GB2448779A - Prefabricated flat panel boat kit - Google Patents

Abstract

A prefabricated boat kit of interconnected flat panels (38, Fig 1) which is cut from common sheet material features simplified alignment and assembly measures for ease of unskilled construction, to achieve an intersecting planar hull form. The boat once constructed has a flat-sided three-dimensional flotation hull form, with fillet pieces 11 and (19, Fig 1) inset at jointing edges or corners and cross-bracing panels 13 spanning the assembled hull form as stiffeners and supports. The completed boat also has deck floor panels (22, Fig 7). Tension ties (33, Fig 3B) may be used to bind together components for edge bonding.

Description

Boat Construction Kit This invention relates to boat construction kits

and is particularly, but not exclusively, concerned with a simplified component (pre-)fabrication, mutual registration, alignment, assembly and connection sequence or assembly schedule.

Build considerations aside, hull behaviour is dictated largely by submerged hull profile, displacement and centre of gravity (c. of g.) in relation to centre of hydrostatic pressure or overall buoyancy and stability considerations. Movement or transitions of c. of. g are also a consideration for dynamic stability. Hull form above the waterline superstructure has a bearing upon wind resistance and vulnerability to uncommanded' wind steerage. A complex (say double) curvature may promote a streamline aerodynamic and/or hydrodynamic performance, but increases build difficulty. This may simply be uneconomc for lower cost hulls.

Overall hull profile and surface contours impact upon the number and complexity of components, so a flatter less curvilinear format is envisaged for simplicity of construction and alignment. An intention of the present invention is that minimal bespoke jigs or fixtures are required and as far as possible, juxtaposed component elements are self-locating and/or self-aligning. For amateur self-build, some in-built or inherent guidance, if not fail-safe, construction technique is desirable.

Flatter, if not wholly flat, panels are simpler to fabricate, align and assemble than curved forms, not least complex curvatures in two planes. Impaired or limited hydrodynamic performance, attendant profile or form drag, of a more slab-sided hull structure may arise, but this is not a prime consideration for low-speed craft where buoyancy, fbtation stability and self-righting ability is of greater importance.

FIat panels, with straight (recti-)linear bounding edges, are more readily juxtaposed and aligned than curved panels. Moreover, butt jointing and bonding is more secure if bending stresses which might otherwise tend to flex panels relative to one another and so to pry joints apart are minimised.

A first-time builder with minimal tools and experience would likely find boat building a daunting challenge absent a transparent, user-friendly design, the relationship between whose component parts is more readily understood from visual inspection.

Prior Art

There have been many and diverse proposals for kit boats of varying complexity, but the ultra-simplistic are rare. The challenge is component simplicity without an unduly compromised assembled form or impaired performance. Aesthetic considerations are not altogether inconsequential, not least if what looks right is and behaves right' as an engineering structure.

Statement of Invention

A boat kit comprising a plurality of generally flat panels, of pre-delineated or pre-cut contour and outer profile; configured for mutual juxtaposition in edge-to-edge relationship, to facilitate mutual jointing and bonding, to create a flat-sided, 3-D flotation hull form, with fillet pieces inset at jointing edges or corners, and cross-bracing panels spanning the assembled hull form, as stiffeners and supports, along with deck floor panels In practice, panels would be prefabricated, say by computer controlled laser-cutting from sheet material, sub-divided in an economical way, from a collection of panel patterns. Rather than single sheets, multiple overlaid sheets can be cut together in a stack at one time. Stiffener, reinforcement or bracing ribs may be cut from the same sheet and can be stacked in laminations for greater overall strength and localised impact resistance. Mechanised and indeed automated cutting, such as from CNC jig or band saws or laser cutters, is more accurate consistent and faithfully repeatable than reliance upon an individual constructor.

The intention is to minimise the need for specialist jigs, fixtures and fittings, which add to expense and assembly complexity and yet are wasteful for one-off usage if they are then simply discarded. Simple ties or tension straps may suffice to pull elements together into intimate contact preparatory to mutual bonding.

As with cutting, some pre-drilling is conveniently undertaken to receive locating pegs, lugs, dowels or fasteners in a panel assembly, relative location and joining step. This relieves the assembler from the laborious tasks of measurement, drill index position, drill size selection and orientation.

As to overall assembled hull profile, a canted or inclined prow is envisaged, along with a shallow V-bottom (planar intersecton) form with superimposed underside ribs or rubbing strips. Opposite sides might be canted slightly outward. An inwardly canted upper edge fillet might also feature in some variants. Hull depth might be even or taper slightly fore to aft. Similarly, in plan-form, a uniform width of a modest taper fore to aft might be employed. A rear panel can be sUffened and profiled to mount an outboard engine.

As a general overall guide, bottom and sides use complementary opposed pairs of panels, bridged at each end by stern and bow boards. A series of longitudinally-spaced transverse ribs span between opposite side upstands and locate to the base panels. Ribs in each transverse array may comprise a corner rib at each side and an intervening spacer rib with a shallow V shape to define the hull base form. External longitudinal rubbing strip ribs are fitted to the underside of each base panel. Inner floor panels surmount the transverse ribs. Inward canted side rails top each side and are set by top corner chamfers on an upright stern board.

Embodiments There now follows a description of some particular embodiments of a boat construction kit according to the invention, by way of example only, with reference to the accompanying diagrammatic and schematic drawings, in which Figures 1 shows a (complete) collection of components laid out in an array (reflecting their derivation from a common flat sheet) for ease of reference, along with an indication of the number off' or repeat; Figures 2A and 2B show construclion of a hull transverse or cross-bracing frame; More specifically Figure 2A shows a juxtaposition of multiple individual cross-frame lamination elements ready for mutual assembly and bonding; Figure 2B shows the laminations of Figure 2A assembled into a laminated composite assembly with upright and slightly splayed outward end posts carried upon a spreader beam with a shallow V-section underside profile to determine a hull base form of planes meeting or intersecting at a common edge; Figures 3A through 3F show a 3D intermediate boat hull assembly with local enlargement detail of certain panel joints; More specifically Figure 3A shows a notional translucent view for ease of reference of a boat hull frame assembly, with infil panels depicted in outline; Figure 3B shows a location and clamping tie detail of a joint between a median transverse rib assembly / hull cross bracing frame and a side wall panel: Figure 3C shows corner bonding fillet detail for the joint of Figure 3B; Figure 3D shows a cross-section of a hull spine jointing fillet/central jointing fillet with lonitudinaI grooves to receive opposed hull base plates set at a shallow V relative inclination; Figure 3E shows a butt-joint variation of Figure 3D; Figure 3F shows a cross-section view of a doweling length used to reinforce and seal joint between side panel and hull base plate; Figures 4A and 4B show underside three-quarter perspective hull views, revealing a shallow V' profile form of planar intersection, with side corner rubbing strips and centre spine joint; Figure 5 shows a translucent 3-D upper perspective view revealing demountable inset deck boards between cross-frames; Figures 6A through 6F show various different hull seating configurations; More specifically Figure 6A shows an upper 3-D perspective view of an assembled full with stepped waisted profile upper side cant rails, and fitted out with stepped bow seats and with an indicative outhoard motor mounted upon a stern board; Figure 6B shows an opposed side and stern end seat combination; Figure 6C shows a centre and stern seat combination; Figure 6D shows a movable cross-board and wrap-around stern corner seat configuration also with an opposed side seat; Figure 6E shows a multiple individual opposed side seat and wrap-around stern corner seat configuration; Figure 6F shows a multiple individual opposed side seat from bow to stern; Figure 7 shows an upper 3-D perspective view of an assembled hull depicting a demountable split deck centre board, a mooring post or flagpole and cylindrical buoyancy bags at prow or bow and stern; Fi9ures 8A through 8C show local hull cross-sectional detail of transverse seat to top rail mounting; More specifically Figure 8A shows an isometric cut away view of a boat hull with a transverse seat to top rail mounting; Figure 8B shows a sectional view of a boat hull with a movable transverse seat to a rail mounting upon rail supports of rib arms and a spring loaded lock to fix seat position; Figures 9A through 9D show variant hull forms; More specifically Figure 9A shows a hull with a pair of oars demountably fixed to opposed side walls, and a rudder for steerage located at the stern; Figure 9B shows a pair of hulls, one larger than the other, confvured to inter-nest when stored one inside the other.

Figure 9C shows a hull of Figure 9A with a sail and mast Figure 9D shows a hull configured with two outboard motors at the stern, and a steering system or he/rn located at the bow.

Figures 1OA through 21 depict assembly sequence of a boat kit, and are taken to be se/f-explanatory when viewed in conjunction with disclosure and earlier Figures.

Referring to the drawings A prefabricated boat kit 10 comprises a set of precut components depicted in Figure 1, taken from a common sheet material, such as marine grade piy (ie with water resistance bonding between ply layers). A cutting layout or form, not shown, allows maximum sheet utilisation by inter nesting the elements. Some items are replicated, typically duplicated or in pairs, as the hull is symmetrical about a longitudinal centre line. A central jointing fillet 11 bridges opposed hull base plates 12.

Similarly, there are three sets of transverse rib assemblies 13, each of two rib arms 34 pieces and paired transverse spacers 36, whose combined upper edges support deck panels (not shown in Figure 1). Rail support pieces 37 to reinforce protrusion of the rib arm 34. A Rail (not shown) can then be fitted onto the rib arm ledge, and a sliding seat/ bench allowed to slide along this rail. A bow plate 15 closes the front edges of opposite side panels 16 and a stern plate 17 their rear edges. A triangular fillet platel8 joints opposed hull base plates 12 and opposed side panels 16. A pair of rubbing strakes 25 are fitted at the junction between sides and base at outer base edges. At the upper edges are fitted canted top rails 20 which sit in respective chamfers 21 at the stern plate 17 upper outer corners. Triangular fillets 19 are fitted between stern plate bottom corners and sides.

Stern plates with notch cut-out 1 7a are for use with a petrol engine, but this not necessary for un-powered boats or those with a telescopic electric engine, which would have a straight cut stern plate 1 7b.

Panels feature can feature pre drilled holes to allow panels to be secured using cable ties 33, reducing the need for jigs & clamps.

Figure 2A shows paired of pre-drilled holes in upstanding side rib arms 34, which are juxtaposed with corresponding holes in the side panels 16. A temporary tension strap or draw tie 33 (such as a disposable self-locking plastics cable tie) can be threaded to pull and bind the elements securely together during edge bonding, as reflected in Figure 3B. Tie tension draws a rb upstand closely to an inner face of a side wall panel, bringing the planes rectilinear. A continuous bondhg filled, such as a water proof epoxy resin, is laid into the opposed corner edges between rib and side panel.

Rail supports 37 reinforce protrusions of the rib arms 34 which can support a rail, in turn supporting a movable cross board 54, to provide a sliding seat (as shown in Figure 8B).

Deck floor panels 22 (not included in the component collection of Figure 1) are overlaid upon transverse laminated beam members 23 of rib assemblies 13. The rearmost deck panel is also supported by triangular stern corner fillets 19. A removable panel 30 is depicted in Figure 5 with an attached cross beam 31.

Side strips 24 are also secured to the inner faces of front side panels 16 to support cross bench panels 46 shown in Figure 6A.

A notch 32 in the underskie profile of each transverse spacer 36 accommodates and locates a centre jointing fillet 11 of triangular cross-section (Figures 3A, 3D and 3E) orientated with a flat face lower most to merge with the hull bottom plate profile (as reflected in Figure 4A).

The jointing abutment edges of panels are profiled (eg chamfered) to maximise the mutual contact area and thus the effect of edge bonding.

Outboard side/rubbing strakes 25 are fitted to the lower outer faces of opposite side walls 16 as reflected in Figures 3D, 4A, 4B and 5.

The basic hull format cannot be fitted out with various seating arrangements, of which Figures 6A through 6F are merely non-exhaustive examples. A combned or convertible table and/or seat (not shown) might be fitted.

Figure 6A shows a modest outhoard motor 40 with its mounting 41 clamped to the notch 32 in the upper stern plate 17.

The stepped bow seats 46, 40 of Figure 6A not only provide seating, but serve as a convenient intermediate step level for ease of access into and out of the boat. They are also important in reinforcing the boat hull, not least since, positioned at the bow, they promote hull integrity, parlicularly during a head-on collision, which might otherwise risk bursting open the hull seams with catastrophic consequence of a sudden wholesale loss of buoyancy and sinking without warning.

Upper canted edge rails 20 merge with end pieces 35 just overlying a front upper cross-board 46. Supplementary mounting detail is shown in Figures 8A and 8B. The slope or cant provides a user-friendly hand-hold or shield.

Figure 7 shows an alternative removable deck plate 30 for access, inspection and baling or drainage (by inversion) of the bilges. Optional supplementary buoyancy bags (not shown) could be located under the deck plates. Alternatively, (cylindrical format) buoyancy bags 49 could be disposed at the bow and/or stern, desirably protected beneath seating, to free up sub-deck space for storage.

An optional mooring post 57, with a possible dual function as a flag pole in a children's version, could be fitted at a hull corner as shown in figure 7 at the prow.

Figures 8A and 8B depict a reinforced rib arm 34, supporting a rail upon which a movable cross bench 46 is slidably mounted, a spring-loaded lock 45 allows the bench to be fixed in a chosen position.

Figure BC depicts and alternative rib arm reinforcement, featuring a rail support 61.

Again the variant forms of Figures 9A through 9D are merely indicative, not exhaustive. Figure 9C shows stern mounting of a rudder 44 for rudimentary steering and stowage of oars 45 upon cant rail fittings. Figure 9A shows inter-nesting of scale hull sizes for compact storage and transport. Figure 9D reflects a twin hull form bridged by a common top deck. Figure 9B depicts a mast 42 and sail 43, for which a fixed or retractable keel would be required. Scale

The various component forms depicted can be expressed to different scales. Thus the Applicant envisages two prime hull lengths respectively of circa 8 feet (2.44m) and 10 feet (3.05m). Transverse span or beam would be in proportion to longitudinal span. Other hull lengths, particularly beyond 10 feet, such as circa 12 feet (6.40m), are also contemplated, Imperial measurements are quoted as traditional in boat building, but metric equivalents can be taken as read by routine conversion.

Decoration A pre-assembly fragmented structure allows pre-painting of individual panels with complex effects upon assembly, leaving for a flial touch up or over-varnish.

In any event the assembled form also lends itself to decoration.

Component List boatkit 11 central jointing fillet 12 hull base plates 13 transverse rib assembly 14 deck panels bow plate 16 side panels 1 7a stern plate with notch cut-out 1 7b stern plate without notch 18 triangular (bow) fillet plate 19 triangular (stern) corner fillet canted top rails 21 chambers 22 deck floor panels 23 transverse beam rubbing strakes 28 epoxy resin bonding 29 buoyancy removable panel 31 crossbeam 32 notch 33 tension tie 34 rib arm end piece 36 transverse spacer 37 rail supports 38 panel pieces outhoard motor 41 motor mounting 42 mast 43 sail 44 rudder oars 46 cross bench 47 helm 48 spring loaded lock 49 cylindrical buoyancy bags bow seat 51 side seat 52 stern end seat 53 centre seat 54 movable cross board stern corner seat 56 individual side seat 57 mooring post / flag poles 61 rail support 62 dowel

Claims (5)

1. Claims 1.

   A (pre-fabricated) boat kit comprising a plurality of generally flat, or planar, pane (38), of pre-delineated or pre-cut contour and outer profile; configured for mutual juxtaposition in edge-to-edge relationship, to facilitate mutual jointing and bonding, to create a flat-sided, 3-D flotation hull form, with fillet pieces inset at jointing edges or corners, and cross-bracing panels spanning the assembled hull form, as stiffeners and supports, along with deck floor panels.
2. 2.

   A boat kit of Claim 1, configured for a hull length of circa 8 feet (2.44m).
3. 3.

   Aboat kit of Claim 1,, configured for a hull length of circa 10 feet (3.05m).
4. 4.

   A boat kit of Claim 1, configured for a hull length of circa 12 feet (6.40m).
5. 5.

   Aboatkitofclaim 1 assembled using tension ties (33) to facilitate jointing and bonding of panels (38)