GB2571960A

GB2571960A - A hybrid boat hull

Info

Publication number: GB2571960A
Application number: GB1804067.5A
Authority: GB
Inventors: Kowalski Frank
Original assignee: Safehaven Marine Ltd
Current assignee: Safehaven Marine Ltd
Priority date: 2018-03-14
Filing date: 2018-03-14
Publication date: 2019-09-18
Anticipated expiration: 2038-03-14
Also published as: GB2571960B; GB201804067D0

Abstract

A hybrid boat hull comprising a monohull forward section 101, a catamaran rear section 103 and a deck 127 bridging the catamaran rear section and monohull forward section. The catamaran rear section comprises a pair of side hull sections 105, 107 laterally spaced apart from each other. The monohull forward section is located between the pair of side hull sections, and the central hull section is located predominantly forward of the pair of side hull sections. The central hull section comprises a transom (110, fig 2) and located adjacent to the bows of the side hull sections. The hull may comprise an underside of deck intermediate the pair of side hull sections that is stepped from front to back, in which there may be at least two steps in the underside of the deck. The underside of the central hull and catamaran sections may also be stepped from front to back. The step feature may also comprise a longitudinal step extending along the side of the side hull adjacent the other side hull. The hull may comprise a hydrofoil either attached to the underside of the hull located adjacent the longitudinal center of gravity of the hull or stern mounted.

Description

“A hybrid boat hull”

Introduction

This invention relates to a boat hull. More specifically, the invention relates to a boat hull particularly suited, although not limited to, operation at high speed in high sea states.

Boat and ship hull design continues to evolve in the search for a hull shape that provides the best combination of performance, efficiency and seakeeping. However, it is generally accepted that there will never be a hull that offers optimal performance in all three criteria, and that there will always be a degree of compromise in hull design.

Broadly speaking, generic boat and ship hull designs can be categorised into three distinct types: Monohull, Catamaran and Trimaran. Each of these types may be further sub-divided into a number of sub-categories. There are advantages and disadvantages of each of the known types of hull design. In particular, there are advantages and disadvantages of each of the known types of hull design when operating at high speed in high sea states.

For example, in relation to Catamaran hull designs, it is well established that there are substantial problems when operating these hull designs in high sea states. More specifically, at a given size, steepness and frequency, waves, especially in head seas, will impact on the flat surface of the bridge deck between the catamaran hulls causing slamming and/or structural damage to the vessel. The same can be related to the conventional trimaran design as it too by necessity has a bridge deck connecting the outer hulls to the main central hull. This problem does not apply to certain wave-piercing trimaran designs which by unique design eliminate this constraint, however these are, by and large, the exception.

In relation to Monohull designs, it is also well established that when operating at high speeds in rough conditions, these hulls suffer from substantial vertical accelerations and impact loadings when impacting the water, heeled over at an angle by wave or wind influence, typically after extreme pitching and becoming airborne off the crest of a wave. In a worst case scenario, this can lead to catastrophic failure of the hull.

-2It is an object of the present invention to provide a hull design that offers increased performance characteristics, most notably in higher sea states. It is a further object of the present invention to provide a useful alternative choice to the consumer.

Statements of Invention

According to the invention there is provided a hybrid boat hull comprising a catamaran rear section and a monohull forward section, a deck bridging the catamaran rear section and the monohull forward section, the catamaran rear section comprising a pair of side hull sections laterally spaced from each other, the monohull forward section comprising a centre hull section located between the pair of side hull sections and in which the centre hull section is located predominantly forward of the pair of side hull sections with a transom of the centre hull section located adjacent to the bow of each of the side hull sections.

By having such a hull, there is provided a vessel that can operate at higher speeds and/or in higher sea states than existing conventional offerings. More specifically, by having the monohull forward section positioned in front of the bridge deck connecting the twin catamaran hulls, this will effectively break the wave and absorb the impact of the wave, lifting the hull over the wave and preventing the flat surface of the bridge deck from directly impacting the water surface. Secondly, by having the catamaran rear section, the catamaran hulls by virtue of their relatively slim body offer less surface area to wave impact allowing a softer entry after extreme pitching or after becoming airborne off the crest of a wave. This will reduce vertical accelerations and impact loadings when the hull impacts the water. Furthermore, the catamaran hulls offer greater initial transverse stability and resistance to wave induced heel in the first instance, and as such the incorporation of catamaran hulls for the main support and planing surface provides for a much softer ride with lower vertical accelerations thereby increasing crew I passenger endurance and safety.

In addition to the foregoing, the hull according to the invention enables a much longer than typically achievable waterline length. There are a number of seakeeping advantages derived from the longer waterline length that are achieved without the

- 3corresponding resistance penalty of a vessel having such waterline length. This is due in part to the fact that the forward monohull section is designed to run mostly dry and clear of the water with very little wetted area at high speeds, with the forward monohull section only coming into effect when cutting through waves or at slow speeds. Finally, the hull design according to the invention allows for greater load variations as the monohull forward section supports a significant percentage of the vessels overall displacement, thereby preventing excessive hull sinkage. On a pure catamaran hull design, hull sinkage results in a significantly reduced bridge deck clearance when heavily loaded. This can have a corresponding negative impact on seakeeping, causing slamming to occur on the bridge deck. This loading constraint is significantly minimised by the hull according to the present invention.

In one embodiment of the invention there is provided a boat hull in which the side hull sections are asymmetrical. This is seen as particularly advantageous as the asymmetrical side hull sections may be blended practically seamlessly into the monohull forward section. Furthermore, asymmetrical side hull sections will facilitate the integration of a hydrofoil into the overall hull design.

In one embodiment of the invention there is provided a boat hull in which the side hull sections are semi-symmetrical. Alternatively, the side hull sections are symmetrical.

In one embodiment of the invention there is provided a boat hull in which the centre hull is a V-shaped hull. The V-shaped hull is seen as particularly suitable for the centre hull for a number of reasons. First of all, the V-shaped hull will be effective in breaking through the waves as the hull re-enters the water after the hull becomes airborne. Secondly, with the V-shaped hull, by virtue of the steep deadrise of the hull shape, the buoyancy of the hull will rise exponentially as the hull is immersed. This configuration will support increases in displacement and prevent excessive hull sinkage, resulting in improved seakeeping performance.

In one embodiment of the invention there is provided a boat hull in which the centre hull is a wave-piercing shaped hull. The wave-piercing hull shape is deemed particularly suitable for those craft with an LOA of the order of 21 metres or longer as the wavepiercing design will offer lower accelerations and will work well for many wave heights for

-4this size of craft. However, on smaller variants, i.e. those craft with an LOA of less than 21 metres, a more traditional deep V-shaped hull with greater reserve buoyancy may be preferable.

In one embodiment of the invention there is provided a boat hull in which the underside of the deck intermediate the pair of side hull sections is stepped from front to back. This is seen as a particularly useful embodiment of the present invention. By having at least one step on the underside of the deck intermediate the pair of side hull sections, the frictional drag from spray impacting the underside of the deck emanating from the forward monohull section will be reduced.

In one embodiment of the invention there is provided a boat hull in which there are provided at least two steps in the underside of the deck intermediate the pair of side hull sections.

In one embodiment of the invention there is provided a boat hull in which the underside of the centre hull section is stepped from front to back. By having a transverse step in the underside of the centre hull section, this will help to reduce wetted area and resistance at speed.

In one embodiment of the invention there is provided a boat hull in which the undersides of the side hull sections are stepped from front to back. Ideally, there are provided a plurality of steps in the hull sections. By having transverse steps in the undersides of the side hulls, the wetted area of these hulls will be reduced and there will be less drag when the hull is operating at speed. This configuration is deemed particularly suitable when surface drive propulsion is used and higher speeds are required.

In one embodiment of the invention there is provided a boat hull in which each of the side hull sections is provided with a longitudinal step extending along the side of the side hull facing the other side hull. By providing a longitudinal step extending along the side of the side hull facing the other side hull, the wetted area along the inner catamaran hull sides will be reduced, thereby reducing wetted surface drag and the effects of the wake interaction emanating from the monohull transom at certain speeds.

- 5In one embodiment of the invention there is provided a boat hull in which each of the side hull sections is provided with a plurality of longitudinal steps extending along the side of the side hull facing the other side hull.

In one embodiment of the invention there is provided a boat hull in which there is provided an air passageway extending through the deck from a position above the deck to a position below the deck intermediate the pair of side hull sections. By having an air passageway, this will prevent a vacuum from being created in the space behind the forward monohull section and the rear catamaran hull sections during operation which would increase drag and reduce performance.

In one embodiment of the invention there is provided a boat hull in which the monohull forward section is between 0.30 and 0.55 times the length overall (LOA) of the boat hull. Preferably, the monohull forward section is between 0.4 and 0.5 times the LOA of the boat hull. More preferably, the monohull forward section is between 0.43 and 0.48 of the overall length of the boat hull.

In one embodiment of the invention there is provided a boat hull in which the catamaran rear section is between 0.4 and 0.8 times the LOA of the boat hull. Preferably, the catamaran rear section is between 0.5 and 0.7 times the LOA of the boat hull. More preferably, the catamaran sections represent, measured from the transom of the catamaran hulls to the intersection of the monohull transom, between 0.5 to 0.6 of the overall length (LOA). Ideally, the catamaran hull sections are each between 0.53 to 0.58 of the overall length (LOA), measured from the centre of the transom of the boat hull at deck level to the bow at deck level (not including any reverse rake on the bow). The catamaran hulls could conceivably be longer than 58% of the LOA, but if the catamaran hulls are less than 50% of the overall length, longitudinal instability could set in (i.e. porpoising) at very high speeds and resistance would be increased.

In one embodiment of the invention there is provided a boat hull in which there is provided at least one hydrofoil attached to the underside of the hull.

In one embodiment of the invention there is provided a boat hull in which there is provided a central hydrofoil attached to the underside of the hull located approximately adjacent the longitudinal centre of gravity (LCG) of the hull. This is seen as a useful embodiment of the invention. A hydrofoil located on the underside of the hull positioned at or about the LCG, will lift the hull thereby reducing wetted area and drag.

In one embodiment of the invention there is provided a hybrid boat hull in which there is provided a stern-mounted hydrofoil.

In one embodiment of the invention there is provided a hybrid boat hull in which the bow of the centre hull section is provided with a reverse-sheer configuration.

In one embodiment of the invention there is provided a hybrid boat hull in which the bow of the centre hull section is provided with a plumb configuration.

In one embodiment of the invention there is provided a hybrid boat hull in which the bow of the centre hull section is provided with a swept back configuration.

In one embodiment of the invention there is provided a hybrid boat hull in which there is provided a spray rail on the outer face of each of the side hull sections.

In one embodiment of the invention there is provided a hybrid boat hull in which there is provided a spray rail on each side of the centre hull section. The spray rails reduce wetted area and add lift. However, there is a fine balance between lift and harshness of the ride. Too many spray rails will increase lift and ultimately speed but do so at the expense of softness of ride. Preferably, there will be provided two spray rails on each side of the hull, one on each side of the monohull section and one on the outer side of the catamaran hull section.

Detailed Description of the Invention

The invention will now be more clearly understood from the following description of some embodiments thereof given by way of example only with reference to the accompanying drawings, in which:- 7Figures 1(a) to 1(h) inclusive are diagrammatic representations of hulls known in the art;

Figure 2 is a diagrammatic representation of a hybrid boat hull according to the invention;

Figure 3 is a perspective view of a first embodiment of hybrid boat hull according to the invention;

Figure 4 is a rendered view of the hybrid boat hull shown in Figure 3;

Figure 5 is a perspective view of a second embodiment of hybrid boat hull according to the invention;

Figure 6 is a rendered view of a third embodiment of hybrid boat hull similar to that shown in Figure 6;

Figure 7 is a perspective view of a fourth embodiment of hybrid boat hull according to the invention;

Figure 8 is a side partially cross-sectional view of a fifth embodiment of hybrid boat hull according to the invention;

Figure 9 is a bottom view of the hybrid boat hull shown in Figure 8;

Figure 10 is a perspective view of a sixth embodiment of hybrid boat hull according to the invention;

Figure 11 is a rendered view of the hybrid boat hull shown in Figure 10;

Figure 12 is a rendered view of a seventh embodiment of hybrid boat hull according to the invention;

- 8Figure 13 is a rendered view of a eighth embodiment of hybrid boat hull according to the invention;

Figure 14 is a side view of an ninth embodiment of hybrid boat hull according to the invention;

Figure 15 is a bottom view of the hybrid boat hull as shown in Figure 3 illustrating the immersed body portions when the boat hull is at rest; and

Figure 16 is a bottom view of the hybrid boat hull as shown in Figure 3 illustrating the immersed body portions when the boat hull is at speed, fully planing.

Referring to Figures 1(a) to 1(h) inclusive, there is shown a plurality of diagrammatic representations of hull types known in the art, including monohull, catamaran and trimaran hull types. The portions of the hulls that are immersed in water when at rest and supporting the weight of the vessel (known as the waterplane area) are shown in hatched outline on each of the individual hull shapes.

Monohulls, as illustrated in Figures 1(a) and 1(b), are best described as a single hull form supporting the entire weight of the vessel. The monohull may have a round bilge shape hull form, a V-shaped hull form (as illustrated in Figure 1(a)) or a wave-piercing hull form (as illustrated in Figure 1(b)). The wave-piercing hull form comprises a very slim hull body. There are a number of variations of these basic monohull hull forms including for example, steep or shallow deadrise configurations of V-shaped hull forms. An angle of 20 degrees or greater would be considered to be a steep (also known as “deep v”) deadrise.

Catamarans, as illustrated in Figures 1(c) to 1(f) inclusive, are best described as a pair of connected hulls each of which supports the vessel weight equally. The pair of side hulls are connected together by a bridge deck therebetween. The catamaran hull shapes come in a range of forms including asymmetrical hull form (as illustrated in Figure 1(c)), symmetrical hull form (as illustrated in Figure 1(d)), wave-piercing hull form (as illustrated in Figure 1(e)), which in itself is a particular type of symmetrical hull form, and small

- 9waterplane area twin hull (SWATH) form. Again, there are a number of variations on these basic catamaran hull types.

Trimarans, as illustrated in Figures 1(g) and 1(h), are best described as a main central hull supporting most of the weight of the vessel with two outer hulls outboard of the main central hull each partially supporting the remainder of the weight of the vessel. The two outer hulls are either fully separate from the main hull with outriggers connecting the outer hulls to the central hull (as illustrated in Figure 1(g)) or the two outer hulls are partially contained within the main hull body with portions of the outer hulls extending beyond the normal footprint of the main hull (as illustrated in Figure 1(h)) with integral wings or the like connecting the outer hulls to the central hull.

Referring to Figure 2, there is shown the hull outline from below of the hybrid hull according to the present invention, indicated generally by the reference numeral 100, with those portions of the hull that are immersed in water when at rest and supporting the weight of the vessel (the waterplane area) shown in hatched outline. It can be seen from the waterplane area that the hull comprises a forward monohull section 101 and a rear catamaran section 103. The rear catamaran section comprises a pair of side hull sections 105, 107 laterally spaced apart from each other and the front monohull section comprises a centre hull section 109 located between and predominantly forward of the pair of side hull sections 105, 107. A transom 110 of the front monohull sections centre hull section is substantially adjacent to the bow of each of the side hull sections. The pair of side hull sections 105, 107 are connected to each other and the centre hull section by a deck 111.

The hybrid hull configuration shown in Figure 2 is unique and significantly different in concept to the existing hull designs known in the art and as illustrated in Figures 1(a) to 1(h). The difference may be more clearly understood by comparison of the waterplane area of the hull shown in Figure 2 with the waterplane areas of the different hulls of Figures 1(a) to 1(h). The hybrid hull configuration as shown in Figure 2 cannot be described within any of the above main categories of monohull, catamaran or trimaran. The closest category is trimaran in that three hulls support the weight of the vessel. However two fundamental differences exist between the trimaran and the hybrid hull configuration according to the invention. First of all, the three hulls of the present

- 10invention are wholly contained within the main body of the vessel. Viewed from directly above or directly below, only a single outline body is visible and the three hulls function in a different hydrodynamic manor than the conventional trimaran concept. Secondly, the two outer hulls of the hybrid hull configuration shown in Figure 2 support most of the weight of the vessel with the centre hull only partially, yet significantly, supporting a lesser portion of the weight of the vessel. The hull design according to the invention can therefore be described as a single body, triple lifting surface (TLS) catamaran I mono hull hybrid.

Referring to Figures 3 and 4, there are shown a perspective view and a rendered view respectively of the first embodiment of hybrid boat hull 100. As with the embodiment shown in Figure 2, the hybrid boat hull comprises a monohull front section 101 and a catamaran rear section 103. The catamaran rear section 103 comprises a pair of side hull sections 105, 107 and the monohull front section 101 comprises a centre hull section 109 located intermediate and predominantly forward of the side hull sections. A deck 111 connects the pair of side hull sections 105, 107 and the centre hull section 109 together. The centre hull section 109 comprises a keel 113 and a spray rail 115 (only one of which is shown) on either side of the centre hull section. There is further provided a transition piece 117 at the intersection of the centre hull section and the side hull sections. Each of the side hull sections 105, 107 further comprises a spray rail 119, a main chine 121 and a keel 123. A tunnel 125 is formed behind the centre hull section 109 and between the two side hull sections 105, 107 and is bounded on three sides by the underside 127 of the deck and the inner side face 129 of each of the pair of the side hulls 105, 107. The side hull sections 105, 107 have an aft planing surface with a deadrise in the order of 20- 24 degrees however depending on the operational requirement a lower deadrise can be utilised.

The centre hull section is described as being located predominantly forward of the pair of side hull sections with a transom of the centre hull section located adjacent to, but typically rearward of, the bow of each of the side hull sections. By predominantly forward, what is meant is that the majority of the length of the centre hull section is located forward of the bow of the side hull sections. There may and indeed preferably there will be a degree of overlap between the centre hull section and the side hull sections in a fore and aft direction however it is envisaged that the degree of overlap (i.e.

- 11 the portion of the centre hull section from the transom forward to the point on the centre hull section in line with the bows of the side hull sections) would be less than or equal to 25% of the overall length of the centre hull section, i.e. by predominantly forward, we mean that greater than or equal to 75% of the centre hull section is forward of the bows of the side hull sections.

Referring to Figure 5, there is shown a perspective view of a second embodiment of hybrid boat hull according to the invention, indicated generally by the reference numeral 200, where like parts have been given the same reference numeral as before. The hybrid boat hull 200 is practically identical to the boat hull 100 with the exception that there is provided a main hydrofoil 201 located adjacent to the longitudinal centre of gravity (LCG) of the hull and a pair of stern foils 203, 205, one at the stern of each of the pair of side hull sections 105, 107 adjacent the keel of the side hull sections.

Referring to Figure 6, there is shown a rendered view of a third embodiment of hybrid boat hull according to the invention, indicated generally by the reference numeral 300, where like parts have been given the same reference numeral as before. The hybrid boat hull 300 is practically identical to the boat hull 200 shown in Figure 5 with the exception that the pair of stern foils 303, 305, at the stern of each of the pair of side hull sections 105, 107 adjacent the keel of the side hull sections are substantially L-shaped.

Referring to Figure 7, there is shown a perspective view of a fourth embodiment of hybrid boat hull according to the invention, indicated generally by the reference numeral 400 and where like parts have been given the same reference numeral as before. The hybrid boat hull 400 differs from the hybrid boat hull 100 illustrated in Figures 3 and 4 in that the hybrid boat hull 400 incorporates a number of measures to reduce wetted surface area and a number of measures to manage the effects of the wake emanating from the centre hull portion 109. Each of the side hull sections 105, 107 is provided with a pair of transverse steps 401 so that the underside of the side hull sections are stepped from front to back. This helps to reduce wetted surface area at high speed and is particularly desirable for surface drive propulsion configurations.

In addition to the side hulls having a stepped configuration, the underside 127 of the deck 111 in the tunnel 125 is also provided with a plurality of transverse steps 403 so

- 12that the underside 127 of the deck 111 is stepped from front to back. The inner side face 129 of each of the pair of the side hulls 105, 107 are also provided with longitudinal steps 405. The transverse steps 403 on the underside of the deck 111 and the longitudinal steps 405 on the inner side faces 129 of each of the side hulls 105, 107 are provided to reduce the wetter area and reduce drag caused by the wake emanating from the centre hull portion.

Referring now to Figures 8 and 9, there are shown views of a fifth embodiment of hybrid boat hull according to the invention, indicated generally by the reference numeral 500 and where like parts have been given the same reference numeral as before. The hybrid boat hull 500 is practically identical to the hybrid boat hull 400 illustrated in Figure 7 with the exception that the centre hull section 109 is also provided with a transverse step 501 so that it is stepped from front to back. This will help to reduce wetted surface area and drag when the vessel is at speed.

Referring now to Figures 10 and 11, there are shown views of a sixth embodiment of hybrid boat hull according to the invention, indicated generally by the reference numeral 600 and where like parts have been given the same reference numeral as before. The hybrid boat hull 600 is practically identical to the hybrid boat hull 500 illustrated in Figures 8 and 9 with the exception that the underside 127 of the deck 111 is not stepped.

Referring now to Figure 12, there is shown a rendered view of a seventh embodiment of hybrid boat hull according to the invention, indicated generally by the reference numeral 700 and where like parts have been given the same reference numeral as before. The hybrid boat hull 700 is practically identical to the hybrid boat hull 500 illustrated in Figures 8 and 9 with the exception that there is provided a third, additional transverse step 701 in addition to the pair of transverse steps 401 on the underside of each of the side hull sections 105, 107.

Referring now to Figure 13, there is shown a rendered view of an eighth embodiment of hybrid boat hull according to the invention, indicated generally by the reference numeral 800 and where like parts have been given the same reference numeral as before. The hybrid boat hull 800 is practically identical to the hybrid boat hull 100 illustrated in

- 13Figures 3 and 4 with the exception that there is provided four spray rails 115 on each side of the hull, two of which are on either side of the centre hull section (four spray rails in total on the centre hull section) and two of which are on the outer side of each of the side hull section 105, 107.

Referring now to Figure 14, there is shown a side view of a ninth embodiment of hybrid boat hull according to the invention, indicated generally by the reference numeral 900 and where like parts have been given the same reference numeral as before. The hybrid boat hull 900 is provided with an air passageway 901 for delivering air from above the deck 111 to a position below the deck 111 in the tunnel 125 behind the centre hull section and between the underside of the deck 111 and the two side hull sections 105, 107. The ambient air provided in this way will prevent a vacuum forming in the tunnel at certain speeds and sea states where the forward intersection between the monohull and catamaran hulls can become closed, resulting in a vacuum forming that causes a suction effect increasing wetted area and resistance. The air passageway could and it is envisaged may be provided with all of the embodiments shown. The air inlet 903 at the top deck is provided in the forward section of the deck 111 well above the waterline will preferably be provided with a cowling 905 to prevent water ingress or blockages occurring.

Referring to Figures 15 and 16, there is shown the waterplane of the first embodiment of hybrid boat hull 100 when the vessel is at rest (Figure 15) and when the vessel is at speed, fully planing (Figure 16). Importantly, it can be seen that at rest, the centre hull section 109 bears a substantial portion of the load however when planing, the centre hull section is practically fully out of the water and only a small portion of the centre hull section is in the water. This reduces drag and permits improved top speeds.

Various modifications could be made to the embodiments hereinbefore described without departing from the spirit of the present invention or the scope of the appended claims. The principle inventive features are for a hull encompassing asymmetrical or semi-symmetrical catamaran hulls transitioning seamlessly, approximately forward of amidships into a V or wave-piercing monohull creating a triple lifting surface (TLS) ‘trimaran type’ hull form combined within a single body (i.e. not utilizing outriggers or appendages to integrate the three hulls). Depending on whether a wave-piercing bow is

- 14utilized or a more conventional bow, preferably, the monohull section represents approximately 30-47% of the length overall (LOA) of the hybrid boat hull.

The hull design is suitable for a range of operational applications, although primarily designed for high speed smaller vessel below 24m, it can be adapted for use in larger vessel applications, it is also suitable for vessels operating at displacement speeds and transitional speeds. Typical applications include: (i) High speed patrol vessels; (ii) High speed Naval craft; (iii) Recreational craft; (iv) Search and Rescue (S.A.R.) craft; (v) Workboats; as well as (vi) Fast Ferries and passenger vessels. Throughout the specification, reference is made to both boat hull and ship hull and these have been used interchangeably. For the avoidance of doubt, when reference is made to a hybrid boat hull, this is also intended to refer to a hybrid ship hull.

In addition to the foregoing, the hybrid hull design is suitable for various propulsion systems determined by design size and speed range including: (i) Waterjet; (ii) Integrated Propulsion System (IPS), inboard or outboard (l/OB); (iii) Surface drive; and (iv) Conventional shaft drive. Surface drive or waterjet are the principle means of propulsion in very high speed applications (equal to or greater than 40 Knots (kts)) where the LOA exceeds approximately 12m. Advantageously, the hybrid boat hull according to the invention offers superior seakeeping abilities in high sea states and reduced resistance. The hull form provides very high levels of dynamic stability and is capable in transverse stepped version, depending on size, of stable speeds up to 100kts or greater.

In this specification the terms “comprise, comprises, comprised and comprising” and the terms “include, includes, included and including” are all deemed totally interchangeable and should be afforded the widest possible interpretation.

The invention is not limited to the embodiment hereinbefore described but may be varied in both construction and detail within the scope of the appended claims.

Claims

Claims:

(1) A hybrid boat hull comprising a catamaran rear section and a monohull forward section, a deck bridging the catamaran rear section and the monohull forward section, the catamaran rear section comprising a pair of side hull sections laterally spaced from each other, the monohull forward section comprising a centre hull section located between the pair of side hull sections and in which the centre hull section is located predominantly forward of the pair of side hull sections with a transom of the centre hull section located adjacent to the bow of each of the side hull sections.
(2) A boat hull as claimed in claim 1 in which the side hull sections are asymmetrical.
(3) A boat hull as claimed in claim 1 in which the side hull sections are semisymmetrical.
(4) A boat hull as claimed in any preceding claim in which the centre hull is a Vshaped hull.
(5) A boat hull as claimed in any of claims 1 to 3 in which the centre hull is a wavepiercing-shaped hull.
(6) A boat hull as claimed in any preceding claim in which the underside of the deck intermediate the pair of side hull sections is stepped from front to back.
(7) A boat hull as claimed in claim 6 in which there are provided at least two steps in the underside of the deck intermediate the pair of side hull sections.
(8) A boat hull as claimed in any preceding claim in which the underside of the centre hull section is stepped from front to back.
(9) A boat hull as claimed in any preceding claim in which the underside of the side hull sections are stepped from front to back.
(10) A boat hull as claimed in claim 9 in which there are provided a plurality of steps in the hull sections.
(11) A boat hull as claimed in any preceding claim in which each of the side hull sections is provided with a longitudinal step extending along the side of the side hull facing the other side hull.
(12) A boat hull as claimed in claim 11 in which each of the side hull sections is provided with a plurality of longitudinal steps extending along the side of the side hull facing the other side hull.
(13) A boat hull as claimed in any preceding claim in which there is provided an air passageway extending through the deck from a position above the deck to a position below the deck intermediate the pair of side hull sections.
(14) A boat hull as claimed in any preceding claim in which the monohull forward section is between 0.3 and 0.47 times the length overall (LOA) of the boat hull.
(15) A boat hull as claimed in any preceding claim in which the catamaran rear section is between 0.5 and 0.7 times the LOA of the boat hull.
(16) A boat hull as claimed in claims 1 to 13 in which the catamaran rear section is between 0.53 and 0.58 times the LOA of the boat hull.
(17) A boat hull as claimed in claim 16 in which the monohull forward section is between 0.43 and 0.48 times the LOA of the boat hull.
(18) A boat hull as claimed in any preceding claim in which there is provided at least one hydrofoil attached to the underside of the hull.
(19) A boat hull as claimed in claim 18 in which there is provided a central hydrofoil attached to the underside of the hull located adjacent the longitudinal centre of gravity of the hull.
(20) A hybrid boat hull as claimed in claim 19 in which there is provided a sternmounted hydrofoil.
(21) A hybrid boat hull as claimed in any preceding claim in which the bow of the centre hull section is provided with a reverse-sheer configuration.
(22) A hybrid boat hull as claimed in any preceding claim in which the bow of the centre hull section is provided with a plumb configuration.
(23) A hybrid boat hull as claimed in any preceding claim in which the bow of the centre hull section is provided with a swept back configuration.
(24) A hybrid boat hull as claimed in any preceding claim in which there is provided a spray rail on the outer face of each of the side hull sections.
(25) A hybrid boat hull as claimed in any preceding claim in which there is provided a spray rail on each side of the centre hull section.