AU644131B2

AU644131B2 - Improvements to keels

Info

Publication number: AU644131B2
Application number: AU71136/91A
Authority: AU
Inventors: Kevin Williams
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-02-16
Filing date: 1991-02-18
Publication date: 1993-12-02
Anticipated expiration: 2011-02-18
Also published as: AU7113691A

Description

id P/00/011 PATENTS ACT 1952 -COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE Short Title: Int Cl: Application* Number: Lodged: Form :.Crjplete Specification-Lodged: Accepted: 0 so 0:Lapsed: Published: *000*0 9Priortty: :0.

0 Soo Related Art: Name. o f Applicant: A djress of Applicant: 0 66 Actual Inventor: Address for Service: Complete Specification TO BE COMPLETED BY APPLICANT KEVIN WILLIAMS 13 Lord Street, KIRRA Q 4225 KEVIN WILLIAMS JOHN R.G. GARDNER Registered Patent Attorney P0 Box 443 MUDGEERABA Q 4213 for the invention entitled: IMPROVEMENTS TO KEELS The foilowing statement is a full description of this invention, including the best method of performing it known to me:-* Note: The description is to be typed In double spacing, pica type face, in an area not exceeding 250 mm In depth and 160 mm In width, on tough white paper of good quality and It Is to be Inserted Inside this form.

1 4599/78- L Printed by C. I. TtnommvoN, Commonwcalth Govcrnmcnt Printer, Canbcrra THIS INVENTION relates to improvements to keels and in a particular aspect to keels which are applicable to usage with sailing craft or other water craft. In a further aspect, the present invention relates to fins for surfboards, sailboards or the like.

The present invention thus provides a keel for a water craft hull comprising a main body portion of blade like form adapted to lie in or be substantially parallel to a normally vertical plane extending along the centre line of said hull, and at least two spaced apart supporting elements adapted to extend between said hull and said body portion so as to support said body portion at a position spaced from said water hull, said supporting elements being such as to substantially rigidly support said body portion to said hull but providing minimum resistance to water flow adjacent said hull.

The term "keel" as use throughout the specification and claims includes boat and ship keels as well as centreboards for sailing craft and fins for surfboards, sailboards or the like, the term "water craft" including such craft as referred to above.

Preferably said supporting elements have a generally aerofoil cross section and extend in use substantially at right angles from the hull of the water craft. In one form the keel may include a plurality of said supporting elements arranged in an array extending :between the water craft and the main body portion.

s'cto Suitably the body portion has an aerofoil crosssection. Infill members may be provided between at least to. 30 some of the supporting elements. Preferably, the body portion is buoyant or formed of a buoyant material but in the case of larger vessels, the body portion may at least, at the centre of the vessel, be formed of a ballast material.

35 The supporting elements may be arranged in one or to more rows extending transversely of the main body portion.

*o One of said supporting elements is preferably arranged at the normally leading or bow end of said body portion and is to. 6<4 inclined upwardly and outwardly from said leading portion.

Reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the invention and wherein:- Fig. 1 illustrates a fin for use with a surfboard or sail board according to the invention; Figs. 2 and 3 illustrate in elevational and plan views, an alternative keel according to the present invention; Fig.s 4 and 5 illustrate in elevational view, application of the keel of Figs 2 and 3 to the central keel and chine keel of a boat hull.

Referring firstly to Fig. 1 there is illustrated a first embodiment of the invention in the form of a fin 23 for use with a surfboard or sailboard, the fin 23 including a connection element 24 for mounting the fin 23 to a conventional fin box fitted to a surfboard or sailboard and a blade portion 25 which is spaced from the 'connection element 24 and supported thereto by a plurality of relatively thin parallel supports 26. The blade portion extends generally longitudinally of the water craft so as to lie in, or be parallel to a longitudinal plane containing the central axis of the surfboard or sailboard.

Suitably the blade portion 25 is of aerofoil cross-section.

The supports 26 for maximum strength may be constructed of spring steel of such a thickness as to provide minimum impediment to water flow past the base of the fin 23 and between the supports 26. If desired respective supports 26 may be interconnected by means of infill members 27 which may be formed of fibreglass material to span respective elements 26. Preferably the members 27 are also of 0 aerofoil cross-section to minimise the effect on flow past the fin 23. Preferably in the infill elements 27 leave a I space 28 adjacent the connection of the supports 26 to the 35 connection element 24 so that minimum flow impedance occurs adjacent to the hull.

ee00 The fin 23 of the embodiment of Fig. 1 is also suited to use with boats for example sailing craft and may e be used in place of a centreboard to be inserted into the centreboard casing or retracted therefrom as required.

This fin 23 also has particular applicability to use with boats of the type which include a cathedral hull in which case a pair of fins 23 are provided on opposite sides of the boat hull and mounted to the boat hull in a manner which permits them to be raised or lowered. The material which forms the blade portion 25 of the fin 23 suitably comprises a material which has buoyancy, such as Q-cell material, h-,wever, the blade portion 25 may of course be constructed of other materials such as conventional glass reinforced plastics materials.

Referring now to Figs. 2 and 3 there is illustrated an alternative embodiment of fin or keel according to the present invention particularly adapted 'or use with boats and including a main body portion 51 supported by a plurality of support elements 52 from the underside of a hull 53. This embodiment is similar to the embodiment of Fig. 1, except that in this instance elements 52 are provided at laterally spaced positions in rows extending transversely of the body portion 51 and hull 53 as well as at longitudinally spaced positions. The elements 52 provide minimum impediment to water flow adjacent the hull 53 but hold the keel body portion 51 substantially rigidly at a position spaced from the hull 53.

The main body portion 51 is of aerofoil crosssection and also includes a thin or relatively thin support 54 which extends from the leading end of the body portion 30 51 to the hull 53 at an inclination as shown. The member 54 which is also preferably of aerofoil cross-section ]has a Soprimary function of deflecting seaweed or other material in Sthe water away from the keel 50. The body portion 51 is supported by the elements 52 to extend longitudinally of 35 the hull and be normally located in or parallel to a generally vertical plane.

:coKeels 50, however, may be located on opposite seoe sides of the centre line of a hull 53 at the chines of the hull 53 in which case the elements 52 which are preferably of aerofoil cross-section are angled as indicated by the dotted lines in Fig. 3 towards the water line of the hull 53 at the bow. The elements 52 may also be interconnected by infill members similar to that described in Fig. 2. The elements 52, however, preferably are of minimum crosssection so as to provide minimum resistance to flow of water adjacent the hull 53.

The keels 50 of the invention may as described above and as exemplified in Fig. 4, be arranged centrally of the hull 53 of a boat to extend along the centre line of the hull 53. The keels 50, however, may be arranged on opposite sides of the hull centre-line for example along the chines, for example as shown in Fig. The keel 50 of Figs. 2 and 3 may be constructed of any suitable material which will provide sufficient rigidity in support but minimum flow resistance.

Keels of the type described in Figs. 2 and 3 are particularly suited to use as the centreboard of a yacht such as a small sailing craft whereby the connecting elements between the main body portions 25 and 51 and the hull break the surface tension between the hull and the main body portion 25 or 51 of the keel. This is particularly useful in downwind sailing conditions where the need to raise the centreboard can be eliminated. The embodiment of Figs. 2 and 3 is also useful for situations where ballast is a necessity but keel drag is a problem.

Thus the ke.- may be employed replacing the normal keel in keel boats or for providing a keel in large power boats and 30 ocean liners.

Whilst the above has been given by way of illustrative embodiment of the invention all such modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the 35 broad scope and ambit of the invention as herein defined in f the appended claims.

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Claims

2. A keel according to Claim 1 wherein said body portion has an aerofoil shaped cross-section.
3. A keel according to Claim 1 or Claim 2 wherein said supporting elements have an aerofoil shaped cross section,
4. A keel according to any one of the preceding claims and including infill members between said supporting elements. A keel according to any one of the preceding claims wherein said body portion is formed of a buoyant material.
6. A keel according to any one of the preceding claims wherein said supporting elements are arranged in one 30 or more rows extending transversely of said main body 4 portion.
7. A keel according to any one of the preceding claims wherein one of said supporting elements is arranged 35 at one end of said body portion and is normally inclined upwardly and outwardly from said one end portion, said one end being normally disposed towards the bow end of said hull.
8. A watercraft hull including a keel as defined in any one of the preceding claims.
9. A watercraft hull according to Claim 8 wherein said main body portion is arranged at the centre line of said hull. A watercraft hull according to Claim 8 wherein said main body portion is arranged laterally of the centre- line of said hull.
11. A watercraft hull according to Claim 10 wherein said supporting elements are angled inwardly towards the bow of said hull.
12. A keel substantially as hereinbefore described with reference to Fig 1, or Figs. 2 and 3 of the accompanying drawings.
13. A watercraft hull including a keel substantially as hereinbefore described with reference to Figs. 4 and of the accompanying drawings. DATED this twenty-ninth day of July 1993 KEVIN WILLIAMS By My Patent Attorney -I- JOHN R. GARDNER S V° a S 5 ?W