US 3797438 A
Method for constructing large floating units, like drilling rigs, comprising forming upright support columns on floating units and floating the floating units to a mounting site; ballasting the floating units with the upright columns thereon to temporarily submerge the units until only the tops of the columns are exposed; forming a rig carrying platform supported on floatable parallelepipedic bodies and floating the platform and bodies to the columns until the platform is over the submerged columns; deballasting the columns and floating units to cause the columns to rise into engagement with the platform and joining the columns and platform.
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Description (OCR text may contain errors)
United States Patent [191 Fayren METHOD FOR THE CONSTRUCTION OF FLOATING UNITS OF GREAT DIMENSIONS  Inventor: Jose Maria Marco Fayren, Vigo,
Spain  Assignee: Hijos De ,1. Barreras S.A., Vigo,
Spain  Filed: June 11, 1971  Appl. No.: 152,057
[111 3,797,438 Mar. 19, 1974 1,412,852 4/1922 Engstrand 114/45 Prir nary Examiner-Trygve M, Blix Assistant Examiner-Stuart M. Goldstein Attorney, Agent, or Firm-Ostro1enk, Faber, Gerb & Soffen 1 7 ABSTRACT Method for constructing large floating units, like drilling rigs, comprising forming upright support columns on floating units and floating the floating units to a mounting site; ballasting the floating units with the upright columns thereon to temporarily submerge the units until only the tops of the columns are exposed; forming a rig carrying platform supported on floatable parallelepipedic bodies and floating the platform and bodies to the columns until the platform is over the submerged columns; deballasting the columns and floating units to cause the columns to rise into engagement with the platform and joining the columns and platform.
9 Claims, 4 Drawing Figures mamcnnm m I 3L797L438 FIG. 2
METHOD FOR THE CONSTRUCTION OF FLOATING UNITS OF GREAT DIMENSIONS This invention is related to the construction of large floating units and especially refers to a method for the construction of semi submersible drilling platforms, built of a large platform resting on two rows of columns, supported by two big floating units having the necessary thrust to keep floating the whole unit. Owing to their shape and great size these platforms seem to have constructional problems, as the shipyards would not have construction space of sufficient capacity available for so big assemblies. This invention gives a solution to this inconvenience by affording a method through which several parts of the floating unit are separately built, finally being assembled out at sea where these parts are moved.
Following this method of invention in a first stage two perelellepiped bodies lengthwisely extended on two building berths separated by a horizontal platform are built, on which theupper platform, where the corresponding equipment is fitted, is erected; in a second stage. by means of ground blocks previously arranged under the paralellepiped bodies that act just like sliding ways, launching of the platform is made; in a third stage on the building berths available the corresponding floating units are built, or elsewhere, fitting on them the corresponding columns totally or partially; in a fourth stage launching of the floating units is effected, which have been previously ballasted to make up for the lack of stability produced by the columns, in a fifth stage, the two floating units are braced together in a calm water area, taking the assemblyto a deep water area where the partial immersion by means of ballast is made, there remaining above the water surface only the upper part of columns, letting go anchors enough to prevent the assembly from important movements owing to marine streams, winds, etc. and in a sixth and last stage the platform is moved over the columns, pumping out the ballast of the floating units so that the columns come up until they contact the lower part of the platform, then making the temporary joints necessary to start welding the columns to the platform in a definitive way.
The advantages and details of this invention can be seen clearly in the'detailed description of the construction method, which the enclosed drawings make reference to, in which:
FIG. 1 is a transverse section view of the building births where the construction is started depicting the platform provided with the parallelepipedic bodies ready for launching.
FIG. 2 shows the platform already in the water.
FIG. 3 shows the floating units already in the water braced together, and 1 FIG. 4 shows the platform located over the column ready for the final coupling after the floating units being emptied.
Regarding the above figures, first on two continuous building berths l separated by a horizontal platform 2 the paralellepipedic bodies 3 are built extended along the berths and on it platform 4 is built, on which part of the corresponding outfit can be arranged, depicted in FIG. 2 under reference 5.
Next launching is effected by means of the corresponding ground blocks 6 arranged under the paralellepipedic bodies 3, the latter acting as sliding ways, and
the platform 4 floating on the paralellepipedic bodies 3 acting as temporary floating units, as shown on FIG. 2.
Once the launching is effected the assembly platform 4 paralellepipedic bodies 3 can be moored to a quay in order to go on with the fitting out.
Next, if the above building berths l are used, or simultaneously, should other berths be used, the construction of the corresponding floating units 7 (FIG. 3) is started, fitting on them the corresponding columns 8 either totally or in a partial way.
Then launching of the floating units 7 is effected, which have been previously ballasted to make up for the lack of stability produced by the columns 8, bracing them by means of the body 9 in a calm water area.
Thence this assembly is moved to a deep water area where its partial immersion is effected by ballasting, there remaining on the water surface-only the upper part of columns 8, to approximately one metre high above the floating level, and letting go anchors enough (not depicted) in order to prevent the assembly from drifting owing to marine streams, winds, etc. remaining the assembly floating unit 7-columns 8, body 9, as shown on FIG. 3.
Next the assembly platform 4-paralellepipedic bodies 3 is moved to place it over the floating assembly 7- columns 8, body 9, just like shown on FIG. 4, leaving a clearance of about one meter between the lower part of the platform 4 and and top of columns 8.
Finally, the ballast of floating units 7 is emptied, in such a way that the columns 8 come up to contact platform 4, then making the temporary joints to proceed to final welding the columns 8 to the platform 4.
The above method has been developed in the memory hereof, for the construction of a drilling rig, but can be applied, with slight modifications, for the construction of other floating assemblies and catamaran vessels.
Likewise in the memory hereof has been explained the preferential way of execution of the method of this invention, but modifications in the different stages can be introduced or else to amplify similar means without for this going out of the scope of this invention.
1. Method for the construction of a large floating unit, especially a submersible drilling rig, with the floating unit having a unit platform that is supported bycolumns which rest upon floating means, comprising the steps of:
in each of two contiguous. building berths that are separated by a platform, positioning a respective 'floatable parallelepipedic body; positioning a carrying platform for carrying items on the parallelpipedic bodies;
arranging ground blocks under the parallelepipedic bodies to act as sliding ways and launching the bodies by sliding them out of their berths; mooring the carrying platform and floating parallelepipedic bodies to a quay for fitting out;
positioning support columns on separate respective floating units; temporarily ballasting the floating units to cause them to have improved stability with the attached support columns; launching the floating units; moving the separate launched floating units together and bracing them together;
moving the floating units to a desired location; partially immersing the columns and floating units through ballasting until only the top portions of the columns remain above water; anchoring the floating units against drifting;
moving the carrying platform and parallelepipedic bodies over the columns; deballasting the columns and floating units until the columns rise into contact with the carrying platform; joining the columns to the carrying platform. 2. Method of construction of a large floating unit, which unit comprises a unit platform that is supported by columns which are carried on floating means, comprising the steps of:
forming a plurality of platform support columns on respective floating means; floating the floating means and platform support columns in a manner such that the columns are upright and the tops of the columns are above the surface of the water;
floating the unit platform above the surface of the water;
then moving the floating unit platform and the floating columns together and moving the tops of the columns into engagement with the unit platform above the surface of the water so as to support the unit platform; said columns being caused to engage the unit platform by being caused to rise into engagement with the unit platform from beneath.
3. The method of construction of a large floating unit of claim 2, wherein before the unit platform and columns are moved together, the floating means are ballasted for stability and to lower the floating height of the column to permit assembly of the unit platform with the platform columns;
the columns are caused to rise by gradually removing ballasting from the floating means.
4. The method of construction of a large floating unit of claim 3, wherein after the columns rise into engagement with the unit platform, the columns are joined to the unit platform.
5. The method of construction of a large floating unit of claim 3, wherein each column is assembled to a respective floating means; each assembled column and floating means is then launched individually next, the assembled columns and respective floating means are moved to desired relative positions and then are braced together; the braced assembled columns and floating means are moved to the desired location for the completed large floating unit and are then anchored at that location;
thereafter performing said shifting of the platform unit over the columns prior to joining thereof.
6. The method of construction of a large floating unit of claim 2, wherein the floating means and platform support columns are floated in a manner such that the columns are upright while the floating means are being supported in berths; then the attached upright columns and the floating means are launched out of their berths to float and afterwards the floating means and platform support columns and the unit platform are floated.
7. The method of construction of a large floating unit of claim 6, wherein before being floated, the unit platform is constructed in a berth and is supported in the berth; and after construction, the unit platform is shifted off the berth to float.
8. The method of construction of a large floating unit of claim 7, wherein the unit platform is constructed by placing a'carrying platform on two spaced apart parallelepipedic bodies that are each seated in a respective berth; and then sliding the parallelepipedic bodies out of their berths into the water, such that the unit platform is carried on the floating parallelepipedic bodies.
from the floating means.