Patent GB-757693-A (GB)
Title: Improvements in or relating to floats for fishing nets
IPC: A01K73/04
Filed: 1952-03-31
Abstract: 757,693. Floats for fishing nets. HANNEN, G. J. and LLOYD, F. R. March 23, 1953 [March 31, 1952; May 20, 1952; Sept. 23, 1952], Nos. 8144/52, 12755/52 and 23871/52. Class 48. [Also in Group V] A float comprises two hemispherical parts 29, 30 made of mineral fibres and a bonding agent and connected to opposite sides of a single central ring 28 formed with an integral handle 31 for attachment to the net. The ring has annular grooves to receive the edges of the hemisphere which are preferably thickened to provide a smooth joint. A hydrofoil in the form of a conical annulus may surround the float and be attached thereto at the smaller diameter of the frustum. The hydrofoil may be moulded separately or it may be made in two half rings each moulded integrally with a hemisphere. The free edge of the hydrofoil preferably lies in the diametral plane of the float. Each hemisphere is formed by applying alternate layers of glass or asbestos cloth and a bonder of the polyester group to a male or a female mould, pressure being applied on the application of each cloth layer. Each cloth layer may be made of several gores. Alternatively a mixture of glass or asbestos fibre and powdered polyester resin is entrained in an air stream and deposited on the underside of a perforated or wire mesh mould which may be rotated slowly. The perforations in the mould may be varied in size or location to vary the thickness of the float at different parts. The mass is then placed in a press on a solid mould and sprayed or painted with liquid resin. The component is cured by the application of heat and pressure or vacuum. To allow for expansion of air within the float when heat is applied in joining the hemispheres to the central ring a vent hole is formed in the float and is subsequently closed by a plug which is cured by application of local heat or by a catalyst at room temperature. An inert mineral filler such as china clay or precipitated chalk may be mixed with the fibres and bonding agent. The first Provisional Specification describes a spherical float formed by two hemispheres which are joined together at their edges. The hemispheres are made of laminations of fibre cloth and bonding agent and a handle of metal or bonded glass fibre cloth is attached to one of the hemispheres during the building process by embedding a part spherical plate on the handle between two laminations. It also describes a float made by joining two hemispheres to the ends of a corrugated cylinder. It also describes a float of substantially tear-drop shape with an extensive ridge projecting therefrom to form a hydrofoil. This float is built of two rectangular plates each having a streamlined blister and each formed in the same way as the laminated hemispheres except that the layers not only cover the mould but also extend to form the hydrofoil. Two blisters may be formed on each plate. Instead of the plane of junction being in the plane of the plates it may be at right angles thereto and transverse or longitudinal to the blisters. It also states that both male and female moulds may be used in constructing each part of a float and that a float may be formed from a single laminated part by placing the part in a split female mould and applying either vacuum to the mould or pressure to the inetrior of the float before the bonding agent has set. The third Provisional Specification states that a half of a handle may be moulded near the lip of each hemisphere of a spherical float so as to butt together when the two hemispheres are-joined, the joint line of the handle being either along its medial plane or along its minor axis.