US3765359A

US3765359A - Apparatus and method of constructing marine float structures

Info

Publication number: US3765359A
Application number: US00269318A
Authority: US
Inventors: I Takezawa; M Muto; K Hori
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Ltd
Priority date: 1972-07-06
Filing date: 1972-07-06
Publication date: 1973-10-16
Anticipated expiration: 1990-10-16

Abstract

Apparatus and a method of constructing a marine float structure, such as a large-sized ship structure, is accomplished by assembling a number of divided ship portions on a ship building base. The first divided portion is transported on the water surface by means of a composite pontoon which is so constructed that each individual portion thereof can be separated from the other up and down or forwardly and backwardly. Then the composite pontoon is caused to sink down in the water so that said first divided portion of the ship can float of its own accord on the water surface. Subsequently the second divided portion of the ship is transported on the water surface using the same pontoon as mentioned above. A part of the composite pontoon is separated from the remaining body and allowed to sink down in the water while said second divided portion of the ship is held by the remaining portion of the pontoon. The separated part of the pontoon is used to float said first divided portion of the ship on the water surface, thereby combining both divided portions of the ship in a single unit on the water surface.

Description

United States Patent 91 Takezawa et al.

[ APPARATUS AND METHOD OF CONSTRUCTING MARINE FLOAT STRUCTURES [75] Inventors: Isoe Takezawa; Masataro Muto;

Koichi Hori, all of Nagasaki City, Japan [73] Assignee: Mitsubishi Jukogyo Kabushiki Kaisha, Tokyo, Japan [22] Filed: July 6, 1972 [21] Appl. No.: 269,318

Related US. Application Data [63] Continuation-in-part of Ser. No. 40,520, May 26,

[52] US. Cl. 114/77 A, 114/65 R, 114/77 R [51] Int. Cl B63b 3/02 [58] Field of Search 114/77 R, 77 A, 65 R,

114/65 A, 44, 45, 46, 49, 15 F, 66.5 F; 6.1/64-68; 9/8 R [56] References Cited UNITED STATES PATENTS 3,680,512 8/1972 Yamura 114/46 3,011,252 12/1961 Svensson 114/65 R 3,464,212 9/1969 Yamagata et al.-.... 61/65 2,732,818 1/1956 Quirin 114/77 R 2,728,319 12/1955 Engstrand 114/77 R 2,480,144 8/1949 Laycock 114/49 2,518,091 8/1950 Stopkevyc ll4/.5 F

FOREIGN PATENTS OR APPLICATIONS 97,144 11/1960' Norway 1l4/65R Oct. 16, 1973 Primary Examiner-Milton Buchler Assistant Examiner-E. R. Kazenske Attorney0tto John Munz [57] ABSTRACT Apparatus and a method of constructing a marine float structure, such as a large-sized ship structure, is accomplished by assembling a number of divided ship portions on a ship building base. The first divided portion is transported on the water surface by means of a composite pontoon which is so constructed that each individual portion thereof can be separated from the other up and down or forwardly and backwardly. Then the composite pontoon is caused to sink down in the water so that said first divided portion of the ship can float of its own accord on the water surface. Subsequently the second divided portion of the ship is transported on the water surface using the same pontoon as mentioned above. A part of the composite pontoon is separated from the remaining body and allowed to sink down in the water while said second divided portion of the ship is held by the remaining portion of the pontoon. The separated part of the pontoon is used to float said first divided portion of the ship on the water surface, thereby combining both divided portions of the ship in a single unit on the water surface.

3 Claims, 11 Drawing Figures I PATENTEDUEI 181973 3.765.359

: P f I L.W.L

1 APPARATUS AND METHOD OF CONSTRUCTING MARINE FLOAT STRUCTURES CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of US. application Ser. No. 40,520, filed May 26, 1970 by the same applicants and now to issue as US. Pat. No. 3,675,606 on July 11, 1972.

BACKGROUND OF THE INVENTION The present invention relates toapparatus and a method of ship building apparatus and more particularly a method of constructing a large-sized ship structure such as a marine vessel by utilizing economical equipment that does not use an inclined ship building base or a dock.

In recent years there is a trend of building marine vessels, ships in large sizes. There are a number of tech nical problems with using an inclined ship building base to construct large-sized marine vessels and a ship constructing dock is generally used instead of a ship building base.

However, enormous expense and considerable time are required in erecting a ship constructing clock. In some instances it is substantially impossible to construct such a large-scale dock by virtue of the geographic conditions of a shipyard.

In view of the above conditions, it has heretofore been proposed as an alternative procedure in ship building to carry out the launching of a ship by the use of an inclined carriage or using pontoons. In the case of the inclined procedure a sliding surface or rollingsurface is required to slide the hull onto the water surface. Further, the cast of this type of equipment is high. Further, the inclined carriage is liable to twistduring the descent of the hull.

According to a conventional procedure for constructing a hull on a horizontal ship building base using a quay and lauching it by means of a pontoon, it is unavoidable that such pontoon must be of a great length. Namely, according to this procedure, as shown in FIG. 1, the height h of the surface'of the ship building base 01, mounted on a dry-land type foundation from the water surface (L.W.L.) at low tide should be at least 4 meters by adding an allowance of water line (draft) about 1 m to the difference 3 m between the periods of low and high tides.

On the other hand, a'hull S constructed on the ship building base 01 can be transferred onto the pontoon only by maintaining the uppersurface of the pontoon P and the surface of the ship building base 01 at equal heights. Consequently it becomes necessary to have the pontoon P with the hull mounted thereon exposed at least 4 m above the water surface. For this purpose, the entire height H of the pontoon withthe addition of deepness below thedraft lineshould be at least twice as much as the above-mentioned h, that is, at least about 8 m. Needless to say, the basis of the calculation has been referred to in the case of using a pontoon corresponding to the entire length of the hull S.

As a result, the conventional methods require the pontoon P itself to be sufficiently large-sized so that the manufacturing cost becomes very high. Also a largesized hull S that is constructed on a horizontal ship building base is rather difficult to be transferred onto the pontoon P and is thus an extremely complicated and time consuming operation.

SUMMARY OF THE INVENTION The object of the present invention is to provide apparatus and a method of manufacturing a large-size ship building base without the above-mentioned disadvantages.

A further object of the present invention is to provide apparatus and a method of constructing marine float structures, comprising the construction of large-sized marine float structures such as large-sized tankers in a suitable number of separately divided portions on a horizontal ship building base by utilizing the facilities of a quay and the use of composite pontoons formed of many upand down or forwardly and/or backwardly separable portions wherein;

first of all, the first divided portion of the hull is transported onto the water surface;

then the composite pontoon is caused to sink down in the water to launch said first divided portion;

subsequently, the second divided portion is transported onto the water surface using the same composite pontoon but in this case a portion of the composite pontoon is separated therefrom so as to sink down in the water and said second divided portion is held in condition exposed above the water surface by means of the remaining portions of the composite pontoon;

and simultaneously said first divided portion is caused to float as exposed above the water using said separated portion of the pontoon so that both divided portions can be jointed on the water surface.

A further object of the invention is to provide a pontoon structure in which a plurality of hermetically sealed modular pontoons can be easily assembled in a spaced relationship to one another to achieve a unitary pontoon structure whereby individual modular may communicate with one another and to provide a stabilized and balanced inclined position for the unitary pontoon structure.

A further object of the invention is to provide a molded plastic longitudinally unitary pontoon structure comprising a plurality of individually detachable unit pontoons having extendible connection means between respective adjacent unit pontoons, wherein said extendible connection means provide a spaced relationship between adjacent individual unit pontoons.

Other objects and advantages of the present invention will become apparent from the following description with reference to embodiments in the construction of a large-sized tanker.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view showing an example of a launch ing procedure using a pontoon of the conventional type.

FIGS. 2 through 7 are views showing a constructing of a marine float structure according to first embodi ment of the present invention. FIG. 2 is a perspective view of a composite pontoon.

FIG. 3 is a side view of a hull which is constructed in divided form.

FIG. 4 through 7 are side views showing examples of construction steps.

FIGS. 8 through 10 show a second embodiment of the present invention. FIG. 8 is a perspective view of another composite pontoon.

FIG. 9 and 10 are side views showing examples of construction steps.

FIG. 11 shows a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION With reference to FIGS. 2 through 7 showing a first embodiment of the present invention, B indicated an almost horizontal ship building base constructed by utilizing a quay, and the hull S is to be constructed thereon in the form of a number of divided portions in the direction of fore and aft parts of the ship.

The height of the ship building base B is determined in such a manner that the upper surface of the base B cannot be immersed in the water at high tide or by the high waves.

As an example, assume the difference in tidal position to be 3 m at low and high tides and adding the allowance draft line thereto, the height h of the ship building base B from the water surface at low tide will be computed to be about 4 m.

The character P indicated the composite pontoon for use in this embodiment and said pontoon P consists of two pontoons P and P which are overlapped in the manner of bieng separated from each other. These unit pontoons P and P are partitioned inside in the form of a plurality of areas to constitute a number of float chambers l and 2.

These float chambers 1 and 2 are adapted to communicate with respective pipes for pouring and discharging water (not shown in the drawings), so that it is possible to adjust the buoyancy and trimming of each pontoon by pouring water into, or discharging it from, each float chamber. It is to be noted that the abovementioned water pouring and discharging apparatus is of conventional construction. The size of the composite pontoon P is such that its length L is about one half of the length of a vessel to be constructed. Its depth H is about two times the above mentioned height h, namely about 8 m, in order that the upper surface of the com posite pontoon may be held in level with the surface of the ship building base B even when tidal position is the lowest and the head drop between the water surface and the surface of the ship buildling base B amounts to a maximum (about 4 m).

When a tanker is constructed using the abovementioned composite pontoon P and the horizontal ship building base, the hull S is constructed in the ship building base B. For example, the hull S may be in the form of four divided parts such as the fore part F, for half part tank TF, aft half part tank TA and aft part A, as shown in FIG. 3.

Subsequently, the composite pontoon P is brought forwardly of the ship building base B and then ballast water is poured into, and discharged from float chamber 1 and 2 in a suitable manner so that the upper surface of the composite pontoon P is adjusted to assume the same height as the surface of the ship building base.

After this operation has been accomplished, the fore part F and the fore half part tank TF are transferred onto the above-mentioned pontoon P.

For this purpose, a transfer carriage is used though it is not illustrated in the drawing.

Along with the progress of this transfer mounting, gravitation acting on the composite pontoon is gradually increased so that it is necessary to discharge the ballast water from each flaot chamber 2, in order to maintain the draft and trimming of the composite pontoon P. In certain instances, as shown by the imaginary line, there is provided a base seat 3 at the bottom of the water beforehand and then the composite pontoon P is brought into contact with the base seat 3 to make use of a stabilizing operation effectively.

In this way, when the fore part F and the fore half part tank TF have been mounted on the composite pontoon by transfer, they are jointed by welding or the like thereon to complete the fore part SF of the hull. The fore part F and the fore half part tank TF are jointed after they have been mounted on the composite pontoon to facilitate their mounting on the composite pontoon P. If necessary, both may be jointed on the ship building base B beforehand and it is also possible to construct them in a body from the beginning without preparing them in divided form.

As mentioned above, in the event that the fore part F and the fore half part tank TF are mounted on the composite pontoon by transfer and are jointed together to complete the fore ship portion SF, the combined unit is transported onto the water surface by means of a towboat or the like while mounting it on the pontoon. Then ballast water is poured into each float chamber 1 and 2 of the pontoon in a suitable position so that it can sink down and the fore ship portion SF only can float of its own accord on the water surface.

Subsequently, as shown in FIG. 5, the aft half part tank TA and the aft part A are mounted on the pontoon by transfer in exactly the same manner using the same pontoon as mentioned above and they are jointed together to complete the aft ship portion SA, which is then transported onto the water surface by means of a towboat or the like.

Thereafter, as shown in FIG. 6, ballast is suitably poured into each float chamber 2 of the lower half unit pontoon P constituting the composite pontoon so that only the unit pontoon P is caused to sink down in the water and be separated from the other unit pontoon P As a result, the aft ship portion SA is destined to be supported by the buoyancy of the unit pontoon P Then only but the whole body is allowed to remain as exposed above the water surface except that the height from the water surface is reduced.

Consequently, the separated unit pontoon 2 is brought right below the fore ship portion SF by means of a towboat or the like. Then the ballast water in each float chamber 2 is suitably discharged therefrom until the fore ship portion SF is allowed to float and be exposed above the water surface.

Then, as shown in FIG. 7, both ship portions are drawn together and their corresponding joint portions are caused to engage each other so that both portions are jointed on the water surface to complete the hull S.

As mentioned above, it is necessary that a pontoon of great depth be used to compensate for the head drop h between the water surface and the surface of the ship building base when the fore ship portion SF and the aft ship portion SA are mounted on the pontoon by transfer as exemplified in this embodiment. But, once both ship portions SF and SA are transported onto the water surface for the purpose of jointing them on the water surface, it is no longer necessary to use the above mentioned pontoon of great depth. So, attention is drawn to the fact that it is possible to achieve the same purpose sufficiently by using the pontoon of about half of the above mentioned depth. For this purpose, to begin with, when the fore ship portion SF and the aft ship portion SA are transferred from the ship building base onto the water surface, the unit pontoons P and P are overlapped to increase the depth of this assembly to achieve the required purpose. Thereafter both pontoons are separated from each other so that the fore ship portion SF and the aft ship portion SA can float and be exposed above the water surface for achieving their joint effect.

Now, a second embodiment of the present invention will be explained in detail with reference to FIGS. 8 through 10.

In this embodiment, as an example, the composite pontoon P consists of five unit pontoons P P, which can be divided forwardly and backwardly as shown in FIG. 8.

The size of this composite pontoon is illustrated to show that its length L is about one half of the ships length. Its depth H shows that it is about twice the height h between the surface of the ship building base B and the water surface at low tide. This is accomplished in the same manner as the aforesaid embodiment, which has already been described in detail.

Though not shown in the drawing, there are provided a plurality of partitioned float chambers in all the respective unit pontoons P, P in the same manner as the afore-explained embodiment. Therefore, it is possible also to adjust buoyancy and trimming by suitably pouring Water into, or discharging it from each float chamber. Also it is possible to provide means for communicating a float chamber with another as hereinafter described.

In order that a ship be constructed using the above mentioned pontoon P, as described in the afore-said embodiment, the hull is constructed in divided form on the ship building base B. Then, as shown in FIG. 9, the fore ship portion SF is transferred onto the water surface. The ballast water is uniformly poured into the floatchamber of each unit pontoon P P to cause the pontoon P to sink down in order to permit the floating of the fore ship portion SF of its own accord on the water surface. Thus, the same composite pontoon is used again to transport the aft ship portion SA onto the water surface. Under these conditions, as shown in FIG. 10, ballast water is poured intothe float chamber of each unit pontoon P P and P respectively and these unit pontoons are separated from the other unit ones P and P, so that the fore ship portion SA is supported by the latter two unit pontoons P and P only.

Subsequently, the separated unit pontoons P P and P, are suitably positioned right beneath the fore ship portion SF after which the ballast water in the float chambers of the unit pontoons P P and P are discharged therefrom to float and expose the fore ship portion SF on the water surface.

Under these conditions, both portions SF and SA are drawn close to each other and jointed by welding to complete the hull S.

In this embodiment, five unit pontoons are used in such a manner that three unit pontoons are arranged for the fore ship portion SF and two unit pontoons for the aft ship portion SA because of which there occurs an imbalance of buoyancy of both ship portions in certain instances. Therefore, in such cases, as shown in FIG. 10, it is also possible to carry out the jointing operation iwth the hull S being somewhat inclined.

FIG. 11 embodiment provides a tubular means for communicating between one float chamber to another. For example, unit pontoon P is provided on each of the respective sidewlls with a slidably mounted tubular member T which is adapted to be either inserted in a cavity passage of pontoon P as shown in dotted lines or to be extended outwardly beyond the sidewall as shown in solid lines. Likewise, a tubular member T, which has a slightly less cross-sectional area than that of tubular member T is constructed on unit pontoon P Thereby, the tubular members of the respective pontoon units may be interconnected in a telescopical manner or the like to provide a passageway for water to flow from one float chamber to another. It is to be understood that suitable closure means as illustrated by closure C are constructed on the unit pontoon to achieve an independent hermetically sealed unit when tubular member T is positioned within the cavity passage or in the extended position.

Further, the respective tubular members in their extended positions also provide a means to secure or fasten one unit to another in a spaced relationship to achieve'the spaced position of the unit pontoon shown in FIG. 10. Further, the tubular members provide a stabilized and balancing effect to the pontoon structure to enable the inclined position of the pontoon units in FIG. 10 to be achieved in a more efficient manner.

It is to be understood that various structural arrangements may be made and still be within the scope of the disclosed FIG. 11 embodiment. For example, it is obvious that the amount of buoyant support can be increased or decreased by adding or subtracitng pontoon units or modules to or from the longitudinal line of units.

As has been described hereinbefore, with reference to the three embodiments of the present invention, the application of this apparatus and method are not limited to the construction of ships or marine vessels but it can be extensively applied to the construction of marine float structures, for example, such as transport barges, floating docks and other marine structures.

In brief, the present invention is intended to provide apparatus and a method of manufacturing marine float structures, comprising constructing large-sized marine float structures in suitably divided form on a horizontal ship building base and using composite pontoons consisting of many upand down or forwardly and/or backwardly separable portions, wherein firstly, the first divided portion of the structure is transported onto the water surface, then said composite pontoon is caused to sink down in the water to permit the floating of said first divided portion of the structure of its own accord on the water surface, successively, the second divided portion of the structure is also transported onto the water surface using the same pontoon, a part of said pontoon is separated from the whole body and caused to sink down in the water, said second divided portion of the structure is held on the water surface using the remaining part of the pontoon and at the same time, the firstly separated part of the pontoon is used to float said first divided portion of the structure on the water surface and to support it thereon and finally, both divided portions of the structure are drawn close to each other so that they can be jointed together on the water.

According to the present invention, the following advantages will be anticipated.

a. It is possible to construct large-sized float structures such as marine vessels without using an inclined ship building base or ship building dock so that various technical and economical problems involved in the use of an inclined ship building base or dock can be extensively solved in a satisfactory manner.

b. As compared with the conventional methods of ship launching, which have heretofore been proposed using pontoons, the present invention makes it easily possible to construct structures of almost the same sizes as conventional structures using pontoons of about half size of also conventional pontoons, thereby proving the apparatus and the method of the present invention to be considerably reasonable and economical.

. After the structure has been constructed in suitably sized and divided form on an almost horizontal ship building base, each portion is separately transferred onto the pontoon for mounting thereon. Thus, the operation of transferring portions of the structures onto the pontoon is rendered very easy.

What we claim is:

l. A method of ship building for constructing largesized ship structures, comprising the following steps:

the first step includes providing at least a first ship portion and a second ship portion for constructing a ship on a ship building base, said ship builidng base being mounted on a dry-land type foundation;

the second step includes constructing the ship portions and transporting said first constructed ship portion onto a water surface using a composite pontoon as a support thereof, thereafter said composite pontoon being sunk so as to float said first portion on the water surface by its own buoyancy without the aid of the composite pontoon, said composite pontoon being constructed with a plurality of individually detachable unit pontoons longitudinally arranged in a spaced relationship to each other to form a forward and backward longitudinal line of pontoons for supporting the ship portions, the height of said composite pontoon being made sufficient to compensate for the intervening height difference between the level of the water surface and the level of the ship building base whenever either one of the ship portions is drawn from said foundation onto the water surface, and

each of said unit pontoons of said composite pontoon having a sufficient buoyancy ofits own to hold each of said ship portions with positive buoyancy supported beneath; the third step includes transporting said second constructed ship portion onto the water surface using said composite pontoon as the support thereof, said composite pontoon held floating on the water surface by virtue of the remaining second one of unit pontoons after the composite pontoon is separated into the first and second ones of unit pontoons and also after the first detached one of the unit pontoons being sunk so as to regain its own buoyancy;

the fourth step includes said first buoyant constructed ship portion being supported in a floating state on the water surface with the aid of said first sunken one of the unit pontoons after regaining its own positive buoyancy, and

the fifth step includes both first and second floated ship portions with the aid of both first and second unit pontoons respectively being drawn to each other and welded together so as to unify them into a single ship unit while being held on the water surface.

2. A method of ship building according to claim 1, and further providing a water flow connection between respective spaced unit pontoons wherein each of the individually detachable unit pontoons includes an extendible tubular member for effecting a connection with an adjacent unit pontoon whereby each formed unitary pontoon structure of individual unit pontoons is adapted to be inclined with respect to the water surface.

3. A method of ship building according to claim 1, further comprising the step of providing each of said unit pontoons with an extendible tubular member mounted thereon for effecting a water connection with an adjacent unit pontoon to form a unitary pontoon structure of individual unit pontoons whereby said unitary pontoon structure may be inclined with respect to the water surface.

Claims

1. A method of ship building for constructing large-sized ship structures, comprising the following steps: the first step includes providing at least a first ship portion and a second ship portion for constructing a ship on a ship building base, said ship builidng base being mounted on a dryland type foundation; the second step includes constructing the ship portions and transporting said first constructed ship portion onto a water surface using a composite pontoon as a support thereof, thereafter said composite pontoon being sunk so as to float said first portion on the water surface by its oWn buoyancy without the aid of the composite pontoon, said composite pontoon being constructed with a plurality of individually detachable unit pontoons longitudinally arranged in a spaced relationship to each other to form a forward and backward longitudinal line of pontoons for supporting the ship portions, the height of said composite pontoon being made sufficient to compensate for the intervening height difference between the level of the water surface and the level of the ship building base whenever either one of the ship portions is drawn from said foundation onto the water surface, and each of said unit pontoons of said composite pontoon having a sufficient buoyancy of its own to hold each of said ship portions with positive buoyancy supported beneath; the third step includes transporting said second constructed ship portion onto the water surface using said composite pontoon as the support thereof, said composite pontoon held floating on the water surface by virtue of the remaining second one of unit pontoons after the composite pontoon is separated into the first and second ones of unit pontoons and also after the first detached one of the unit pontoons being sunk so as to regain its own buoyancy; the fourth step includes said first buoyant constructed ship portion being supported in a floating state on the water surface with the aid of said first sunken one of the unit pontoons after regaining its own positive buoyancy, and the fifth step includes both first and second floated ship portions with the aid of both first and second unit pontoons respectively being drawn to each other and welded together so as to unify them into a single ship unit while being held on the water surface.