US3016867A

US3016867A - Ship's hull construction

Info

Publication number: US3016867A
Application number: US632140A
Authority: US
Inventors: Albiach Vincent
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-01-07
Filing date: 1957-01-02
Publication date: 1962-01-16
Anticipated expiration: 1979-01-16

Description

1952 v; ALBIACH 3,016,867

SHIPS HULL CONSTRUCTION Filed Jan. 2, 1957 2 Sheets-Sheet 1 r 20 L/ J 2 Sheets-Sheet 2 Filed Jan. 2, 1957 WS S 3315,86? Patented Jan. 16, 1962 fice 3,916,857 SiiilPS HULL tIGNSTRUCTION Vincent Aihiach, 76 Rue Spontini, Paris, France Filed Jan. 2, 1957, Ser. No. 632,1 Claims priority, application France Jan. 7, 1956 4 Ciaims. (Cl. lid-79) This invention relates to improvements in the construction of ships hulls, particularly designed for shipping loose freight of a nonuniform character.

Ships adapted to be laden at the same time or at different times with freight in bulk or loose condition, such as mineral ore, coal, cereals, sugar, cement, various powder goods, freight in liquid form or comprising mixtures of different viscosity, having widely differing inherent characteristics, should desirably be capable of a correspondingly wide range of different behaviour characteristics both as regards cruising, and loading and unloading facilities. For this purpose the various characteristics of the ship including stability and trim, capacity and layout of the hold compartments and liquid ballast tanks such as hold and hull recesses, would have to satisfy a number of conflicting conditions which have not generally been satisfied in conventionally built ships.

it is an object of the present invention to strike an optimum compromise between the various conflicting requirements imposed on the design of a merchantman by the non-uniform character of the cargo to be shipped, and particularly with regard to the diiferences of specific gravity thereof.

Another object is to provide a ships hull construction which will enable the ship to be laden substantially at all times to its full carrying capacity or burden, regardless of the particular nature and composition of the freight carried by her.

Another object is to provide sutficient hold capacity to carry a full burden of lightweight freight, e.g. oats or similar low-density materials.

A further object is to provide a hull construction Wherein the centre of gravity of the hold when carrying a lightweight cargo and the volume centre of the hold, will be so positioned that the craft will sink down substantially to its maximum load draught and will hence possess maximum stability without requiring additional ballast.

Simultaneously it is also an object of this invention to provide for the condition where high-density freight is being carried, e.g. mineral ore having an apparent density of 2.5, whereby the hold capacity is only partly filled and the centre of gravity of the cargo is thus substantially lowered and imparts excessive stability to the craft, a condition that is objectionable both because of the excessive stresses imposed on the hull and the reduced maneuverability of the ship. In preventing such a condition it has generally been necessary to provide a particular distribution of the freight lengthwise of the ship such that normal trim conditions are satisfied, and the stresses applied to the hull under all conditions, including swell and the like, do not exceed the structural safety limits. Further, it has been necessary for the same reason to increase the elevation of the ballast tank tops in the bottom of the hold, in order to bring the centre of gravity to a position consistent with acceptable stability conditions even with the more heavyweight cargos. As a result, the capacity of the bottom tanks normally assigned to the ships ballast when cruising on ballast is often liable to exceed the maximum capacity required for this purpose, and this in turn entails the necessity of increasing other dimensional characteristics of the ship including hold depth, in order to provide the minimum hold capacity specified for the most lightweight cargo.

The net result is a ship dimensioned in excess of specification requirements with a corresponding increase in cost. Moreover the framing structure of the afore-mentioned bottom tanks of increased elevation must be made strong enough to withstand the freight load, and this further complicates the construction and increases cost.

In accordance with the invention the ballast tank capacity is held down to the specified minimum. Hence, the distribution of the more heavyweight freight must be such as to ensure that the vertical position of the centre of. gravity of the load will remain at all times within the specified limits and said distribution accordingly must be made nonuniform throughout the length of the ship; thus in some cases some of the hold compartments may have to be kept empty while others are overloaded.

It is therefore an object of the invention to provide a ship structure wherein the structural elements will be adapted to withstand the local stresses transmitted from such nonuniform loading in addition to the normal stresses imposed on the craft at sea, including bending moments due to swell, shear forces, torsion moments due to rolling and due to the fact that the craft may be heading at an angle to the direction of swell.

A further object is to provide a ships hull construction wherein the lay-out and construction of the various hold tanks or compartments is so designed as to facilitate loading and unloading and ballasting operations.

The above and further objects, features and advantages of the invention will be made apparent as the description proceeds. An exemplary embodiment of the invention will now be described for purposes of illustration but not of limitation with reference to the accompanying drawings wherein:

FIG. 1, shows one half vertical, transverse cross section of a ships hull, constructed in accordance herewith, the section being drawn through an ordinary frame;

FIG. 2 is a similar section relating to a modification.

As shown, in accordance with the conventional construction of tankers, the bottom plating 1 and deck plating 2 are stilfened by the provision of longitudinal ribs 3 constructed and arranged to withstand the general stresses imposed on the ships girder as well as the local stresses due to the liquid cargo, Water-ballast and heavy sea.

The fioor 4 defining the top of the ballast tank directly supports the cargo upon it and is stilfened with transverse ribs 5 secured to the central keelson 6 and supported from the side keelsons 7. Selected ones of the ribs 5, e.g. every other rib, are laterally extended through side ballast tanks as far as the ships side 9 where they are attached to reinforcing members 9' extending in vertical direction along the side walls 9 of the ship. Reinforcing members 9 being attached to the side Walls and forming lateral frame structures for bracing and stiffening the same. The ribs 5 will therefore transmit the weight of the cargo at least in part to the reinforcing members 9' and to the sides 9 attached thereto, and further to the longitudinal bulkhead stays 10 of the side tanks 8 more fully described hereinafter, since the ribs 5 are connected to reinforcements or uprights 40 of such longitudinal bulkheads. Accordingly, the transverse ribs 5 of the floor or ballast tank top are essentially designed and constructed to withstand the local stresses and owing to their inherent arrangement they are not subjected to the over-all stresses to which the ships girder is subject.

The arrangement just described as involving a correlation of the longitudinal system for the outer shell with the transverse system for the floor or ballast-tank top, within the bottom hull recess, thus serves to prevent a dangerous superposition of the local stresses due to cargo over the over-all ships girder stresses, in any given structural element.

The floor or ballast top transverses 5 extend unbroken athwart the hull and their end sections on each side project into box compartments 11 having diagonal tops 12 so as to define the bottom portions of the side compartments or tanks 8 which are also adapted to receive cargo therein.

in a modified construction shown in FIG. 2 the ribs 5 of the floor or ballast-tank top 4 have tie members 38 associated with them in the form of rolled steel rod sections of round or polygonal cross section or strips or profiled sections, adapted to transfer the cargo load applied to the fioor 4 directly to the longitudinal bulkhead and/ or the ships side shell 9.

The tie members 38 are preferably made from steel material having higher elastic and yield points than the steel forming the ordinary hull plating. The ties may be positioned in a condition of pie-stressed tension so that the framing as a whole will be subjected to more uniform stress when the ship is under load. Such a measure will prevent the occurrence of overloads due to a superposition of the over-all stresses over the local stresses and thereby enables a reduction in Weight of the structure.

The shell and longitudinal bulkheads are constructed in the transverse system with

horizontal stringers

13 and 15 arranged with downwardly sloping webs to facilitate loading of freight such as cereals which can be stowed into the side tanks or compartments.

The shell stringers 13 are coupled by diagonal ties 14 (FIG. 1) with the uprights 40 on the longitudinal bulkheads Which bound the compartments 8 on the inboard side thereof. The sloping webs of the stringers further provide for a more efficient uptake up of the stresses transmitted through the ties.

The longitudinal bulkheads it are coupled with the sloping tops 16 of the side tanks 8 and the sloping bottom of said tanks.

It will be noted from FIG. 1 that the bottom end of the bulkhead It) is offset as at 39 towards the uprights 4t) and the web of the latter is cut at an angle, so that the load supported by the base of the bulkhead and gussets 19 will not cause a secondary bending of the main portion of the bulkhead.

The transverse bulkheads separating the respective hold compartments or tanks extend across the breadth of the ship between the longitudinal bulkheads and in those sections where the longitudinal bulkheads are omitted the transverse bulkheads extend right across to the sides of the shell.

Some of the said bulkheads may not necessarily be of watertight construction throughout their vertical extent and may be coupled with tweendecks and/or hoppers for receiving freight therein, so that the centre of gravity of the cargo may thus be raised' Slidable or pivoted sections may be included in the bulkhead to facilitate loading and unloading.

The arrangement described further makes it possible to transmit directly to the longitudinal bulkhead and shell plating part of the load of the more heavyweight freight which otherwise would rest directly on the ballast-tanks.

The tops 16 of the side tanks are assembled (see FIG. 1) with the stringer defining the base 31 of the binding strakes or carlings 32 extending along the side of the hatch openings 33. The carlings such as 32 are of unbroken construction throughout the length of the vessel, and are preferably free of any direct attachment with the hatch coaming members such as 30.

The transmission of loads at the junction nodes where a plurality of different stressed webs intersect, such as the intersections of the longitudinal shell sides, side tank tops and floor, is taken care of by the provision of a plate having-an enlarged bead thereon, with the ends of the stressed Webs bu te ded in the beaded plate. Such an arrangement is economical and facilitates fitting and welding operations.

What I claim is:

1. In a ships hull particularly in the hull of a bulk and ore carrier, comprising a bottom, a deck and a shell defining side walls, in combination, a plurality of first platings connected with each other and constituting said deck; a plurality of second platings connected with each other and constituting said bottom; a plurality of first rib members spaced from each other and extending in longitudinal direction of said hull and attached to said first platings for bracing and stiffening same; a plurality of second rib members spaced from each other and extending in longitudinal direction of said hull and attached to said second platings for bracing and stiffening same; a plurality of third platings connected with each other and constituting one side wall; a plurality of lateral frame structures spaced from each other and extending substantially vertically and bein attached to said third platings for bracing and stiffening same; an intermediate floor extending substantially parallel with said bottom between said side walls and adjacent to but spaced from said bottom to define a ballast room; keelson means extending longitudinally along said bottom; a plurality of transversal frame structures spaced from each other and supporting said intermediate floor for bracing and stiffening the latter, said transversal frame structures being attached to said keelson means and having ends directly connected to said lateral frame structures while bypassing said second rib members so as to transmit a substantial part of the load that may be imposed by cargo on said intermediate floor, to said shell of said hull, each of said transversal frame structures being unconnected to the other transversal frame structures by stress-transmitting reinforcements and constructed to Withstand the local stresses imposed by cargo without transmitting them to said other transversal frame structures and said second rib members whereby dangerous superposition of local stresses imposed by cargo in the region of each of said transversal frame structures over the overall girder stresses in the ship structure is prevented.

2. A hull as set forth in claim 1, wherein said shell includes a second inner side Wall spaced from said one side Wall and thereby defining longitudinally extending bulkheads between said side walls, a plurality of ties connecting said inner side wall with said lateral frame structures, said transversal frame structures having intermediate portions attached to said ties.

3. A hull as set forth in claim 1, wherein tensionally pre-stressed tie members are connected between said keelson means and said lateral frame structures for reinforcing and bracing said transversal frame structures.

4. In a ships hull particularly in the hull of a bulk and ore carrier, in combination, an outer shell forming substantially vertical side walls and a substantially fiat bottom wall of the hull; a plurality of first reinforcing members being spaced from each other and extending in substantially vertical direction along and being attached to said side walls for bracing and stiffening the same; a plurality of second reinforcing members being spaced from each other and extending in longitudinal direction of said ship along and being attached to said bottom wall for bracing and stiffening the same; an intermediate floor extending substantially parallel with and adjacent to but spaced from said bottom wall between said side walls, said intermediate floor and said bottom wall defining a ballast tank; a plurality of third reinforcing members being spaced from each other and extending in transverse direction of the ship along and being attached to said intermediate floor for supporting the same, all of said third reinforcing members being spaced from said bottom wall and said second reinforcing members, so that stress deformations of said third reinforcing members will not be transmitted to said second reinforcing members and vice versa and each of said third reinforcing members being constructed to Withstand local stresses due to load placed on said intermediate door in the region of the respective third reinforcing member and unconnected by stress-transmitting reinforcements to the other third reinforcing members whereby, on the one hand, each of said third reinforcing members is not subjected to the overall stresses to which the ships girder system is exposed and, on the other hand, dangerous superposition of the local stresses due to load in the region of the respective third reinforcing member over said overall girder stresses in the ship is prevented; and means directly connecting said third reinforcing members supporting said intermediate floor with said first reinforcing members attached to said side walls so as to transmit a substantial part of the load that may be imposed by cargo on said intermediate floor to said side walls of said ship.

References Cited in the file of this patent UNITED STATES PATENTS Stuart May 7, 1895 Reid et al June 24, 1913 Isherwood Feb. 7, 1928 Bartenfeld Aug. 7, 1928 Benthem Sept. 2, 1941 Lackie Apr. 27, 1948 Bartenfeld Aug. 22, 1950 Bartenfeld Apr. 15, 1952 Albiach Apr. 10, 1956 McAleer May 1, 1956 FOREIGN PATENTS Great Britain of 1907