WO2005118385A1

WO2005118385A1 - A marine hull

Info

Publication number: WO2005118385A1
Application number: PCT/AU2005/000791
Authority: WO
Inventors: Christopher Hodges
Original assignee: J & C Hodges Nominees Pty Ltd
Priority date: 2004-06-03
Filing date: 2005-06-03
Publication date: 2005-12-15

Abstract

A marine hull has a lip (6) protruding downwardly from the hull running surface (2) and extending transversely along the running surface (2). The lip leading face is located a distance of between 0.15 times the longitudinal water line length (LWL) to 0.65 times the LWL forward of the hull transom (4).

Description

A MARINE HULL Field of the Invention The present invention relates to marine hulls and particularly relates to₅ although is not limited to, planing, power driven marine hulls. Background of the Invention Power driven planing marine hulls typically require a large amount of power and corresponding high speed to bring the hull onto plane and continued high throttle settings and speed to maintain the plane. Planing hulls typically ride with the bow elevated high above the water whilst getting on the plane. The bow may also sit relatively high whilst on the plane, although at a lower position to that during transition getting on the plane. Travelling with the bow high results in some lateral hull instability, inhibiting the ability to carry passengers or cargo comfortably, and also inhibits driver vision. Planing hulls that are heavily loaded often have difficulty in obtaining, or are unable to obtain, a planing attitude. Many semi-planing and displacement type hulls also experience difficulty in carrying large loads, with the hull riding low in the water. To improve the trim of the hull, lifting the stern and lowering the bow, trim tabs are known to be mounted behind the transom, or under the aft sections, of a planing hull and adjusted mechanically in an attempt to better trim the hull to a more horizontal orientation. Trim tabs operate by deflecting water downward after having left the running surface behind the transom. The use of retractable blades mounted on the transom of a planing hull has also been proposed to adjust the trim of the marine hull by generating lift on the rear portions of the hull immediately forward of the retractable blade. The retractable blades, when deployed into the water flowpath beneath the transom, act to slow/dam the water flow in front of the blade thereby increasing the water pressure acting on the hull forward of the blade. The increased lift generated on the rear portions of the hull act to lift the aft end of the hull, assisting planing and semi-planing hulls getting onto and maintaining the plane. Whilst trim tabs and transom mounted blades act to lift the stern of the vessel to improve trim, they do not significantly lift the overall hull, and as such are often insufficient to enable planing hulls with large loads to obtain a planing attitude. Object of the Invention It is the object of the present invention to overcome or substantially ameliorate the above disadvantage. Summary of the Invention There is disclosed herein a marine hull having: a longitudinally and vertically extending central plane, a static longitudinal water line length (LWL) defined in said central plane, a transom, an underside running surface terminating in a trailing edge at said transom; and a lip protruding downwardly from said running surface and extending transversely along said running surface, said lip having a leading face; wherein said lip leading face is located a distance of between 0.15 times said LWL to 0.65 times said LWL forward of said transom. The lip leading face may be located a distance of between 0.35 times said LWL to 0.65 times said LWL forward of said transom, or more preferably 0.45 and 0.65 times said LWL forward of said transom. Typically, in any reference plane parallel to said central plane and intersecting said lip; said lip leading face has a leading face profile defined by the intersection of said lip leading face and said reference plane; said running surface has a local buttock line defined by the intersection of said reference plane and said running surface immediately forward of said lip leading face, said leading face profile meeting said local buttock line at a juncture point; and said leading face profile has a depth measured from said juncture point in a depth direction peφendicular to said local buttock line and lying in said reference plane; further wherein, for at least substantially all said reference planes located across at least a substantial transverse extent of said lip, said leading face profile is inclined by less than 135 degrees with respect to said local buttock line at at least substantially all points along at least a length of said leading face profile which extends across a substantial portion of said depth thereof. Preferably, said leading face profile is inclined by less than 135 degrees with respect to said local buttock line at at least substantially all points along at least said length of said leading face profile for all said reference planes located across the entire transverse extent of said lip. Typically, said substantial portion of said depth of each said leading face profile extends across at least the lower half of said depth. Said lip leading face profile is preferably substantially planar. Said lip leading face profile may be inclined with respect to said local buttock line by approximately 90 degrees for at least substantially all said reference planes located across at least a substantial transverse extent of said lip. Said lip leading face profile may be inclined with respect to said local buttock line by approximately 90 degrees for all said reference planes located across the entire transverse extent of said lip. Alternatively, said lip leading face profile may be concave for at least substantially all said reference planes located across at least a substantial transverse extent of said lip. Said lip may be integrally formed with said hull. Alternatively, said lip may be formed separate to and secured to said hull. The lip may extend across the entire transverse extent of said running surface. Alternatively, said lip may be formed in segments, each extending along part of the transverse extent of running surface. Typically two lip segments will be provided, one located on each side of said central plane. Typically, said depth of said leading face profile is at least 8 mm for at least substantially all said reference planes located across at least a substantial transverse extent of said lip. Typically, said depth of said leading face profile is less than 100 mm, more typically less than 60 mm. Typically, said leading face profile has a transverse width of at least 1/3 times the static water line width (WLW) of said hull. When said lip is formed of two said lip segments, the transverse width of the leading face profile of each said lip segment may be at least 1/6 times said hull WLW. Typically said leading face profile has an aspect ratio, defined by the transverse width of said lip leading face profile divided by the depth of said leading face profile, of at least 15, preferably at least 30. The hull may have a gas outlet provided in said running surface, adjacent to and aft of said lip, said gas outlet communicating with a gas supply. Alternatively, the gas outlet may be provided in a trailing face of said lip. Said lip leading face may transversely extend substantially perpendicular to said central plane, or may extend at an acute angle to said central plane. Said lip leading face may be provided with one or more water inlets communicating with an engine cooling system. Said marine hull may further have a fransom lip protruding downwardly from said running surface and extending transversely along or adjacent to said frailing edge, said transom lip having a leading face. The transom lip leading face may be configured in any of the various manners defined above in relation to said lip. In another form, said marine hull further has a fransom lip extending transversely along or adjacent to said frailing edge, said fransom lip having a leading face and being displaceable between a refracted position about said frailing edge and an extended position protruding below said trailing edge. Again, the transom lip leading face may be configured in any of the various manners defined above in relation to said lip. When said marine hull has no transom lip, said lip leading face may be located a distance of between 0.15 to 0.35 times said LWL forward of said fransom. There is further disclosed herein a marine hull having: a longitudinally and vertically extending central plane, a transom, a static longitudinal water line length (LWL) defined in said central plane; an underside running surface terminating in a frailing edge at said fransom; and a lip extending transversely along said running surface, said lip having a leading face and being displaceable between a retracted position and an extended position protruding below said running surface; wherein said lip leading face is located a distance of between 0.15 times said LWL to 0.65 times said LWL forward of said fransom when in said extended portion. The lip leading face may be located a distance of between 0.35 times said LWL to 0.65 times said LWL forward of said transom, or more preferably 0.45 and 0.65 times said LWL forward of said transom. Typically, in any reference plane parallel to said central plane and intersecting said lip: said lip leading face has a leading face profile defined by the intersection of said lip leading face and said reference plane; said running surface has a local buttock line defined by the intersection of said reference plane and said running surface immediately forward of said lip leading face, said leading face profile meeting said local buttock line, or a linear extension thereof, at a juncture point when said lip is in said extended position; and said leading face profile has a depth, when said lip is in said extended position, measured from said junction point in a depth direction perpendicular to said local buttock line and lying in said reference plane; further wherein, for at least substantially all said reference planes located across at least a substantial transverse extent of said lip, said leading face profile is inclined, when said lip is in said extended position, by less than 135 degrees with respect to said local buttock line at at least substantially all points along at least a length of said leading face profile which extends across a substantial portion of said depth thereof. Preferably, said leading face profile is inclined, when said lip is in said extended position, by less than 135 degrees with respect to said local buttock line at at least substantially all points along at least said length of said leading face profile for all said reference planes located across the entire transverse extent of said lip. Typically, said substantial portion of said depth of each said leading face profile extends across at least the lower half of said depth. Said lip leading face profile is preferably substantially planar. Said lip leading face profile may be inclined, when said lip is in said extended position, with respect to said local buttock line by approximately 90 degrees for at least substantially all said reference planes located across at least a substantial fransverse extent of said lip. Said lip leading face profile may be inclined, when said lip is in said extended position, with respect to said local buttock line by approximately 90 degrees for all said reference planes located across the entire fransverse extent of said lip. Alternatively, said lip leading face profile may be concave for at least substantially all said reference planes located across at least a substantial fransverse extent of said lip. The lip may extend across the entire fransverse extent at said running surface. Alternatively, said lip may be formed in segments, each extending along part of the fransverse extent of said running surface. Typically two lip segments will be provided, one location on each side of said central plane. Typically, said depth of said leading face profile is at least 8 mm for at least substantially all said reference planes located across at least a substantial fransverse extent of said lip. Typically, said depth of said leading face profile is less than 100 mm, more typically less than 60 mm. Typically, said leading face profile has a transverse width of at least 1/3 times the static water line width (WLW) of said hull. When said lip is formed of two said lip segments, the fransverse width of the. leading face profile of each said lip segment may be at least 1/6 times said hull WLW. Typically said leading face profile has an aspect ratio, defined by the transverse width of said lip leading face profile divided by the depth of said leading face profile, of at least 15, preferably at least 30. Said displaceable lip may be linearly displaceable between said refracted and extended positions. Alternatively, said displaceable lip may be pivotally displaceable between said retracted and extended positions. Said lip leading face may transversely extend substantially perpendicular to said central plane, or may extend at an acute angle to said central plane. Said lip leading face may be provided with one or more water inlets communicating with an engine cooling system. Said marine hull may further have a fransom lip protruding downwardly from said running surface and extending fransversely along or adjacent to said trailing edge, said fransom lip having a leading face. The fransom lip leading face may be configured in any of the various manners

, defined above in relation to said lip. In another form, said marine hull further has a transom lip extending transversely along or adjacent to said frailing edge, said fransom lip having a leading face and being displaceable between a refracted position about said frailing edge and an extended position protruding below said frailing edge. Again, the transom lip lending face may be configured in any of the various manners^' defined above in relation to said lip. When said marine hull has no fransom lip, said lip leading face may be located a distance of between 0.15 to 0.35 times said LWL forward of said transom. Said hull may be a planing type hull. Alternatively, said hull may be a displacement type hull. Brief Description of the Drawings Preferred forms of the present invention will now be described by way of example with reference to the accompanying drawings wherein: Figure 1 is a side elevation view of a marine hull with a midships lip. Figure 2 is an inverse plan view of the marine hull of Figure 1. Figure 3 is a side elevation view of a marine hull having an alternate midships lip. Figure 4 is an inverse plan view of the marine hull of Figure 3. Figure 5 is a side elevation view of the marine hull having another alternate midships lip. Figure 6 is an inverse plan view of the marine hull of Figure 5. Figures 7 through 11 are each side elevation cross sectional views of various midships lip configurations. Figure 12 is a side elevation view of a marine hull having a stepped running surface and midships lip. Figure 13 is an inverse plan view of the marine hull of Figure 12. Figures 14 through 16 are each side elevation cross sectional views of various midships lip configurations on stepped hulls. Figures 17 through 19 are each side elevation cross sectional views of various midships lip configuration vented by a gas outlet. Figure 20 is a perspective view of a midships lip incorporating a water inlet. Figure 21 is a side elevation view of the lip of Figure 20. Figure 22 is a perspective view of an alternate midships lip incorporating a water inlet. Figure 23 is a side elevation cross sectional view of a linearly displaceable midships lip. Figure 24 is a side elevation cross sectional view of a linearly displaceable midships lip on a stepped hull. Figure 25 is a side elevation cross sectional view of a marine hull having an alternate linearly displaceable midships lip. Figure 26 is a side elevation cross sectional view of a rotatably displaceable midships lip. Figures 27 through 31 depicts various configurations of fixed transom lips. Figure 32 is a side elevation cross sectional view of the aft section of a marine hull having a linearly displaceable transom lip in an extended position. Figure 33 is a side elevation cross sectional view of the marine hull aft section of Figure 32 with the linearly displaceable fransom lip in a refracted position. Figure 34 is a side elevation cross sectional view of the aft section of a marine hull with an alternate linearly displaceable fransom lip. Figure 35 is a cross sectional side elevation view of the aft section of a marine hull with another alternate linearly displaceable fransom lip. Figure 36 is a side elevation view of the aft section of a marine hull having a rotatably displaceable fransom lip. Detailed Description of the Preferred Embodiments Referring to Figures 1 and 2 of the accompanying drawings, a marine hull 1 has an underside running surface 2 terminating in a frailing edge 3 forming the junction between the rumiing surface 2 and the transom 4 of the hull 1. The hull 1 has a static longitudinal water line length (LWL), being the longitudinal length of the hull at the static water line W. The LWL is measured along the longitudinally and vertically extending central plane C of the hull 1. The hull 1 also has a static water line width (WLW), being the maximum fransverse width of the hull at the static water line W, measured perpendicular to the central plane C. The hull has a lip 6 protruding downwardly from the running surface 2 and extending transversely along the running surface 2. The lip 6 is typically in a generally midships location and is thus termed a midships lip 6. The leading face 7 of the midships •lip 6 is located anywhere between a position 0.15 times the LWL to 0.65 times the LWL forward of the fransom 4. Typically, the lip leading face will be located between 0.35 and 0.65 times the LWL forward of the fransom, and more typically between 0.45 times and 0.65 times the LWL forward of the fransom 4. Accordingly, the midships lip 6 will typically be located in the general vicinity of the hull's centre of gravity CG. Similar to the retractable fransom mounted blades discussed above, the midships lip leading face 7 acts to slow/dam the water flow passing over the running surface 2 in front of the midships lip 6, thereby increasing the water pressure acting on the hull running surface 2 forward of the midships lip 6. This increased water pressure acting forward of the midships lip 6 acts as lift under the hull 1, tending to lift the hull 1 out of the water, and for planing hulls, towards the planing condition. With the midships lip 6 typically being located in a generally midships location as described above, there is no significant moment created about the centre of gravity CG (or in fact the centre of pressure acting on the hull), such that the attitude of the hull 1 is not significantly affected. The midships lip 6 may be used in conjunction with a fransom lip 8 protruding downwardly from the running surface 2 and extending fransversely along or adjacent to the trailing edge 3 of the running surface 2. The leading face 9 of the transom lip 8 will act to slow/dam water flow in front of the transom lip 9, thereby generating increased lift on the rear portions of the hull 2 in the same manner as the known retractable fransom blades. The transom lip 8 is accordingly used to lift the aft end of the hull, thereby improving the trim of a planing hull or semi-planing hull, assisting the hull to get onto or maintain the plane. The midships lip 6 may extend across the entire lateral extent of the running surface 2, or alternatively may extend across a portion of the lateral extent of the running surface 2. hi the configuration depicted in Figures 1 and 2, the midships lip 6 extends across approximately two-thirds of the lateral extent of the running surface 2. Similarly, where a fransom lip is utilised, the fransom lip may extend across the entire frailing edge 3, as depicted in Figure 2, or may only extend across part of the trailing edge 3. The midships lip leading face 7 may fransversely extend substantially perpendicular to the central plane C, as depicted in Figure 2, or alternatively extend at an acute angle to the central plane C. Such a configuration is depicted in Figures 3 and 4 where the midships lip 6 is formed as two lip segments each having their leading face 7 inclined at an acute angle of approximately 80 degrees to the central plane C. In this embodiment, the transom lip 8' is also formed as lip segments on each opposing side of the central plane C. Referring to Figures 5 and 6, a marine hull 1 is depicted where the midships lip segments 6 are located aft of the centre of gravity CG such that lift generated as a result of the midships lip 6 will provide a pitching moment about the centre of gravity CG tending to raise the transom 4 of the hull 1 and lower the bow 5. In this configuration, the transom lips have been eliminated, with the midships lips 6 providing both overall lift to the bulk of the hull and also providing a pitching moment tending to lift the fransom 4. In this configuration where no transom lip is utilised, the lip leading face will typically be located between a position 0.15 times the LWL to 0.35 times the LWL forward of the fransom 4, although lips placed further forward, without a transom lip, are still envisaged. It is also envisaged that the midships lip 6 might be used in conjunction with fransom mounted trim tabs rather than a transom lip. The preferred configuration of the lip leading face 7 will now be described with reference to Figure 7 of the accompanying drawings. The configuration of the lip leading face 7 is best described in relation to the leading face profile 7' defined by the intersection of the lip leading face 7 and a cross sectional reference plane R. The cross sectional reference plane R is parallel to a longitudinally and vertically extending central plane C running along the centre line of the hull 1, as depicted in Figure 2. Such a lip leading face profile 7 is defined in any reference plane R which intersects the lip 6. The cross sectional reference plane R also defines a buttock line 2' where it intersects the running surface 2. The leading face profile T meets the buttock line 7' (or a linear extension thereof) at a juncture point 10. At any point L along the leading face profile 7' the leading face profile T is inclined by an angle with respect to the buttock line 2' immediately forward of the juncture point 10. The angular measurement is taken with respect to the buttock line 2' at a portion of the buttock line 2' immediately forward of the juncture point 10, here termed the local buttock line, as the buttock line 2' may be curved, in which case a tangent is taken at the local buttock line. The angle of inclination is less than 135 degrees at all points L along a length C of the leading face profile T which extends across a substantial portion of the depth D of the leading face profile. That is, the included angle of the leading face profile, at the points L, with respect to an imaginary continuation of the buttock line above the lip is more than 45 degrees. The lip leading face accordingly acts generally as a bluff face. The depth D is measured from the juncture point 10 in a depth direction which is peφendicular to the local buttock line 2' and lying in the reference plane R. Whilst the lip leading face profile 7' depicted in Figure 7, is inclined by less than 135 degrees at all points L along the length 1, it will be sufficient for the leading face profile 108' to meet this inclination condition for 'only substantially all points L along the length 1. The angular inclination condition described above should be met for at least substantially all reference planes R located across at least a substantial fransverse extent of the lip 6, and will most preferably be met for all reference planes R located across the entire transverse extent of the lip 6. The lip 6 will be most effective if the length 1 of the leading face profile T meeting the angular inclination condition described above extends across at least the lower half of the depth D of the leading face profile 7', as is the case with the lip leading face profile 7' depicted in Figure 7. The lip leading face 7 will typically have a protruding depth D of at least 8mm. The most suitable lip depth will be dependent upon the specific characteristics of the hull, and may be determined by trial and error. Lip leading face depths D of the order of 20mm may be suitable for larger hulls up to 50 feet (15.2m) in length. In general, the lip leading face depth D will usually be less than 60 mm for hulls up to 100 feet (30.4 m) in length, although depths up to 100 mm may be applicable to even larger hulls. The lip (or combination of lip segments) will fransversely extend across a significant width of the running surface 2, with the lip leading face 7 typically having a fransverse width of at least 1/3 times the WLW. If the lip 7 is formed of two lip segments (as per the configurations of Figures 1 to 6) each lip segment leading face will typically extend across at least 1/6 of the WLW. The aspect ratio of the lip leading face 7, defined as the ratio between the lip leading face transverse width and depth, will typically be greater than 15, and regularly greater than 30. Perhaps the simplest configuration of midships lip 6 is depicted in Figure 8. The midships lip 106 is formed as an elongate rectangular section affixed to the hull running surface 2. The lip leading face 107 is inclined with respect to the running surface 2 by approximately 90 degrees. The lip 106 may be formed of any suitable material, with plastics or composite materials such as fibreglass being particularly suitable. The lip may be bonded or fastened to the hull. In an alternative configuration depicted in Figure 9, the midships lip 206 has a tapered frailing edge so as to reduce turbulence in the water flow passing beyond the lip 206. In the configuration depicted in Figure 10 the lip 306 is integrally formed with the hull running surface 2. Figure 11 depicts a midships lip 406 where the lip leading face 407 is inclined by about 85 degrees with respect to the hull running surface 2. Referring to Figures 12 and 13, a midships lip may be applied to a hull 101 having a stepped running surface 102. The step 102' in such a stepped running surface 102 appears as a rearwardly facing lip having a frailing face rather than a leading face. With such a stepped running surface 102, a midships lip 6 may be located at or adjacent the running surface step 102'. Again, a transom lip 8 may also be employed. Specific configurations of lips suitable for stepped running surfaces 102 are depicted in Figures 14 to 16. In Figure 14, the lip 506 is formed as a plate secured to the frailing face of the step 102', with the midships lip leading face 507 protruding beneath the running surface 102 immediately forward of the step 102'. In the configuration of Figure 15, the midships lip 106 is formed as an elongate rectangular section (as per the lip 106 of Figure 8) secured to the running surface 102 immediately forward of the step 102'. Referring to Figure 16, the lip 606 is integrally formed with the hull running surface 102 immediately forward of the step 102'. Whilst the leading face of a midships lip will slow/dam the water flow in front of the lip, creating a water pressure increase forward of the lip, acceleration of the water flow over the rear of the lip may create a pressure decrease immediately aft of the lip. This waterflow acceleration results from the water attempting to fill the space directly behind the lip, if the lip does not have a tapered rear face as per that of, for example, Figure 9. To alleviate this potential reduction in pressure, the rear of the lip may be ventilated in the manner depicted in Figure 17. Specifically, a gas outlet 11 is provided in the running surface 2 adjacent to and aft of the lip 106. The gas outlet 11 may communicate with the atmosphere outside of the hull by way of a conduit 12. A plurality of small gas outlets 11 would typically be spaced across the transverse extent of the lip 106, rather than having a single elongate gas outlet, so as not to compromise the structure integrity of the hull. With the gas outlet 11 communicating with the atmosphere, any reduction in pressure aft of the lip frailing face 113, that would normally be created by acceleration of the water flow, will be offset by the introduction of air into the area below the running surface 2 aft of the lip trailing face 113 at atmospheric pressure. Rather than communicating the gas outlet 11 with the atmospheric air, the conduit 12 may alternatively be connected to the engine exhaust or some other supply of gas. In the configuration depicted in Figure 18, an alternate lip 706 to be used in conjunction with gas outlet 11 has an inclined frailing face 713 which assists in directing the gas passing through the gas outlet 11 aftwardly along the running surface 2 rather than directly downwardly. In the configuration depicted in Figure 19, the gas outlet 811 is incoφorated in the frailing face 813 of the midships lip 806. The midships lip 806 has a hollow interior 814 communicating with the gas outlet 811 and a conduit 812 communicating with the atmosphere or engine exhaust. A series of gas outlets 811 will typically be spaced across the lateral extent of the lip trailing face 813 rather than having a single gas outlet extending across the fransverse extent of the lip trailing face 813, again for reasons of structural integrity. Referring to Figures 20 and 21, an alternate configuration of midships lip 906 is depicted wherein a water inlet 926 is provided in the lip leading face 907. A series of water inlets 926 would typically be provided, spaced across at least part of the lateral extent of the lip leading face 907 so as not to comprise the structural integrity of the lip 906. As best depicted in Figure 21, the water inlets 926 communicate with a hollow interior 914 of the lip 906 which inturn communicates with a water conduit 927 that supplies the ingested water to the cooling system of an engine fitted to the hull. Whilst the water inlets 926 reduce the area of the left solid portion of the lip leading face 907, the water inlets 926 themselves still assist in slowing/damming water flow in front of the lip leading face 907, as the water flow is restricted and slowed as it attempts to enter the water inlets 926. This is particularly the case when the area of the water conduit 927 is smaller than that of the total area of the water inlets 926. Figure 22 depicts a similar configuration of lip 906 where the water inlets 926 extend across the entire lateral extent of the lip leading face 907. Referring to Figure 23, rather than having a fixed midships lip, a displaceable midships lip 1006 is provided. Here the midships lip 1006 is linearly displaceable between an extended position, as depicted in Figure 23 where the lip protrudes below the running surface 2 and a refracted position where the lip 1006 will typically be retracted above the running surface 2. Here the refractable midships lip 1006 is in the general form of a blade. The midships blade 1006 is mounted in a housing 1014 affixed to the interior of the hull and is actuated between the extended and refracted positions by way of an hydraulic actuator cylinder 1015. The midships lip 1006 may be operated by the driver of the vessel as desired to generate lift when needed. Typically, the lip 1006 will be extended at slow speeds whilst attempting to get the hull 2 up onto the plane, and / or when heavy loads are being carried. The displaceable lip 1006 can then be refracted at high speeds when the hull is able to generate sufficient lift of its own accord. Figure 24 depicts an equivalent linearly displaceable lip 1006 mounted to a stepped hull 102. Figure 25 depicts an alternate linearly displaceable midships lip 1106. This lip

1106 is mounted within a laterally extending recess 16 formed in the running surface 2 of the hull 1. In this arrangement, the lip 1106 is formed as a blade 1106 that is integrally formed with an elastically flexible membrane 1117. The blade 1106 and membrane 1117 are typically moulded from an elastomeric material such as rubber or neoprene. The blade 1106 and membrane 1117 are mounted within a housing formed by an upper component 1118 fixed to the underside of the recess 16 and front and rear wedge components 1119. The wedge components 1119 are secured to the housing upper component 1118 by way of fasteners 1120, with opposing free end portions of the membrane 1117 fastened therebetween. A expandable chamber 1120 is defined between the membrane 1117 and the housing upper component 1118. The chamber 1120 is communicated with a pressure supply 1121 by a conduit 1124 and seacock 1125 that pass through the hull structure. The seacock 1125 forms the only possible point of water ingress into the hull 1, and can be closed so as to seal the hull when not in use. The pressure supply 1121 may incoφorate a fluid reservoir, pump and supply valve.

When the pump is deactivated and the valve closed, such that the chamber 1120 is depressurised, the membrane 1117 remains in its undeflected state as depicted in Figure 25 such that the blade 1106 is in a retracted position above the running surface 2. When the chamber 1120 is pressurised by activation of the pump and opening of the supply valve, the pressure in the chamber 1120 deflects the membrane 1117 downwardly against the wedge components 1119, thereby displacing the blade 1106 downwardly so as to protrude below the running surface 2. With reference to Figure 24, rather than have the midships blade linearly displaceable, it is envisaged that a rotatable midships lip / blade 1206 may be provided which is rotatable between a retracted position within a recess 16 in the hull and an extended position, as depicted in Figure 26 in broken lines, where the lip 1206 extends generally peφendicular to the hull running surface 2. Figures 27 through 31 depict various configurations of transom lip 8 which might be utilised in combination with the midships lip. The transom lip 8 may be fixed to the running surface 2 and/or transom 4, or may be integrally formed with the running surface 2. The fransom lip leading face 9 will generally have a profile meeting the limitations discussed above in relation to the midships lip discussed in relation to Figure 7. Referring to Figures 32 and 33, a linearly displaceable transom lip 108 is depicted. The linearly displaceable lip 108 is mounted within a housing 130 fastened to the hull transom 4. The lip 108 is in the form of a blade 108 which is displaceable between the extended position, as depicted in Figure 32, where the lip protrudes below the running surface trailing edge 3 and a retracted position, as depicted in Figure 33, where the lip is refracted to a position above the running surface trailing edge 3. The blade 108 depicted in Figures 32 and 33 is hydraulically actuated between the extended and retracted positions. Referring to Figure 34, an alternate form of linearly displaceable fransom blade 208 is depicted. Here the linearly displaceable blade 208 is mounted adjacent the running surface frailing edge 3 forward of the fransom 4 such that it protrudes through the hull running surface 2 when in the extended position, as depicted in Figure 34. The blade 208 is displaced by way of an hydraulic actuator 240. Referring to Figure 35, an alternate linearly retractable blade 308 is depicted wherein the blade 308 is integrally formed with a bladder 331 defining an elastically expandable chamber 332. The bladder 331 and blade 308 are integrally formed of elastomeric material such as rubber or neoprene. The bladder 331 and blade 308 are mounted within a two part housing 333 having a cavity 334 within which the bladder 331 and blade 308 are received. The upper portion of the bladder 331 is restrained at the top of the housing cavity 334 by virtue of a bulbous protrusion 335 restrained within the housing 333. The blade 308 is slideably displaceable within a lower portion 334a of the housing cavity 334. The housing 333 is fastened to the fransom by way of fasteners 336. The expandable chamber 332 communicates with a pressure supply 337 by way of a conduit 338. Pressurisation of the chamber 332 from a fluid stored in the pressure supply 337 will typically be controlled via a supply valve and pump, activated from the cockpit. Upon pressurisation of the chamber 332, the bladder 331 will expand, pushing the blade 308 downwardly into the extended position depicted in broken lines in Figure 35, at which it protrudes below the running surface trailing edge 3. Upon depressurisation of the chamber 332, the elastic memory of the bladder 331 will draw the blade 308 back up into the refracted position a depicted in Figure 35. Figure 36 depicts a rotatably displaceable fransom blade 408 mounted on the fransom 4 by way of a bracket 441. The pivotably displaceable blade 408 is pivotably driven about a pivot pin 442 on the bracket 441 by way of an hydraulic actuator 443. The blade 408 is pivotably displaceable between an extended position, as depicted in Figure 36, at which the blade leading face 409 protrudes below the running surface frailing edge 3, and a retracted position at which the blade is located entirely above the running surface frailing edge 3. Various combinations of midships lips with or without transom lips are envisaged. Fixed midships lips may be used in combination with fixed transom lips, or with displaceable fransom lips. Similarly, it is envisaged that fixed transom lips might be utilised in combination with displaceable midships lips. The various lips may be applied to planing, semi-planing / semi-displacement or displacement hulls. They may be retrofitted to existing hulls, or formed at initial hull manufacture. In a particularly preferred configuration, a fixed midships lip will be utilised in conjunction with a displaceable transom lip. Having only the transom lip displaceable will simplify confrol of the lip systems, rather than needing to attempt to balance both midships and transom adjustable lips. The person skilled in the art will appreciate other possible combinations and variations of the lip systems described.

Claims

CLAIMS:

1. A marine hull having: a longitudinally and vertically extending cenfral plane, a static longitudinal water line length (LWL) defined in said cenfral plane, a transom, an underside running surface terminating in a frailing edge at said fransom; and a lip protruding downwardly from said running surface and extending fransversely along said running surface, said lip having a leading face; wherein said lip leading face is located a distance of between 0.15 times said LWL to 0.65 times said LWL forward of said transom.

2. The hull of claim 1 wherein said lip leading face is located a distance of between 0.35 times said LWL to 0.65 times said LWL forward of said transom.

3. The hull of claim 1 wherein said lip leading face is located a distance of between 0.45 and 0.65 times said LWL forward of said transom.

4. The hull of claim 1 wherein, in any reference plane parallel to said cenfral plane and intersecting said lip; said lip leading face has a leading face profile defined by the intersection of said lip leading face and said reference plane; said running surface has a local buttock line defined by the intersection of said reference plane and said running surface immediately forward of said lip leading face, said leading face profile meeting said local buttock line at a juncture point; and said leading face profile has a depth measured from said juncture point in a depth direction peφendicular to said local buttock line and lying in said reference plane; further wherein, for at least substantially all said reference planes located across at least a substantial fransverse extent of said lip, said leading face profile is inclined by less than 135 degrees with respect to said local buttock line at at least substantially all points along at least a length of said leading face profile which extends across a substantial portion of said depth thereof.

5. The hull of claim 4 wherein said leading face profile is inclined by less than 135 degrees with respect to said local buttock line at at least substantially all points along at least said length of said leading face profile for all said reference planes located across the entire transverse extent of said lip.

6. The hull of claim 4 wherein said substantial portion of said depth of said leading face profile extends across at least the lower half of said depth.

7. The hull of claim 4 wherein said lip leading face profile is substantially planar.

8. The hull of claim 4 wherein said lip leading face profile is inclined with respect to said local buttock line by approximately 90 degrees for at least substantially all said reference planes located across at least a substantial fransverse extent of said lip.

9. The hull of claim 8 wherein said lip leading face profile is inclined with respect to said local buttock line by approximately 90 degrees for all said reference planes located across the entire transverse extent of said lip.

10. The hull of claim 4 wherein said lip leading face profile is concave for at least substantially all said reference planes located across at least a substantial transverse extent of said lip.

11. The hull of claim 1 wherein said lip is integrally formed with said hull.

12. The hull of claim 1 wherein said lip is formed separate to and secured to said hull.

13. The hull of claim 1 wherein said lip extends across the entire transverse extent of said running surface.

14. The hull of claim 1 wherein said lip is formed in segments, each extending along part of the fransverse extent of said lip.

15. The hull of claim 14 wherein two said lip segments are provided, one located on each side of said central plane.

16. The hull of claim 4 wherein said depth of said leading face profile is at least 8 mm for at least substantially all said reference planes located across at least a substantial fransverse extent of said lip.

17. The hull of claim 16 wherein said depth of said leading face profile is less than 100 mm.

18. The hull of claim 16 wherein said depth of said leading face profile is less than 16 mm.

19. The hull of claim 4 wherein said leading face profile has a fransverse width of at least 1/3 times the static water line width (WLW) of said hull. ,

20. The hull of claim 15 wherein the fransverse width of the leading face profile of each said lip segment is at least 1/6 times the static water line width (WLW) of said hull.

21. The hull of claim 4 wherein said leading face profile has an aspect ratio, defined by the transverse width of said lip leading face profile divided by the depth of said leading face profile, of at least 15.

22. The hull of claim 20 wherein said aspect ratio of said leading face profile is at least ^■30.

23. The hull of claim 1 wherein said hull has a gas outlet provided in said running surface, adjacent to and aft of said lip, said gas outlet communicating with a gas supply.

24. The hull of claim 1 wherein said hull has a gas outlet provided in a frailing face of said lip, said gas outlet communicating with a gas supply.

25. The hull of claim 1 wherein said lip leading face fransversely extends substantially peφendicular to said cenfral plane.

26. The hull of claim 1 wherein said lip leading face fransversely extends at an acute angle to said central plane.

27. The hull of claim 1 wherein said leading face is provided with one or more water inlets communicating with an engine cooling system.

28. The hull of claim 1 further having a transom lip protruding downwardly from said running surface and extending fransversely along or adjacent to said frailing edge, said transom lip having a leading face.

29. The hull of claim 1 further having a fransom lip extending fransversely along or adjacent to said trailing edge, said fransom lip having a leading face and being displaceable between a refracted position about said frailing edge and an extended position protruding below said frailing edge.

30. The hull of claim 1 wherein said lip leading face is located a distance of between^' 0.15 to 0.35 times said LWL forward of said fransom.

31. A marine hull having : a longitudinally and vertically extending cenfral plane, a transom, a static longitudinal water line length (LWL) defined in said cenfral plane; an underside running surface terminating in a frailing edge at said transom; and a lip extending transversely along said rui ing surface, said lip having a leading face and being displaceable between a retracted position and an extended position protruding below said running surface; wherein said lip leading face is located a distance of between 0.15 times said LWL to 0.65 times said LWL forward of said fransom when in said extended portion.

32. The hull of claim 31 wherein said lip leading face is located a distance of between 0.35 times said LWL to 0.65 times said LWL forward of said transom.

33. The hull of claim 31 wherein said lip leading face is located a distance of between 0.45 and 0.65 times said LWL forward of said fransom.

34. The hull of claim 31 wherein in any reference plane parallel to said central plane and intersecting said lip: said lip leading face has a leading face profile defined by the intersection of said lip leading face and said reference plane; said running surface has a local buttock line defined by the intersection of said reference plane and said running surface immediately forward of said lip leading face, said leading face profile meeting said local buttock line, or a linear extension thereof, at a juncture point when said lip is in said extended position; and said leading face profile has a depth, when said lip is in said extended position, measured from said junction point in a depth direction peφendicular to said local buttock line and lying in said reference plane; further wherein, for at least substantially all said reference planes located across at least a substantial fransverse extent of said lip, said leading face profile is inclined, when said lip is in said extended position, by less than 135 degrees with respect to said local buttock line at at least substantially all points along at least a length of said leading face profile which extends across a substantial portion of said depth thereof.

35. The hull of claim 34 wherein said leading face profile is inclined, when said lip is in said extended position, by less than 135 degrees with respect to said local buttock line at at least substantially all points along at least said length of said leading face profile for all said reference planes located across the entire transverse extent of said lip.

36. The hull of claim 34 wherein said substantial portion of said depth of each said leading face profile extends across at least the lower half of said depth.

37. The hull of claim 34 wherein said lip leading face profile is substantially planar.

38. The hull of claim 34 wherein said lip leading face profile is inclined, when said lip is in said extended position, with respect to said local buttock line by approximately 90 degrees for at least substantially all said reference planes located across at least a substantial fransverse extent of said lip.

39. The hull of claim 38 wherein said lip leading face profile is inclined, when said lip is in said extended position, with respect to said local buttock line by approximately 90 degrees for all said reference planes located across the entire fransverse extent of said lip.

40. The hull of claim 34 wherein said lip leading face profile is concave for at least substantially all said reference planes located across at least a substantial fransverse extent of said lip.

41. The hull of claim 31 wherein said lip is integrally formed with said hull.

42. The hull of claim 31 wherein said lip is formed separate to and secured to said hull.

43. The hull of claim 31 wherein said lip extends across the entire transverse extent of said running surface.

44. The hull of claim 31 wherein said lip is formed in segments, each extending along part of the transverse extend of each said lip.

45. The hull of claim 44 wherein two said lip segments are provided, one located on each side of said central plane.

46. The hull of claim 34 wherein said depth of said leading face profile is at least 8 mm for at least substantially all said reference planes located across at least a substantial fransverse extent of said lip.

47. The hull of claims 34 wherein said depth of said leading face profile is less than 100 mm.

48. The hull of claim 46 wherein said depth of said leading face profile is less than 16 mm.

49. The hull of claim 34 wherein said leading face profile has a fransverse width of at least 1/3 times the static water line width (WLW) of said hull.

50. The hull of claim 45 wherein the fransverse width of the leading face profile of each said lip segment is at least 1/6 times the static water line width (WLW) of said hull.

51. The hull of claim 34 wherein said leading face profile has an aspect ratio, defined by the transverse width of said lip leading face profile divided by the depth of said leading face profile, of at least 15.

52. The hull of claim 51 wherein said aspect ratio of said leading face is at least 30.

53. The hull of claim 31 wherein said displaceable lip is linearly displaceable between said refracted and extended positions.

54. The hull of claim 31 wherein said displaceable lip is pivotally displaceable between said refracted and extended positions.

55. The hull of claim 31 wherein said lip leading face transversely extends substantially peφendicular to said cenfral plane.

56. The hull of claim 31 wherein said lip leading face fransversely extends at an acute angle to said cenfral plane.

57. The hull of claim 31 further having a fransom lip protruding downwardly from said running surface and extending fransversely along or adjacent to said frailing edge, said fransom lip having a leading face.

58. The hull of claim 31 further having a fransom lip extending fransversely along or adjacent to said frailing edge, said fransom lip having a leading face and being displaceable between a refracted position about said frailing edge and an extended position protruding below said trailing edge.

59. The hull of claim 31 wherein said lip leading face is located a distance of between 0.15 to 0.35 times said LWL forward of said transom.

60. The hull of any one of claims 1 to 59 wherein said hull is a planing type hull.

61. The hull of any one of claims 1 to 59 wherein said hull is a displacement type hull.