Abstract: A molded fiberglass-reinforced resin boat hull provided with in situ holes to accommodate through-hull fittings, such as a fitting adapted to receive a rudder post. The boat hull is molded on a female mold having locating holes drilled therein in registration with the holes to be formed in the hull. Anchored by a bolt locked in each locating hole is a plug of non-stick material which projects above the mold and has a configuration defining the hole to be formed in situ in the hull. Laid down on the female mold and surrounding the projecting plugs are the reinforcing fiberglass materials and flowable uncured resin for creating the hull. When the resin is cured, it is not bonded to the plugs and the plugs and their anchoring bolts are removed to expose the in situ holes. The finished hull is then withdrawn from the female mold.

Abstract: The manufacture of moldable concrete products with deferred mold release incorporates molding means bm1 into optimized rotary structures 1, 5, 7, 9, 12 in the form of modular cylinders having at least two faces, the cylinders being equipped and/or associated with means which group together the main work-stations MP, MT, B, D, NH so as to assign a rotary travel of more than 270.degree. and preferably equal to 360.degree. to the curing of the molded material with or without recourse to any means for accelerating the curing.

Abstract: An apparatus for forming surface texture on contoured surfaces includes a laminar, dimensionally stable, flexible mold having an impression of the surface texture to be formed on one side thereof. An adhesive material is provided on the side of the mold opposite that having the impression of the surface texture for adhering the mold to a recipient surface. A plurality of backing strips are provided on the adhesive backed side extending transversely to the longitudinal axis of the mold and are individually removable from the mold.

Abstract: A method of fabricating a sit-on-top kayak having a recessed cockpit surface and an integrally formed hatch flange surrounding a hatch opening. The hatch flange is substantially parallel to the cockpit surface. Such a kayak is formed with a mold having a void formed therein, the void having a recess portion for forming the flange. The recess portion of the void provides negative draft to the mold. Space is provided in the mold such that, during rotational molding, a mass of molten polyethylene accumulates adjacent to the recess containing the polyethylene that will form the flange. When the polyethylene cools and shrinks, the shrinkage of the mass of polyethylene pulls the flange at least partly out of its recess, allowing the kayak blank to be withdrawn from the mold.

Abstract: Rotational molding apparatus for molding a kayak and the like in a mold (12). The apparatus includes an oven (A) having an oven chamber (40). A frame (B) pivotally supports oven (A) above a ground floor (10). Mold (12) rotates about a roll axis (123) on a carriage (C) while in oven chamber (40). Oven (A) pivots about a pivot axis (72) in counter-pivotal movement. Oven pivot axis (72) is spaced a distance "d" from roll axis (123) of mold (12). This causes a pendular motion to be imparted to the mold (12). Mold (12) thus swings to and fro in an arc as oven (A) pivots. Mold (12) rotates about its roll axis (123) at the same time. A well-controlled, even distribution of plastic material in the mold occurs by this combination of motions. A desired pattern of heat distribution is applied along the length of mold (12) by a series of hot air openings (50a-50d) and a like number of openings on an opposing side of a hot air plenum (49).

Abstract: A method of manufacturing a thin-walled article of synthetic resin, in particular a large-sized article, while using an inner and an outer template, the synthetic resin being supplied via one or more apertures in one of the two template portions and whereby a partial vacuum is maintained via one or more air discharge apertures downstream of the synthetic resin front.

Abstract: A rotational molding system is disclosed in which a pair of large boat molds carried on separate carriages are alternately heated in a double open-ended oven having opposing cantilevered side sections for receiving concentric drive arrangements wherein the molds may be driven about two perpendicular axes in a rocking or full rotational motion.

Abstract: Molds for the production of fiber reinforced plastics material boat hulls filled with hard foam plastics material are constructed of plastics material and reinforced against deformation by rigid cores and tension bands to accurately shape the hulls even when subjected to high stresses during molding and foam filling. The molds have separable top and bottom halves connected around their peripheries by interfitting flanges forming a seal and also provided with ventilating channels. The outer shell of the bottom mold half between the flanges has a free catenary curve configuration supporting the reinforcing cores for the molding surface or inner shell of the mold.