Ship

Abstract

 A ship comprising cargo tanks (4,5) that have a completely or approximately circular or elliptic cross sectional shape and smooth inner walls (6,7) with the cross section of the ship's hull (l3) corresponding to the shape of the cargo tank along essential portions, is characterized by the fact that the cargo tank walls (7,8) and the ship's skin (l3) are made of plate material with longitudinal braces (l5,l6), said cargo tank walls extending continuously through the entire cargo area (L) of the ship, with substantially unchanged cross sectional distance between the cargo tank wall and the skin and with the ship's skin forming an integrated continuous structure with transversal frames (l4) between said cargo tank wall (6,7) and said skin (l3), and where the longitudinal braces (l5, l6) are support­ed by said transversal frames (l4).

Description

[0001] The present invention relates to a ship comprising cargo tanks that are completely or approximately circular or elliptic in cross section and have smooth inner walls, the cross section of the hull corresponding to the shape of the cargo tank in large areas.

[0002] Cargo tanks having smooth inner walls and a completely or approximately circular or elliptic cross section are known in many embodiments. By way of example, the known spherical tank freighters and tankers or bulk freighters having horizontal approximately cylindrical or slightly conical cylinder tanks may be mentioned. It is common to these known approaches that the cargo tanks are provided in a conventional hull of a ship and that the cargo tanks do not enter into the very hull structure as they do in conventional tankers.

[0003] According to the invention a completely novel ship hull concept is suggested, in which the design of the hull is determined on the basis of the design of the cargo tanks, and in which the cargo tanks are incorporated in the hull forming structural members thereof.

[0004] According to the present invention a ship as mentioned above is, thus, proposed, said ship being characterized by the fact that the cargo tank walls and the hull skin consist of plate shaped material provided with longitudinal braces, said cargo tank walls being extended continuously throughout the entire cargo area of the ship with an essentially.unchanged cross sect­ional area between the carco tank wall and the skin, and with the ship skin forming an integrated continuous structure pro­vided with a transverse frame between cargo tank wall and skin, where said longitudinal bracers are supported by the transverse frame members.

[0005] Such a ship structure will provide a cargo tank showing no in­terior structural elements or braces, at the same time as said cargo tank will contribute efficiently to strengthen the ship both transverse and along the ship. With the present invention the advantages of shell-type structures are employed and great savings as regards consumption of materials are achieved. As to strength, advantages are achieved due to the fact that vulnerable and heavily loaded corners and sharp angles found in conventional hull cross sections are eliminated. Loads on the hull will be much more efficiently absorbed by the arcuate shapes reducing cracking to a minimum.

[0006] Said cargo tanks may be used for liquid cargo as well as for bulk cargo, e.g. grain, cement, ore, etc.

[0007] The space or spaces between the cargo tank wall and the hull skin may be used for ballast, simple kinds of cargo, or fuel.

[0008] The cargo tanks are preferably cylindrical, but they may, of course, depart from a pure cylinder shape, e.g. having the shape of a truncated cone adapted to the lines of the hull. The continuous tanc structure is suitably divided internally by transversal bulkheads, preferably in the shape of domed or vaulted.transversal bulkheads. Such vaulted transversal bulk­heads may be built without braces to maintain smooth interior tank walls.

[0009] The midship frame of the new hull will have a shape resulting in good hull lines and little resistance. The new ship will have good stability when heeling over.

[0010] An advantageous embodiment of the new ship is characterized by two horizontal cylinder tanks provided side-by-side, the ship's side in cross section being shaped like semicircles about said cargo tanks before they are shaped into a bow and sternpost respectively at the ends.

[0011] The invention shall be more fully described with reference to the drawings, wherein:

Fig. l is a diagrammatic elevational view of a ship according to the invention,

Figure 2 is a top vie of said ship,

Figure 3 is a sectional view along line III-III in Figure l, shown in a larger scale,

Figure 4 is a partial perspective view of the ship according to Figure l, showing the area near sectional line III, and

Figures 5 and 6 show two further possible cross sectional shapes of the new ship.

[0012] In Figures l and 2 a ship l is shown. The ship comprises a sternpost portion 2, a bow portion 3, and a cargo area L provid­ed between said portions. In the cargo area the ship has an essentially constant cross section. Said cross section is shown in Figure 3.

[0013] The ship's cargo area L is an integrated continous structure, in the present case comprising two horizontal cylindric tanks 4 and 5 as supporting elements of the hull 6.

[0014] Each of the cylindric tanks 4, 5 is, thus, designed as a tube shaped body 7, 8 which is closed by domed end bulkheads 9, l0 and ll, l2, respectively. Said two cylindric tanks 4, 5 are placed side-by-side, as will appear from Figures l, 2, and 3, and are connected with the ship's skin l3 by transversal frames l4. The ship's skin consists of steel plates reinforced by langitudinal braces l5. The cylindric tanks 4, 5 are, correspondigly, built with steel plates welded together and reinforced by longitudinal braces l6.

[0015] It will appear, especially from Figure 3, that the cross section of the hull in large portions corresponds to the cross sectional shape of the cargo tank, the ship's sides in cross section being here shaped as semicircles about said circular cylindric cargo tanks.

[0016] In Figure 4 the structural design of the cargo area L of the ship is shown in a partial perspective view. It appears how the horizontal cylindric tanks 4, 5 are constructed as tube shaped bodies made of steel plates that are welded together and externally reinforced by longitudinal braces l6. The ship's skin l3 is constructed as a tube shaped body, made from steel plates that are welded together and internally reinforced by longitudinal braces l5. Between said skin l3 and the cargo tank walls 6, 7 transversal frames l4 are arranged supporting the longitudinal braces l5, l6.

[0017] It will appear from Figures l - 4 that at least in the cargo area the ship is constructed with shell-type structures that are mutually reinforced and connected into an integrated continuous tube shaped structure.

[0018] The cross sectional distance between a cargo tank wall 7 or 8 and the adjacent ship's skin l3 will essentially be constant in the longitudinal direction of the ship for the extent of the cargo area L.

[0019] In Figures l and 2 it is shown how said cargo tanks may be divided internally by transversal bulkheads l7,l8. Said bulk­heads are advantageously designed as semi-spherical shells and are welded to frame members l9,20 which are formed by portions of transversal frames l4 extended into the cylindrical tanks 4 and 5, respectively. The object with this is just to achieve a more advantageous welding of the transversal bulk­heads l7, l8 to the supporting frames.

[0020] Figures 5 and 6 show further possible cross sectional shapes of the new ship.

[0021] In Figure 5 a cargo tank 2l with a circular cross section is shown. About said cargo tank there is a transversal frame 22 and then the skin 23 of the ship's hull. The transversal frame 22 supports longitudinal braces 24, 25 against said skin and tank wall, respectively.

[0022] The ship's hull shown in Figure 6 is constructed in the same fundamental manner as the ship's hull shown in Figure 5. The only difference is that in stead of one cargo tank in the cross section there are four cargo tanks 26, 27, 28, and 29. A transversal frame is designated 30 and longitudinal braces 3l, 32 are indicated. The location and function of these members are the same as disclosed and shown above in connection with Figure 5, and in connection with Figures l-4, respectively.

[0023] In Figures 5 and 6 only a few longitudinal braces are shown, and in Figures 3-4 longitudinal braces l5, l6 are shown for the whole cross section of the ship, but the number shown is much reduced as compared to the number of braces used in practice. This is done so as to avoid cluttering the drawing with too many details.

[0024] The present invention, thus, results in a ship that has several advantages as compared to existing ships with a double skin, a double bottom, and double decks, etc.

[0025] Among such advantages the following may be mentioned in view of a typical ship with a cargo volume of l00,000 m³:

[0026] Enlarged cargo volume, enlarged ballast volume, a simplified midship frame structure, reduced weight of steel material, simple adaption of sections during construction work, reduced number of cargo tanks, maintenance of the steel, i.e. the steel structure is simplified, reduced hazard of cracking, more efficient tank cleaning and removal of gas and vapour from the cargo tanks is rendered possible, it is possible to carry pure ballast according to the MARPOL definition, and a minimum size of slop-tanks.

[0027] Totally, the new ship concept, thus, has conclusive advantages.

Claims

1. A ship comprising cargo tanks (4,5) that have a complete­ly or approximately circular or elliptic cross sectional shape and smooth inner walls (6,7) with the cross section of the ship's hull (l3) corresponding to the shape of the cargo tank along essential portions, characterized in that the cargo tank walls (7,8) and the ship's skin (l3) are made of plate material with longitudinal braces (l6,l5), said cargo tank walls extending continously through the entire cargo area(L) of the ship, with substantially unchanged cross sectional distance between cargo tank wall and skin and with the ship's skin (l3) forming an integrated continuous struct­ure with transversal frames (l4) between said cargo tank wall (6,7) and said skin (l3), where the longitudinal braces (l5, l6) are supported by said transversal frames (l4).

2. A ship as defined in claim l,
characterized in two horizontal cylindrical tanks (4,5) provided side-by-side, the ship's sides in cross section being shaped as semicircles about said cargo tanks and towards the ends being shaped as a bow (3) and a sternpost (2), respectively.

Drawing