WO2005077747A1

WO2005077747A1 - A cargo-ship hull

Info

Publication number: WO2005077747A1
Application number: PCT/SE2005/000145
Authority: WO
Inventors: Pierre Thiger; Percy Sundquist
Original assignee: Drottninghamns Jordbruksförvaltning Ab
Priority date: 2004-02-11
Filing date: 2005-02-07
Publication date: 2005-08-25
Also published as: SE0400294D0; SE525245C2; SE0400294L

Abstract

A hull for cargo-ships, particularly for the transport of oil and chemicals, containers, cars or the like. The hull is composed of mutually connected, parallel and tube-shaped elements, forming cargo compartments, arranged in the longitudinal direction of the hull, and enclosed in and connected to an outer hull to form a generally box-shaped structure having an essentially rectangular cross section, and being at both ends adapted for optional dismountable connection of a stern part and a stem part, respectively. The outer hull is preferably composed of an inner plate and an outer plate with an intermediate cellular plastic material glued to both plates.

Description

A cargo- ship hull

Field of the invention

The invention relates to a hull for cargo-ships, particularly for the transport of oil and chemicals, containers, cars or the like.

Background of the invention

Ship hulls of today for merchant vessels are typically built with single or double hulls from plates on frames, stringers and longitudinals, regardless of the field of use. In order to obtain increased security, international rules has pushed the evolution towards double hulls A typical distance between the outer hull and the inner hull is less than approximately 3 m. A framework is arranged between the hulls.

Although double hulls have evidently resulted in significantly increased security at low energy ground impacts, the solution is far from optimal. The construction is significantly more expensive, and the lack of counter pressure from the water on the inner hull give rise to tension problems, and the significantly larger total plate area, which is approximately 2,5 times larger than for a single hull, give rise to increased corrosion problems and increased maintenance costs. During mechanical stress on the outer hull, the tensile problems, which give rise to cracks in the steel plate, are by means of a framework between the hulls transferred to the inner hull, which may therefore also crack, with leakage as a result. Further, there is a potential risk for explosions due to the formation of gas between the outer and inner hulls as low viscous substances from the oil or similar is pressed through cracks and welding air holes due to the lack of a counter pressure, in contrast to single hulls when the water provides a counter pressure from the outside of the ship. Therefore, this space must be kept full of inert gas, resulting in increased costs and risk of leakage, as well as difficulties when inspecting the ship between the hulls.

Hence, there is a great need for an improved ship hull in which the risk for leakage of cargo at ground impacts and collisions is reduced or eliminated.

There is also a great need for a ship hull having improved buoyancy, and which is preferably unsubmersible . This applies to tanker ships but also transporting ships for other goods, thus typically involving very large ships. A hull construction of this kind is described in the Swedish patent application SE-A- 0302765-3 having the same applicant as the present application.

Summary of the invention

It is an object of the present invention to provide a ship hull with an eliminated or at least substantially reduced risk of leakage in the case of ground impacts and collisions.

Another object of the present invention is to provide a ship hull with improved buoyancy and which is preferably unsubmersible .

Still another object of the present invention is to reduce or eliminate the need for ballast tanks and counter pressure, today resulting in great technical and environmental problems, costs and risks.

Still another object of the present invention is to facilitate maintenance and the removal of vegetation on the hull.

Still another object of the present invention is to provide a considerable addition of strength as compared with the current configuration . Still another object of the present invention is to drastically reduce the time for loading and unloading.

These and other objects are obtained by means of the present invention which is defined in the following claims.

According to the invention, a hull for cargo-ships, particularly for the transport of oil and chemicals, containers, cars or the like, is composed of mutually connected, parallel and tube- shaped elements, forming cargo compartments, arranged in the longitudinal direction of the hull. The cargo compartment elements are enclosed in, and are connected to, an outer hull to form a generally box-shaped structure having an essentially rectangular cross section, and being at both ends adapted for optional dismountable connection of a stern part and a stem part, respectively.

The outer hull is preferably composed of an inner plate and an outer plate with an intermediate cellular plastic material glued to both plates. The tube-shaped cargo compartment elements may be glued together mutually and to the outer hull over a layer of cellular plastic material. The glue used is preferably a glue that forms an elastic or visco-elastic glue line.

The box-shaped structure may at both ends, connecting to the stern part and stem part, respectively, be provided with connecting means for loading and unloading of cargo, which may be liquid, containers, cars, etc.

The tube-shaped elements may be shaped with a square cross- section, or a hexagonal cross-section, wherein cavities formed next to the outer hull are packed with cellular plastics or tube-shaped tanks. The cellular plastic material may be expanded polypropylene, expanded polythene, expanded PVC, expanded polystyrene, expanded PET, cross linked or non-cross linked materials, and preferably 5 expanded polypropylene. The tube-shaped cargo compartment elements are preferably manufactured from high-strength steel plates .

By means of the hull according to the invention, an optimal 10 utilization of the load capacity of the hull is obtained. Moreover, the hull construction according to the invention enables the load capacity to increase many times in relation to ship hulls of today. Basically, any dead spaces normally occurring in a ship are eliminated. 15 Environmentally, great crucial benefits are also obtained. The risk for discharge of oil and other pollutants are eliminated by no longer requiring ballast tanks, since the strength of the inner structure is capable of withstanding the water pressure 20 when the ship runs empty.

Furthermore, the time for building a ship hull according to the invention is estimated to approximately 6 months, as compared to the normal time of building being approximately 2 years for a 25 tanker. Using safe bulkheads between the tanks, a very powerful structure is obtained. Further, by selecting a thickness of the cellular plastic adapted to the loading capability, the ship can be made unsubmersible.

30. Preferably, the outer hull is manufactured from a high strength steel. Further, the outer hull is preferably of a type described in SE-A-0302765-3 mentioned above, i.e. with inner and outer hulls and a cellular plastic material glued between them. Thus, the buoyancy of the hull is achieved primarily by means of this cellular plastic layer, and not by the cellular plastic layer between the tube-shaped elements.

Presently preferred embodiments of the invention will be described in more detail below.

Detailed description of preferred embodiments

The hull according to the invention is composed of an outer hull enclosing tube-shaped cargo compartment elements arranged mutually parallel in the longitudinal direction of the hull. The cross section of the formed cargo compartments may have different shapes, but is preferably triangular, square, hexagonal, or octagonal. The cargo compartment elements are glued together mutually and to the outer hull.

Between the individual cargo compartment elements and between the cargo compartment elements and the outer hull, respectively, a layer of a cellular plastic material is provided which is glued to surrounding surfaces using a glue that forms an elastic or visco-elastic joint, the outer hull is preferably composed of an inner plate and an outer plate with an intermediate cellular plastic material glued to both plates. Thus, the cellular plastic material glued between the cargo compartment elements and between these and the inner plate provides a stiffening result, but acts furthermore as a blocking layer and to a certain extent also as a shock-absorbing zone.

If the cross section of the tubes is not square, tube-shaped cavities are formed during the gluing together, depending on the selected tube cross section and where it is located, i.e. either between adjacent tubes or between a tube and the hull plate. Preferably, these cavities are packed with tube-shaped tanks or cellular plastics. The tubes forming the cargo compartments are preferably also manufactured from high-strength plates. The company of SSAB, Lulea in Sweden produces and sells a high strength steel, named Domex 500, having the desirable properties for the outer hull.

Preferably, the glue used for gluing the cellular material onto the plate is a glue that gives rise to a dilatation joint in addition to being oil resistant, e.g. a two-component polyurethane glue. Further examples of useful glues are epoxy resin and moisture-hardening one-component polyurethane adhesives and different types of prepegs .

The cellular material shall chiefly contain closed cells, and may be manufactured from various different types of material, and also mixtures thereof, e.g. expanded polypropylene, expanded polythene, expanded PVC, expanded polystyrene, expanded PET. Depending on current requirements, the materials may be cross linked or non-cross linked. A preferred material is expanded polypropylene .

Further, the cellular material should preferably be flame- resistant, and in that case expanded graphite particles may be introduced in the cellular plastic material or in the adhesive, which in the case of a fire will expand and form an incombustible layer. It is also possible to provide graphite as a layer united with the cellular material or the adhesive.

The thickness and density of the cellular plastic material may differ. When the outer hull described in the above-mentioned SE- A-0302765-3 is utilized, the cellular plastic material therein provides buoyancy and preferably also unsinkable properties to the hull. The layer thickness of the cellular plastic material between the elements forming cargo compartments, is thus chiefly selected with respect to structural considerations, and a stiffening of the cargo compartment elements is primarily desired. The density of the cellular plastic material may thus be between approximately 60 and approximately 400 kg/m³, normally between 100 and 150 kg/m³, and the thickness may be approximately 0,01 - approximately 0,3 m, depending on the current conditions.

The thickness of the hull plate is determined when dimensioning the ship in accordance with international classification rules. Using a high strength steel will provide a saving in weight since the thickness can be reduced, at the same time still obtaining excellent characteristics such as extremely high strength at break during deformation at ground impacts, collisions, explosions etc.

The hull according to the invention can be designed basically as a box, e.g. having a width of approximately 60 m, a height of approximately 30 m and a length that may amount to approximately 500 m. The cargo compartment elements are made up by tubes with a cross section of a triangular, square, hexagonal, or octagonal shape that can be manufactured as completed lengths by longitudinally welding the above-mentioned plates of high strength steel. The size of the tubes are selected depending on the intended usage, and in order to obtain a wide range of application, the tubes can be designed as square tubes, e.g. 2,50 m in width and 2,80 m in height. Thereby, the ship can carry standard-sized containers as well as liquid cargos .

As the hull has been packed with tubes, a "cover" can be firmly glued and welded, in order to provide a symmetrical box. The ends of the box should be adapted and formed such that a stern part and a stem part, respectively, can be fitted thereon with loading and unloading devices adapted to the cargo department tubes as well as any equipment necessary for the propulsion and operation of the ship. Of course, further modifications and combinations of the above- described embodiments are possible within the scope of the invention. Thus, the invention is not limited to the described embodiments only, but is generally defined by means of the following claims .

Claims

1. A hull for cargo-ships, particularly for the transport of oil and chemicals, containers, cars or the like, characterised in that the hull is composed of mutually connected, parallel and tube-shaped elements, forming cargo compartments arranged in the longitudinal direction of the hull, which are enclosed in, and are connected to, an outer hull to form a generally box-shaped structure having an essentially rectangular cross section, and being at both ends adapted for optional dismountable connection of a stern part and a stem part, respectively.

2. A hull according to claim 1, characterised in that outer hull is composed of an inner plate and an outer plate with an intermediate cellular plastic material glued to both plates.

3. A hull according to claim 1 or 2, characterised in that the tube-shaped cargo compartment elements are glued together mutually and to the outer hull over a layer of cellular plastic material.

4. A hull according to claim 2 or 3, characterised in that the glue used is a glue that forms an elastic or visco-elastic glue line .

5. A hull according to any of claims 1-4, characterised in that the box-shaped structure at both ends, connecting to the stern part and stem part, respectively, is provided with connecting means for loading and unloading of a cargo, which may be liquid, containers, cars, etc.

6. A hull according to any of claims 1-5, characterised in that the tube-shaped cargo compartment elements are shaped with a square cross-section.

7. A hull according to any of claims 1-5, characterised in that the tube-shaped elements are shaped with a hexagonal cross- section, wherein cavities formed next to the outer hull are packed with cellular plastics or tube-shaped tanks.

8. A hull according to any of claims 1-7, characterised in that the cellular plastic material is expanded polypropylene, expanded polythene, expanded PVC, expanded polystyrene, expanded PET, cross linked or non-cross linked materials, and preferably expanded polypropylene.

9. A hull according to any of claims 1-8, characterised in that the tube-shaped cargo compartment elements are manufactured from high-strength steel plates.