AU2002342428A1 - Multi-hull marine craft - Google Patents

Description

WO 03/045769 PCT/AU02/01612 -1 MULTI-HULL MARINE CRAFT Technical Area This invention relates to the area of the manufacture of marine craft and in particular to the development of craft which is stable and easily handled in adverse weather conditions while having an interior which is substantially similar to a conventional craft. Background to the invention For the purpose of improving stability and comfort when compared to mono-hull boats it is known for multi-hull boats such as catamarans and trimarans to be used. Catamarans are relatively stable but of necessity have flat floors and therefore do not have the interior area of a conventional monohull boat. Trimarans, having a central hull and two laterally positioned stabilising hulls are very stable however they extend across a large area while having relatively little useful space other than in the central hull. In addition trimarans have a significantly greaterwetted surface area than a catamaran and consequently, although being fairly stable vessels, have a greater drag and consequent resistance to movement.

WO 03/045769 PCT/AU02/01612 -2 Outline of the invention It is an object of this invention to provide a marine craft which is relatively stable and easily handled in rough water and permits the main body or hull of the craft to be minimally affected by waves. It is a further object of this invention to maximise the headroom available in the forward, interior, part of the boat. The invention is a marine craft having a hull which is effectively elevated above two lateral hull devices and having a bow associated with a third centrally located hull device which device is positioned generally towards the bow of the craft. It is preferred that the third centrally located hull device has an upper surface which is open to the interior of the craft. It is preferred that the third hull device have a draft which is generally less than that of the lateral hull devices It is preferred that the craft hull, above the lateral hull devices, be relatively conventional in shape and that it have floors above, and substantially across, the lateral hull devices but which extend into the interior of the central hull device. Therefore the interior of the hull could be generally flat bottomed but V shaped, or whatever shape was required, in the vicinity of the central hull device.

WO 03/045769 PCT/AU02/01612 -3 It may be further preferred that the central hull device be an effective shallow keel and that it may extend continuously down from the craft's bow for more effective wave penetration. It is preferred that the lateral hull devices be planing hulls. These may however be wave penetrating hulls if that is preferred and the size and shape of all three hull devices may be of a length and shape that is suited to a particular application. It is preferred that the lateral hull devices extend along the length of either side of the craft hull however this is not essential. It may be preferred that the lateral hull devices extend forward of the central hull device or, alternatively, it may be preferred that the central hull device be relatively short and that the lateral hull devices be positioned further astern than the central hull device. Whatever the arrangement of these hull devices their use provides a marine craft having the stability of a catamaran with the headroom provided by a conventional monohull where the central hull device is located. In order that the invention may be more readily understood we will describe by way of non limiting example a specific embodiment thereof. Brief Description of the Drawing Figures Fig. 1 shows a side elevation of the marine craft of the invention; Fig. 2 is a view of the marine craft of the invention from below; WO 03/045769 PCT/AU02/01612 -4 Fig. 3 is a view of the marine craft of the invention from the rear; Fig. 4 shows a cross-section along line A - A' of Fig. 2 through a forward section of the marine craft; Description of an Embodiment of the Invention A preferred embodiment of the invention is shown in Figures 1 to 4. The marine craft 10 of the invention is a marine craft having a hull 12 which is relatively conventionally shaped, in the form of mono-hull boats, except that its hull is effectively elevated above two lateral hull devices 14. The hull has floors above and substantially across the lateral hull devices but which descend down into a third hull device 20, which is oriented along the centreline of the craft, which in the embodiment of the invention described here has a leading edge 21 which is effectively a continuation of the bow of the boat. This third hull device 20 has an opening 22 into its interior and in this embodiment of the invention is substantially V shaped. As shown in Figure 4 this hull device 20 can be provided with a floor 23 to provide a convenient platform upon which a person can stand. Irrespective of the improved handling characteristics provided bythe central hull device, the fact that its upper surface is open means that the headroom above it is much increased. Increased headroom is provided generally over the distance which the central hull device extends aft of the bow. It is preferred however that the extra headroom WO 03/045769 PCT/AU02/01612 -5 provided by this device 20 be accessible inside the cabin of a craft to a person after passing through the hatchway 30 as shown in Figure 3. Figure 4 shows a cross-section through the craft along the section A-A' as shown in Figure 2. The interior seats 24 are separated by a space which extends into the opening 22 into the interior of the central hull device 20 thereby providing space for a person's legs and consequently increased headroom. In this embodiment of the invention as shown in Figure 3 the central hull device extends in the vertical to a depth less than that of the lateral hull devices. In calm water the central hull device provides little if any extra drag to the craft. In rough seas it provides the craft with greatly improved handling characteristics unlike a standard catamaran type hull. It has been found that the craft of the invention performs extremely well in rough seas as well as providing good headroom in its cabin. The precise shape, location on the hull and longitudinal extent of the central hull device is not restricted in the invention. It must however be dimensioned appropriately to permit the craft to be easily and effectively manoeuvred and therefore is best located proximate to the bow. In this embodiment of the invention the lateral hull devices have an outer edge 15 which is substantially aligned with the sides of the craft and extend substantially along and below the sides. The lateral hull devices as shown in Figures 1 and 2 extend forward of the hull and have sharp leading edges 16 for wave piercing however any WO 03/045769 PCT/AU02/01612 -6 desired shapes can be used. It may be preferred that the lateral hull devices be shaped so as to be surface performing, i.e. planing hulls, and generally for small craft of 5m to 13m the lateral hull devices would be buoyant. The lateral hull devices are primarily used for buoyancy and support of the boat hull and superstructure however they could also be used for storage of equipment used on the boat or for whatever was required by a user. The effect of the presence of the two lateral hull devices below a boat hull means that there is a large area of boat which can be supported, unlike conventional trimarans. In addition the drag associated with a the craft of the invention is significantly reduced compared to that of a monohull, while the presence of the third central hull device provides manouverability and ease of handling through rough seas and increased headroom as well. The result is a marine craft which is not only more functional than many other such craft but is able to handle rough sea conditions in a stable and manoeuvrable fashion. We have described here one particular embodiment of the invention however the size and shape of all three hull devices may be of any length and shape that is suited to a particular application. For example it may be preferred that the central hull device be relatively short and that the lateral hull devices be positioned further astern than the central hull device WO 03/045769 PCT/AU02/01612 -7 however it is preferred that the lateral hull devices extend along the length of either side of the craft hull. Whilst we have described herein specific embodiments of the invention it is to be understood that variations and modifications in this can be made without departing from the scope thereof.

Claims (12)

1. A marine craft having a hull which is effectively elevated above two lateral hull devices and having a bow associated with a third centrally located hull device which device is positioned generally towards the bow of the craft.

2. A marine craft as claimed in claim 1 wherein the third hull device has a draft which is generally less than that of the lateral hull devices.

3. A marine craft as claimed in claim 1 or claim 2 wherein the third hull device is open to the interior of the craft.

4. A marine craft as claimed in claim 2 or claim 3 having a generally conventional hull shape with floors which are generally fiat except in the area of the third hull device which has an open upper surface.

5. A marine craft as claimed in claim 4 wherein the third hull device has a leading edge which is an extension of the bow.

6. A marine craft as claimed in claim 5 wherein the third hull device is generally V shaped and is provided internally with a flat floor.

7. A marine craft as claimed in any one of claims 1 to 6 wherein the lateral hull devices are of a wave penetrating shape. WO 03/045769 PCT/AU02/01612 -9

8. A marine craft as claimed in any one of claim 1 to 6 wherein the lateral hull devices are planing or surface performing hulls.

9. A marine craft as claimed in any one of claims 1 to 8 wherein the lateral hull devices extend along the full length of either side of the craft hull.

10. A marine craft as claimed in claim 9 wherein the lateral hull devices extend forward of the central hull device.

11. A marine craft as claimed in claim 9 wherein the central hull device extends forward of the lateral hull devices.

12. A marine craft substantially as herein decribed with reference to the accompanying drawings.