GB2390573A - Kit of parts to form a boat hull - Google Patents

Abstract

A boat hull is formed as a kit of parts in which the kit comprises a hull base section 1 formed from glass reinforced plastics and a hull upper section 4 and 5 formed from sheet plywood. The hull is formed as two halves which are then joined together for use Fig. 3 and which can be stacked inside each other when not in use Fig. 4. The base section of each of the halves of the hull is formed from a single piece of glass reinforced plastic and may incorporate a centreboard case anchorage 2. A lip is formed around the upper edge of each base section to which the upper section comprising several panels of plywood is attached with screws. Joints between the base section and the upper section and the panels of the upper section are sealed with fibreglass tape and resin. The two halves of the hull can then be bolted together.

Description

Improved Kit Construction for SmaI! Boats This invention relates to an

improved form of constru*ion for small boats which facilitates home constru*ion. One of the most popular forms of hull constru*ion for small craft is moulded, glass-reinforced plastic otherwise known as fibreglass or GRP. This has the advantage of being suited to production manufacturing methods. Although a robust material and requiring little maintainence, fibreglass or GRP is difficult for the unskilled amateur to work with and therefore provides limited scope for the home constructor. Also hulls constru*ed in GRP materials tend to be heavier in weight than the equivalent hull constructed in marine grade plywood. The object of the present invention is to provide a hull constru*ion which retains some of the advantages of GRP constru*ion while facilltabng the home completion of a small boat from a kit.

According to the broadest aspe* of the present invention there is provided a floor portion of a boat hull constru*ed in moulW GRP and to which topsides are be fitted to complete the hull, the rigid floor extending only as far as the chine on a singlchine hull; a chine on a multi-chine hull; the turn of the bilge in a round bilge hull or the region of the waterline. The floor may include the transom, a portion of the transom or securing means for the transom, also it may include the stem, portion of the stem or securing means for the stem. Preferably the floor also includes essential moulded-in features such as the keel strip and bilge strokes and anchorages for the centre- board case and buoyancy bags.

Although the constru*ion according to the present invention is suitable for round bilge hull construction it is particularly adapted to single or multiple-chine constructions and is not restricted to small boats; it is for example, useful for mono and multi-hulled craft.

According to yet further aspens of the present invention there can also be provided a kit of parts comprising the above described moulded floor, and topsides formed of sheet material for example marine grade plywood and a method of securing the topsides to the hull floor according to the present invention.

An embodiment of the present invention is applied to the construction of a 'split hull' canoe sterned sailing dinghy; approximately 4.3m in length. This craft is sometimes referred to as a yl. An attribute of this 'double ended' type of craft is that it can be symmetrical longitudinally as well as laterally. This enables the craft to be built in two halves (front and rear) each ending in identical transverse frames or transoms. These end frames are locked together by removeable connectors at the the craft's midsection to form the complete hull. By constructing the rear section slightly longer than the front section and providing removeable thwarts the completed craft can be disassembled at its mid-section and the front section nested within the rear section for ease of storage and transportation.

The main components of a kit of parts enabling an amateur boat builder to complete the craft will now be descibed with reference to accompanying drawings in which; Figure 1 is an exploded view illustrating the main components of a kit of parts according to the present invention;and Figure 2 is a similar perspective view showing the final stage in construction of the split hulls; and Figure 3 is a perspective view of the completed hulls assembled for use.

Figure 4 is a perspective view of the completed hulls disassembled for storage or transport.

Shown in Fig.1 is the GRP moulded floor 1 for the forward section of the craft provided with integral centreboard case anchorage 2 and other floor mounted features such as buoyancy bag anchorages. It will be noted that floor 1 includes an integral moulded lip that protrudes above the chine and _

in- line with the angle of the topsides to be fitted. An internal wooden strip or batten 3 is provided to assist in the fixing of the pre-cut marine grade plywood topsides 4 to the outside of the protruding lip on floor 1. Also provided is a transom piece 5. A similar set of parts are provided for the rear hull section To construct the hull, the wooden strip 3 is attached to the inside of the lip on floor 1; as shown in the enlarged joint view in Fig 1. Conventional wood screws and epoxy glue are used to secure the outer plywood topsides 1 through to the inner batten 3 thereby sandwiching the protruding moulded GRP lip of the floor section within a strong laminated joint construction. The whole joint may then be further sealed with fibreglass tape and resin on the inside of the hull. The transom piece 5 is similarly anchored to the floor section.

Shown in Fig 2 are the two hull sections in their final stage of construction. The plywood topsides 4 are joined at the bow; either directly using fibreglass tape and resin or screwed and glued through a wooden stem-piece, and similarly at the stern through the transom-piece 5. Also shown is a temporary spacer bar 6 to provide the plan shape to the topsides during construction.

Strength and rigidity are imparted by the addition of the laminated wooden gunwhale strips 7 screwed and glued to the topsides of each hull section. The temporary spacer bar can then be removed on completion of the gunwhale assembly.

The two hull sections are constructed in a similar manner and the final craft assembled for use by locking the two transoms together with suitable bolted or adjustable/removeable connectors. A perspective view of the completed hulls assembled for use is illustrated in Fig 3. A further perspective view of the completed hulls disassembled for ether storage or transport is illustrated in Fig. 4 Alternative configurations for the joint between the rigid moulded floor and the topsides may be used. For example a further strip may be attached to the outside of the topsides at chine level creating a further lamination at this point.

Alternatively a deck may be fitted to the plywood topsides using conventional wooden boatbuilding techniques Athough the present invention has been particularly described with reference to a collapsible split hull sailing dory;it will be appreciated that the construction technique may be applied to any other small boat hull form without modification.

Claims (1)

1. Claims

   It will readily be appreciated that the hull construction according to the present invention affords the following advantages: 1) An effective amalgamation of two popular materials currently used in small boat construction to optimise on lightness and strength and facilitate the provision of a 'quick-build' kit.

   2) A robust means of securing sheet plywood topsides to a pre-formed GRP moulded floor section. 3)The heavier GRP material is concentrated below the waterline where it is most desirable.

   4)The hull is virtually maintenance-free below the waterline where it can be subjected to the greatest wear, tear and immersion, while above the waterline the topsides may be of faced plywood, which is of pleasing appearance and lends itself to easy customization or repair of collision damage 5)A kit according to the present invention can readily be assembled by the home constructor in a few hours using mainly conventional woodworking tools and equipment 6)The construction according to the present invention overcomes the difficulty of the amateur achieving the correct underwater shape to specified lines by providing a pre-formed rigid moulded floor which also enables the correct overall hull shape to be achieved provided the topsides have been cut to the corre* shape when in a planar condition.

   filed as f ll ws dments to the claims h Claims 1) This invention describes a boat hull as a kit of parts wherein the kit comprises a lower hull or base formed from moulded glass reinforced plastic (GRP) and the upper hull or topsides formed from sheet plywood.

   2) This invention effectively amalgamates two popular materials used in small boat construction within a kit which significantly reduces the build time and optimises on lightness, strength and versatility for customization.

   3) The method of joining these materials at a chine line or turn of bilge ensures a strong and reliable watertight hull. This is achieved by creating a screwed and glued overlapping laminated joint formed between the outer upper plywood skin; the projecting lip from the lower preformed GRP floor section and an inner wooden batten.

   4) The provision of a pre-formed GRP floor as a building platform relieves the amateur builder of forming and fairing the underwater shape and the construction provides a secure method for the attachment of the plywood topsides without the need for complex intermediate support frames. 5) The rigid split-hull kit concept which utilises this construction technique described within this invention, provides for an attractive craft which can be conveniently constructed in two separate parts and which 'nest'within each other for ease of storage and transportation.

   6) As both split hulls represent two separate craft, there is no requirement for special arrangements to create a watertight seal when the two hulls when they are connected back to back via their respective transoms.

   7) Although the embodiment of the construction concept described by this invention relates specifically to a split hull canoe-sterned Dory symmetrical both in longitudinal and plan shape; it equally applies to other types of longitudinally symmetrical craft, such as punts and catamarans etc.