Moulded boat hull with integrally contained reinforced inserts

#This invention relates to a reinforced integrally molded plastic boat hull structure of the type shown in U.S. Pat. No. 5,458,844, which is formed of peripherally joined low density polyethylene inner and outer shells. Preferably a plurality of longitudinally extending stiffening members connect the interior region of the inner and outer shells. In accordance with the present invention, regions of localized high density polyethylene reinforcement members are integrally molded into the hull to strengthen the hull at high load points and distribute the load. This significantly reduces the concentration of forces, which might otherwise lead to early hull damage. More specifically, the present application is directed to the addition of such reinforcement members at the locations of the bow having threaded inserts for attachment to the cleats or other members, which would tend to create regions of high localized forces.

#The materials of construction for a boat hull require the combination of formability, strength, attractive appearance, low maintenance and durability in the marine environment. For a very substantial period of time boat hulls of varying sizes have been constructed of wood. However, such boat hulls disadvantageously require substantial maintenance and are subject to deterioration. In addition wooden hulls require substantial labor costs for construction and use of increasingly costly wood materials.

#More recently boat hulls have been increasingly constructed of fiberglass. Fiberglass materials can be formed into the shape of boat hulls and the resulting boat hull structure is sufficiently strong for boat hulls and advantageously has greater resistance to deterioration in the marine environment as compared to wooden boats. Hence, fiberglass boat hulls have become an increasingly popular material for boat construction.

#These as well as other of the present invention will become apparent upon consideration of the following description and drawings.

#FIG. 1 is a side view of an integrally moulded plastic boat hull structure, showing the location of a typical region adapted for the reception of the reinforcement structure of the present invention.

#FIG. 2 is a cross sectional view corresponding to a half section at an intermediate section of the moulded boat hull, as shown by arrows 2--2.

#With respect to FIG. 1 of the drawings there is provided an integrally moulded plastic boat hull generally indicated by arrow 1. As is the subject of aforementioned U.S. Pat. No. 5,458,844, the hull 1 is formed from a moldable plastic material and comprises an inner, or deck, shell 2 and an outer, or hull, shell 3. The inner shell 2 is joined to the outer shell 3 along a joint line 4. The outer shell 3 comprises a keel 5 and outboard planing strake or chine 6 and planing strake 7 disposed between the keel 5 and joint line 4 and extending longitudinally from the region of the bow 8 to the transom region at the stern 9 of the hull 1.

#The hull 1 is preferably formed by means of a rotary shell mould with complementary inner and outer shell moulds (as shown in U.S. Pat. No. 5,458,844) forming the boat hull unit as shown in FIG. 2, which is peripherally joined at 11. Longitudinal stiffening members are advantageously provided which have thickened lower faces 25, 26 and 27, upper flanges 28, 29 and intermediate webs 30. The stiffening member provide a series of longitudinally extending internal supports.

#During moulding of the hull, the complementary inner and outer shell moulds are separated by a predetermined amount and a polymer moulding powder poured in the space between mechanism (not shown). The moulding powder may typically be a low density polyethylene, such as Dupont 8405 polyethylene, although other polymer moulding powders may be used. The assembled mould filled with the moulding powder is then heated by a suitable means, such as by a gas fired oven, into which the assembled mould may be placed, to a predetermined temperature, and is rotated and tilted according to a predetermined program cycle, and the complementary moulds moved towards each other. This ensures that the powder contained within the assembled mould flows over the entire opposed surfaces of the inner and outer shell moulds and melts to form a skin of a predetermined thickness. During this process the mould plastic is still in a soft state. Plastic at the opposed peripheral mould surfaces will be squeezed towards the interior of the mould so that a smooth peripheral the joint of a predetermined thickness will be formed at 11.