Method of constructing tubular spars and apparatus for use in carrying out the method

Abstract: A method of constructing tubular spars, particularly spars for use on sailing vessels, comprises the steps of placing in a channel section mould 10 a layer or layers of fibre reinforced plastics material 13 to form part of the periphery of the tubular spar, removing side wall portions 12 of the mould 10, placing on the moulded plastics material 13 in longitudinally spaced apart relationship a plurality of formers 15, placing over the formers 15 a sheet-like skin 15 a and securing it to the formers 15, and then placing in contact with the sheet-like skin 15 a a layer or layers of fibre reinforced plastics material 16 to form the remainder of the periphery of the moulded tubular spar.

Description: This invention relates to a method of constructing tubular spars and particularly, but not exclusively, to a method of constructing tubular spars for use on sailing vessels, such as yachts, and vessels provided with auxiliary sail propulsion. US-A-3 765 360 and FR-A-2 564 416 disclose different methods of constructing masts for sailing vessels. US-A-3 765 360 teaches the use of an inner core of cruciform cross-section with foam material disposed in the open regions between the outwardly extending arms of the core, reinforcing wires secured around the foam material, and a resinous covering imbedding the wires and providing a smooth contour. FR-A-2 564 416 teaches the use of a steel core tube covered with glass or carbon fibre reinforcing material. Neither reference teaches the method of tubular spar construction disclosed by the present invention, which uses, inter alia, longitudinally spaced formers. According to the present invention a method of constructing tubular spars, is characterised in that it comprises the steps of placing in a channel section mould a layer or layers of a plastics material to form part of the periphery of the tubular spar, removing side wall portions of the mould, placing on the moulded plastics material in longitudinally spaced apart relationship a plurality of formers, placing over the formers a sheet-like skin, securing the skin to the formers, and then placing in contact with the skin a layer or layers of plastics material to form the remainder of the periphery of the moulded tubular spar. Preferably the mould has a flat base in cross-section but the base can be of any other desired cross-sectional shape, such as arcuate. The formers are preferably substantially oval in shape but they may be of any other desired shape. The formers may be removed after the plastics material has set or hardened or they may be left in situ in the tubular member so as to serve to strengthen the tubular spar. An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a cross-sectional view through a mould used in carrying out the method of the invention; Figure 2 is a cross-sectional view of the mould showing a step in the method of the invention; Figure 3 is a cross-sectional view showing part of the mould removed and formers placed on the partly moulded tubular member; and Figure 4 is a cross-sectional view of the completely moulded tubular spar still supported on the mould. The mould is indicated generally at 10 and consists of a base 11 and side walls 12 which define a channel section mould of any desired length. The side walls 12 are detachably secured to the base 11 in any desired manner, such as by screws, and the mould may be formed of wood or any other suitable material. The side walls 12 taper in width and decrease from the base 11 towards their upper end. The mould 10 is shown as having a flat base in cross-section but the base can have any desired cross-sectional shape, such as an arcuate shape. The method of constructing a tubular spar for use on sailing vessels or vessels provided with auxiliary sail propulsion, will now be described. Firstly a layer or layers of fibre reinforced plastics material 13 is placed on the mould 10 to form a part 14 which forms part of the periphery of the tubular spar. The part 14 has at each side a longitudinally extending upstanding side portion 14 a which tapers upwardly. When the plastics material 13 has set or hardened the side walls 12 of the mould 10 are removed, as shown in Figure 3, and a plurality of spaced apart formers 15 are placed in an upright position on the moulded part 14. The formers 15 are shown as having a substantially oval shape in side view, but they may have any other desired shape. The formers 15 may be spaced apart at any desired spacing and they may be formed of plywood or metal or other suitable material. The formers 15 may be set up on the moulded part 14 before the moulded part 14 has set or hardened and before the side walls 12 have been removed. The bottom portion of each former 15 fits exactly into the shape of the upper side of the moulded part 14. Placed in contact with the formers 15 is a sheet-like skin 15 a which is secured thereto by bonding or other securing means. After the formers 15 have been set up a layer or layers of fibre reinforced plastics material 16 is placed in contact with the skin 15 a secured to the formers 15 to form the remaining remainder portion 17 of the periphery of the moulded tubular member. The connection of portion 17 to the part 14 is achieved by an overlapped or lapped joint with the side portions 14 a . The skin 15 a supports the material 16. After the plastics material 16 has set or hardened the formers 15 may be removed. Alternatively, the formers 15 may be left in situ in order to strengthen the moulded tubular member. The reinforced plastics material 13, 16 may be glass or carbon or aramid fibre reinforced plastics material and the lay-up of the material may be by the wet lay method or by the pre-impregnated method using any of the commercially available resin matrix systems.

Claims: A method of constructing tubular spars, characterised in that it comprises the steps of placing in a channel section mould (10) a layer or layers of a plastics material (13) to form part of the periphery of the tubular spar, removing side wall portions (12) of the mould, placing on the moulded plastics material (13) in longitudinally spaced apart relationship a plurality of formers (15), placing over the formers a sheet-like skin (15 a ), securing the skin to the formers, and then placing in contact with the skin a layer or layers of plastics material (16) to form the remainder of the periphery of the moulded tubular spar. A method as claimed in Claim 1, in which the formers (15) are removed after the plastics material (16) has set or hardened. A method as claimed in Claim 1, in which the formers (15) are left in situ in the tubular spar to strengthen the tubular spar. A method as claimed in any preceding claim, in which a longitudinally extending upstanding side portion (14) which tapers upwardly is formed at each side of the moulded part formed by the layer or layers of plastics material (13) placed in the mould (10) and the layer or layers (16) which are placed on the skin (15 a ) overlap the side portions (14). A method as claimed in any preceding claim, in which the plastics material (13, 16) comprises a fibre reinforced plastics material. A method as claimed in any preceding claim, in which the mould (10) has a flat or arcuate base (11). Apparatus for use in carrying out the method claimed in any preceding claim, characterised in that it comprises a channel section mould (10) having removable side walls (12), a plurality of formers (15) which can be placed in longitudinally spaced apart relationship on moulded material (13) when placed in the mould, and a sheet-like skin (15 a ) which can be placed over the spaced apart formers (10) and secured thereto.

Inventors: HOWLETT IAN CHARLES, HOWLETT, IAN CHARLES
Applicants: HOWLETT IAN C, HOWLETT, IAN CHARLES
Application year: 1990
Main classification: B63B15
IPC codes: B63H9, B29D99