초록 ▼

A bottom hull for a jet type watercraft is comprised of fiber reinforced plastic (FRP) outer liner and a separately produced FRP inner liner having stiffeners within the inner liner and which are joined uniquely to form a sandwich construction which provides a lightweight hull with increased strengt

A bottom hull for a jet type watercraft is comprised of fiber reinforced plastic (FRP) outer liner and a separately produced FRP inner liner having stiffeners within the inner liner and which are joined uniquely to form a sandwich construction which provides a lightweight hull with increased strength, increased speeds, and steady planing of the craft over the water.

대표청구항 ▼

1. In jet type watercraft having a hull, said hull having a top portion and a bottom portion, the improvement in said bottom portion comprising; an outer liner and an inner liner spaced therefrom, both liners being pre-molded of gel-coated exposed surface fiber reinforced plastic, said outer line

1. In jet type watercraft having a hull, said hull having a top portion and a bottom portion, the improvement in said bottom portion comprising; an outer liner and an inner liner spaced therefrom, both liners being pre-molded of gel-coated exposed surface fiber reinforced plastic, said outer liner having in transverse cross-section, a generally Vee-shaped outward portion intersecting at exterior chines with upwardly and outwardly directed sides and outward then upward lips, said inner liner in said transverse cross-section being generally Vee-shaped in its central portion intersecting at interior chines with upward sides thence extending substantially horizontally outward to downwardly extending lips positioned inside said upward lips, said inner liner having reinforcing wood stringers premolded therewith as a means to attach propulsion equipment and accessories thereto, said inner liner being spaced from said outer liner, said space being filled with polyurethane foam. 2. A method of making a bottom hull including stem, sides, and transom for a jet type watercraft comprising the steps of: forming, in a first open mold, an outer liner comprised of a gel-coat exterior and a fiber reinforced plastic interior, said outer liner being in transverse cross-section of a generally Vee-shape defined by a central portion and upwardly stepped outer portions on each side of said central portion intersecting at exterior chines with upwardly and outwardly directed sides and outward then upward lips; leaving said outer liner in said first open mold; forming in a second open mold an inner liner comprised of a gel-coated interior and fiber reinforced plastic, said inner liner, in transverse cross-section, having a generally Vee-shaped central portion that is substantially parallel to said central portion of said outer liner with upward interior sides, thence extending essentially horizontally outward forming a gunwale to downwardly extending lips, said inner liner including reinforcing and other means to support propulsion equipment for said watercraft; applying a polyurethane foam forming material to said interior central portion of said outer liner; removing said inner liner from said second open mold; positioning said inner liner into the interior of said outer liner whereby said central portions are aligned and said downwardly extending lips of said inner liner nest inside said upwardly extending lips of said outer liner and whereby a longitudinal space is formed on each side between said upward interior sides and said gunwale of said inner liner and said upwardly directed sides of said outer liner; positioning a press mold of shape substantially equal to said interior configuration of said inner into the inner liner to apply pressure to said inner liner and outer liner; and injecting into said longitudinal side space polyurethane foam forming materials. 3. A jet type watercraft having a hull, said hull having a top portion and a bottom portion, said bottom portion comprising: an outer hull and a nested inner hull spaced therefrom, the contour of the outer hull having, in transverse cross-section, a keel, a central portion extending on each side of said keel to a left and a right upward step thence outward to a port chine and a starboard chine thence upwardly forming sides of said hull to a rub-rail; the contour of said inner hull having, in said transverse cross-section, a central portion generally parallel to said contour of said central portion of said outer hull to a left and a right upward step which abuts with said respective left and right upward steps of said outer hull to thereby create a substantially sealed space between said outer hull and said inner hull, said sealed space being filled with a polyurethane foam, said contour of said inner hull continuing with upward port and starboard interior sides to a substantially horizontal gunwale thence outward to sealed engagement with said rub-rail, said interior sides being spaced from said respective port and starboard sides of said outer hull forming respective port and starboard flotation chambers. 4. The craft of claim 3 wherein said flotation chambers are polyurethane foam filled. 5. The craft of claim 3 wherein said rub-rail is comprised of an upward lip in said outer hull, a downward lip in said inner hull which nests inside said upward lip of said outer hull. 6. The craft of claim 3 wherein inner and outer exposed surfaces of said outer hull and said inner hull are smooth. 7. The craft of claim 3 wherein said outer hull and said inner hull are formed of FRP, with smooth gel-coated interior and exterior exposed surfaces. 8. The craft of claim 7 wherein said inner hull includes on an unexposed side of said central portion, longitudinal and transverse reinforcing wood stringers premolded therewith, and at least one wood plate in said port and said starboard sides thereof. 9. The craft of claim 8 including a bottom opening adjacent a transom, a housing covering said opening and bonded to said inner hull, and means to attach a jet propulsion system to said housing. 10. The craft of claim 3 wherein said top portion of said hull rests upon and is bonded to said gunwale of said inner hull and further including an outer downward lip that forms the outside portion of said rub-rail.