TECHNICAL FIELD

The invention relates to the field of shipbuilding and is used in connection with the building of transport vessels, various floating crane vessels, rescue vessels, hydrographical vessels, vessels intended for scientific research, cruise and passenger ships, landing ships, and coastal defence vessels.

PRIOR ART

The main structure of a catamaran- type vessel consists of a platform supported on two floats or hulls. The invention relates to a rotatable hinge module for connecting a catamaran-type vessel's platform and hull, which makes possible turning the hull with respect to the platform and changing the draft.

Since deep draft significantly restricts the possibilities for landing and berthing, as well as operation in shallow waters, various solutions have been proposed for reduction of the draft. Most of them specify reduction of the draft by way of turning the hulls or floats by hinges connected to the platform, as described in US2004149196A1, US2007028822A1, JP2003026075A, US7278364B2, and in the solutions of US5237947A and EP 1685021 Bl , which are the closest to the present invention from the viewpoint of technical design, or lowering of waterproof work platforms, thereby forcing the hulls out of the water. The latter solution has been described in EP 1919766B1.

In the patent application US5237947A "Variable draft hull", published 24 Aug 1993, displacement pods (pontoons) are attached to a main hull through pivotable arms that allow positioning of the submersible pods at locations within a range of horizontal and vertical locations. The displacement pods also include hydrofoils and other controllable surfaces to provide dynamic lift and attitude control of the vessel. A gearing arrangement has been provided as well to turn portions of said pods with respect to the hull of the vessel. A rotatable hinge allows changing the vessel's draft. The rotation also allows choosing optimal inclination of the pods depending on the vessel's speed and orientation with respect to the waves.

The greatest disadvantage of the rotatable hinges described in prior art is that their small cross-sections would not endure great loads, for which reasons they cannot be used under harsh marine conditions and in large vessels. For this reason, the hinges have been used on smaller vessels only, which limits their area of application.

Another disadvantage is the complexity of the moving elements and the resulting low reliability, which in turn results in insufficient seaworthiness. A further disadvantage is the low rigidity of the joints, for which reason catamaran-type vessels are subjected to rapid wear and tear.

SUMMARY OF THE INVENTION

The objective of this invention is to design for the connection of the platform and hull of a catamaran-type vessel such devices allowing turning of the vessel hull that remain reliable under harsh marine conditions, increase the torsional and flexural rigidity of the hull, and facilitate the design and building of catamaran-type vessels as modules.

The rotatable hinge module for connecting a catamaran-type vessel's platform and hull allows turning the hull and changing the draft.

In general, the structural elements of the platform of a catamaran-type vessel are integrated permanently with structural elements of the vessel hull. Since these joints connecting the vessel platform and hulls are subjected to the greatest loads, they are designed spatial and sufficiently large to avoid stress concentrations and reduce internal tensions. The greatest forces inducing bending moment in said joints arise under the beam sea conditions and are approximately equal to the hull's displacement (Dubrovsky, V., Lyakhovitsky.A., 2001 , "Multi Hull Ships", Backbone Publishing Co., USA, 495 pp, Dubrovsky et al, 2007). The vessel hull is subjected to bending and twisting. The higher above the water is the vessel's platform, the greater is the bending moment.

The most suitable cross- sectional shape of the joint is a circle, which is also known to be the most efficient from the viewpoint of torsion endurance.

To achieve the objective of this invention, the rigid spatial (usually polygonal) joint is replaced with a hinge module of equivalent strength allowing rotation of the vessel hull. Spatial rigidity is ensured by a tubular joint and connecting elements, which are interconnected, and by deceleration and fixation mechanisms. The hinge module for connecting a catamaran-type vessel's platform and hull is implemented as a rotatable hinge to allow turning the vessel hull with respect to the platform between a lower position and an upper position.

According to the invention, the hinge module is built as an individual module separately from the vessel's platform and two hulls and later connected to the platform sides using a connecting plate of the platform and to the hulls using a connecting plate of the hull.

The hinge module consists of a pipe sealable in a watertight manner, the diameter of which is approximately equal to the structural height of the platform, a connecting plate of the platform attached to the platform, and a connecting plate of the hull attached to the vessel hull, which is connected through alternately positioned connecting elements of the connecting plate of the platform, connecting elements of the connecting plate of the hull, and a saddle to the pipe so that the connecting plate of the hull is rotatable around the pipe axis over a half-circle to allow turning of the vessel hull between a lower and an upper vertical position and the pipe dimensions have to correspond to the following requirements:

D > H;

D ~ 1/9 L,

where

D - pipe diameter,

H - structural height of the catamaran-type vessel's platform,

L - pipe length.

The pipe ensures necessary strength and especially torsional stiffness for the catamaran- type vessel and allows the vessel hull to turn approximately over a half-circle between the lower vertical position and the upper vertical position with respect to the platform. The pipe sealed hermetically from both ends ensures at least double reserve buoyancy. Introduction of the pipe will help a catamaran-type vessel to withstand torsional and bending forces, as well as reduce stress concentrations in cross-section. The inside of the pipe can be used as useful vessel space.

For connection of the platform and hulls of a catamaran-type vessel, connecting plates of the platform are rigidly attached to two sides of the platform of the catamaran-type vessel and connecting plates of the hull are attached to the vessel hulls, followed by connection thereof to the pipe through alternately positioned connecting elements and the saddle. The connecting plate of the platform and the pipe are rigidly interconnected by at least five connecting elements of the connecting plate of the platform.

At least four connecting elements of the connecting plate of the hull are rigidly connected to the connecting plate of the hull. The connecting elements of the connecting plate of the platform and the connecting elements of the connecting plate of the hull are hollow, and there are communication apertures on the connecting plate of the platform and the connecting plate of the hull above the cavities.

There are communication apertures sealable in a watertight manner between the connecting elements of the connecting plate of the platform and the pipe.

The hinge module is equipped with devices required for turning of the vessel hull, decelerating and position fixation, and allows turning the vessel hull over a half-circle. The turning also allows choosing optimal inclination of the hulls depending on the vessel's speed and orientation with respect to the waves.

The solution is suitable for catamaran-type vessels of length from 15 metres to 150 metres, also expanding the possibilities for their use in connection with landing and a variety of maritime operations where low draft is required.

By turning the hinge module, it is possible to raise the hulls above the waterline, all the way to the vertical position, in order to either repair or maintain the hulls and propulsion devices or for berthing the vessel in tight conditions.

Introduction of the invention also allows swapping the hulls and platforms of a catamaran-type vessel as desired. In other words, vessels can be built by combining various platform and hull modules or a damaged hull quickly replaced with a new one.

Introduction of the invention also allows increasing the vessel's reserve buoyancy. LIST OF FIGURES

The device is described in more detail in FIG. 1 through FIG. 7, where:

FIG. 1 is a front view of a catamaran-type vessel with a hinge module;

FIG. 2 illustrates the hinge module for connecting the platform and hull of a catamaran- type vessel; FIG. 3 illustrates individual elements of the hinge module;

FIG. 4 illustrates connection of the hinge module elements;

FIG. 5 is a perspective view of a catainaran-type vessel with the hinge module;

FIG. 6 illustrates a catamaran-type vessel with the hinge module, the hulls of which vessel are turned parallel to the water line plane; and

FIG. 7 illustrates a catamaran-type vessel with the hinge module, the hulls of which vessel are turned to an upper position perpendicular to the waterline plane.

EXEMPLARY EMBODIMENT

FIG. 1 is a front view of a catamaran-type vessel with a hinge module, based on which the external forces acting on the vessel can be determined and the moments of resistance of structures calculated. The hinge module for connecting the catamaran-type vessel's platform and hull, which allows rotation of the vessel hull, as illustrated in FIG. 2 to FIG. 4, ensures the necessary strength and rigidity of the vessel.

FIG. 3 depicts individual hinge module elements. The hinge module consists of connecting elements 1 of the connecting plate of the platform, connecting plate 2 of the platform, pipe 3, connecting plate 4 of the hull, saddle 5, and connecting elements 6 of the connecting plate of the hull.

Spatial rigidity is ensured by the pipe 3 of a diameter approximately equal to the structural height of the platform and by connecting plates 2 and 4 of the platform and hull, respectively, which are interconnected. The left and right hinge modules are symmetrical.

FIG. 3 illustrates connection of the hinge module elements; FIG. 2 depicts the assembled hinge module.

The connecting plate 2 of the platform is rigidly attached (welded, for example) through five connecting elements 1 of the connecting plate of the platform to the pipe 3 sealed in a watertight manner, depicted in FIG. 1 to FIG. 7 and serving as the main element of this invention. Four connecting elements 6 of the connecting plate of the hull are rigidly connected (welded, for example) to the connecting plate 4 of the hull. The connecting plate 2 of the platform and the connecting plate 4 of the hull are connected through alternately positioned connecting elements 1 of the connecting plate of the platform, connecting elements 6 of the connecting plate of the hull, and saddle 5 to the pipe 3 so that the connecting plate 4 of the hull can be rotated to allow turning of the vessel hull 8 between a lower and an upper position around the axis Z of the pipe 3 over a half-circle. The pipe dimensions must comply with the requirements:

D > H;

D ~ 1/9 L,

D - pipe diameter,

H - structural height of the catamaran-type vessel's platform,

L - pipe length.

The connecting plate 2 of the platform is attached to the platform 7 of a catamaran-type vessel (by bolted joints, for example) and the connecting plate 4 of the hull to the hull 8 (by bolts, for example), allowing rotation of vessel hull 8 with respect to the platform 7.

The hinge module is provided with the necessary watertight apertures for communications and mechanisms for turning, deceleration, and fixation. The ends of the central pipe 3 can be sealed by waterproof hatches and waterproof rigidity bulkheads can be installed inside it, if required. Various vessel equipment, cargo, or crew spaces can be housed inside the pips.

The connecting elements 1 of the connecting plate of the platform and the connecting elements 6 of the connecting plate of the hull are hollow, and there are communication apertures on the connecting plate 2 of the platform and the connecting plate 4 of the hull above the cavities. There are watertight closable communication apertures between the connecting elements 1 of the connecting plate of the platform and pipe 3.

The hinge modules with their hermetically sealable pipes 3 ensure at least double buoyancy reserve to the catamaran-type vessel.

If necessary, stiffening ribs can be added inside the pipe. Metals and/or composite materials can be used.

FIG. 5 is a perspective view of a catamaran-ty e vessel with the hinge module, the hulls of which vessel are perpendicular to the platform and the draft is the largest. In FIG. 6, the hulls 8 have been turned to a parallel plane with the platform 7 by the hinge modules. FIG. 7 depicts the same catamaran-type vessel with the hulls turned up. If sailing in shallow waters is required, the hulls are out of water and landing is possible.

Since catamaran-type vessels have a relatively short history and sufficient statistics for development of proper algorithms for design thereof are lacking, establishment of the geometric parameters of each vessel turns into solving of a rather labour-intensive optimization task. Introduction of the hinge modules facilitates vessel design, since the overall weight of the vessel is known prior to vessel hull design, which allows selection of suitable parameters for the vessel hulls.

Introduction of the hinge module allows application of a modular method novel in the building of catamaran-type vessels, i.e., the vessel platform, hulls, and hinge modules are built separately and assembled afterwards. It also allows replacement of damaged hulls and vessel repair and maintenance while the vessel is afloat. Moreover, such a building method allows unification of individual modules, for example, vessel hulls and hinge modules. In addition, introduction of the hinge modules presupposes design and building of novel platform modules and novel vessel hulls, followed by assembly thereof into a single whole.