EP1992559A1

EP1992559A1 - Stabilizing fin for watercraft

Info

Publication number: EP1992559A1
Application number: EP07425280A
Authority: EP
Inventors: Calogero Falletta; Pierluigi Ausonio
Original assignee: Mondo Marine Eng Srl
Current assignee: Mondo Marine Eng Srl
Priority date: 2007-05-15
Filing date: 2007-05-15
Publication date: 2008-11-19

Abstract

A stabilizing fin (10) for watercraft is, at least for a part (14) thereof, made of flexible material, such as a composite material, a mesh, a perforated lamina, or a textile material. At least the aforesaid flexible part (14) is selectively controllable, via actuators such as fluid actuators, in a movement between a retracted resting position and an active extended position with respect to the hull of the watercraft. In a preferred way, the fin comprises a fixed part (12) that forms a casing for receiving the mobile part (14) of the fin when said fin is in a retracted resting position.

Description

Field of the invention

The present invention relates to stabilizing fins for watercraft.

Description of the known art

The solution of providing stabilizing fins in watercraft corresponds to a widely experimented technique, as emerges from the patent literature, for example, the documents US-A-3 757 723 , US-A-5 434 830 , or JP-A-60029393 .
In particular, a widely known technique provides for making fins in the form of retractile fins, hence mobile between a resting position and an active position in which, respectively, the fin is retracted and projects from the hull of the watercraft.
Stabilizing fins of a conventional type have been devised and studied with the intent of countering the movements of roll of the watercraft during navigation. Consequently, these fins are substantially conceived according to a compromise between the stabilizing action, which would require fins of dimensions as wide as possible, and the need to prevent the fin from offering excessive resistance to the advance of the watercraft, a requirement that would call, instead, for minimization of the dimensions of the fin.
In particular, the fact of possibly making the fin as a retractile structure moves in the direction of enabling the fin to "disappear" when its stabilizing function is not required.
In the case of watercraft for pleasure boats, the problem of stabilization in regard to the motions about the longitudinal axis through the body of the watercraft (i.e., the "roll-control" function) tends to be perceived from a slightly different standpoint. These are in fact watercraft designed to be used frequently as prestige dwellings proper, particularly in conditions of mooring in a port or in open berth, hence in conditions in which movements of roll, which are normally acceptable in navigation tend to be perceived as in practice intolerable.
This imposes as practically imperative the choice of providing stabilizing fins of large dimensions, hence ones able to exert their stabilizing action, interacting with the fluid medium in stationary or practically stationary conditions. The fact of providing stabilizing fins of large dimensions in turn induces, however, problems linked to the splaying-out of the fins, which, obviously, must be retractable during navigation.

Object and summary of the present invention

The object of the present invention is to provide a solution that is able to meet in an ideal way the needs outlined previously, which in themselves are in contrast with one another.
According to the present invention, that object is achieved thanks to a stabilizing fin having the characteristics called for specifically in the ensuing claims.
The claims form an integral part of the disclosure of the invention provided herein.

Brief description of the annexed drawings

The invention will now be described, purely by way of non-limiting example, with reference to the annexed drawings, wherein:

Figure 1 is a partial cross-sectional view of a watercraft provided with stabilizing fins of the type described herein;
Figures 2 and 3, approximately corresponding to a cross-sectional view according to the line II-II of Figure 1, illustrate a stabilizing fin of the type described herein, respectively in the resting position, where it is retracted, and in the active position, where it is extended;
Figure 4 is a cross-sectional view according to the line IV-IV of Figure 2; and
Figures 5 and 6 are cross-sectional views according to the lines V-V and VI-VI of Figure 3.

Detailed description of examples of embodiment

In the cross-sectional view of Figure 1, the reference C indicates as a whole the hull of a watercraft in cross-sectional view (the so-called "midship section").
Of course, Figure 1 shows only part of that section and makes clearly evident, in a particularly advantageous form of use, a stabilizing fin 10 located in a position corresponding to an edge S of the hull C.
In a particularly preferred embodiment, the fin 10 comprises a fixed part 12 and a mobile part 14.
The fixed part 12 substantially resembles a fin keel that extends from the hull C and preferentially has "streamlining" (more correctly, favourable fluid-dynamic) characteristics, given, for example, by the presence of a radiusing part 13, located at the end of the fin facing the bow of the watercraft.
Preferentially, the fixed part 12 of the fin 10 is also designed to constitute a sort of hollow shell that is able to receive inside it the mobile part 14 in the retracted position.
As may be immediately appreciated from the comparison of the views of Figures 2 and 3, the aforesaid mobile part 14 is selectively mobile between:

a resting position (represented in Figure 2), in which the mobile part 14 is retracted within the fixed part 12; and
an active position (represented in Figure 3), in which the mobile part 14 projects on the outside of the fixed part 12.

As regards the choice of the materials, the fixed part 12 is typically made in the form of a hollow shell made of a material (for example, a structural composite material) of the type commonly used for making the hulls of watercraft, such as pleasure boats.
The mobile part 14 assumes the form of a flexible element, such as for example a fibre-based composite material.
Without prejudice to the characteristics of flexibility of the part 14, for construction thereof alternative choices are of course possible, such as for example a mesh, a perforated lamina, or also textile materials, such as, for example, the materials used for making sails.
The movement of splaying-out of the mobile part 14 of the fin 10 is controlled via actuators, constituted, for example, by three fluid jacks 16, mounted within the fixed part 12, the cylinders 18 of which support the mobile part 14 of the fin 10 in positions distributed along its longitudinal extension.
Just to give an idea (of course, without this implying any limitation of the scope of the invention), the fin 10 can have an overall length (common to the fixed part 12 and to the mobile part 14, hence neglecting the radiusing part 13) of in the region of four to six metres.
The "width" of the mobile part 14 (and hence the homologous dimension of the fixed part 12 that receives it in the retracted position) can be in the region of approximately 50 cm. This means that, in the extended position (Figure 3), the fin 10 as a whole projects from the hull C for an amount equal to approximately one metre.
Instead, in the retracted position of Figure 2, the fin 10 (with the mobile part 14 retracted within the fixed part 12) projects with respect to the hull by an amount equal to approximately 50 cm.
The dimensions indicated above (which are not intended in a limiting sense) in any case give quite a precise idea of the fact that the movement of splaying-out of the mobile part 14 (more fully represented in the sequence of Figures 4 to 6), involves the translation of the stems of the jacks 16 with extents of travel on somewhat extensive relative distances, distances which, in the presence of a mobile rigid part 14, would easily give rise to phenomena of jamming, with consequent jamming of the fin.
In the solution described herein, possible phenomena of jamming are prevented precisely because the mobile part 14 is flexible (and possibly also very flexible).
The choice of making the mobile part 14 with a flexible material is in open contrast with the most evident choices linked to the construction of stabilizing fins of a traditional type, designed to be used during navigation. Fins of this type, made with characteristics of flexibility, would in fact have a very adverse effect on the characteristics of advance of the watercraft.
At the same time, the fact that the mobile part 14 is flexible also facilitates reception of the same mobile part 14 in the retracted position within the fixed part 12 (or, possibly - according to a possible variant embodiment (not illustrated) - directly within the hull).
Even though the figures presented herein refer to a mobile part 14 that substantially maintains its shape during the movement between the extended position and the retracted position, the flexibility of the fin also makes it possible to impart thereon possible deformations in the sense of at least partial folding, with consequent reduction of the volume occupied in the retracted condition.
The embodiment illustrated herein, with the fin 10 comprising a fixed part 12 and a mobile part 14, presents two important advantages:

it enables creation of a stabilizing fin of a hybrid type, usable both in navigation (with the mobile part 14 retracted within the fixed part 12), and at anchor (with the mobile part 14 splayed out on the outside of the fixed part 12); and
it enables the installation of the fin 10 also on already existing hulls; the assembly comprised of the fixed part 12 and the mobile part 14 can in fact constitute a sort of self-contained kit that may be applied on a pre-existing hull, preferentially in an edge position.

The reference number 20 designates ultrasound generators (represented just in Figure 1), located in a position corresponding to the area around the opening of the fixed part 12, through which the movement of extension of the mobile part 14 is obtained. The generators 20 are designed to perform an counteracting function with respect to the formation of encrustations and of deposits of micro-organisms, seaweed etc., which could jeopardize free movement of extension and retraction of the mobile part 14.
Of course, without prejudice to the principle of the invention, the details of construction and the embodiments may vary widely with respect to what is described and illustrated herein, without thereby departing from the scope of the present invention, as defined by the annexed claims. For example, even though the embodiment illustrated herein envisages that the fin 10 is flexible only in the mobile part 14, the invention also applies to the case where the entire fin 10 presents characteristics of flexibility and/or where the entire fin is retractile within the hull. Furthermore, it is possible to envisage that, in particular conditions of use, the movement of splaying-out of the fin will occur only partially, i.e., without reaching the position of complete extension.

Claims

A stabilizing fin (10) for watercraft, characterized in that it is, at least for a part (14), flexible.
The fin according to Claim 1, comprising a flexible part (14) constituted by a flexible structure.
The fin according to Claim 1 or Claim 2, comprising a flexible material chosen between a composite material, a mesh, a perforated lamina, and a textile material.
The fin according to any one of the preceding claims, in which, at least in said flexible part (14), the fin (10) is selectively controllable (16) in a movement between a retracted resting position and an active extended position.
The fin according to Claim 4, coupled to at least one actuator element (16) for controlling said movement between said retracted resting position and said active extended position.
The fin according to Claim 4, with associated thereto a plurality of actuator elements (16) acting on said fin (10) in a position corresponding to a flexible part (14) of the fin (10) itself.
The fin according to Claim 5 or Claim 6, in which said at least one actuator element (16) is a fluid actuator.
The fin according to any one of the preceding claims, comprising:
- a fixed part (12); and

- a mobile part (14), selectively controllable (16) in a movement between a retracted resting position and an active extended position.
The fin according to Claim 8, in which said fixed part (12) forms a casing for receiving said mobile part (14) in said retracted resting position.