Abstract: This invention relates to a method of boat hull construction. The method comprises mounting a former having an external configuration conforming to the internal configuration of the hull to a vacuum forming bed, heating a sheet of thermo-plastic material, supporting the heated sheet above the former by supporting one side of the sheet material on a first frame member, and supporting the opposed sides of the sheet to each side of the one side from a pair of second frame members. The second frame members are pivotally mounted to the first frame member about an axis perpendicular to the plane of the sheet material. On lowering the sheet over the former air is extracted from the space between the former and sheet material.