EP1403179A1

EP1403179A1 - Catamaran

Info

Publication number: EP1403179A1
Application number: EP20030256051
Authority: EP
Inventors: Nigel Mercer Guy
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-09-26
Filing date: 2003-09-25
Publication date: 2004-03-31
Also published as: GB2393425A; GB2393425B; GB0222329D0

Abstract

The catamaran comprises a pair of substantially rigid elongate hulls (1) each provided with buoyancy means. The hulls (1) are detachably mounted one to the other parallelly in use, but are re-mountable one to the other to form a single transportable body when out of use. In this configuration an upper surface of a first hull (1) opposes an upper surface of a second hull (1) to form an enclosed hollow body, in which other components of the craft may be stored.

Description

The present invention relates to a boat of catamaran form which may be disassembled for convenient storage and transportation on land. More particularly but not exclusively, it relates to such a boat which is easily convertible between a sail-powered form and a motor-propelled form, so as to be able to perform a variety of functions.
The catamaran or twin-hull configuration for a water craft has many advantages over a conventional single-hull configuration. A catamaran is usually faster, since the hydrodynamic resistance experienced by two parallel hulls of high length-to-beam ratio is less than that experienced by a broader single hull of equivalent displacement. Single-hulled vessels having a high length-to-beam ratio often have stability problems, whereas a catamaran has a large overall beam and is much more difficult to tip over.
However, the large overall beam of a catamaran renders it more difficult to handle out of the water. Various proposals have been made for catamarans which can be folded to reduce their beam sufficiently for them to be transported on a trailer of conventional size, towed behind a motor vehicle. However, these are still cumbersome, and in any case the motor vehicle could not tow both a trailer and a caravan, for example.
Boats of catamaran form have therefore not become as popular for pleasure sailors and the like as they might otherwise have been. One of the reasons that windsurfing, for example, has become as popular as it has, is that a windsurfing rig can easily be transported on top of a motor vehicle.
Catamarans having inflatable hulls have been proposed to overcome storage and transport problems. However, inflatable vessels have buoyancy problems if they are punctured, and it is also very difficult to produce an inflatable hull having a suitable shape, particularly at the bow.
A more easily transportable yet safe catamaran would therefore be of great benefit. Such a boat would also be useful in motorised form, as a speedboat for recreational use, or as an easily storable workboat or tender for a larger vessel. It is particularly desirable that windsurfers should be accompanied by a safety boat, should they lose the wind when remote from land or should they get into difficulties. A boat of easily transportable form would clearly be of benefit in this application also.
It is hence an object of the present invention to provide a water craft of catamaran form which may conveniently be disassembled for transportation on a motor vehicle. It is a further object of the present invention to provide such a craft which may safely perform a wide range of alternative functions with minimal modification.
According to a first aspect of the present invention, there is provided a water craft comprising a pair of substantially rigid elongate hull means each provided with buoyancy means, the hull means being detachably mounted one to the other substantially parallelly in use, and so configured that they are mountable one to the other to form a single transportable body when out of use.
Preferably, said hull means are configured to be mountable one to the other for transport with an upper, in use, surface of a first hull means opposing an upper, in use, surface of a second hull means.
Advantageously, said hull means are mountable one to the other to form an enclosed hollow body, in which other components of the craft may be stored.
Said hull means may be mountable one to the other with a bow of the first hull means adjacent a stem of the second hull means, and vice versa.
Said hull means are preferably substantially identical.
Each hull means may comprise a raised bow portion, and a correspondingly recessed portion adjacent its stem to receive a raised bow portion of the other hull means.
The hull means are preferably mounted one to the other in use via connecting means disconnectably mountable to each hull means.
Said connecting means may comprise a plurality of substantially horizontal panel means, optionally adapted to form a deck extending between the two hull means.
The panel means closest to a bow and the panel means closest to a stem of the craft may each comprise a generally vertical panel extending between the two hull means.
One of said panel means, preferably the panel means closest to the bow, may be provided with mounting means to which a mast may be stepped.
The craft may then be provided with a mast and with rigging means connectable thereto and to each hull means.
The craft may optionally be provided with flexible deck means, such as net means or flexible sheet means, extending between the hull means and between two said panel means.
Each hull means may be provided adjacent a stem thereof with dismountable rudder means.
The panel means closest to the stem may be provided with mounting means to which outboard motor means may be mounted.
Alternatively, each hull means may be provided adjacent a stem thereof with mounting means to which outboard motor means may be mounted.
Preferably, each hull means is provided with inflatable buoyancy means.
Advantageously, each said inflatable buoyancy means comprises a generally cylindrical inflatable body mounted within a respective hull means.
Each inflatable body may extend along substantially the whole length of a respective hull means.
Optionally, each inflatable body extends in an inflated configuration above an upper, in use, surface of a respective hull means, thus increasing its freeboard.
Each inflatable body may taper towards a bow end thereof to conform generally to a bow portion of a respective hull means.
Each inflatable body may be debatable for transport, to leave a generally hemicylindrical recess within which dismantled components of the craft may be stored.
Alternatively, each inflatable body may be dismountable from a respective hull means before or after deflation.
Each inflatable body may comprise a fabric material coated with a durable, waterproof, flexible plastics material, such as nylon fabric coated with chlorosulphonated polyethylene.
Each hull means may be provided with permanent buoyancy means.
Said permanent buoyancy means may comprise closed-cell foamed plastics material, optionally extending within each hull means along each side thereof.
The craft may be provided with detachable keel means, such as dagger board means slideably mountable through slot means extending generally vertically through each hull means.
Each hull means may be provided with two said slot means, disposed one adjacent each side thereof.
Each hull means may comprise a bilge compartment, defined by a bottom skin of the hull means and the buoyancy means thereof, to contain ballast water.
Each hull means may be provided with inlet means through which water may enter to provide ballast.
The inlet means may comprise inlet apertures adjacent a bow of each hull means, connected to the bilge compartment thereof.
The inlet means may alternatively or additionally comprise the recessed portion of each hull means adjacent its stern, connected to the bilge compartment thereof.
Alternatively or additionally, the inlet means may comprise an inlet, connected to the bilge compartment of each hull means, located in an upper part of each slot means thereof.
One or more outlet valve means may be provided mounted in the stem of each hull means, to drain ballast water from the bilge compartment thereof before transport or storage on land.
Said outlet valve means may be openable when the water craft is in use to release excess ballast water from a respective bilge compartment.
Said outlet valve means may also be operable as inlet valves to allow ballast water into the bilge compartment of each hull means.
According to a second aspect of the present invention, there is provided a kit of parts assembleable to form a water craft as described above.
According to a third aspect of the present invention, there is provided a water craft comprising a pair of substantially rigid elongate hull means each provided with buoyancy means, the hull means being detachably mounted one to the other substantially parallelly in use, wherein said buoyancy means comprises a generally cylindrical inflatable body mounted within each hull means.
Preferably, said inflatable bodies extend along substantially the whole length of each hull means.
Advantageously, each inflatable body extends, in an inflated configuration, above an upper, in use, surface of a respective hull means, thus increasing its freeboard.
Each inflatable body may taper towards a bow end thereof to conform generally to a bow portion of a respective hull means.
Each hull means may comprise a raised bow portion.
Each inflatable body may be deflatable for transport or storage, and optionally may be dismountable from a respective hull means for transport or storage.
Each inflatable body preferably comprises a fabric material coated with a durable, flexible, waterproof material, such as nylon fabric coated with chlorosulphonated polyethylene.
Each hull means may further be provided with permanent buoyancy means, optionally comprising closed-cell foamed plastics material.
An embodiment of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which:

Figure 1 is a plan view of a water craft embodying the present invention, assembled in a sailing configuration;
Figure 2 is a side view of a hull of the water craft of Figure 1 in use with its buoyancy tube inflated;
Figure 3 is a side view of the hulls of the water craft of Figure 1, mounted one to the other for transport or storage;
Figure 4 is a plan view of a separated hull of the water craft with its buoyancy tube deflated or removed;
Figure 5 is a cross-section of the hull of Figure 4 taken along the line V-V;
Figure 6 is a cross-section of the stored hulls of Figure 3, taken along the line VI-VI;
Figure 7 is a bow view of the hull of Figure 2;
Figure 8 is a cross-sectional view of the hull of Figure 4 taken along the line VIII-VIII;
Figure 9 is a stem view of the hull of Figure 2;
Figure 10 is a cross-section of an alternative hull form;
Figure 11 is a cross-section of a pair of hulls of Figure 10 mounted one to the other for transport or storage;
Figure 12 is a cross-section of the hull of Figure 2 taken along the line XII-XII;
Figure 13 is a cross-section of a further hull variant, taken along a line corresponding to the line VIII-VIII of Figure 4;
Figure 14 is a stem view of the hull variant of Figure 13;
Figure 15 is a stem view of the water craft of Figure 1; and
Figure 16 is a plan view of the water craft of Figure 1, in a configuration for motor propulsion.

Referring now to the Figures, and to Figure 1 in particular, a water craft of catamaran form comprises two substantially identical hulls 1 made from a strong, substantially rigid material, such as glass fibre reinforced polyester resin (GRP). Each hull 1 has a bow section 2 tapering to a relatively sharp prow and a stem section 3 which is substantially flat. Each hull 1 holds a cylindrical inflatable buoyancy tube 4 with a tapering bow portion 5. The buoyancy tubes 4 are made from a woven nylon fabric coated with chlorosulphonated polyethylene, for example as sold under the registered trade mark HYPALON. Each hull 1 has a laterally-extending rim 6 comprising its upper surface.
The hulls 1 are connected by a number of horizontally aligned rigid panels 7, each of which is detachably fastened at opposite ends thereof to a rim 6 of a respective hull 1. The panels 7 abut to form a deck for the craft. A foremost panel 8 is provided with a vertical fore bulkhead 9 which prevents water washing over the deck and an aftermost panel 10 is provided with a similar, almost vertical aft bulkhead 11. The foremost panel 8 and the fore bulkhead 9 support a mounting 12 to which a mast (not shown) may be stepped. The rigging for the mast is of conventional form for a catamaran craft. In the configuration shown, four panels 7 are used so that the mast is mounted to the craft slightly forward of a midpoint of the craft, this usually being the optimum position for a single-masted sailing vessel. The craft may also be used with some or all of the deck panels 7 replaced by a net, as on racing catamarans. Alternatively, some or all of the rigid deck panels 7 may be replaced with a sheet of flexible waterproof material, such as that used for the buoyancy tubes 4, optionally provided with bracing struts.
As shown in Figure 2, the buoyancy tube 4 extends well above the level of the rim 6 of the hull 1, increasing the freeboard of the hull 1 as well as supplying unswampable buoyancy. It also provides a comfortable seat for the sailor. The bow section 2 of the hull 1 is raised, better to cut through waves, and the bow portion 5 of the buoyancy tube 4 is tapered to conform generally to the shape of the bow section 2. The rim 6 also follows the profile of the bow section 2.
A detachable keel or dagger board 13 is mounted to each hull 1 when the craft is rigged to be sailed. Each hull 1 has a vertical slot 14 adjacent each side thereof, down which a dagger board 13 may be inserted. A dismountable rudder (not shown) is mounted to the stem 3 of each hull 1, the conventional position for a catamaran.
The hulls 1 are laterally symmetrical, and either can act as a port or a starboard hull. Both rims 6 of each hull are provided with attachment points for the panels 7, 8, 10, and the dagger boards 13 are inserted down whichever two slots 14 are disposed adjacent each outer side of the craft as a whole.
As shown in Figure 3, when the craft has been dismantled, and the buoyancy tubes 4 have been deflated and/or removed, the two hulls 1 can be mated together, bow to stem, with their respective rims 6 in contact. The raised bow section 2 of each hull 1 is received by a corresponding recess 15 in the other hull 1, adjacent its stem 3. This also helps to lock the hulls 1 together.
Figures 4 and 5 show the form of the hull 1 with the buoyancy tube 4 removed or deflated. The hull 1 is recessed immediately below the rim 6 and then bulges outwardly. Except near the bow section 2 and stem 3, the hull 1 at its broadest point 16 is of substantially the same width as it is across the rim 6.
The hull 1 shown has a generally hemicylindrical inner hull 17 to hold the respective buoyancy tube 4. As shown in Figure 6, when the two hulls 1 are mated together, an enclosed compartment 18 is defined by the respective inner hulls 17, in which may be stored the deck panels 7, 8, 10, the dagger boards 13, the deflated buoyancy tubes 4, possibly the mast and any other components of the craft. The mated hulls 1 thus form a transport or storage case for the remainder of the craft. This can easily be transported on a roof rack of a motor vehicle, and because of its elongate form, other cargo, such as windsurfing boards, water-skis or personal luggage, can be carried alongside it. The two hulls 1 can be lashed together, or fastened together by their respective rims 6.
Figure 7 shows the profile of the bow section 2 of each hull 1 from a forward direction. The rim 6 of the hull 1 follows the raised profile of the bow section 2, helping to deflect spray as the bow section 2 cuts through the water. The form of the bow portion 5 of the buoyancy tube 4 also contributes to the effectiveness of the bow profile.
As shown in Figure 8, the inner hull 17 tapers within the bow section 2, to support the bow portion 5 of the buoyancy tube 4 and to reinforce the hull 1.
Figure 9 shows how the stem 3 of the hull 1 is relatively flat, with the hull 1 only tapering slightly towards the stem 3. The contribution of the buoyancy tube 4 to the overall freeboard of the hull 1 is shown, as is the correspondence of the recess 15 within the stem 3 to the shape of the bow section 2.
Because the inflatable buoyancy tubes 4 are mounted within the hulls 1, they are well protected from damage, for example from impact with submerged objects or other craft. Even if one or both buoyancy tubes are deflated, the hulls 1 are reasonably buoyant by dint of their shape.
However, it may be desirable to provide the hulls 1 with more permanent buoyancy, for example in case the buoyancy tubes 4 were lost or damaged in conditions which might swamp an open-topped hull form. As shown in Figure 10, inserts 19 of a closed-cell foamed plastics material can be provided, extending along each side of each hull 1 and providing buoyancy even in the absence of the buoyancy tube 4. A bilge compartment 20 is formed between the buoyancy tube 4, the foam inserts 19 and the hull 1, the function of which is described below.
When foamed inserts 19 are provided, the inner hull 17 may be omitted. When the two hulls 1 are then mounted together for transport, a larger enclosed compartment 18 is formed, as shown in Figure 11.
The hulls 1 may alternatively be provided with elongate inflatable or inflated inserts extending along each side of each hull 1 in place of the foamed inserts 19 shown.
Figure 12 shows in more detail the form of the slots 14 through which the dagger boards 13 are inserted. Where the hull 1 is provided with foam inserts 19, the slots 14 are conveniently formed extending through a respective insert.
Although a craft of catamaran form is resistant to tipping over, it is desirable to ballast the hulls 1, to provide a greater righting moment should one hull 1 rise out of the water. The bilge compartment 20 can be allowed to fill with water to provide this ballast. The buoyancy of the buoyancy tube 4 and/or foam inserts 19 is more than sufficient to make up for the water in the bilge compartment 20, and the mass of this water at a lowest part of the hull greatly adds to the stability of the craft.
It is convenient to provide inlets through which water can enter the bilge compartment 20 as the craft is sailed along. For example, the slots 14 for the dagger boards 13 may be provided with apertures (not shown) connecting an upper part of each slot 14 to the bilge compartment 20. As the hull 1 rides through the water, water within the slot 14 will periodically slop through these apertures into the bilge compartment 20.
A bilge compartment 20 can also be formed between the hull 1 and an inner hull 17, where present, or a purpose-built compartment 20 can be built into the hull 1. Figure 13 shows a purpose-built compartment 20 which is filled with water entering through inlet channels 21, located adjacent the bow section 2 of the hull, which collect run-off from the rim 6 of the hull 1, 2.
The recesses 15 adjacent the stem 3 of each hull 1 may also be employed to collect water from splashes and spray and pass it to a respective bilge compartment 20.
Controllable outlet valves 22 may be provided in the stem 3 of each hull 1, connected to the bilge compartment 20. When the craft is beached, these valves 22 allow the ballast water to be drained from each hull 1 before the craft is disassembled. The outlet valves 22 may also be opened when the craft is being used as a speedboat or is being sailed in racing trim, to release excess ballast water collected in the bilge compartment 20 which could slow the craft down. On the other hand, should substantial quantities of ballast water be required, the outlet valves 22 may be operable as inlet valves to fill the bilge compartment 20 rapidly.
As well as forming a safe and easily transportable sailing craft, the water craft of the present invention is equally useful as a powered craft.
As shown in Figure 16, the foremost panel 8 may be mounted further forwards, with additional deck panels 7 being provided to add to the carrying capacity of the craft. (A craft sized to be carried on a motor vehicle has sufficient buoyancy to carry one to two tonnes payload, depending on the conditions). Dagger boards 13 are not used in this configuration of the craft.
A conventional outboard motor can be used to propel the craft, and this is most conveniently mounted to the aft bulkhead 11. A notch 23 is provided in the aft bulkhead 11, so that the motor can be mounted at a correct height above the water (outboard motors are normally built with a standard separation between their mounting brackets and their propellers).
As is shown in Figure 15, the buoyancy tubes 4 and the fore and aft bulkheads 9, 11, (which extend to the same height as the tubes 4 and are faired to fit their profile) form a crew or cargo compartment raised above the water and protected to a degree from spray. The craft is thus usable as a speedboat, or could be used as a workboat or a tender for a larger vessel, being as easy to store on the deck of such a vessel as it would be on top of a motor vehicle. The craft is ideally suited as a safety boat for watching over windsurfers, or following sailing dinghies or other small craft. With a sufficiently powerful motor, the craft may be used to tow water skiers, the low hydrodynamic resistance of the catamaran shape being equally as beneficial when motor-driven as when sailing.
The craft can be provided with mooring ropes, grab handles, tie-downs and the like, as for any water craft. In relatively calm conditions, the buoyancy tubes 4 make excellent seats, or seating arrangements can be installed on the deck panels 7. The basic design is extremely versatile, and the buoyancy tubes 4 provide excellent buoyancy within the protective and hydrodynamically efficient hulls 1, while the entire craft can be disassembled and stored/transported within the case formed by the mated hulls.

Claims

A water craft comprising a pair of substantially rigid elongate hull means (1) each provided with buoyancy means (4,19), characterised in that the hull means (1) are detachably mounted one to the other substantially parallelly in use, and are so configured that they are mountable one to the other to form a single transportable body when out of use.
A water craft as claimed in claim 1, characterised in that said hull means (1) are configured to be mountable one to the other for transport with an upper surface of a first hull means opposing an upper surface of a second hull means to form an enclosed hollow body, in which other components of the craft may be stored.
A water craft as claimed in claim 2, characterised in that said hull means are substantially identical and are mountable one to the other with a bow (2) of the first hull means adjacent a stem (3) of the second hull means, and vice versa, each hull means comprising a raised bow portion (2) and a correspondingly recessed portion (15) adjacent its stem to receive a raised bow portion (2) of the other hull means (1).
A water craft as claimed in any one of the preceding claims, characterised in that the hull means (1) are mounted one to the other in use via connecting means (7), which are disconnectably mountable to each hull means, and which comprise a plurality of substantially horizontal panel means, adapted to form a deck extending between the two hull means.
A water craft as claimed in claim 4, wherein the panel means (8,9) closest to a bow and the panel means (10, 11) closest to a stem of the craft each comprise a generally vertical panel extending between the two hull means, one provided with mounting means (12) to which a mast may be stepped, and one provided with mounting means (23) for outboard motor means.
A water craft as claimed in either claim 4 or claim 5, characterised in that it further comprises flexible deck means, extending between the hull means and between two said panel means.
A water craft as claimed in any one of the preceding claims, characterised in that it further comprises dismountable rudder means mounted to each hull means adjacent a stem thereof.
A water craft as claimed in any one of the preceding claims, characterised in that inflatable buoyancy means (4) comprising a generally cylindrical inflatable body are mounted within a respective hull means (1), preferably to extend along substantially the whole length of a respective hull (1) and when in an inflated configuration to rise above an upper, in use, surface of a respective hull means (1) to increase its freeboard.
A water craft as claimed in any one of the preceding claims, characterised in that each hull means is provided with permanent buoyancy means (19), such as closed-cell foamed plastics material, optionally extending within each hull means (1) along each side thereof.
A water craft as claimed in any one of the preceding claims, characterised in that detachable keel means, such as dagger board means (13), are slideably mountable through slot means (14) extending generally vertically through each hull means.
A water craft as claimed in any one of the preceding claims, characterised in that a bilge compartment (20), defined by a bottom skin of one or each hull means (1) and the buoyancy means (4) thereof, is provided to contain ballast water.
A water craft as claimed in claim 11, characterised in that inlet means through which water may enter the bilge compartment (20) to provide ballast comprise inlet apertures (21) adjacent a bow of each hull means, and/or the recessed portion (15) of each hull means adjacent its stem.
A water craft as claimed in either claim 11 or claim 12, characterised in that one or more outlet valve means (22) are provided in each hull means, to drain ballast water from the bilge compartment (20) thereof before transport or storage on land.