AU730629B2

AU730629B2 - Improvements in boat hulls

Info

Publication number: AU730629B2
Application number: AU76094/98A
Authority: AU
Inventors: Ronald John Webster
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-07-10
Filing date: 1998-07-10
Publication date: 2001-03-08
Anticipated expiration: 2018-07-10
Also published as: AU7609498A

Description

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AUSTRALIA

Patents Act 1990 RONALD JOHN WEBSTER

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Improvements in Boat Hulls Invention Title: The following statement is a full description of this invention including the best method of performing it known to us:- 2 Improvements in Boat Hulls Technical Field The present invention relates to boat hulls and more particularly to flat bottomed hulls.

Background to the Invention Existing flat bottomed boat hulls produce a substantial amount of wake when moving at speed through the water as the blunt leading edge of such a hull needs to push a substantial amount of water aside as it pushes forward.

Furthermore, existing flat bottomed boats must develop a substantial amount of speed before the hull will lift and the boat starts to plane.

Consequently, there is a wide range of lower speeds at which the drag of such hulls is relatively high.

Summary of the Invention The present invention proposes the addition of a pair of elongate pontoon portions extending along at least substantially the length of the flat 0 15 bottom portion of a flat bottomed boat hull, said pontoon portions being at opposite sides of the hull, each pontoon portion bounding a respective side of and extending downwardly from the flat bottom portion of the hull respectively and finishing at a forward end of the hull, bow deflector portions extending from the forward end of each pontoon portion, said bow deflector 20 portions being disposed to form a scoop whereby water is preferentially diverted between the pontoons during forward motion of the hull through water.

In operation, a hull of the present invention channels water inwardly of the pontoons as the hull moves forward through water. The channelling of 25 water beneath the hull and between the two pontoons is effected so that the hull is lifted at relatively low speed to provide a reduction in hull drag as compared with conventional flat bottomed hulls. A further effect of the hull of the present invention is that displacement wake radiating from the sides of the hull as it is pushed through the water, is substantially reduced. At least part of the water, which would for a conventional hull be displaced outwardly, is directed inwardly by the bow deflectors to be held between the pontoon portions.

In one embodiment of the invention each elongate pontoon portion is formed as a semi-circular cross-section shape with a transition of that shape along each bow deflector from that semi-circular shape to a pointed tip, the 3 outer edge of each bow deflector remaining in alignment with the outer edge of each half round pontoon portion while the inner edge of each bow deflector curves outwardly from the centre line of the hull.

In other embodiments of the invention the cross section of each elongate pontoon may be semi-elliptical, triangular, rectangular, or another cross sectional shape, with a transition along each bow deflector of the cross sectional shape to a pointed tip.

Each bow deflector is preferably formed with a keel having a relatively sharply defined edge at the forward extremity of the bow deflector while merging into the cross sectional shape of the elongate pontoons at the rearward extremity of the bow deflector.

The forward extremity of the keel of each bow deflector may extend substantially perpendicular to the flat bottom portion of the boat hull, forming a thin leading edge of the bow deflector which, in use, is substantially vertical and slices through the water, with water that passes on the inward side of the leading edge being deflected inwardly and passing underneath the hull. The lower extremity of the leading edge may be substantially aligned with a continuation of a lower extremity of the respective elongate pontoon portion.

20 The bow deflectors preferably extend forward into an upturned nose portion of the flat bottomed hull.

The bow deflector and the elongate pontoon may be manufactured in a single piece and attached to the hull, or may be manufactured and attached **as separate pieces.

Brief Description of the Drawings The present invention will now be described by way of example with reference to the accompanying drawings in which:- Figure 1 is an inverted plan view of a boat hull of one embodiment of the present invention; Figure 2 is a rear view of the boat hull of Figure 1; Figure 3 is a side elevation of the hull of Figure 1; and Figure 4 shows a bow deflector according to one embodiment of the present invention.

Detailed Description of the Preferred Embodiments Boat hull 10 comprises a flat bottomed portion 11, upturned bow portion 12 and a pair of pontoon portions 13 at each lateral extremity.

Pontoons 13 extend over the length of the flat bottomed portion 11 of hull 10 and at their forward ends are formed with nose cones 14 acting as bow deflectors. Each pontoon portion 13 is formed as a semi-circular crosssection as shown in Figure 2, while nose cones 14 are shaped from their forward ends 15 to smoothly merge with the semi-circular cross-sectional shape of each respective pontoon portion 13. Nose portion 14 is formed with a keel 16 having a relatively sharply defined edge at forward extremity while merging into the semi-circular cross-sectional shape of pontoon 13 at its rearward extremity where nose cone portion 14 joins pontoon 13.

In operation of boat hull 10 as it moves through water, the water contacting nose cones 14 is deflected inwardly of the hull to pass beneath hull 11 and be entrained between pontoons 13. A substantial degree of aeration of water occurs as it is directed by nose cones 14 and constrained by pontoons 13 and that aeration appears to give a lifting effect to hull 15 substantially reducing drag and enabling a flat bottomed hull of the invention to achieve improved performance compared with a conventional flat bottomed hull. There is also a substantially reduced hull wake resulting from this embodiment of the present invention.

Figure 4 shows an embodiment of the invention in which the forward 20 extremity 15 of the nose cone portion 14 extends substantially perpendicular to the flat bottom of boat hull 11, forming a thin leading edge. In this embodiment, the lower extremity of the leading edge 15 is substantially aligned with a continuation of a lower extremity of the respective pontoon 13. The water that passes on the inward side of the leading edge 15 will preferably be deflected inwardly, and will pass under the hull 11 between the *pontoons 13.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

1. A flat bottomed boat hull including a flat bottom portion and a bow portion and a pair of elongate pontoon portions extending along at least substantially the length of the flat bottom portion, said pontoon portions being at opposite sides of the hull, each pontoon portion bounding a respective side of and extending downwardly from the flat bottom portion of the hull respectively and finishing at a forward end of the hull, bow deflector portions extending from the forward end of each pontoon portion, said bow deflector portions being disposed to form a scoop whereby water is preferentially diverted between the pontoons during forward motion of the hull through water.

2. The boat hull as claimed in claim 1, wherein the bow deflector portions take the shape of nose cone portions, said nose cone portions being tapered towards a forward extremity of each nose cone. 15 3. The boat hull as claimed in claim 1 or 2, wherein each elongate pontoon portion has a semi-circular cross-sectional shape. The boat hull as claimed in any one of claims 1 to 3, wherein each bow deflector has a cross sectional shape which progresses from a shape matching the cross sectional shape of the pontoon at its rearward extremity to a 20 pointed tip at its forward extremity.

5. The boat hull as claimed in any one of claims 1 to 4, wherein the bow portion is upturned.

6. The boat hull as claimed in any one of Claims 1 to 5, wherein the ***pontoons extend into the bow portion of the boat hull.

7. The boat hull as for any one of Claims 1 to 6, wherein the bow deflectors respectively extend into the bow portion of the boat hull.

8. The boat hull as for any one of Claims 1 to 7, wherein the respective bow deflectors are formed with a keel having a relatively sharply defined edge at its forward extremity while merging into the cross sectional shape of the elongate pontoons at the rearward extremity of the bow deflector.

9. The boat hull as for claim 8 wherein the forward extremity of the keel extends substantially perpendicular to the flat bottom portion of the boat hull, forming a thin leading edge of the bow deflector which is substantially vertical in use. 6 The boat hull as for Claim 9, wherein a lower extremity of the leading edge is substantially aligned with a continuation of a lower extremity of the respective elongate pontoon.

11. The boat hull as claimed in any one of claims 1 to 10, wherein each elongate pontoon and the accompanying bow deflector are manufactured in one piece and attached to the hull as a single attachment.

12. The boat hull as claimed in any one of claims 1 to 11, wherein the hull, pontoons and bow deflector portions are aluminium. Dated this tenth day of July 1998 RONALD JOHN WEBSTER Patent Attorneys for the Applicant: F B RICE CO o* o