AU603571B2 - Boat mast - Google Patents

Description

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i -I i AU-AI-723 6 4/ 8 7 WORLD INTELLECTUAL PROPERTY ORGANIZATION International Bureau

PCT

0 INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification 4 (11) International Publication Number: WO 87/ 05962 E04H 12/08, 12/32 B63B 15/00 Al. (43) International Publication Date: 8 October 1987 (08.10.87) (21) International Application Number: PCT/AU87/00088 (74) Agent: TAYLOR, Paul; Arthur S. Cave Co., Gold Fields House, I Alfred Street, Sydney, NSW 2000 (22) International Filing Date: 2 April 1987 (02.04.87) (AU).

(31) Priority Application Number: PH 5295 (81) Designated States: AT (European patent), AU, BE (European patent), BR, CH (European patent), DE (Eu- (32) Priority Date: 2 April 1986 (02.04.86) ropean patent), DK, FI, FR (European patent), GB (European patent), IT (European patent), JP, KR, LU (33) Priority Country: AU (European patent), NL (European patent), SE (European patent), US.

(71) Applicant (for all designated States except US): FAST MASTS PTY. LIMITED [AU/AU]; 14-2 nin Str:et, Published The Jci.on, S W.2291 (AU).2,5PA "-coAo With international search report.

(72) Inventors; and Inventors/Applicants (for US only) ABRAHAM, Jo- Cl\ seph [AU/AU]; 14 U i. Si.. T. o f 2 NOV 1987 22- HAMONET, Michael [AU/AU]; 3 War- 8 hurst Street, Toronto, NSW 2283 GRACIE, Phillip [AU/AU]; RoVe Street, Coal Point, NSW 2283 A TRALA HOOD, Warwick [AU/AU]; Sthl treet, 2 AU Balmain, NSW 2041 20 OCT 1987 PATENT OFFICE (54) Title: MAST W 3 7 (57) Abstract A pole structure comprising two elongated sheet metal or extruded sections (1 and 2) which are joined together by spacers to provide a gap between the adjacent edges of the elongated sections (1 and This structure provides access to the interior and is most suitable for utilization as a mast of a sailing yacht, being lighter in weight than the standard masts yet being as structurally stable and flexible.

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This doctiment contains the L S L amendments made under Section 49 and is correct for !7 Z printing I A 0135p:mmb The present invention relates to an improved construction of a metal pole, and in particular, to an improved tubular metal mast for use in sailing yachts.

The usual method of manufacture of metal (typically aluminium alloy) masts for use in sailing yachts is by the extrusion, through a die, of an oval. or elliptical cross-section tube. For masts which require a larger crosssection than may be extruded in one piece through the size die that is available in the largest extrusion presses, it is usual for the mast to be built up from two extruded pieces which are *0S@ connected by welding or other means in the longitudinal e g.

direction.

For masts that require a longer length than may be

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extruded in one piece, it is usual for the masts to be built up from two extruded pieces which are connected by welding or other means in the transverse direction.

5550 It is usually desirable for masts to be tapered. That is *ee 0 •0 to say that they have a smaller cross-section at the top than the maximum extruded cross-section for the particular die. In the normal method of construction this taper is obtained by cutting long, wedge shaped pieces out of the side walls of the ooo• mast, and closing the wedge shaped gaps by welding the edges together.

Masts made by the extrusion process are normally of an aluminium alloy which is heat treated after extrusion so as to develop fully its desirable strength factors. Subsequent welding reduces substantially the strength factors over an area extending from the centre of the weld to points out beyond each 2 i I r ~I 01 3 5 p: mmb side of the weld. This area is known as the "heat affected zone" and its extent varies depending on welding techniques, heat input and type and thickness of parent material.

In masts constructed from this normal method, Ehe crosssection is a tube. Access to the interior of these masts for the attachment and servicing of the essential rigging fittings is only possible from each end. This situation is neither convenient nor entirely satisfactory. As a result, no'rmally constructed masts are usually provided with fittings which are attached to the mast by a number of "blind" riveting processes and/or by bolts from one side of the mast to the other.

ooto S° Welding is not normally used for the previously mentioned reason of reducing the strength of the mast. Further, once *5 these fittings are attached it is usually not desirable to reposition them, because the drilling of more attachment holes further weakens the structural integrity of the mast.

gue The present invention seeks to ameliorate these S disadvantages by providing a boat mast adapted to be held in place by stays, comprising: a fore elongated shell member having a top, a bottom and a length therebetween, and edges and defining a curved profile

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:o:o with an open trailing side; an aft elongated shell member having a top, a bottom and a length therebetween, and edges and defining a profile including at least one wall and an open side; the open side of the aft member being disposed generally opposite and facing the open trailing side of the fore member, the edges of the fore and after members being disposed -3- 1 0135p:mmb generally opposite each other and spaced apart; spacers, disposed at intervals along the length of the mast, joining opposing edges of the aft and fore members while producing a gap separating the opposing edges; the gap defined between opposing edges providing access to an interior of the mast; the interior of the mast defining a neutral axis and being adapted to receive a fitting for providing anchorage points for rigging, the fitting being positioned along the neutral axis so that loads transmitted by the rigging are applied adjacent the neutral axis of the mast.

00*• Each elongated shell member can be a one piece construction or made up of several sections of varying Oe Iti cross-section.

The invention will now be described with reference to the accompanying drawiLgs which: goes Figure 1 illustrates a mast section according to an 0050 as 0 embodiment of the present invention showing sections of the mast taken at different positions along the mast; Figure 2 shows a section through a mast according to a second embodiment of the present invention showing one of the a6s• spacers connecting the two mast members together; and Figure 3 and 4 are exploded cross-sectional views of alternate configurations.

Preferably the mast members are formed from flat strips of metal by a continuous metal forming process known as "roll forming." If the arrangement of the rollers during the passage of the entire length of the strip through the metal forming machine remains unchanged, a section will be obtained which has 4 0135p:mmb no taper.

If, however, the arrangement of the rollers is continuously adjusted, either manually or by a pre-arranged automatic system, a tapered section will be produced. A mast may then be constructed from these sections which has any desired amount of taper from the maximum section. This taper may extend from any point to the top and/or bottom of the mast, as shown in Figure i.

Furthermore, the metal strip for fabrication by the roll forming process is normally supplied in a coil, which is much 0Se* more readily and economically stored and transported than the usual extruded mast sections. Also the metal strip, being a material produced in a rolling mill and not by extrustion and S heat treatment, is less expensive to purchase. The aluminium alloy preferred for use in the invention is one having a major alloying element magnesium. This type of alloy develops its **to desirable strength characteristics and properties by work hardening, i.e. the process of rolling pressing or bending it improves its strength. Heat treatment is not necessary. This type of alloy is also readily welded with its strength characteristics very little degraded by this particular joining :process. The connection of the various parts of the mast to each other, and of fittings to the mast by welding is therefore possible, without diminishing the strength characteristics and thus performance parameters of the material and, therefore, the mast.

As shown in Figure i, one embodiment of the present invention comprises a leading edge mast member 1 which is 0135p:mmb connected to the trailing edge member 2 by spacers 7 which are welded across the two members. The two members 1 and 2 are, in this case, of different profiles extruded to the desired lengths. Each member could be of a single profile o as in the two top sections shown in Figure 1 produced by welding together similar profiles of small dimensions to obtain a pronounced taper.

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0 0@ However, preferably the taper of the mast is obtained by having the top section 8 of the mast formed by welding the edges 12 of the mast members 1 and 2 together.

In general the taper of the mast is formed by having an increasing gap 5 between the edges 12 of the leading mast member 1 and the trailing mast member 2 down the length of the mast, as shown in Figure 1, whereby different width spacers 7 are welded between the two mast members 1 and 2.

At the trailing edge 14 of the member 2, a track 9 can be welded or bolted into position to support by means of a slide the luff rope of the mainsail (not shown).

Where the mast is under localized stress such as in the area of the spreaders and the attachment of the boom (not shown) the spacers 7 can be moved closer together to strengthen the sections of the mast.

A further embodiment of a mast produced in accordance with an embodiment of the present invention is shown in Figure 2 wherein the leading edge member 1 is bolted to a brace 10 and the trailing edge mast member 2 is bolted to a similar brace 11. These braces 10 and 11 are held apart by means of fittings 3. Preferably the braces 10 and 11ii are bolted to the 6 0135p:mmb re-entrant flanges 4.

A longitudinal gap 5 is formed in each side wall of the mast, as shown in Figure i, which allows ready access to the interior of the mast at any point. Ropes necessary for the hoisting and lowering of sails, and electrical wiring for navigational equipment and instruments, are usually led internally on yacht masts. This invention, allowing as it does easy access to the interior of the mast for installation, inspection and repair of these wires and ropes, greatly improves this area of mast construction and rigging.

In addition to the abovementioned fittings which not only 5000 connect the various longitudinal pieces of the mast itself, but also provide anchorage points for rigging wires 25 used to

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hoist and control the sails, small metal clips are bolted to the longitudinal lips at the necessary spacing to maintain the various longitudinal pieces, which comprise the body of the *59S mast in the correct location, with respect to each other. As shown in Figure 2 a central fitting 3' is located on the central or neutral axis 27 of the mast so that loads applied by S too the rigging wire 25 secured to the centrally located fitting 3' are applied at the neutral axis 27. The fitting 3' has a eeoc larger diameter than fitting 3.

Furthermore, the variation of the length and the position of the clips allows even further control of the amount and position of fore and aft taper.

On the completion of the assenmbly of the mast, the continuous gaps 5 arranged longitudinally in the mast may be covered with a thin self-adhesive aluminium or plastic, which -7 L-S U 0 Ow 01 3 can be readily removed for access to the interior of the mast.

These can, of course, be subsequently replaced. Alternatively a "snap-in" extruded plastic strip may be used.

The back of the mast, that is to say the edge oi the mast against which the leading edge of the mainsail is attached, is provided with a groove to support directly the luff rope of the mainsail. The invention also allows for the provision of a track or groove on the forward side of the mast for the purpose of attaching a spar, known as the spinnaker boom, to the mast 00 and allowing the mast end of the spar to be positioned at any desired height. This track or groove on the forward side may 00** .e *extend over any length of the mast.

The invention relates also to the possibility of making

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masts with varying wall thicknesses over any fore and aft cross-section. For example, in a mast comprising two longitudinal pieces, that is a leading edge section 1 and a o e. trailing edge section 2, the requirement of aerodynamic drag reduction makes it desirable that the said leading edge 1 s. hould have a smooth surface, and that in most cases its shape *0e is that of a circular arc or part of an ellipse. The trailing S edge 2, however, being located in the turbulent and usually separated air flow "downstream" from the leading edge may be made to any shape to suit the strength needs of the mast. For example the stiffness strength as a column) of the mast may be increased, while its weight is reduced by forming the trailing edge part 2 of the mast from metal which is thinner than that section during the roll forming process, as shown in Figure 3.

8 S0135p:mmb Figure 1 shows the body of a mast for a racing yacht 12.2 metres long, which employs the principles of the invention.

The drawing shows a longitudinal gap 5, in the side walls of the mast which disappears -entirely at the top of theimast. The edges 12 of the meta± at each side of this gap 5 are reinforced by folding or bending these edges 12 inwards towards the interior of the mast, thus forming stiffening flanges 15 to which the various fittings may be attached by bolts. 'These stiffening flanges 15 are not restricted by the invention to a simple single bend, as shown on the drawing (Figure 1).

Rather, they may incorporate, particularly for large masts (for yachts in the 20 to 30 metre length range), further bends 6 at S 90 degrees (see Figure 3) or corrugations 17 (see Figure 4) to provide an additional stiffening effect and other flanges (lips) to which fittings may be attached.

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Claims (8)

1. 2. A mast according to claim 1, wherein the fore and aft members are disposed such that the gaps separating the opposing edges at the bottom of the mast exceeds the gap separating the opposing edges at the top of the mast.
2. 3. A mast according to claim 2, wherein the fore and aft RA4 J-j Kr>', U 01 3 7 p:mmb 0O e *0 C C. S P 35 S 5@ S S. elongated shell members each define a constant cross-section, whereby the resultant mast is tapered from bottom to top.
3. 4. A mast according to any one of the preceding claims, wherein an edge of the fore and aft elongated shell members is re-enterant. A mast according to any one of claims 1 to 4, further including a bolt for joining the spacers to the fore and aft elongated shell members.
4. 6. A mast according to any one of claims 1 to 5, wherein the fore and aft elongated shell members are extruded metal.
5. 7. A mast according to any one of claims 1 to 5 wherein the fore and aft elongated shell members are rolled alloys.
6. 8. A mast according to claim 7 wherein the fore and aft elongated shell members are welded to the spacers.
7. 9. A mast according to any one of the preceeding claims, wherein the fore and aft elongated shell members are aluminium alloy including magnesium as an alloying element. A mast according to any one of the preceding claims, wherein the fore and aft elongated shell members define asymmetrical cross-sections with respect to one another.
8. 11. A boat mast substantially as hereinbefore described with reference to the accompanying drawings. DATED this 10th day of August, 1990. 3. 0 @9 C C 0 FASTS MASTS PTY LTD By Its Patent Attorneys ARTHUR S. CAVE CO. -11