GB2275646A - Method of construction of marine hull - Google Patents

Abstract

A marine hull of sandwich construction is constructed from a single flat panel on which the subsequent bending and culling is marked out while still flat. The panel is first bunt to a constant section, comprising bottom panel 4, radiussed chine 5 and topside panels 6. The bent panel is then cut and sections removed (Figs 4 and 5, not shown) and the cut edges joined to form the hull. The shaping, by cutting away and cutting into and the bending of that constant section is done in such a way that most of the time consuming tasks normally associated with such construction are eliminated. i.e. without the need for the usual framing, measuring, setting up and assembly of numerous pieces associated with other one-off methods. The hull is completed after shaping by adding the remaining material required to nest the scantling specification to the skins. The invention particularly applies to "radiussed chine" hulls, consisting of topsides, bottom panel and radiussed chine between. <IMAGE>

Description

ONE-PIECE MARINE HULL The invention relates to the construction of marine hulls using fibre-reinforced plastic (FRP) sandwich construction (lightweight core material with dense skins on each side).

The majority of FRP hulls are made in expensive production moulds. t present, where the expense of the production mould is not justified, usually due to the requirement for a single or a small number of hulls, various methods are used. These methods are called "one-off" methods. Such methods are comparatively time consuming, require considerable skill, assembly from numerous pieces and most require shape control in the form of a number of accurately shaped and positioned frames or bulkheads.

Hulls are usually designed to be either hard chine, where the shape is produced from developed flat panels or sheet material or from shapes that include compound curvature. The compound curvature can be the whole hull or just part of the hull between developed panels.

The "radiussed chine8 hull is a well know shape that allows most of the hull area to be built from developable panels but still presents the builder with time consuming operations to control the shape and to achieve the compound curvature of the radius chine area.

According to the present invention, the construction of the sandwich hull starts from a single +lat panel on which the subsequent bending and cutting is marked out while still flat.

The working and the bending of that panel to form the required shape is done in such a way that most of the time consuming tasks normally associated with such construction are eliminated. i.e.

without the need for the usual framing, measuring, setting up and assembly of numerous pieces associated with other one-off methods. The invention particularly applies to "radiussed chine" hulls, consisting of topsides, bottom panel and radiussed chine between. Such hull designs are chosen for single hulled yachts or commercial craft or for catamarans or trimarans.

The manufacture of a hull, using this "one piece" method, consists of the following operations 1. Making a single flat panel which is partly of the complete sandwich of outside skin, core and inside skin and partly of one skin and core only. The panel may be initially made in two or more parts and joined before proceeding to 2.

2. The marking of the panel, with control lines and marks for the subsequent operations on that panel. Where the panel is made on a mould table, the marks can be made initially on the table in such a way that they transfer to the panel when the panel is lifted.

3. Bending the panel to a constant section shape, which is the shape, in section, of the maximum section. The area with the single skin only will allow the panel to bend without forcing or building in stresses. R small number of similar outside frame supports control the shape at this stage.

4. Adding an inner skin to the sandwich where the second skin was originally omitted. This completes the sandwich for the whole of the length of the bent panel.

5. Tapering the ends as required by a. removing a section from the keel line. The shape of the section removed is a slim, approx. "triangular" shape where the long sides of the "triangle" are curves.

b. making a number of cuts and removing some material by cutting into the bottom panel and the chine area to allow the sides of the hull to be bent, to close thieftapshen the "triangular" section was cut away.

Normally the stern will be tapered by cutting away a "triangle" that is entirely within the bottom panel. Rt the bow the "triangle" will include an area of the chine radius, to bring the topsides together at the lowest point of the stem or topside panels.

Adding material to bond the cut areas together.

7. Rt this stage the hull will be a complete shape but with a straight or near straight keel line when viewed in elevation. If the design requires the keel line to be less straight (rising towards both the bow and the stern from the deepest point in the midships area) a section is removed from the lower edge of the topsides and cuts made into the radiussed chine area to enable the keel line to be bent towards the deck line. Trim each end of the topsides as required.

8. Adding to the skins both inside and outside to complete the skins to the required scantlings over the area that has been worked.

The usual time consuming operations of a. working with many pieces or parts b. making and setting up of a number of very accurate frames to control the shape and c. the required checking of the shape are eliminated by x. working from a single panel for the whole of the hull, y. starting by the setting out of all the control markings on that panel while still flat and z. by making use of the stiffness of the hull side panels (scantlings are designed to take up the required curve without forcing) that then take a fair line in the final shape, to control the overall shape. i.e. The topside panels and deck line are easily bent to shape using the above procedure and the rest of the shape is built onto it.

Bending a single skin and core, then adding inner skin to complete a sandwich structure, makes a rigid shape and maintains its shape when cut and "tailored" as described above.

Many core materials such as some PVC foams and honeycomb will bend without damage to the final sandwich structure. Other materials my require to be cut to suit. Rigid PVC Foam is often supplied already cut to be able to bend in this way.

The sandwich materials will normally be as follows : Skins - Fibres of glass, kevlar or carbon in polyester resin or epoxy resin or similar. In some instances, plywood can be used in the skins.

Core - Foam, honeycomb or balsa.

fi specific embodiment of the invention will now be described by way of the example with reference to the accompanying drawing in which Fig 1. Shows a section through a panel with the relative positions of the core material and the skins prior to bending.

Fig 2. Shows a section through the constant section shape after bending.

Fig 3. Shows in perspective, the constant section shape as produced after bending as fig 2.

Fig 4. Shows the constant section as fig 3 in plan view, with hull upside down, and with the marking of the sections to be cut away and the cuts to achieve the tapering at bow and stern.

Fig 5. Shows the elevation view of the hull and the marking of the cut away areas and the cuts required to bend, prior to bending the keel line.

Fig 6. Shows the final hull shape in perspective.

Refering to the drawing the hull panel comprises a core I and skins 2 and 3. The hull shape comprises bottom panel 4, radiussed chine area 5 and topsides 6.

The ommission of one skin, of the flat panel, from the chine area allows the panel to bend from the flat panel to the constant section shape as shown in fig 2 and .

The cutting away of the "triangular" sections 7 and the cuts S, made into the bottom panel and the radiussed chine area, cutting in direction away from the keel, as illustrated in fig. 4, allows the ends to taper.

The cutting away of the "triangular" sections 9 and the cuts 10 into the radiussed chine, cutting in direction away from the topsides, as illustrated in fig 5 allow the keel line to bend and fill in the area from where the cut away sections were removed.

Claims (3)

CLAIMS.

1. fi marine hull of sandwich construction that starts from a single flat panel on which the subsequent bending and cutting is marked out while still fiat. The panel is first bent to a constant section. The working and the bending of that panel to form the required shape is done in such a way that most of the time consuming tasks normal lav associated with such construction are eliminated. i.e. without the need for the usual framing, measuring, setting up and assembly of numerous pieces associated with other one-off methods. The invention particularly applies to "radiussed chine" hulls, consisting of topsides, bottom panel and radiussed chine between. Such hull designs are chosen for single hulled yachts or commercial craft or for catamarans or trimarans.

2. n marine hull as in claim 1 in which the panel is first bent to a tapered shape. i.e. the section is wider at one end than the other.

3. marine hull as in claim 1 or 2 in which the angle of the topside panel may vary along its length. i.e. with a varying radius or curve at the chine.