Damper device for mooring watercraft

Abstract: A damper device for mooring watercraft, of the type comprising at least two rigid elements (1, 2), to one end of each of which there can be secured a mooring rope or chain, said elements being able to move coaxially in opposition to each other against the action of an elastic body (3) which comprises at least one member (10) constructed of an elastically deformable material.

Description: This invention relates to a damper device for mooring watercraft in accordance with the pre-characterising part of the main claim. In known devices of the aforesaid type the elastic element consists simply of a spring. The main drawback of known devices is their noise. In this respect the rolling movement of the watercraft results in continuous stressing of the device, with consequent stressing of the spring which in extending or compressing to return to its rest position produces a very annoying noise. It is well known that an extending spring is easily subject to yielding and, in the limit, to breakage due to excess load. In the aforesaid known devices with an extending spring, this drawback is obviated or at least limited by the addition of a by-pass safety chain which however, when in operation, eliminates the damping effect with the inevitable consequence that impact forces arise. It should also be noted that as said devices are constructed completely of rigid materials, they can cause damage to the bottom of the watercraft by bruising and/or rubbing during mooring and during pulling-in of the mooring line or chain. In addition, known devices have an "open" structure and are therefore completely exposed to the water which, particularly if sea-water, deteriorates the device components and especially the elastic element. In this respect with the passage of time this latter, because of the action of the water, tends to rust and/or become less elastic. This on the one hand causes a further increase in the noise of the device and on the other hand results in lower device efficiency. FR 2360797 discloses a damper device comprising two rigid elements, to one end of each of which there can be secured a mooring rope or chain, said elements being able to move coaxially to each other against the action of an elastic body comprising one member constructed of an elastically deformable material. FR 2 267 487 discloses a damper device according the preamble of claim 1. An object of this invention is to provide a damper device for watercraft which obviates the aforesaid drawbacks, particularly by not being noisy and by providing excellent resistance to deterioration effects caused by water. These and further objects which will be apparent to an expert of the art are attained by a device in accordance with the characterising part of the main claim. The invention will be more apparent from the accompanying drawing, which is provided by way of non-limiting example and on which: Figure 1 is a perspective schematic view of the device, and Figure 2 is a schematic longitudinal section therethrough. With reference to said figures, a device according to the invention comprises two U-bent elements 1 and 2, and a central elastic body 3 arranged to oppose the movement of the two elements 1, 2 in the opposing directions D1 and D2 respectively. In correspondence with their U-bent head 4 the rigid elements 1 and 2 comprise a disc 5 acting as an abutment for the elastic body 3, and having four equidistant holes for passage of the arms 1A, 2A of the elements 1 and 2. Advantageously, the head 4 has a diameter S1 greater than the diameter S2 of the arms 1A, 2A. Furthermore, between the head 4 and the disc 5 there is fixed a spacer and stiffening bar 6. The free ends of the arms 1A, 2A have a threaded portion 7 to receive a nut 8 on which a protection cap 9 can be pressure-mounted. In the illustrated example, the central elastic body 3 comprises six hollow, frusto-conical, circular-based members 10 of elastic plastic material open at their major base. In their minor base 11 these members comprise four equidistant holes for passage of the arms 1A, 2A. To facilitate sliding of the arms, plastic bushes 12 are provided in these holes to prevent the arms 1A, 2A making contact with the material of the members 10. At the centre of the inner face of the minor base 11, the members 10 comprise a cross-shaped stiffening part 13 provided along the diameters connecting together the passage holes for the arms 1A, 2A. Advantageously the rigid elements 1 and 2, the discs 5, the bars 6, the nuts 8 and the caps 9 are constructed of stainless steel, whereas the members 10 can be constructed of any known deformable material suitable for the purpose, preferably rubber having a Shore hardness of between 50 and 90 and maintaining its characteristics unaltered within a temperature range of -30°C to +80°C. It should be noted that when the device is assembled the elastic body 3 is sealedly clamped against the discs 5, hence the central part of the device is isolated from the water. It has been shown experimentally that the device is totally silent while providing a performance substantially similar to that of traditional devices. Finally it should be noted that the aforedescribed embodiment is provided by way of example and that numerous modifications are possible all falling within the same inventive concept, for example the number and/or form of the members 10 could be different from that described, as could the number and form of the elements 1 and 2 to which the mooring lines are connected.

Claims: A damper device for mooring watercraft, of the type comprising at least two rigid elements (1, 2), to one end of each of which there can be secured a mooring rope or chain, said elements being able to move coaxially to each other against the action of an elastic body (3), said elastic body (3) comprising at least one member (10) constructed of an elastically deformable material, the rigid elements (1, 2) being of U-shape to form each two arms (1A, 2A), in correspondence with their head (4) and their ends there being provided discs (5) acting as abutments for the elastic body (3), the arms (1A, 2A) of the rigid elements longitudinally penetrating the elastic body, characterised in that said member (10) comprises a plurality of holes for the passage of the arms (1A, 2A), said holes being provided with tubular elements (12) to facilitate the sliding of said arms through said holes. A device as claimed in claim 1, characterised in that the deformable material is a plastic material. A device as claimed in claim 1, characterised in that the member (10) of elastically deformable plastic material comprises a plurality of modularly associable parts so as to be able to vary the deformability characteristics of the elastic body (3). A device as claimed in claim 1, characterised in that the elastically deformable member (10) is of frusto-conical form. A device as claimed in claim 1, characterised in that the heads (4) have a diameter (S1) greater than the diameter (S2) of the arms (1A, 2A). A device as claimed in claim 1, characterised in that each member (10) is hollow and comprises a stiffening part (13) that is provided along the diameters of the member (10), on its inner face, connecting together the passage holes for the arms (1A, 2A) of the rigid elements.

Inventors: BAJELI MARIO, PEDRUZZI CARLO, BAJELI, MARIO, PEDRUZZI, CARLO
Applicants: GIA FRA MA S P A, GIA.FRA.MA. S.P.A.
Application year: 1998
Main classification: B63B21
IPC codes: F16F3, B63B21