WO1994011237A1

WO1994011237A1 - A boat manufactured of metal plates

Info

Publication number: WO1994011237A1
Application number: PCT/FI1993/000477
Authority: WO
Inventors: Pertti Pasanen
Original assignee: Pertti Pasanen
Priority date: 1992-11-13
Filing date: 1993-11-12
Publication date: 1994-05-26
Also published as: AU5423394A

Abstract

A boat manufactured from a metal sheet, such as an aluminium sheet. Both edges of sheet strips extending longitudinally of the boat are folded to form connecting flanges (14, 13, 15), provided therebetween with reinforcement flanges (4, 5) for supporting a floor board (9) and for building between the connecting flanges on the outside of the bottom a gap (17) for a filling compound. The sheet is folded adjacent to the outer edge and/or in the mid-section of said sheet strips (1, 2) to form a riser web (12), which is a ridge protruding from the general outline of the bottom.

Description

A BOAT MANUFACTURED OF METAL PLATES.

The present invention relates to a boat manufactured from (j metal sheets, such as aluminium sheet, comprising sheet strips extending lengthwise of the boat and fixed together at the edges thereof by means of longitudinal connecting joints, for which the strip edges are provided with bent connecting flanges.

This type of boat is easy to manufacture and it is also flexible and sturdy in structure. Especially, the boat can be provided with a hull that is long and straight for achieving a correct swimming angle and a slight water drag.

This type of boat is prior known from Patent publication DE-59732. In this prior known solution, however, attention has not been paid to designing the sheets in a manner to achieve a correct swimming angle and a slight water drag. The joints are also designed in a manner that the proper sealing thereof is not possible. Along the centre line, the fastening bolts are directly exposed to the influence of water and corrosion.

An object of the invention is to provide an improved boat, which is sturdy, light and easy to manufacture and whose bottom sheets are properly designed for reducing the water drag and sealing the joints as well as for preventing the corrosion of fastening elements in all joints.

* This object is achieved by means of the invention on the basis of the characterizing features set forth in the annexed claims.

A particular advantage is achieved by virtue that the boat has a smooth mid-section, i.e. there are no projections that would produce bubbles or vortexes within the sphere of action of the propeller. This increases considerably the propulsion power of the propeller.

The combined effect achieved by the above aspects is that the boat can use a substantially less powerful engine than the aluminum boats of a corresponding size having a traditional construction and design. Thus, savings are made both in the price and fuel economy of the engine. Hence, an engine less powerful than before will be able to lift this type of boat to "the surface plane", i.e. to swim without a detrminetal draft or displacement.

However, a problem here is that such a boat does not have a sufficient directional stability in cornering. In cornering, the boat winds up in sideslip and loses its directional stability. If the centre line of a boat is provided with a keel, it will produce bubbles or vortexes around the propeller, thus reducing the propulsion power of the propeller.

According to a preferred embodiment of the invention the problem is overcome in such a manner that on either side of the bottom mid-line, at a substantial distance from the mid-line there are longitudinal flanges, which extend from the bottom and are provided with holes or openings and which in cornering work against the sideslip of a boat. The holes or openings are necessary for the reason that otherwise the water flowing below the bottom edge of a flange prevents the sufficient immersion of the flange in water. In that case, the flange would only prevent the tilting of a boat and would not provide a sufficient adhesion with water for preventing a sideslip. When water and possible air are capable of flowing through holes in the flange, the latter remains well submerged in water for effectively preventing the sideslip of a boat in cornering.

The manufacturing of sheet sections for an aluminium boat of the invention by folding proceeds quickly since all sheet sections can be made in series with large foldings in a folding machine. At the same time, the sheets can be given a desired shape in a manner such that the bottom will be provided with so-called riser webs which have a lightening effect on the run of a boat.

The storage of folded sheet sections or semi-products does not take a lot of space since the folded sheet sections fit tightly on top of each other.

The assembly of semi-products into a finished boat can be made quickly by using bolt connections. The assembled boat is turned upside down and the joint grooves are filled with a sealing compound. Hence, the need for storage space is also reduced as most of the storage can be focused on semi-products instead of finished boats.

A particular operational advantage is achieved by virtue that the substantially flat-bottomed boat is not prone to capsize. When the boat is stationary and rests over its entire flat bottom on water, the boat is hardly at all tilted as compared to a boat having a sharp, curved bow.

A boat of the invention becomes sturdy as it only requires little or no weldings. Even at its folding points, an intact metal sheet is always stronger than a welded point. The connecting joints between the sheets provide reinforcements for for an increased boat strength. Thus, the sheet thickness can be small and it can be graduated as desired .

A boat of the invention becomes light as the boat structure requires no additional reinforcements, which are generally responsible for a substantial extra weight in larger aluminum boats.

Since the components for a boat of the invention can be fabricated in series production and the assembly work proceeds quickly, the price of a boat becomes considerably lower than that of a traditionally manufactured aluminium boat.

A boat is generally the more seaworthy the longer it is, since the bottom of a long boat reaches simultaneously the crest of several waves for less rocking and a smoother passage. In a traditionally manufactured aluminium boat each additional meter costs proportionally more as more reinforcements are required and that adds to labour, material and weight and, thus, a more powerful engine is also required. As for the bottom of a boat made by a folding machine, the making of a long folding bend does not require more time than the making of a short folding bend and, thus, the price of a longer boat is only increased by material costs and those are negligible considering the advantages gained in terms of seaworthiness. By virtue of the invention, the buyer receives, for almost the same price, a longer boat which, in addition to seaworthiness, has also more space.Since even a longer boat will be relatively lightweight, such longer boat hardly requires an engine more powerful than a short one.

The invention will now be described in more detail with reference made to the accompanying drawings, in which fig. 1 shows a cross-section of a boat of the invention; (wherein thickness of the sheets is largely exaggerated) ;

fig. 2 shows a detail of fig. 1 in a larger scale;

fig. 3 is a perspective view showing the basic design of a folded bottom sheet;

fig. 4 is a perspective view showing the basic design of a reinforcement;

fig. 5 is an end view showing the central section of the bottom of a boat according to a preferred embodiment of the invention;

fig. 6 is a perspective view showing the end of a flange used for preventing a sideslip; and

figs. 7 and 8 show a general illustration of a boat hull in a plan and a side view, respectively.

A boat according to the exemplary embodiment shown in figs. 1 and 2 comprises On either side of the centre axis longitudinal sheet strips 1 , whose both edges are folded to form connecting flanges 13, 14 provided with holes for bolts 21 or like fastening elements. Between the longitudinal connecting flanges 14 is secured a reinforcement 4 provided with holes in its lower edge in alignment with the holes of flanges 14. The top end of reinforcement 4 is bent to form a flange 4a provided with holes for fastening to a deck board 9. The reinforcement flange 4 covers only part of the height of connecting flanges 14, thereby leaving between the connecting flanges 14 on the outside of the bottom a gap or groove 17 for a sealing compound. Along the centre axis of a boat there is a web 16, covering the sealing compound gap 17 and including a flange 18 penetrating and engaging inside the sealing compound. The web 16 can be an aluminium profile made by extrusion.

Adjacent to an outer edge 20 included in the sheet strips 1 is made a riser web 12 by bending said strip 1 along a folding line 11 to form a ridge projecting from the general shape of the bottom. The connecting flange 13 providing the outboard facing side of said riser web ridge 12 is inclined towards the centre axis of a boat so as to create a sharp setback 20. By virtue of the riser web 12, a moving boat rises more readily to the surface of water, i.e. "to plane". This reduces the drag created by a boat. By virtue of the setback 20, the moving boat strives to suck air below the bottom, which further reduces the drag.

The next bottom sheet strips 2 are shaped basically the same way as bottom sheet strips 1. The sheet strips 2 are also provided with connecting flanges 15, 13 and a bend 11 to form a riser web 12 as well as a setback 20. A reinforcement web 5 fitted between flanges 13, 15 is fastened by a flange 5a to the floor board 9 and, respectively, a reinforcement web 6 fixed to flange 13 is fastened to the floor board 9. The reinforcement web 5 is secured between connecting flanges 13, 15 by means of fastening bolts 21 , said web 5 only covering a part of the height of flanges 13, 15 so as to leave a sealing compound groove facing towards the bottom. In similar fashion, dthe reinforcement web 6 is also secured between the flange 13 and the fastening flange of a side sheet 3. The side sheet 3 is fastened with an inner lining sheet 8 to the outer edge of floor board 9 and between sheets 3, 8 is possibly fitted a brace 7. The described technique produces an extremely strong box-type structure, whereby the sheets can have a small wall thickness. For example, the sheet 1 can have a wall thickness of 4 mm, sheet 2 a wall thickness of 3 mm, and sheet 3 a wall thickness of 2 mm. In fig. 1, the wall thicknesses are illustrated close to a real scale, although in other respects the cross-sectional view is a reduction in size of nearly ten times in relation to the real scale.

When the sheets are assembled together into a box structure as shown in fig. 1, the bottom is turned upwards and the gaps or grooves between connecting flanges 14, 14 and 13, 15 are filled with a sealing compound. Thus, it is important that the gaps or grooves be sufficiently large to accommodate a sufficient amount of compound, whose inherent elasticity provides continuously a good tightness in the connecting joints. If desired, the other joints can also provided with e.g. an aluminium web to serve as a filling and mechaniccal protection for the sealing compound. However, such a web is not necessary with the exception of web 16 covering the centre joint.

The sheet strips 1, 2 illustrated in fig. 1 need not be made of two different sheets. In view of reducing the number of connecting joints, said sheets 1 and 2 can be replaced with a single sheet, whose mid-section is provided with a riser web 12 made by folding. This alternative embodiment is shown in fig. 1 with dash and dot lines.

The sheet strips 1 and 2 or a respective continuous strip and the foldings made therein are straight or linear over the entire bottom of a boat. Such linear foldings can be made quickly and readily by means of a folding machine. The bow of a boat assembled from a sheet strip is fitted with a plastic-made bow piece 23, which is inserted a small distance inside the box structure. The same bow piece fits in boats of varying lengths, whose cross- sectional profile can be the same. The aft of a boat is closed e.g. with a transom 24, made of an aluminium sheet and fixed by welding to the ends of sheets 1, 2, 3.

The embodiment shown in fig. 5 is also provided with a T- web 16, covering a sealing compound gap 17 on the centre axis of a boat and including a T-stem penetrating and engaging within the sealing compound. The T-cap provides a substantially flat riser web along the centre axis of a boat.

The outer bottom surface has a substantially smooth central area, i.e. it includes no protrusions that would create bubbles or vortexes within the sphere of action of the propeller. However, it is necessary to provide longitudinal flanges, which protrude from the bottom and in cornering prevent the sideslipping of a boat and facilitate the directional control in cornering. For this purpose, on either side of the centre axis of the bottom, at a substantial distance from the centre axis there are longitudinal flanges 10 which extend e.g. 30 mm from the bottom. The flanges 10 are provided with holes or openings 10a for allowing water and possible air to flow there¬ through, whereby the flanges 10 can be immersed in water although the boat has a certain kinetic component in lateral direction, i.e. in the transverse direction relative to flanges 10.

The shape and size of openings 10a may vary a great deal. In particular, the openings 10a may be elongated slots.

The distance between flanges 10 must be substantially larger than the diameter of a circle circumscribed by the tips of the propeller blades upon its rotation.

The flanges 10 comprise one of the flanges of an L-web, while the other flange 10b is attached with an adhesive to the surface of bottom sheet 1. In the illustrated case, the flanges 10 are fastened to the riser web 12 and, thus, are located adjacent to the joint area between two bottom sheet strips 1, 2. The flanges 10 may cover most of the length of the hull of a boat. The flanges 10 may also comprise a number of shorter successive lengths of flange with necessary flow ports therebetween.

Claims

1. A boat manufactured from metal sheets, such as aluminium sheet, comprising sheet strips extending lengt¬ hwise of the boat and fixed together at the edges thereof by means of longitudinal connecting joints, c h a r a c - t e r i z e d in that at least both edges of strips (1) located on either side of the centre axis are folded to form substantially upwards or obliquely upwards directed connecting flanges (14, 13) provided with holes for bolts (21 ) or like connecting elements, that between the connecting flanges (14; 13, 15) are fitted spacer sheets (4, 5) so as to leave between the connecting flanges on the outside of the bottom a gap (17) which is filled with a sealing compound, and that adjacent to the outer edge (20) and/or in the mid-section of said sheet strips (1) is provided a riser web (12) by folding the strip to form a ridge protruding from the general outline of the bottom.

2. A boat as set forth in claim 1, c h a r a c t e r ¬ i z e d in that outboard facing side of the riser web ridge (12) is inclined towards the centre axis of a boat so as to create a sharp setback (20).

3. A boat as set forth in claim 1 or 2, c h a r a c ¬ t e r i z e d in that between the connecting flanges (14; 13, 15) coupled together with the connecting elements (21) are fitted reinforcement flanges (4, 5, 6), at least some of which extend into a space below a floor board for supporting a floor board (9) and which reinforcement flanges (4, 5, 6) only cover a part of the height of the connecting flanges (14; 13, 15) in order to leave said gap (17) between the connecting flanges on the outside of the bottom.

4. A boat as set forth in any of claims 1-3, c h a r a c ¬ t e r i z e d in that along the centre axis of a boat is fitted a web (16), covering the sealing compound gap (17) and provided with a flange (18) penetrating and engaging within the sealing compound.

5. A boat as set forth in claim 1 or 3, c h a r a c ¬ t e r i z e d in that the connecting flanges (13) folded at the outer edges of said sheet strips (1, 2) are inclined from vertical plane slightly towards the centre axis of a boat for creating said setbacks (20).

6. A boat as set forth in claim 1, c h a r a c t e r ¬ i z e d in that on either side of the centre axis of the bottom, at a substantial distance from the centre axis, there are longitudinal flanges (10), protruding from the bottom and including hodles or openings (10a) for preventing the sideslipping of a boat in cornering.

7. A boat as set forth in claim 6, c h a r a c t e r ¬ i z e d in that the distance between said flanges (10) is substantially greater than the diameter of a circle circumscribed by the tips of the propeller blades upon its rotation and that over a section between the flanges (10) the bottom of a boat is substantially smooth, i.e. there are no protrusions which would produce bubbles or vortexes within the sphere of action of the propeller.

8. A boat as set forth in claim 6 or 7, c h a r a c ¬ t e r i z e d in that along the centre axis of the boat, between the connecting flanges (14) fastening said bottom sheet strips (1) together is fitted a T-web (16), whose T- cap produces a substantially flat riser web along the centre axis of the boat.

9. A boat as set forth in claim 6, c h a r a c t e r ¬ i z e d in that the flanges (10) comprise one of the flanges of an L-web while the other flange (10b) is fixed with an adhesive to the surface of the bottom sheet (1), especially to the riser web (12).

10. A boat as set forth in any of claims 1-9, c h a r - a c t e r i z e in that the fore of the boat is fitted with a separate bow piece (23) which is made of a fiber- reinforced plastic.