US3834339A

US3834339A - Construction of ships

Info

Publication number: US3834339A
Application number: US00297629A
Authority: US
Inventors: R Rutherford
Original assignee: SWAN HUNTER GROUP Ltd
Current assignee: SWAN HUNTER GROUP Ltd
Priority date: 1971-10-21
Filing date: 1972-10-16
Publication date: 1974-09-10
Anticipated expiration: 1991-09-10
Also published as: SE7213614L; IT969769B; GB1346919A; ES408038A1; DE2251273A1; FR2157633A5; JPS4862187A; NL7214113A

Abstract

A fore end structure for a ship, and method of constructing same, consisting of a number of prefabricated units adapted to be assembled to form said fore end, the port and starboard of said units being of an orthogonal nature in that the webs interconnecting the sideshell portion and associated bulkhead of said units extend normally to the waterline of the ship, thereby to improve the efficiency of the sideshell stiffening.

Description

United States Patent 1191 Rutherford 1 Sept. 10, 1974 CONSTRUCTION OF SHIPS 3,698,344 10/1972 Maeda 114/77 R [75] Inventor: Robert Rutherford, North Shields, FOREIGN PATENTS OR APPLICATIONS England 26,467 11/1909 Great Britain 114/77 R [73] Assignee; Swan Hunter Group Limited, 1,194,724 6/1965 Germany 114/77 A Wallsend, Northumberland, England Primary Examiner-George E. A. Halvosa 22 Filed; Oct 1 1972 Assistant Examiner-Stuart M. Goldstein [21] Appl. No.: 297,629

[57] ABSTRACT [30] Foreign Application Priority Data A fore end structure for a ship, and method of con- Oct. 21, 1971 Great Britain 43990/71 Strueting same, consisting of a number of prefabricated units adapted to be assembled to form said fore [52] U.S. Cl 114/77 R nd, h port and starboard of said units being of an [51] Int. Cl B63b 3/02 hogo al nature in that the webs interconnecting the [5 8] Field of Search 114/77 A, 77 R, 65 R sideshell portion and associated bulkhead of said units extend normally to the waterline of the ship, thereby [56] References Cit d to improye the efficiency of the sideshell stiffening.

UNITED STATES PATENTS 6 Claims, 6 Drawing Figures 3,447,503 6/1969 Myers 114/65 R v CONSTRUCTION OF SHIPS This invention relates to the construction of ships and more particularly to an improved fore end construction for ships.

Present fore end structures commonly comprise a large number of shaped webs and face plates such as side, deck and bottom transverses and centreline webs. Such structures necessarily lead to costly sub-assembly work and difficulty in erection and fairing at the berth.

Another criticism of present fore end structure is the inefficiency of the side transverses which support the sideshell of the ship and break up the span of the side stringers. FIG. 1 of the accompanying drawings clearly shows the general arrangement of the transverses 1 and sideshell 2 at the fore end of a ship. It can be seen that, because of the shaping of the fore end of the ship towards the centreline of the ship, the side transverses l, which are normal to the centreline of the ship, meet the shell 2 at quite an acute angle a. Thus the efficiency of the transverses 1 as strength members is greatly reduced.

According to the present invention there is provided a ship having a fore end and/or stern comprising a plurality of prefabricated units including port and starboard units each of which have a sideshell portion, an elongate bulkhead spaced from and extending substantially parallel with the associated sideshell portion, and a plurality of webs extending between said bulkhead and sideshell portion to be substantially normal to the sideshell portion.

Conveniently the units further include a base unit, a stem unit and an upper unit. The units themselves may each comprise a series of sub-units depending on the cranage available at the berth.

A method of constructing the fore end and/or the stern of a ship comprises the steps of:

a. prefabricating the above detailed units b. locating the base unit in position 0. locating and securing the port and starboard units on the base unit d. locating and securing the stem unit to the base,

port and starboard units, and

e. locating and securing the upper unit on the stem,

port and starboard units.

By way of example only, the invention will now be described in greater detail with reference to FIGS. 2 to 6 of the accompanying drawings, of which:

FIG. 2 is a horizontal section through part of the fore end of a ship according to the invention;

FIG. 3 is a transverse vertical section through the fore end showing typical webs;

FIG. 4 is a plan view of the fore end at the forecastle deck;

FIG. 5 is a vertical section along the centreline of a ship at the fore end, and

FIG. 6 is an exploded perspective view of a fore end constructed according to the invention.

The present invention has been formulated with a view to reducing substantially the complexity of the 7 The invention will be detailed in relation to oil tankers, although it is equally applicable to bulk carriers and other cargo ships. Oil tankers commonly have at least one row of tanks extending centrally over the cargo tank range of the ship, and port and starboard wing tanks. The latter tanks are separated from the centre tanks by longitudinal bulkheads extending between the bottom plating of the hull and the upper deck, and longitudinally parallel with the centreline of the ship.

Referring to FIGS. 2 to 6 of the drawings, the longitudinal bulkheads 3, between the centre and wing tanks, are terminated at the transverse fore peak bulkhead 4, which extends from the bottom plating of the hull to the upper deck.

Forward of this bulkhead 4, the fore end comprises five basic units, shown as A to D in FIG. 6. Depending on the cranage capacity available, these basic units can themseleves each comprise a series of sub-units without departing from the scope of the invention.

1 Unit A is a double bottom structure comprising a fully plated tank top 6 which extends forward from the transverse bulkhead 4'to the extremity of the bow (or bulb if fitted) and transversely from one side of the ship to the other. This unit is prefabricated by building it upside down with the top 6 forming the base during construction. The transverse floors 8, longitudinal girders and all stiffening members are attached to the top 6, the hull plating or shell 10 then being fitted to form the complete double bottom unit A. This structure is then positioned on a berth to act as a building platform for the rest of the fore end.

The port and starboard side units B extend forward from the bulkhead 4 to the stem unit C and upward between the top 6 and the upper deck unit D. The units each comprise an extension bulkhead 12 extending from the transverse bulkhead 4 forward to the stem unit C. These bulkheads 12 are substantially parallel with the adjacent outer shell 16 of the fore end, and slope inwards towards the centreline 14 of the ship as shown in FIG. 2.

Transverse webs 18 extend normally from the bulkheads 12 between said bulkheads and the shell 16, said webs therefore being substantially normal to said shell and at an acute angle to the centerline 14, such orientation of the webs improving the strength of the fore end compared with the arrangement of FIG. 1 where the webs will be seen to be perpendicular to the centerline and at an acute angle with respect to the shell.

The units B are each prefabricated with the bulkhead 12 as the base, horizontal flat members 20 being attached outboard of the bulkhead 12 at various optimum levels to break up the span of the vertical panel webs 18. After all stiffening members have been attached, the outer shell 16 is fitted in position.

The units B can then be located on unit A and faired in position. The horizontal brackets 22 which extend between the forward ends of the two longitudinal bulkheads 12 are fitted at various height intervals to tie the port and starboard units together. The remaining brackets 23 at the tank top 6, transverse bulkhead 4 etc. are then fitted.

It is to be noted that the transverse floors 8 of unit A run normal to the ships centreline and then crank over to line up with the webs 18 of units B.

The stem unit C extends from the open ends of units B to form the front extremity of the ship, the unit being located on the bottom unit A to extend upwards to the upper deck 28. In prefabricating this unit, a simple jig is made to take the shape of the web 24 which provides a base to the unit during construction. The centreline web 26, horizontal flats, breasthooks, stiffeners, shell and stem plates are then fitted in position. The completed unit'is then brought into position at the forward end of unit A, fitting onto the open ends of units B.

The upper deck unit D extends forward from the forecastle front to the stem of the ship, and transversely from one'side of the ship to the other. In construction, the upper deck 28 forms a base for the unit, the centreline bulkhead and all other internal bulkheads, together with all webs, stiffeners and the forecastle front, being erected on the upper deck. The forecastle deck 30 is fitted over this structure to form a sandwich and the shell plating is then fitted to complete the unit which is located on the previously assemblied units to complete the fore end. I In order to minimize scantlings, the sloping bulkheads -12, the tank top 6 and web 24 are non-watertight so that the entire fore peak tank i.e. within the boundaries of the outer shell of the fore end can be used for water ballast. Alternatively, the centre tank 34 as defined by the

bulkheads

4, 12, the web 24, the tank top 6 and the upper deck 28 could readily be used as a clean ballast tank by making all the defining boundaries watertight. The space outside the components defining the central tank 34 is then a dry space and forms a cofferdam offering a secondary barrier against side or bottom shell damage. This dry space, which contains most of the structure, will not require painting whereas the centre tank, being substantially flat-surfaced, can easily be painted.

There are a number of advantages to be gained from a fore end constructed as detailed above, and from the method of construction according to the invention.

In particular, the invention affords simplicity of unit breakdown, the structure being designed for manufacture by modern steelworking facilities.

Accessability throughout the whole fore end structure is greatly improved by access openings at each successive working platform, thus enabling any further internal staging readily to be erected.

The prefabrication of the individual units minimizes work content at the ship, it merely being necessary to assemble the units at the berth.

The described structure enables anchorage arrangements to be designed so as not to interfere with any primary structure. It can be seen in FIG. 4 that the hawse pipe 36 from the chain storage locker 38 to the ships shell does not cut through any of the transverse webs 18 as it would in conventionally constructed fore ends.

The plurality and positioning of the bulkheads in the forecastle tweendecks allows the heavy loading from deck machinery and shipped seas on the deck to be dis tributed evenly throughout the structure, thus eliminating pillars with their concentrated point loads.

Although described in relation to the fore end of tankers, to which it is particularly suited, the invention can be applied to the construction of, and method of constructing. the stern of a ship. In all cases the simplicity of construction and the orthogonal relationship between the webs l8 and the shell of the ship provide particular advantages over established arrangements.

What I claim and desire to protect by Letters Patent l. A method of constructing the fore endof a ship comprising steps of:

a. prefabricating the port, starboard, stem, base and upper units; b. locating the base unit in position; 0. locating and securing the port and starboard units on the base unit; d. locating and securing the stem unit to the base,

port and starboard units, and e. locating and securing the upper unit on the stem,

port and starboard units. I 2. A method according to claim 1, in which said port and starboard units each comprise an elongated sideshell, an elongated bulkhead spaced from and extending substantially parallel to the elongated sideshell, and a plurality of webs extending between said bulkhead and said sideshell substantially perpendicular to the sideshell, the method being further characterized in that the port and starboard units are located and secured on the base unit with the elongated shell portions thereof at an angle to the longitudinal axis of the ship and with the webs of the port and starboard units at an angle other than 90 to the longitudinal axis of the ship.

' 3. A ship having a fore end, the fore end comprising port, starboard, base, stem and upper units, the port and starboard units being located on and secured to the base unit as is also the stem unit forwardly of the port and starboard units, said upper unit being located on and covering said stem and said port and starboard units, each port and starboard unit comprising an elonated sideshell, an elongate bulkhead spaced from and extending substantially parallel to its associated sideshell and a plurality of webs extending between said sideshell and said bulkhead, said sideshells being (a) angularly disposed relative and in converging relation to the longitudinal axis of the ship and (b) with said plurality of webs perpendicularly related thereto, said webs by virtue of their perpendicular orientation to the sideshell and the angular converging orientation of the latter with respect to the longitudinal axis of the ship, being disposed at an acute angle relative to said longitudinal axis.

4. A ship according to claim 3, including a bulkhead extending transversely from one side of the ship to the other and upwardly from the bottom plating of the ships hull to the upper unit, the fore end of the ship.

' projecting forwardly from said bulkhead.

5. A ship according to claim 4, in which the port and I ship to the other.

Claims

1. A method of constructing the fore end of a ship comprising steps of: a. prefabricating the port, starboard, stem, base and upper units; b. locating the base unit in position; c. locating and securing the port and starboard units on the base unit; d. locating and securing the stem unit to the base, port and starboard units, and e. locating and securing the upper unit on the stem, port and starboard units.

2. A method according to claim 1, in which said port and starboard units each comprise an elongated sideshell, an elongated bulkhead spaced from and extending substantially parallel to the elongated sideshell, and a plurality of webs extending between said bulkhead and said sideshell substantially perpendicular to the sideshell, the method being further characterized in that the port and starboard units are located and secured on the base unit with the elongated shell portions thereof at an angle to the longitudinal axis of the ship and with the webs of the port and starboard units at an angle other than 90* to the longitudinal axis of the ship.

3. A ship having a fore end, the fore end comprising porT, starboard, base, stem and upper units, the port and starboard units being located on and secured to the base unit as is also the stem unit forwardly of the port and starboard units, said upper unit being located on and covering said stem and said port and starboard units, each port and starboard unit comprising an elonated sideshell, an elongate bulkhead spaced from and extending substantially parallel to its associated sideshell and a plurality of webs extending between said sideshell and said bulkhead, said sideshells being (a) angularly disposed relative and in converging relation to the longitudinal axis of the ship and (b) with said plurality of webs perpendicularly related thereto, said webs by virtue of their perpendicular orientation to the sideshell and the angular converging orientation of the latter with respect to the longitudinal axis of the ship, being disposed at an acute angle relative to said longitudinal axis.

4. A ship according to claim 3, including a bulkhead extending transversely from one side of the ship to the other and upwardly from the bottom plating of the ship''s hull to the upper unit, the fore end of the ship projecting forwardly from said bulkhead.

5. A ship according to claim 4, in which the port and starboard units each extend forwards from said transverse bulkhead to the stem unit.

6. A ship according to claim 5, in which the base unit comprises a double walled structure extending forwardly from said transverse bulkhead to the front extremity of the ship and transversely from one side of the ship to the other.