on respective upper and lower rails secured to or integral with said hull, said upper rail disposed internal of the gunnel of said boat, and said lower rail disposed external of said hull.

Preferably said upper flap flexibly bends over and abuts against the gunnel of said boat. BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 is a perspective view of a rigid-hulled inflatable boat in accordance with a first embodiment of the present invention.

Fig. 2 is a plan view of the rigid-hulled inflatable boat shown in Fig. 1. Fig. 3 is a side view of the rigid-hulled inflatable boat shown in Fig. 1.

Fig. 4 is a plan view of an inflatable modular sponson unit used in the sponson assembly of the rigid-hulled inflatable boat shown in Fig. 1.

Fig. 5 is a side view of the inflatable modular sponson unit shown in Fig. 4.

Fig. 6 is an enlarged front-end view of the inflatable modular sponson shown in Fig. 4, along with an enlarged detail of the rail disposed thereon.

Fig. 7 is a schematic cross-sectional view of two inflatable modular sponson units as shown Fig. 4 connected to each other.

Fig. 8 is a rear-end view of an inflatable modular bow sponson used in the sponson assembly of the rigid-hulled inflatable boat shown in Fig. 1. Fig. 9 is a plan view of the inflatable modular bow sponson shown in Fig. 8.

Fig. 10 is a rear perspective view of one the trailing portions of the modular bow sponson shown in Fig. 8.

Fig. 11 is a cut-away rear perspective view of the bow (fore end) of the rigid hulled inflatable boat shown in Fig. 1, along with an enlarged detail of the groove disposed thereon. Fig. 12 is a perspective view of a rigid-hulled inflatable boat in accordance with a second embodiment of the present invention.

Fig. 13 is a front perspective view of an inflatable modular sponson unit used in the sponson assembly of rigid-hulled inflatable boat in accordance with a third embodiment of the present invention.

Fig. 14 is a side view of the inflatable modular sponson unit of Fig. 13.

Fig. 15 is a front view of the inflatable modular sponson unit of Fig. 13. Fig. 16 depict a front view of two inflatable modular sponsons of Fig. 13, showing the same type of modular unit could be used on either side of the sponson assembly of a boat.

Fig. 17 is a cut-away end view of the gunnel of a rigid hulled inflatable boat with attachments to which an inflatable modular sponson unit of Fig. 13 has been slidably attached.

Fig. 18 is a front perspective view of four inflatable modular sponson units of Fig. 13 shown connected to each other in an end-to-end relationship.

Fig. 19 is a rear perspective view of the four inflatable modular sponson units of Fig. 18.

BEST MODE OF CARRYING OUT THE INVENTION

Figs. 1 to 3 depict a first embodiment of a rigid-hulled boat 1, having a hull 2 and a sponson assembly 3. Hull 2, which is V-shaped and preferably made of aluminium, has a bow 10, two gunnels 11 extending on each side and a transom 12. Boat 1 is of the type that has an outboard motor (not shown) attached to transom 12.

Sponson assembly 3 is made up of a plurality of inflatable modular sponson units 5 and an inflatable bow sponson 6. Modular units 5 and bow sponson 6 are each made of a flexible material such as PVC or synthetic rubber.

Each inflatable sponson modular unit 5, herein referred to as a“modular unit” has its own internal chamber inflatable and deflatable via a valve 7. Likewise bow sponson 6, also has a valve 7 for inflation and deflation purposes. Only Fig. 1 depicts valves 7, and they have been omitted from other figures for clarity and ease of reference.

Each modular unit 5 has a fore portion 8 which is frusto-conical and has a bulbous free end 9, as best seen in Figs 4-7. The fore portion 8 with its bulbous free end 9 may be considered a “male member”. Each modular unit 5 also has a rear portion 18 with a bulbous opening 19 that may be considered a“female receiving portion” which is obverse and complimentary to the “male member”. As such when fore portion 8 and bulbous free end 9 (the male member) of one modular unit 5, is brought into engagement with rear portion 18 and bulbous opening 19 (the female receiving portion) of another like modular unit 5, and both are inflated with air, then both units 5 will become securably engaged as depicted in Fig. 7. Removal of air from both units 5 will allow for them to be disengaged. Inflatable bow sponson 6, as shown in Figs. 8 and 9 have a nose end 21 and two trailing portions 22, 23 on either side. The detail of trailing end 22 is shown from a rear perspective in Fig. 10. Each trailing portion 22,23 has a female receiving portion 28a, 28b respectively, each of which is shaped substantially the same as the rear portion 18 and bulbous free end 9 of modular unit 5. As such a fore portion 8 and bulbous free end 9 (the male member) of a modular unit 5 can be securably engaged with either of a female receiving portion 28a, 28b of inflatable bow sponson 6, in a similar fashion to engaging with a like modular unit 5.

Because modular units 5 engage with each other and bow sponson 6, it should be understood that the fore portion 8, bulbous free end 9 and female portion 18, of modular unit 5 may be of thicker or reinforced material. Likewise, female receiving portion 28a, 28b of bow sponson 6, may also be of thicker or reinforced material.

In use, bow sponson 6 and modular units 5 are each individually slidably engaged with channels 31 on hull 2. In this embodiment each of modular units 5 has two spaced apart elongate rails 30a, 30b projecting there from and extending axially there along. In this embodiment you can see has a sizeable“head”.

Rails 30a, 30b which each slidably engage with two respective spaced apart elongate C- section channels 31 axially disposed on a gunnel 11 of hull 2. Bow sponson 6 also has rails 30c, 30d like rails 30a, 30b that engage with channels 31 that extend from gunnels 11 to bow 10 of hull 2. Channels 31 are best seen in Fig. 11. When inflated each modular unit 5 has an axially extending first substantially flat face 15 disposed between two rails 30a, 30b which abuts against a second substantially flat face on gunnel 11 disposed between the two channels 31, when modular unit 5 is fitted thereto.

When bow sponson 6 and a plurality of modular units 5are slidably engaged onto hull 2 and securably engaged to each other by insertion and then bow sponson 6 and each modular unit 5 are inflated, a“sponson assembly” 3 is formed. As can be seen in Figs 1 to 3, boat 1 has four modular units 5 on each side, secured to each other in end-to-end relationship, the lead modular units 5 are secured to bow sponson 6.

An advantage of such construction of boat 1 is that should any modular unit 5 or bow section 6 of boat 1 become damaged or fail, it can be removed for individual repair and replacement. This replacement could readily be done by a user without need for a specialised workshop. Another advantage is that a user, particularly a user operating a plurality of such boats can keep one or more spare modular units 5 or bow sponsons 6, for quick and easy replacement on any of its like boats. Also, because each modular unit 5 and bow sponson 6 is considerably smaller than prior art single piece U-shaped sponsons, the storage and cost handling for spares and repair of modular unit 5 and bow sponson 6 is reduced.

A further advantage is that the same modular units 5 and bow section 6 can be used on different length boats. For example, as you can see in Fig. 1 sponson assembly 3 of boat 1 has eight modular units 5, four on each side. In a second embodiment as shown in Fig. 12, boat la with hull 2a is like boat 1 of the first embodiment. However, it is shorter in length with its sponson assembly having only six modular units 5, three on each side but having a similar bow section 6. As such the“building block” nature of modular units 5 means that they can be used to build“sponson assemblies” for different length boats of similar design. For example, a certain size of modular unit 5 and bow sponson 6, could be used to construct sponson assemblies for a range of smaller length boats of say two and a half to five metres. Another larger size of modular unit 5 and bow sponson 6 could for example be used for boats of length five and a half to nine metres.

Modular units 5 and bow 6, may be provided with attachment means (not shown) and/or handles (not shown). The attachment means for attaching rope and the like.

An end cap (not shown) could be optionally fitted to the free end of the modular unit 5 at the trailing end of sponson assembly 3.

It should be understood that whilst the abovementioned embodiments utilise a particular“slide on tube” design utilising two spaced apart rails 30 on the tubes (modular units 5 and bow sponson 6) with C-section channels 31 on the hull 2, it should be understood that other“slide- on tube” designs could be employed. In another not shown example the head of the rail and the groove it engages may differ to that shown. And in a further not shown example the rail may be on the hull, and the respective groove it engages with is on the flexible tube component (modular unit or bow sponson).

It should also be understood that a modular unit 5 of the abovementioned embodiments, when provided with appropriate attachment means may be used alone as a fender for a larger boat, so it has a multi- purpose. Figs. 13 to 16 depict a depict third embodiment of an inflatable modular sponson unit 55.

Each inflatable sponson modular unit 55, herein referred to as a“modular unit” has its own internal chamber inflatable and deflatable via a valve 54. Only Figs. 13 and 14 depict valve 54, and this valve 54 has been omitted from other figures for clarity and ease of reference.

Each modular unit 55 is made of a flexible material such as PVC or synthetic rubber.

Each modular unit 55 has a fore portion 58 which has a free end 59, as best seen in Figs 13-15. Modular unit 55 is“pillow-shaped” with a substantially curved outer surface portion (the portion that extends outwardly from a boat gunnel when fitted thereto), and substantially a flat portion (the portion disposed at or near the boat gunnel when fitted thereto). As best seen in Fig. 15, two flaps 56 each respectively extend axially along the top and bottom from the curved portion of modular unit 55 near its substantially flat portion. Each flap 56 has an elongate bead 57 at its free end that extends axially along its whole length.

The fore portion 58 with its free end 59 may be considered a“male member”. Each modular unit 55 also has an opening 60 at its rear end that may be considered a“female receiving portion” which is obverse and complimentary to the“male member”. As such when fore portion 58 with free end 59 (the male member) of one modular unit 55, is brought into engagement with opening 60 (the female receiving portion) at the rear of another like modular unit 55, and both are inflated with air, then both units 55 will become securably engaged. Removal of air from both units 5 will allow for them to be disengaged.

In use, modular units 55 are each individually slidably engaged with an aluminium boat hull 90. Fig. 17 depicts an end view of a modular unit 55 with its attachment to hull 90 via upper and lower rails 85, with hull 90 and rails 85 shown in cross-section. Rails 85 are preferably made of extruded aluminium section with channel 86 at one end, with the“upper” rail 85 secured via rivets 88 to the internal side of gunnel 91 disposed at the upper portion of hull 90 with the opening of channel 86 facing upwardly.

“Lower” rail 85 is secured to a lower portion of the external side of hull 90 via rivet 88.

The“lower” flap 56 shown in Fig.17 extends downwardly and bead 57 at its free end is slidably engaged with channel 86 in Tower” rail 85. The“upper” flap 56b is shown bent over gunnel 91 with bead 57 at its free end slidably engaged with channel 86 in‘upper” rail 85 disposed internally of gunnel 91. In use, flap 56b when fitted not only secures modular unit 55 but also provides protection to the upper portion of gunnel 90. It should be understood that modular units 55 are designed in such a way that they can be used on either side of a boat, and Fig. 16 shows how two inflatable modular sponsons on opposed sides of a boat can have their upper flaps 56a, 56b bent for attachment to the hull, as as shown in Fig.17 for upper flap 56b.

Figs 18 and 19 depict how a plurality, of modular units 55, in this embodiment four modular units 55, are engagable to each other in an end-to-end relationship.

In the Figs. 13 to 19 of the abovementioned third embodiment only modular units 55 have been shown, without depiction of the“bow sponson unit” necessary for use therewith on an inflatable boat. However, the not shown bow sponson for use with the third embodiment, would like bow sponson 6 of the first embodiment, have a“nose end” and two“trailing portions” on either side. The two trailing portions would like that of modular units 55 have flaps and beads that engage with rails in similar fashion to that shown in Fig. 17. However, the nose end of the bow sponson of the third embodiment would not have flaps and beads like that of modular units 55.

It should be understood that the shape, size and configuration of the modular units 5,55 and the bow sponsons, as well as how they slidably engage with the hull of the boat, may differ to those described and shown in the abovementioned embodiments.

The terms“comprising” and“including” (and their grammatical variations) as used herein are used in an inclusive sense and not in the exclusive sense of“consisting only of’.

Claims

1. An inflatable boat comprising a rigid hull and a sponson assembly slidably attached to said rigid hull, wherein said sponson assembly comprising a plurality of elongate inflatable modular units, each of said modular units having at least one chamber inflatable by air, said modular units are engagable to each other in an end-to-end relationship.

2. An inflatable boat as claimed in claim 1, wherein each of said modular units has a male member at one end and a female receiving portion at the opposed end, and when two modular units are engaged to each other said male member of one of said two modular units is insertably engaged into said female receiving portion of the other of two said modular units.

3. An inflatable boat as claimed in claim 2, wherein said male member of each of said

modular unit is inflatable and fluidally connected to its respective chamber, and when said male member of one of said two modular units is insertably engaged into the female receiving portion of the other of two said modular units, it is done so when at least partially deflated, and both of said two modular units are fully inflated to cause said engagement there between.

4. An inflatable boat as claimed in claim 3, wherein when two modular units are engaged in end-to-end relationship, they are at least partially deflated in order to for the modular units to disengage from one another.

5. An inflatable boat as claimed in any of claims 1 to 4, wherein each of said modular units has two spaced apart elongate rails projecting there from, each rail extending axially there along, and wherein said rails slidably engage with two respective elongate channels axially disposed on a gunnel of said rigid hull.

6. An inflatable boat as claimed in claim 5, wherein each said modular sponson has an axially extending first substantially flat face that abuts against an axially extending second substantially flat face on said gunnel, said first substantially flat face disposed between said two rails, and said second substantially flat face disposed between two said channels.

7. An inflatable boat as claimed in claims 2 to 6 wherein said sponson assembly further comprising an inflatable bow sponson slidably attached to said rigid hull, and said bow sponson has two space apart trailing portions with free ends disposed on opposite sides of said rigid hull, and each of said free ends has a female receiving portion similar to that of each said modular units, each free end of said bow sponson is capable of engaging with said male member of a respective modular sponson.

8. An inflatable boat as claimed in claim 7, wherein said bow sponson and said modular units include attachment means and/or handles.

9. An inflatable boat wherein said attachment means is for attaching rope.

10. An inflatable boat as claimed in claim 8, wherein at least one of said modular units can also be used independently of said inflatable boat as a fender for a different water vessel.

11. An inflatable boat as claimed in 7 wherein said modular units and said bow sponson each have at least one valve through which said unit and bow sponson is inflated and deflated.

12. An inflatable boat as claimed in claim 1, wherein each modular unit has an axially

extending upper flap and an opposed axially extending lower flap, with said upper flap and said lower flap each having an elongate axially extending bead at its free end.

13. An inflatable boat as claimed in claim 12, wherein said respective beads of said upper flap and said lower flap are slidably engagable with respective channels disposed on the hull of a boat.

14. An inflatable boat as claimed in claim 13, wherein said respective channels are disposed on respective upper and lower rails secured to or integral with said hull, said upper rail disposed internal of the gunnel of said boat, and said lower rail disposed external of said hull.

15. An inflatable boat as claimed in claim 14, wherein said upper flap flexibly bends over and abuts against the gunnel of said boat.

16. A modular sponson unit for attachment to a rigid hulled boat, said unit having at least one chamber inflatable by air, said unit having a male member at one end and a female receiving portion at the opposed end, said unit engagable to a like unit in an end-to-end relationship, wherein said male member of said unit engages with said female engaging portion of said like unit, and both said unit and like unit are slidably attachable to said rigid hull.

17. A modular sponson unit as claimed in claim 16, wherein said male member of said

modular sponson unit is inflatable and fluidally connected to said chamber, and when said male member is insertably engaged into said female receiving portion of said like modular sponson unit, it is done so when at least partially deflated, and both of said modular sponson unit and said like modular sponson unit are fully inflated to cause said engagement there between.

18. A modular sponson unit as claimed in claims 16 or 17, wherein said modular sponson unit has two spaced apart elongate rails projecting there from, each rail extending axially there along, and wherein said rails slidably engage with two respective elongate channels axially disposed on a gunnel of said rigid hull, and said unit has an axially extending first substantially flat face that abuts against an axially extending second substantially flat face on said gunnel, said first substantially flat face disposed between said two rails, and said second substantially flat face disposed between two said channels.

19. A modular sponson unit as claimed in claim 16, wherein an inflatable bow sponson having two spaced apart free ends each of which has a female receiving portion similar to that of said modular sponson unit, said free ends capable of engaging with said male member of said modular unit, said inflatable bow sponson is slidably attached to the bow end of said rigid hull.

20. A modular sponson unit as claimed in claim 16, wherein said modular unit includes

attachment means for attaching rope.

21. A modular sponson unit as claimed in claim 16, wherein said modular sponson unit can also be used independently of said inflatable boat as a fender for a different water vessel.

22. A modular sponson unit as claimed in claim 16, wherein a valve is disposed thereon, through which said modular sponson unit is inflated and deflated.

23. A modular sponson unit as claimed in claims 16, wherein said modular sponson unit has two spaced apart flaps projecting there from, each flap extending axially there along, and wherein each of said flaps has an axially extending bead that slidably engages with a respective elongate channel axially disposed on the hull of said boat.

24. A modular sponson unit as claimed in claim 23, wherein said respective elongate channels are disposed on respective upper and lower rails secured to or integral with said hull, said upper rail disposed internal of the gunnel of said boat, and said lower rail disposed external of said hull.

25. A modular sponson unit as claimed in claim 24, wherein said upper flap flexibly bends over and abuts against the gunnel of said boat.

26. A modular sponson assembly for attachment to a rigid hull of an inflatable boat, said assembly comprising:

(i) a plurality of elongate inflatable sponson modular units, each unit having at least one first chamber inflatable by air, and a male member at one end and a female receiving portion at the opposed end, said unit engagable to a like unit in an end-to-end relationship, and said male member of said unit sponson engages with said female engaging portion of the like unit, said unit slidably attachable to said rigid hull; and (ii) an inflatable bow sponson having at least one second chamber inflatable by air and two spaced apart free ends each of which has a female receiving portion similar to that of said unit, and each of said free ends is capable of engaging with said male member of said unit, said inflatable bow sponson is slidably attached to the bow end of said rigid hull.

27. A modular sponson assembly as claimed in claim 26, wherein each said unit has two spaced apart elongate rails projecting there from, each rail extending axially there along, and wherein said rails slidably engage with two respective elongate channels axially disposed on a gunnel of said rigid hull, and said unit has an axially extending first substantially flat face that abuts against an axially extending second substantially flat face on said gunnel, said first substantially flat face disposed between said two rails, and said second substantially flat face disposed between two said channels.

28. A modular sponson assembly as claimed in claim 26, wherein said male member of each said unit is inflatable and fluidally connected to said chamber, and when said male member is insertably engaged into the female receiving portion of said like unit, it is done so when at least partially deflated, and both of said modular sponson and said like modular sponson are fully inflated to cause said engagement there between.

29. A modular sponson assembly as claimed in claim 26, wherein each said unit has two

spaced apart flaps projecting there from, each flap extending axially there along, and wherein each of said flaps has an axially extending bead that slidably engages with two respective elongate channels axially disposed on the hull of said boat.

30. A modular sponson assembly as claimed in claim 29, wherein said respective elongate channels are disposed on respective upper and lower rails secured to or integral with said hull, said upper rail disposed internal of the gunnel of said boat, and said lower rail disposed external of said hull.

31. A modular sponson assembly as claimed in claim 30, wherein said upper flap flexibly bends over and abuts against the gunnel of said boat.