US3656446A

US3656446A - Method of constructing a ship

Info

Publication number: US3656446A
Application number: US24273A
Authority: US
Inventors: John J Heffernan
Original assignee: Bethlehem Steel Corp
Current assignee: Bethlehem Steel Corp
Priority date: 1970-03-31
Filing date: 1970-03-31
Publication date: 1972-04-18
Anticipated expiration: 1989-04-18

Abstract

In constructing and launching a ship, a construction area and a way area, both lying in the same horizontal plane, are provided. Sections of the ship are made in the construction area. Each section rests on a gas cushion support pallet. While so supported, the sections are moved to the way area where they are joined together to form the ship. From the way area and while still supported on the gas cushion support pallets, the ship is moved horizontally to a drydock which is ballasted and rests on an underwater supporting structure. The drydock is then deballasted, moved from its position above the supporting structure, and ballasted. The ship is then floated out of the drydock.

Description

United States Patent Heffernan 5] Apr. 18, 1972 {54] METHOD OF CONSTRUCTING A SHIP 3,392,800 7/1968 Swamy ..180/125 1 lnvenwfi J Heffernan, pp FOREIGN PATENTS OR APPLICATIONS Assigneei Bethlehem Steel Corporation 782,892 4/1968 Canada ..180/125 [22] Wed: 1970 Primary Examiner-Milton Buchler [21] Appl. No.: 24,273 Assistant E.\'aminerF. K. Yee Attorney-Michael J. Delaney [52] U.S. Cl. ..ll4/77 R, 61/64 57 AB TRACT [51] Int. Cl ..B63b 3/02 1 S [58] Field f Se ch 1 14/77 R, 77 A, 72, 65, 44.49, In constructing and launching a ship, a construction area and a 114/435; 61/64-68; 180/124, 125, 116, 117, 120, way area, both lying in the same horizontal plane, are pro-- 121; 104/23 FS, 242, 245, 247; 53/33 vided. Sections of the ship are made in the construction area. Each section rests on a gas cushion support pallet. While so 56] References Cited supported, the sections are moved to the way area where they are omed together toform the sh1p. From the way area and UNITED STATES PATENTS while still supported on the gas cushion support pallets, the ship is moved horizontally to a drydock which is ballasted and Brena X rests on an underwater pp i g Structure The drydock i 3,468,393 9/1969 Harrlson 180/1 16 the" debanasted, moved f i itio above the support- 3478525 I [/1969 Van Der Hoeven X ing structure, and ballasted. The ship is then floated out of the 3,318,276 5/1967 Nemec ..114/43.5 drydock 2,33'7,l01 12/1943 Harris ..1 14/65 3,465,533 9/1969 Payne ..1 14/45 X 3 Claims, 5 Drawing Figures METHOD OF CONSTRUCTING A SHIP BACKGROUND OF THE INVENTION This invention relates generally to a method of constructing a ship and specifically to a method of constructing a ship which eliminates the need for inclined ways and facilitates the movement and joining together of sections of the ship. In the past, ships have been built on inclined ways, which by necessity are designed to accommodate a ship having a certain maximum size and weight. Thus the size and weight of a ship which can be built by a given shipyard is limited by the capacity of its inclined ways. In addition, construction procedure in a shipyard is limited by the capacity and location of the lifting equipment available at the shipyard. A section of a ship cannot weigh more than the weight which can be raised by such equipment, and the section must be built at a location accessible to the lifting equipment.

SUMMARY OF THE INVENTION An object of this invention is to provide a method of constructing a ship which eliminates the need for inclined ways.

Another object of this invention is to allow greater flexibility in the construction procedure for a ship.

The above objects can be attained by providing a construction area and a way area which lie in substantially the same horizontal plane, prefabricating sections of the ship on the construction area while supporting the sections on gas cushion pallets, supplying gas under pressure to the pallets to support the sections and pallets on a gas film, moving the sections from the construction area to the way area while maintained on the gas-supported pallets, arranging the sections on the way area in accordance with their designated positions in the ship while so maintained and supported and joining the sections together.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a construction area, a way area and a drydock for practicing this invention.

FIG. 2 is an elevation view showing a ship leaving the way area and entering a drydock.

FIG. 3 is a partial sectional elevation view of a gas cushion support pallet.

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 1.

FIG. 5 is a sectional view taken along the line 55 of FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS Referring to the drawings, and in particular FIG. 1, there is provided a construction area and a way area 11, comprising concrete slabs, both of these areas lying in substantially the same horizontal plane. The construction area 10 may be enclosed by a roof (not shown) and walls 12 with a suitable access opening 13. The way area 11 may include a number of ways 14 which extend perpendicular to a body of water 15. Tracks 16 extend along the way area and support cranes 17 which are used primarily to lift equipment onto the sections 18 and ship 19.

Sections 18 of a ship are prefabricated on the construction area 10, moved to the way area 11 and arranged each in accordance with its designated position in the ship. On the way area, the sections are joined together to form a ship 19.

Referring to FIG. 3, during prefabricating on the construction area 10, each section 18 is supported by a gas cushion support pallet 20. Gas cushion support pallets 20 are well known in the art and include a horizontally extending member 21 to which are attached a plurality of pads 22. The pads 22 may be attached to the member 21 by a bolt and nut assembly 23. Each pad 22 includes a gas inlet nozzle 24 which admits gas, such as air, under pressure to a flexible diaphragm 25. This gas pressure inflates the diaphragm 25 and tends to cause a seal between the diaphragm 25 and the way area 11. As the gas pressure increases, gas from the diaphragm 25 escapes at a controlled rate through holes 26 in the diaphragm 25 to form a gas film under the diaphragm 25. This gas film which supports the pallet 20 has an extremely low coefficient of friction and allows a vertical pallet load of substantial size to be moved horizontally in any direction by 'a small horizontal force. In addition, the gas cushion pallet 20 may be rotated to allow a section 18 of the ship to be turned within a minimum space on the construction or way area.

Gas under pressure may be supplied to the pads 22 through a hose 27 from any convenient source. Gas under pressure for the pads may be stored in tanks formed within a section 18 of the ship and supplied to the pads 22 by a hose 28, as shown in FIG. 4. Gas under pressure may also be stored in a tank 29 positioned within a section 18 of the ship and supplied through a hose 30, as shown in FIG. 5. The arrangements for supplying gas under pressure as shown in FIGS. 4 and 5 are particularly advantageous when moving the ship 19 from the way area 11 to a dry clock 31, as shown in FIG. 1, since hoses need not be extended from the way area 11 to the dry dock 31.

As shown in FIG. 4 the pallets 20 are spaced from the ends of the sections 18 so that free access is provided to the ends of the sections 18 which are joined together by welding or other suitable fastening means. Trenches 32 are provided in the way area 11 to allow access to the underside of the sections 18. During joining together of sections 18 to form a ship 19, the ends of adjacent sections 18 are positioned directly above a trench 32. Removable covers 33 allow the gas cushion support pallets 20 to move over the trenches 32. To facilitate aligning the sections 18 prior to joining them together, the gas pressure in the pads 22 of a section 18 may be varied and in so doing a section 18 may be raised, lowered or canted.

As shown in FIGS. 1 and 5, portable guide member 34 comprises an upright member 35 removably secured to the way area 11 and supports a vertically positioned anti-friction bearing mounted roller 36 in contact with the sides of the ship 19 or its sections 18 and provides lateral restraint to the ship 19 or its sections 18 as they move along the way area 11. The plurality of gas pads 22 which support each section 18 automatically act to overcome any wind effect which would tend to overturn a section 18 or the ship 19. This automatic action is present since the pads 22 on the windward side will tend to lose their pressure while those on the opposite side will increase their lifting force and counteract the wind effect.

As shown in FIGS. 1 and 2, a dry dock 31 is positioned in the water 15 adjacent the way area 11. When ballasted, the drydock 31 rests on a supporting structure comprising supporting piers 37 connected together by horizontally extending beams 38 with the inner bottom of the drydock 31 horizontally aligned with the way area 11. Cables 39 may be used to further secure the drydock 31 adjacent the way area 11. After the ship 19 is moved onto the drydock 31 by means of the gas cushioned support pallets 20, as shown in FIG. 1, the drydock 31 is deballasted, floated off the supporting structure, and ballasted once again. The ship 19 is then floating free of the drydock 31.

The method of constructing a ship according to this invention may comprise the following steps: (1) Sections 18 of a ship are prefabricated in a horizontally extending construction area 10 while resting on gas cushion pallets 20. (2) Gas under pressure is supplied to the gas cushion pallets 20 to provide a gas film which supports the sections 18 and pallets 20 off the construction area 10. (3) While so supported, the sections 18 and pallets 20 are moved to a way area 11 which lies in the same horizontal plane as the construction area 10. (4) The sections 18 on the way area 11 are arranged each in accordance with its designated position in the ship 19. (5) The sections 18 are positioned above trenches 32 in the way area 11. (6) The air pressure in the air cushioned support pallets 20 of adjacent sections is varied to properly align the sections 18. (7) The sections 18 are joined together to form a ship 19. (8) While supported on the pallets 20, the ship 19 is moved to a ballasted drydock 31 horizontally aligned with the way area 11. (9) The drydock 31 is deballasted and floated away from the way area 11. (10) The drydock 31 is ballasted and the ship 19 allowed to float free of the drydock 31.

lclaim:

l. A method of constructing a ship including the following stepsL:

a. providing a construction area and a way area including a plurality of trenches, both areas lying in substantially the same horizontal plane,

b. prefabricating sections of said ship on said construction area, each section resting on support means including a gas cushion pallet,

c. supplying gas under pressure to said gas cushion pallet to provide a gas film which supports the section and pallet above the construction area,

d. moving the sections from the construction area to the way area, while maintained on the gas-supported pallets,

e.arranging the sections on said area while maintained on the gas-supported pallets, with the ends of adjacent sections to be joined together positioned directly above a trench to facilitate step each in accordance with its designated position in the ship, and

f. joining the sections together to form a ship.

2. The method of claim 1, further including varying the gas pressure in the gas cushion pallet to facilitate aligning the sections prior to joining the sections together.

3. The method described in claim 2, wherein the way area of subparagraph includes spaced guide members and in arranging the sections according to subparagraph the guide members contact the sides of said sections, and the gas of subparagraph is supplied from tanks located in the section to be supported, and further including moving the ship horizontally from said way area to a ballasted drydock positioned in a body of water while mintained on the gas-supported pallets, deballasting said drydock, moving said drydock away from said way area, and ballasting said drydock to float said ship.

mg UNITED STATES PATENT OFFICE QERTIFICATE OF CORRECTIQN,

Patent No, Dated April 18, 1972 Inven fls) John J. Heffernan It is certified that error appears the above-identified patentand that said Letters Patent are hereby corrected as shown below:

1 Column 3, line 2, claim 1, "stepsLz" should read --steps:--.

Column line 2, after "step" insert --(f),-

Column line 9, after subparagraph insert --(a)--. Column A, line 10, after "suboaragraph" insert --(e) Column line 11, after "subparagraph" insert --{'c)- Signed and sealed this 31st day of October 1972.

(SEAL) Attest:

.FLETCHER JR. 7 ROBERT GOTTSCHALK fi fs i flg Officer Commissioner of Patents

Claims

1. A method of constructing a ship including the following steps: a. providing a construction area and a way area including a plurality of trenches, both areas lying in substantially the same horizontal plane, b. prefabricating sections of said ship on said construction area, each section resting on support means including a gas cushion pallet, c. supplying gas under pressure to said gas cushion pallet to provide a gas film which supports the section and pallet above the construction area, d. moving the sections from the construction area to the way area, while maintained on the gas-supported pallets, e. arranging the sections on said way area while maintained on the gas-supported pallets, with the ends of adjacent sections to be joined together positioned directly above a trench to facilitate step, each in accordance with its designated position in the ship, and f. joining the sections together to form a ship.

3. The method described in claim 2, wherein the way area of subparagraph includes spaced guide members and in arranging the sections according to subparagraph the guide members contact the sides of said sections, and the gas of subparagraph is supplied from tanks located in the section to be supported, and further including moving the ship horizontally from said way area to a ballasted drydock positioned in a body of water while maintained on the gas-supported pallets, deballasting said drydock, moving said drydock away from said way area, and ballasting said drydock to float said ship.