WO2001089920A1

WO2001089920A1 - Keel assemblies

Info

Publication number: WO2001089920A1
Application number: PCT/NZ2000/000082
Authority: WO
Inventors: Thomas William Schnackenberg
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-05-25
Filing date: 2000-05-25
Publication date: 2001-11-29
Anticipated expiration: 2002-11-25
Also published as: AU2000249592A1

Abstract

A keel structure for a yacht which includes a ballast weight and means extending transversely beneath the hull with respect to which the ballast weight is moveable. Preferably a loop type keel form on which the ballast weight is moveable is contemplated so as to enhance the righting moment for a given carried ballast weight and for a given sail loading as well as reducing leeway without the penalty of excess draft.

Description

KEEL ASSEMBLIES

FIELD OF INVENTION

The present invention relates to boat keel structures, boats including such keel structures, and the use thereof.

BACKGROUND TO THE INVENTION

The keel or centre board of a sailing boat is used to generate forces necessary to allow the adequate control and powering of the boat from the wind. Keel structures in some instances as foils enhance the generation of helpful forces. In the simplest forms however a keel serves the function of providing a sufficient righting moment to counteract heeling moments (as a result of wind pressure in the sails) as well as providing a "bite" in the water to minimise leeway.

In order to provide a maximal resistance to heeling which can enable a greater sail powering of a boat frequently very heavy masses, (e.g. of lead) are carried a considerable distance below the water line.

The present invention is preferably directed to boat keel structures, hulls including such keel structures, yachts or other sail boats (whether wind powered by rigid or flexible sails or aerofoils, or a hybrid thereof) which will provide the prospect of enhancing the righting moment on a boat hull from a keel structure (for a given carried ballast and for a given sail loading) and reducing leeway without the penalty of excess draft.

BRIEF DESCRIPTION OF THE INVENTION

Accordingly in a first aspect the present invention consists in a keel structure for a boat hull or a boat hull having a keel structure therefor or a yacht or other sail boat having a keel structure, the keel structure comprising or including a ballast weight, means to extend or extending transversely beneath the boat hull and spaced therefrom (hereafter "transverse means") relative to which said ballast weight is moveable also transversely of the boat hull to which it is to be associated or is associated, and means (hereafter "connecting means") to support said transverse means (preferably from at or adjacent each transverse extent thereof) to the hull, the weight of the ballast weight being carried (at least in part) from said transverse means. Preferably said transverse means and said connecting means form or will form a loop type or bight (rounded or transitioned) keel form to and from the hull.

Preferably said transversal means that extends transversely is at least as extensive transversely of the hull axis as the transverse spacing of the points of connection of the connecting means to the hull thereof.

In some forms of the present invention the transverse means that extends transversely may be curved (eg; so as to blend with each part of the connection means) whereas in other, perhaps more preferred forms of the present invention, said transverse means extends substantially rectilinearly.

Preferably said connecting means is or are attached to the hull and shaped in such a manner as to act as a keel foil form to reduce leeway and preferably each itself is a foil (eg, see Figure 2).

Preferably said ballast weight is a single weight but in other forms it may be a multiple of weights of the same or different forms.

Preferably said ballast weight is or is to be remotely moveable transversely of the hull.

Preferably said remote moving is under the action of mechanical or hydraulic or electrical, or a hybrid, means that preferably extend at least down one or both of said connection means (eg a rope from either side).

Preferably said ballast weight takes the form of a drag reducing shape (eg bulbous) as a complement to a foil defined at least in part by said transverse means.

Preferably said transverse means with its ballast weight and each connecting means is configured when viewed from the direction of advancement so as to provide a small impediment to advancement consistent with the derivation of any requisite foil induced force characteristic considered desirable.

In another aspect the present invention consists in a keel structure which provides without a penalty of excessive draft an efficient leeway resisting assembly coupled with an effective means of providing a righting moment by use of a transversely movable ballast weight supported below the hull.

Preferably said support is from a transverse region of a loop or bight type keel.

In yet another aspect the invention consists in a hull or yacht having a pair of bilge keels supporting a transverse beam relative to which a ballast weight can move.

In a further aspect the present invention consists in the use of a keel structure or boat hull or sail boat as previously defined.

In some forms the more leeward connecting means (eg foil) can be extended downwardly, eg, by a leeboard. This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

DESCRIPTION OF PREFERRED EMBODIMENT

The invention consists in the foregoing and also envisages constructions of which the following gives examples.

Preferred forms of the present invention will now be described with reference to the accompanying drawings;

Figure 1 A is a diagrammatic view of a yacht from astern heeling to port showing the weight at one extent of its movement relative to the transverse means, such position providing a maximum righting moment,

Figure IB is the opposite heeling effect to that of Figure 1 A showing how the weight has been moved to again underlie the hull in an optimum position,

Figure 1C shows the weight intermediate the extremes of Figures 1A and IB, as the weight might be positioned for directly downwind sailing or for motoring or towing of the yacht under no sail load, for example, in a harbour scenario, showing how there is a prospect of a reduction in draft of the keel assembly in the form of Figure 1C over that of the extremes shown in Figures 1A and IB,

Figure 2 shows a foil form that may be appropriate for the transverse means and/or the ballast weight, and

Figure 3 shows a side view of the hull of a boat showing an appropriate foil like connecting means supporting a foil like transverse means that preferably carries a foil complementing or foil like ballast weight.

The present invention relates to a boat keel which will enable, for a specific sail boat, the prospect of customising a keel form taking into account all of the usual parameters as well as the desired draft for such a boat under wind loadings and under no wind loadings (e.g. in a harbour or anchorage scenario).

The present invention recognises the prospect of tailoring foil like closed loop, bight or the like type foils that extend down from a hull from one side (away from the centre line of the hull), extend transversely under the hull and extend back to the hull on the other side of the centre line in a similar manner without, for example, a need for reinforcing of a kind as described for such a structure in UK Patent 2177353 (Rennie et al). In that patent specification a curved structure of that form is described in various forms. Such a curve structure falls within the scope of the present invention although preferably the transverse means of the present invention is more flattened than the apexed or almost pointed arrangement in the aforementioned British patent.

Various stabilising mechanisms in the past have been disclosed in respect of minimising rocking in boats ranging from pumping systems within a hull for the movement of water from one side to the other of a boat. Some solid form weight moving devices within a hull have also been devised.

For a fixed central keel pivotal arrangements have been mooted which may provide some of the advantages to which the present invention is directed. Such structures however have not found wide spread success owing to the stresses and forces frequently involved and the interference such structures have with the overall performance of a boat.

The present invention recognises the advantages to be derived from providing a keel system whereby a moveable ballast weight (by sliding or other appropriate association with a loop keel) can move (preferably more or less at a constant distance below the boat hull proper) from one extreme position to another extreme position, each disposed laterally of the centre line of the boat, thereby providing a prospect of remote or other movement of that ballast weight to maximise the righting moment.

In the most preferred forms of the present invention it is envisaged that divergent connection means from the hull proper act as bilge keels (possibly toed in) which may confer the best possible theoretical advantage as far as resisting leeway is concerned whilst maximising the transverse movement available for the ballast weight. Such an arrangement at the same time enables a shallow draft for the boat when the boat is in a strict upright condition such as it will be in anchorage situations.

The accompanying drawings show a hull 1 of a sail boat with a mast or masts 2 and a keel structure comprising two connection means 5 and 6 (bilge keels) connected from the hull, a transverse means supported (preferably at the outer ends) by each of the connection means and a moveable weight 3.

Preferably each of the connection members 5 and 6 are sufficiently hollow to allow communication down to the weight and the transverse means so as to enable the remote movement therefore. It is envisaged that the weight 3 is preferably movable relative to the transverse means 4 as a result of rotation within the transverse means 4 of a worm screw rotatable under action of either hydraulic or electrical means or even mechanical means extending down one or both of the connection means 5. Any appropriate means of moving the ballast weight 3 from the extreme shown in Figure 1 A and IB so as to optimise its position is within the scope of the present invention (eg a rope from other side).

Ideally the foil like form shown in Figure 2 with its advance edge 7 is preferably used for the transverse means 4.

Preferably a correctly shaped foil and/or correctly toed connection foils are used to minimise leeway and drag.

The bilge keel dependent structure in situations of grounding will enable an upright stance and could be designed to support the weight of the yacht.

Preferably said connecting means are designed in such a manner as to provide efficient foil shapes and angles of attack so as to reduce both the leeway of the yacht and the keel system induced drag. I believe that the transverse means also has an effect on both leeway and induced drag and that this may be further improved by attention to the design detail.

Furthermore I expect that the foil system will have a stability effect in the vertical motions of the yacht (pitch and heave) and that this feature is also subject to improvement by attention to design detail. The present invention therefore provides synergy.

Claims

What I claim is

1. A keel structure comprising or including: a ballast weight, means to extend or extending transversely beneath a boat hull and spaced therefrom (hereafter "transverse means") relative to which said ballast weight is moveable also transversely of the boat hull to which it is to be associated or is associated, and means (hereafter "connecting means") to support said transverse means to the hull, the weight of the ballast weight being carried (at least in part) from said transverse means.

2. A structure of claim 1 wherein said connecting means supports said transverse means at or adjacent each transverse extent thereof (i.e. at what is a transition from transverse means to connecting means on each end of said transverse means).

3. A structure of claim 1 or 2 wherein said transverse means and said connecting means form or will form a loop type or bight (rounded or transitioned) keel form to and from the hull with said transverse means.

4. A structure of any one of the preceding claims wherein said transverse means that extends transversely is at least as extensive transversely of the hull axis as the transverse spacing of the points of connection of the connecting means to the hull thereof.

5. A structure of any one of the preceding claims wherein said connecting means is or are attached to the hull and shaped in such a manner as to act as a keel foil form to reduce leeway.

6. A structure of any one of claims 1 to 4 wherein the connecting means is of two spaced parts each having a foil form.

7. A structure of any one of the preceding claims wherein said ballast weight is a single weight.

8. A structure of any one of claims 1 to 6 wherein said ballast weight is a collection of multiple of weights of the same or different forms.

9. A structure of any one of the preceding claims wherein said ballast weight is or is to be remotely moveable transversely of the hull.

10. A structure of claim 9 wherein said remote moving is under the action of mechanical or hydraulic or electrical, or a hybrid, means that preferably extend at least down one or both of two spaced parts of said connection means.

11. A structure of any one of the preceding claims wherein said ballast weight takes the form of a drag reducing shape (eg bulbous) as a complement to a foil defined at least in part by said transverse means.

12. A structure of any one of the preceding claims wherein said transverse means with its ballast weight and each of two spaced parts of said connecting means is configured, when viewed from the direction of intended advancement, so as to provide a small impediment to advancement consistent with the derivation of any requisite foil induced force characteristic considered desirable.

13. A structure of any one of claims 1 to 12 the more leeward part of said connecting means can be extended downwardly by a leeboard.

14. A keel structure substantially as hereinbefore described with reference to any of the accompanying drawings.

15. A boat including a keel structure which provides, without a penalty of excessive draft, an efficient leeway resisting assembly coupled with an effective means of providing a righting moment by use of a transversely movable ballast weight supported below the hull.

16. A boat of claim 15 wherein said support is from a transverse region of a loop or bight type keel.

17. A boat having a keel structure of any one of claims 1 to 14.

18. A boat of claim 16 which is a yacht or sailboat.

19. A hull or yacht having a pair of bilge keels supporting a transverse beam relative to which a ballast weight can move.

20. The use of a keel structure of any one of claims 1 to 16 or boat hull or sail boat of claim 19.

21. A method of operating a yacht or sailboat substantially as hereinbefore described generally with reference to the accompanying drawings