SAIL AND MAST STRUCTURE

Abstract: A sail suitable for sailboards and having an aerofoil cross-section formed by two sail sheets which encompass mast (13). Each sheet is shaped by battens (23) located in pockets in the sheet. The sheets are generally co-extensive, although preferably of unequal horizontal extent to enable sail deformation, the battens in the shorter sheet being further slidably held in pockets (24) in the longer sheet. The sail is fitted over T-piece (25) at the mast head and vertically tensioned by line (19). A wishbone boom may be provided having a transverse pin slidably passing through the mast. Transverse movement of this boom can alter the aerofoil cross-section of the sail. The mast is horizontally rotatable, being telescoped over pin (15).

Description: "SAIL AND MAST STRUCTURE" The present invention relates to wind driven craft and more particularly but not exclusively to the said.and mast structures thereof. BACKGROUND ART It is a particular disadvantage of sailing vessels that the sails thereof are only a rough approximation of an aerofoil. An aerofoil cross section is the most efficient sail configuration. In particular sail craft such as sail boards, also known as "wind surfers", are even further remot from a true aerofoil cross section and accordingly such craf are very inefficient in the use of air movement. It is an object of the present invention to overcome or substantially ameliorate the above disadvantages. DISCLOSURE OF INVENTION There is disclosed herein a sail and mast construction in which said sail includes a first and a secon sail sheet which are generally co-extensive so as to encompass the mast, and batton means secured to both sheets so as to bias the sheets to form an aerofoil cross-section. A preferred form of the present invention will n'ow b described by way of example with reference to the accompanyi drawings, wherein: BRIEF DESCRIPTION OF DRAWINGS Figure 1 schematically depicts a water sail craft; Figure 2 schematically depicts the mast and bottom assembly of the craft of Figure 1; Figure 3 schematically depicts the sail configuration as seen if the sail and mast of Figure 1 were sectioned along the line 3-3; Figure 4 schematically depicts a sail board; Figure 5 is an end elevation of the board of Figure 4 Figure 6 is an end elevation of the mast and sail assembly of the board of Figure 4; Figure 7 is a plan view of the mast and sail assembly of Figure 6; and Figure 8 is a plurality of sections taken through the sail and mast assemblies of Figure 4. OMPI BEST MODE OF CARRYING OUT THE INVENTION In Figure 1 there is schematically depicted a sail water craft 10 having a hull 11 adapted to receive a person to manipulate the craft 10. Extending upwardly from the craft 10 is a sail and mast combination 12 which consists of a mast 13 and a sail 14 fixed thereto. The mast 13 is secured to the hull 11 by being telescopically fixed over a metal pin 15 secured to the hull 11. It should be appreciated that the mast 13 is rotatable about its longitudinal axis. There is also provided a thrust washer between the lower portion of the mast 13 and the hull 11. Fixed to the mast 13 is a forwardly extending projection 16 to which is secured the front lower portion of the sail 14. Also fixed to the mast 13 by means of a universal joint is the beam 17 to which is fixed the lower rear extremity of the sail 14. The sail 14 is further fixed to the mast by means of an eyelet 18 attached to the sail 14 and a flexible line 19 engaged by a cleat 20 fixed to the mast 13. The flexible line 19 would be pulled taut so as to place the sail 14 under tension. Now with reference also to Figure 4, it can be seen that the'sail 14 consists of two sheets 21 and 22 which are each provided with battons 23 so as to aid the sheets 21 and 22 to be deformed by the wind to form a general aerofoil cross-section. The battons 23 would be located in pockets formed in the sheets 21 and 22 while the battons located within the pockets of the sheet 22 would further be slidably held by pockets 24 formed in the sheet 21. Additionally, it should be appreciated that the sheet 22 is of a shorter horizontal length than the sheet 21 to enable the sail 14 to deform to meet various wind directions. Additionally there is provided at the upper extremit of the mast 11 a T-piece 25 which engages the upper portion of the sail 14, while additionally the sail 14 is inserted over the T-piece 25 so as to encompass the mast 13. In Figures 4 to 7 there is depicted a sailing vessel 40 having a hull 41 to which is pivotally attached a mast 42 so that the mast is pivotable about a horizontal axis _ OMPI extending generally longitudinally of the hull 42, as well a horizontal axis extending generally transverse of the hul 41. Attached to the mast 42 is a sail assembly 43 which as can be seen from Figure 8, consists of two sheets 44 and 45 encompassing the mast 42 and with the aid of battons 46, is biased to form a generally aerofoil cross section. The lower extremities 47 of the sail 43 are secured to the lower portion of the mast 42 so that the sail 43 may be vertically placed under tension. Movably attached to the mast 42 is a wishbone boom 48 which consists of left and right longitudinal members 49a and 49b coupled at their forward and rear ends as well as intermediately by means of transverse pin 50. The transverse pin 50 also slidably passes through the mast 42 so as to guide the wishbone boom 48 in its movement generally transverse of the vessel. In operation and as can be seen from Figures 6 and 8 upon a rider of the vessel exerting a transverse force on th boom 48 so as to move same either leftward or rightward, the sail is caused to form a generally aerofoil cross section as demonstrated in Figure 7 particularly. With particularly reference to Figures 4 and 8, ther is included in the illustration of the sail 43 an alternativ sail size represented by the lines 43a. The reduced sail area is advantageous when used with said boards.

Claims: CLAIMS 1. A sail and mast construction in which said sail includes a first and a second sail sheet which are generally co-extensive so as to encompass the mast, and batton means secured to both sheets so as to bias the sheets to form an aerofoil cross-section. 2. The construction of claim 1 wherein said mast ha at its upper extremity a generally horizontally extending sail support over which said sail is fitted. 3. The construction of claim 1 or 2 wherein said sail is secured to said mast adjacent the lower end of the mast so as to be placed in tension. 4. The construction of claim 1, 2 or 3 wherein said batton means includes a plurality of battons which are slidably engaged by at least one of said sheets. 5. The construction of claim 4 wherein said second sheet has a horizontally longitudinal length less than that of said first sheet. 6. The construction of claim 4 or 5 wherein said battons are slidably attached to both sheets with said secon sheets engaging said battons over the majority of each of th batton lengths. 7. The construction of any one of claims 1 to 6 further including a wishbone boom which is transversely slidably supported by said mast and adapted to engage the forward and rearward lower portions of said sail. 8. A wind powered craft including a hull and a construction according to claim 7, said craft further including a universal joint securing the lower end of said mast to said hull. 9. A sail and mast construction substantially as hereinbefore described with reference to the accompanying drawings.

Inventors: WALKER TERENCE JAMES
Applicants: PLECTRUM PTY LTD, WALKER TERENCE JAMES
Application year: 1982
Main classification: B63H9
IPC codes: B63B35, B63H9