Method for producing a hull for a watercraft

Abstract

A method for producing a hull for a watercraft, in which a negative mould (1) of the hull, defining an outer surface, is provided and multiple blanks are placed into the negative mould (1), pre-positioned and pressed against the negative mould (1) by a vacuum being applied. Great accuracy and straking lines are achieved by the air between the negative mould (1) and the blanks (5, 6), consisting of laminated wood, being extracted through suction openings (7) in the negative mould (1) and the blanks (5, 6) then being connected to one another while the vacuum is maintained.

Description

[0001] Method for producing a hull for a watercraft

[0002] The invention relates to a method for producing a boat hull for a watercraft, in which a negative mold defining the outer surface of the boat hull is provided, several blanks are inserted into the negative mold, pre-positioned and pressed onto the negative mold by applying a vacuum.

[0003] In the sense of the invention, the hull is referred to as the hull, or the deck or the hull including the deck, with or without the transom.

[0004] It is well known that laminated wood is an excellent construction material for boats and other watercraft. It makes it possible to achieve high strength with low structural weight.

[0005] Basically, the boat hull to be manufactured is divided into several segments, each of which represents a developable surface and corresponds to a cut.

[0006] A well-known method for constructing a boat hull from multiple cut pieces of plywood is to first create an internal structure from frames and the like, and then lay the individual cut pieces on top, clamp them, and glue them together. This process is very laborious, and it is very difficult to create straight lines, meaning that the curvature of the boat hull—apart from any edges, such as those found on a chine—is subject only to uniform and subtle changes. Very often, the undesirable "hungry horse" phenomenon occurs, in which, particularly on the hull, more strongly curved sections at the frames alternate with less curved sections in between. This is not only visually unsightly but also impairs the hydrodynamic properties of the hull.

[0007] A further development of the above process is the so-called stitch and glue process, in which the individual cut pieces are connected by wire loops during the manufacture of the fuselage, thus essentially defining the final shape. However, even with this process, it is not possible to achieve a high level of precision while simultaneously reliably preventing the "hungry horse" phenomenon.

[0008] Methods are known from GB 111 843 A or US 2,411,497 A in which the approach is reversed. In this case, blanks are placed in several layers coated with adhesive over a mold, which is a positive mold, i.e. the surface of the mold represents the inside of the future hull. The blanks are covered with a film, the air between the mold and the film is sucked out, and the layers are pressed onto the mold using the film under atmospheric pressure or the increased pressure in a chamber. This makes it impossible to specify the outer contour of the hull precisely. A further problem is that the blanks consist of individual layers of wood and a layered structure only comes about during production. This impairs the precision and strength of the layered composite, which cannot compare to that of industrially produced laminated wood.Furthermore, the hull must be removed from the positive mold in order to insert frames and other support structures, which means that the fixation of the mold cannot be guaranteed until it is fully stiffened.

[0009] It is therefore an object of the invention to provide an alternative method by which a boat hull of a watercraft can be manufactured simply, inexpensively and accurately.

[0010] This task is solved by a process in which the air between the negative mold and the plywood blanks is sucked out through suction openings in the negative mold and then the blanks are joined together while the vacuum is maintained.

[0011] A key feature of the inventive method is that the air is extracted not between the mold and a film, but directly between the negative mold and the blanks. This allows the inner surface of the blanks to remain freely accessible during production, making it easy to join the individual blanks together on the inside at their edges in the correct position and with great precision. This ensures that the straight lines remain in the finished hull. The negative mold defines the outer surface of the hull and is essentially a cavity into which the blanks are inserted.

[0012] To further minimize possible deformation after the vacuum application has ended, a preferred embodiment of the method according to the invention can provide for an internal structure to be attached to the blanks while the vacuum is maintained. The internal structure, for example in the form of frames, is applied in the correct position, thereby maintaining the desired shape defined by the negative mold even when the vacuum is no longer applied and the hull is removed from the negative mold. Minor changes in shape may occur due to the stresses present in the blanks, but these are generally negligible.

[0013] It's also beneficial to attach bulkheads, a transom, and / or an inner stem to the blanks while maintaining a vacuum. All attached components contribute to stabilizing the structure and minimizing deformation.

[0014] It is usually necessary to coat the inside of the boat hull, preferably by applying at least one layer of epoxy resin to the cut parts and, if necessary, to the internal structure.

[0015] When performing the above process, one blank at a time is preferably inserted into the negative mold, pre-positioned, and pressed against the negative mold. The advantage of this procedure is that the sequential approach increases accuracy and that the energy-intensive extraction process is only required for one blank, or even just for a section of a blank, while the previously vacuumed blanks only need to be held in position. This way, the required power of the vacuum system can be kept low.

[0016] When dealing with large blanks, it is advantageous to place at least one blank into the negative mold, preposition it, and press it against the negative mold by applying a vacuum in a first vacuum section. Vacuum is then applied to another vacuum section of the blank to press this additional vacuum section against the negative mold. This can further reduce the required extraction power.

[0017] A further particularly preferred variant of the method according to the invention provides that a first structural section of the boat hull is produced in a first negative mold and at least one further structural section of the boat hull is produced in at least one further negative mold. The negative molds are then joined together while the vacuum is maintained, after which the correctly positioned structural sections are connected to one another before the vacuum is stopped. The first structural section is, for example, the hull and a further structural section is the deck of a boat. These are produced in two initially separate negative molds, which are then brought together in the correct position while the vacuum is still maintained. This ensures that the hull and deck that have just been produced are also placed together in the correct position and can thus be connected to one another. In this way, extremely high precision can be achieved.The invention also relates to a device for producing a boat hull of a watercraft with a negative mold that defines the outer surface of the boat hull.

[0018] According to the invention, the device is characterized in that the negative mold has several suction openings connected to a suction device for pressing plywood blanks against the negative mold. Such a device is particularly suitable for carrying out the method described above. The particular advantage of the device lies in the high level of accuracy that can be achieved using simple means.

[0019] Preferably, the negative mold has several vacuum sections that can be applied with vacuum separately, with each vacuum section being assigned to a blank. However, some blanks can also be assigned several vacuum sections. This allows the vacuum to be built up section by section, one after the other.

[0020] It is particularly advantageous if the vacuum sections are sealed off from the outside by a circumferential sealing cord. This largely prevents the ingress of false air.

[0021] Complex or large boat hulls can be easily manufactured in particular by providing a first negative mold and at least one further negative mold and by the negative molds having positioning devices which enable the negative molds to be joined together to form a common negative mold.

[0022] The invention will be explained in more detail below using a non-limiting embodiment illustrated in the figures, which schematically show:

[0023] Fig. 1 shows a first embodiment of a negative mold in a plan view;

[0024] Fig. 2 shows a section along line II - II in Fig. 1;

[0025] Fig. 3 shows a detail of Fig. 1 in section; and

[0026] Fig. 4 shows a further embodiment variant in a section corresponding to Fig. 2.

[0027] A negative mold 1 according to Fig. 1 has a recess 2 whose shape corresponds to the outer surface of the hull to be produced, which in this example is a boat's hull. The blanks on the starboard side have been omitted for clarity; however, overall, the starboard and port sides are constructed symmetrically.

[0028] The starboard side of the negative mold 1 has four vacuum sections 3a, 3b, 3c and 4, of which the first three vacuum sections 3a, 3b, 3c are provided for a lateral blank 5, while the fourth vacuum section 4 is provided for a keel-side blank 6.

[0029] Suction openings 7 are connected to a vacuum pump 9 via lines 8, whereby the vacuum supply to the vacuum sections 3a, 3b, 3c and 4 can be regulated separately.

[0030] Fig. 3 shows a sealing cord 11 in the form of an O-ring, with which the blank 5 is sealed against the negative mold 1. The sealing cord 11 is received in a groove 12, which on the one hand fixes the position and on the other hand allows the blank 5 to lie flat against the negative mold 1.

[0031] The method according to the invention is carried out, for example, in the following manner:

[0032] A lateral blank 5, for example, is inserted into the negative mold on the starboard side and temporarily pressed against the negative mold 1, particularly in the bow area, i.e., in the bow-side vacuum section 3a. The correct position is ensured by markings or positioning pins (not shown). A vacuum is then created in the bow-side vacuum section 3a to subsequently achieve a tight fit of the blank 5 in this area. While the air is being extracted, the correct position of the blank 5 can be checked and corrected if necessary.

[0033] Once the side blank 5 is firmly seated in the bow-side vacuum section 3a, the vacuum only needs to be maintained, and suction can then begin in the middle vacuum section 3b. Finally, the stern-side vacuum section 3c is subjected to vacuum so that the blank 5 lies completely flat against the negative mold 1. The keel-side blank 6 is then brought into the correct position in a single step, after which the analogous port-side blanks 5, 6 are installed in the same way.

[0034] Subsequently, the blanks 5, 6 are connected to each other at their wheels, and the frames 10 are inserted and also connected to the blanks 5, 6. Afterward, the vacuum application can be terminated, and the hull, now completed in its shell, can be removed from the negative mold 1.

[0035] Fig. 4 shows an embodiment in which a hull is produced as the first structural section 20 of the boat body in a first negative mold 1a, and a deck is produced as a further structural section 21 of the boat body in a further negative mold 1b. Then, with the vacuum still maintained, the two negative molds 1a, 1b are joined together in the correct position according to arrow 13 using several positioning pins 19, after which the structural sections 20, 21 arranged therein can be connected to one another in exact alignment, after which the vacuum application is terminated.

[0036] The present invention enables the simple and cost-effective production of high-quality plywood boat hulls.

Claims

PATENT CLAIMS 1. A method for producing a boat hull for a watercraft, in which a negative mold (1) defining the outer surface of the boat hull is provided, a plurality of blanks are placed in the negative mold (1), pre-positioned and pressed onto the negative mold (1) by the application of a vacuum, characterized in that the air between the negative mold (1) and the blanks (5, 6) consisting of laminated wood is sucked out through suction openings (7) in the negative mold (1) and then the blanks (5, 6) are joined together while the vacuum is maintained.

2. Method according to claim 1, characterized in that an internal structure is also attached to the blanks (5, 6) while the vacuum is maintained.

3. Method according to claim 2, characterized in that frames (10) are attached to the blanks (5, 6) as an internal structure.

4. Method according to one of claims 1 to 3, characterized in that a mirror and / or an inner stem are attached to the blanks (5, 6) while the vacuum is maintained.

5. Method according to one of claims 1 to 4, characterized in that at least one layer of epoxy resin is applied to the blanks (5, 6) and optionally to the internal structure.

6. Method according to one of claims 1 to 5, characterized in that one blank (5, 6) after the other is inserted into the negative mold (1), pre-positioned and pressed against the negative mold (1).

7. Method according to one of claims 1 to 6, characterized in that at least one blank (5, 6) is placed in the negative mold (1), pre-positioned and pressed against the negative mold (1) by applying vacuum in a first vacuum section (3a), and then vacuum is applied in a further vacuum section (3b, 3c) of the blank (5, 6) in order to press this further vacuum section (3b, 3c) against the negative mold (1).

8. Method according to one of claims 1 to 7, characterized in that a first structural section (20) of the boat hull is produced in a first negative mold (1a) and at least one further structural section (21) of the boat hull is produced in at least one further negative mold (1b), and then, with the vacuum maintained, the negative molds (1a, 1b) are joined together, after which the correctly arranged structural sections (20, 21) are connected to one another before the application of vacuum is ended.

9. Device for producing a boat hull of a watercraft with a negative mold (1) which defines the outer surface of the boat hull, characterized in that the negative mold (1) has a plurality of suction openings (7) which are connected to a suction device (9) in order to press blanks (5, 6) consisting of plywood onto the negative mold (1).

10. Device according to claim 9, characterized in that the negative mold (1) has a plurality of vacuum sections (3a, 3b, 3c, 4) which can be subjected to vacuum separately from one another, each vacuum section (3a, 3b, 3c, 4) being assigned a blank (5, 6).

11. Device according to claim 10, characterized in that several vacuum sections (3a, 3b, 3c, 4) are assigned to at least one blank (5, 6).

12. Device according to one of claims 10 or 11, characterized in that the vacuum sections (3a, 3b, 3c, 4) are delimited to the outside by a circumferential sealing cord (11).

13. Device according to one of claims 9 to 12, characterized in that a first negative mold (1) and at least one further negative mold (1) are provided and that the negative molds (1) have positioning devices (19) which enable the negative molds (1) to be joined together to form a common negative mold (1).

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