STERN PLUG FOR INSERT INTO THE STERN OF THE INFLATABLE BOTTOM OF THE JET BOAT

Abstract

The invention relates to a small-sized shipbuilding. In particular, to a stern plug to be inserted into a stern portion of an inflatable bottom of a water jet boat, the plug is made such that it follows a shape of a front portion of the bottom of the boat, based on a hollow volume that is open at one base and comprises a closed second base and a lateral surface, the lateral surface is arranged along an outer contour of the closed base, and the closed base is made such that it follows a shape of the front portion of the bottom, and the lateral surface is made in a form of shelves, where an upper shelf is made straight, wherein the plug is made in a form of a monolithic cast piece of an elastic shape-retaining material, where the open base has a mesh cellular structure, where a lower shelf of the bottom is made straight, and plate-shaped guides for fixing to the boat are mounted on the shelves.

Claims

1. A stern plug to be inserted into a stern portion of an inflatable bottom of a water jet boat, the plug is made such that it follows a shape of a front portion of the bottom of the boat, based on a hollow volume that is open at one base and comprises a closed second base and a lateral surface, the lateral surface is arranged along an outer contour of the closed base, and the closed base is made such that it follows a shape of the front portion of the bottom, and the lateral surface is made in a form of shelves, where an upper shelf is made straight, wherein the plug is made in a form of a monolithic cast piece of an elastic shape-retaining material, where the open base has a mesh cellular structure, where a lower shelf of the bottom is made straight, and plate-shaped guides for fixing to the boat are mounted on the shelves.

2. The plug according to claim 1, wherein it is made of a polyurethane.

3. The plug according to claim 1, wherein it is made of an ethylene vinyl acetate (EVA).

4. The plug according to claim 1, wherein the plate-shaped guides for fixing to the boat are mounted on the bottom and on an upper portion of the plug.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 illustrates an arrangement of the invention (an interior view as seen from an internal open side of the base).

[0017] FIG. 2 illustrates an arrangement of the invention (a plane view as seen from the internal open side of the base).

[0018] FIG. 3, FIG. 6, FIG. 7 illustrate an example of the boat with the mounted plug according to the invention.

[0019] FIG. 4 and FIG. 8 illustrate an example of the boat with an overlapping gluing that is used when manufacturing PVC boats, in which a bottom is assembled from a stern by gluing pieces of a deck and the bottom itself by means of overlapping one piece onto another one.

[0020] FIG. 5 illustrates an example of the manufactured plug according to the invention (with no guides mounted) as seen from the closed side of the base.

[0021] FIG. 9 illustrates an example of fixing the plug to the front portion of the boat stern.

[0022] FIG. 10 illustrates an example of the plug that is already fixed to the front portion of the boat stern.

DETAILED DESCRIPTION

[0023] A stern plug (see FIG. 1, FIG. 2) is to be inserted into a stern portion of an inflatable bottom of a water jet boat. It is made such that it follows a shape of a front portion of the bottom of the boat based on a hollow volume that is open at one base and comprises a closed second base and a lateral surface 1, the lateral surface is arranged along an outer contour of the closed base. The closed base is made such that it follows a shape of the front portion of the bottom, and the lateral surface is made in a form of shelves, where an upper shelf 5 is made straight.

[0024] What is novel is that the plug is made in a form of a monolithic cast piece of an elastic shape-retaining material.

[0025] The open base (see FIG. 5) has a mesh cellular structure. Mesh cells may be formed by intersected parallel partitions 2.

[0026] A lower shelf of the bottom 4 is also made straight, and plate-shaped guides 3 for fixing to the boat are mounted on the shelves.

[0027] Preferably, a polyurethane is used as the elastic material. However, the plug also may be made of an ethylene vinyl acetate (EVA), if needed. The plug may be made of the EVA in order to provide it with insulating properties to reduce its thermal conductivity.

[0028] The plug is manufactured by a casting method in a one single piece, e.g., by molding or pouring.

[0029] During its use, it is pasted into the front part of the stern of the inflatable bottom of the water jet boat.

[0030] The plug pasting process is simple and illustrated in FIG. 9 and FIG. 10.

[0031] Upon glued to the boat, the plug provides a stable geometry of the bottom (see FIG. 3, FIG. 6, FIG. 7) which, in turn, improves the boat's driving performance.

[0032] In contrast to the prototype, the claimed solution has the monolithic mesh cellular structure made of the elastic material, rather than a box-shaped one.

[0033] This design of the plug provides a larger rigidity, while in case of loads acting onto the bottom (a wave, a hit etc.) it is able to compensate a created increased pressure in the bottom of the water jet boat and to provide a return to the initial geometry due to making from the elastic material and to the provision of the partitions 2 of the mesh cells.

[0034] In contrast to the prototype, no pasting of the bottom “in tension” along the perimeter is performed. The provision of the guiding plates 3 which are fixed on the side shelves allows to achieve a more accurate arrangement of the plug relative to the bottom and, thus, the overall geometry (see FIG. 6).

[0035] The plate-shaped guides 3 for fixing to the boat may be mounted, e.g., on the bottom 4 and on the upper shelf 5 of the plug. They also may be mounted in other locations of the side surface 1, if needed.

[0036] For comparison, a variant of the boat (see FIG. 3) with the mounted plug according to the invention and a variant with an overlapping gluing (see FIG. 4) that is used when manufacturing PVC water jet boats, in which a bottom is assembled from a stern by gluing pieces of a deck and the bottom itself by means of overlapping one piece onto another one.

[0037] This plug forms the stern portion of the bottom of the water jet boat, in particular, its longitudinal geometry, more precisely as seen from the comparison between the variant according to the invention (see FIG. 7) and the variant with the overlapping gluing (see FIG. 8) that is used when manufacturing PVC boats, in which the bottom is assembled from the stern by gluing pieces of the deck and the bottom itself by means of overlapping one piece onto another one.

[0038] As seen from the comparison between FIG. 7 and FIG. 8, the overlapping gluing provides a rounded shape of the stern end (FIG. 8) (alteration of the bottom geometry) as compared to the variant according to the invention (FIG. 7), where the end is chopped. The chopped end of the stern results in improved driving performance of the water jet boat, since the bottom becomes smoother with no curvatures both in a longitudinal section and in forming a tunnel for a water jet nozzle.

[0039] The pasting of the plug according to the invention is performed as follows.

[0040] A glue is applied along the perimeter of the side surface 1 of the plug and on the stern portion of the pieces of the boat's bottom and deck. The glue is applied on the guides 3 as well.

[0041] Then, the plug is pressed to the stern portion of the water jet boat (see FIG. 9) and, by means of the guides 3, the plug 3 is arranged more accurately relative to the bottom of the boat, since the guides 3 which are arranged at least on the bottom 4 and on the upper shelf 5 provide a more rigid leaning of the tern bottom of the boat against the shelf of the bottom 4 of the plug as well as they are markers (reference points) of the stern of the water jet boat to which the plug should be glued by the guides 3.

[0042] Therefore, the claimed stern plug being supplemental to the transom allows to form a more stable water flow in a shallow water within a water jet tunnel in order to feed it to an intake of a water jet motor. Besides, the invention provides a stable geometry of the bottom when forming a water jet channel, thereby improving operational characteristics of the water jet boat.