Title of Invention	SINKING METHOD USED IN A TANDEM SHIPBUILDING PROCESS
Abstract	A sinking method used in a tandem shipbuilding process, in which a plurality of ships is sequentially constructed in a single dock through assembling and floating steps, is disclosed. The method includes the steps of constructing ship blocks according to a general tandem shipbuilding process in a dock (S100) ; mounting at least one of main installed parts to a tandem ship, which is a target to be sunk, before a ship to be launched is floated in the dock (S200); sinking the tandem ship at the same position by allowing seawater to naturally flow into a cargo hold/ballast and a partial double bottom tank of the tandem ship when floating the ship to be launched, by introducing seawater into the dock (S400a); and continuing construction work for the tandem ship at the same position after the floated ship to be launched is towed out of the dock by a tugboat and a dock gate is closed (S600).

Title of Invention

SINKING METHOD USED IN A TANDEM SHIPBUILDING PROCESS

Abstract

A sinking method used in a tandem shipbuilding process, in which a plurality of ships is sequentially constructed in a single dock through assembling and floating steps, is disclosed. The method includes the steps of constructing ship blocks according to a general tandem shipbuilding process in a dock (S100) ; mounting at least one of main installed parts to a tandem ship, which is a target to be sunk, before a ship to be launched is floated in the dock (S200); sinking the tandem ship at the same position by allowing seawater to naturally flow into a cargo hold/ballast and a partial double bottom tank of the tandem ship when floating the ship to be launched, by introducing seawater into the dock (S400a); and continuing construction work for the tandem ship at the same position after the floated ship to be launched is towed out of the dock by a tugboat and a dock gate is closed (S600).

Full Text	[DESCRIPTION] [invention Title] INUNDATION METHOD USED IN TANDEM SHIPBUILDING PROCESS [Technical Field] The present invention relates to a sinking method used in a tandem shipbuilding process, and more particularly, to a tandem shipbuilding process using a method in which the hull of a tandem ship is sunk by mounting at least one mounting part on the tandem ship or a method in which lashing is employed in addition to complete sinking or partial sinking of a tandem ship to increase the force for holding the tandem ship so that shipbuilding tasks can be finished at an original position without moving the hull of the tandem ship. [Background Art] As is generally known in the art, in a traditional shipbuilding yard, rails are laid on an inclined surface, and a ship is constructed on the rails, so that, when the construction of the ship is completed, the ship can slide down the inclined surface on the rails into the seawater. This type of launching system is called an inclined launching platform. The inclined launching platform is still employed in small and mid-sized shipbuilding yards and in some large scale shipbuilding yards. However, recently, in order to ensure safety and improve efficiency when constructing large ships, the general trend is to construct a ship in a shipbuilding dock. In this case, a ship is constructed in a dock, and when launching the ship, the dock is filled with seawater and a dock gate is opened so that the constructed ship can be towed out of the dock and remaining shipbuilding tasks can be conducted outside the dock. In detail, this method is implemented in a manner such that a ship that is shorter than the dock is constructed and floated by introducing seawater into the dock, the dock gate is opened, the floated ship is towed out of the dock using a tugboat, and the remaining shipbuilding tasks are conducted outside the dock. Nevertheless, this method has a problem in that space utilization efficiency in the dock is poor, and therefore, the method is inefficient for the mass production of ships. In order to solve this problem, a tandem shipbuilding process has been proposed in the art. In this process, by improving space utilization efficiency in a dock, two to four ships can be simultaneously constructed in one dock. In the tandem shipbuilding process, when a constructed ship is floated and towed out of the dock, a partially constructed ship, for which some construction tasks have been conducted, is necessarily floated together with the constructed ship to be launched. Then, after the constructed ship to be launched is towed out of the dock, a dock gate is closed to position the partially constructed ship in place, and seawater is discharged out of the dock. Thereafter, other construction tasks are conducted in a moved position or in an original position. [Disclosure] [Technical Problem] The conventional tandem shipbuilding process has the drawbacks described below. In the case that a tandem zone has a length no greater than 55% of the LOA (length overall) of a ship due to the limitations in the specification of a dock, since floating is implemented in a manner such that the number of mounting parts to be mounted on a tandem ship is limited in order to secure a draft (of 7.1 m at the maximum) for floating a ship, the time for performing construction work in the dock is decreased, which impedes the tandem shipbuilding process and makes it necessary to rush the construction work, thereby causing problems due to the simultaneous implementation of an increased number of working steps. In the conventional tandem shipbuilding process, the mounting parts, which are not mounted on the tandem ship before the floating is conducted, includes a main engine, tail and intermediate shafts, an aft block, a lashing bridge, a hatch cover, and so forth. Due to the limitation in the number of mounting parts that can be mounted on the tandem ship before the floating, when construction work is performed on the tandem ship in the dock after it is floated, problems are caused as described below. Since the mounting of a deck house is delayed due to the mounting of the tail and intermediate shafts and the main engine after the floating, the supply of shore power (from facilities on the shore) is likely to be difficult. Also, since a final sighting task as an operation for inspecting the verticality of a rudder is delayed due to the mounting of the aft block after the floating, less time is available for mounting a propeller and the rudder. Further, floated ship blocks are not securely held but move so that they are likely to collide against each other or against the wall of a dock, whereby the ship blocks under construction may be broken or damaged. Moreover, it is difficult to float the ship blocks while maintaining the balanced states of the ship blocks. In addition, after the ship blocks are floated, when the ship to be launched is towed out of the dock, seawater must be discharged from the dock so that the floated ship blocks can be placed in a position for performing construction work. In this regard, lots of time and labor are required to place the ship blocks in an original position or a moved position. Accordingly, the present invention has been made in an effort to solve the problems occurring in the related art, and an object of the present invention is to provide a tandem shipbuilding process using a sinking method in which at least one of a main engine, tail and intermediate shafts, an aft block, a lashing bridge and a hatch cover is mounted to a tandem ship such that, when a ship to be' launched is floated in a dock, the tandem ship is not floated but is sunk to the bottom of the dock, and such that, after the ship to be launched is towed out of the dock, construction work can be performed at the same position so that the construction of the tandem ship in the dock can be completed within a short period. Another object of the present invention is to provide a tandem shipbuilding process using a sinking method in which at least one of a main engine, tail and intermediate shafts, an aft block, a lashing bridge and a hatch cover is mounted to a tandem ship such that, when a ship to be launched is floated in a dock, the tandem ship is sunk to the bottom of the dock or is not fully floated by sinking the tandem ship to a predetermined depth, with the position of the tandem ship fixed through lashing, and that, after the ship to be launched is towed out of the dock, construction work can be performed at the same position so that the construction of the tandem ship in the dock can be completed within a short period. [Technical Solution] In order to achieve the first object, according to one aspect of the present invention, there is provided a sinking method used in a tandem shipbuilding process in which a plurality of ships is sequentially constructed in a single dock through assembling and floating steps, the method comprising the steps of: constructing ship blocks according to a general tandem shipbuilding process in a dock; mounting at least one of main mounting parts to a tandem ship, which is a target to be sunk, before a ship to be launched is floated in the dock; sinking the tandem ship at the same position by allowing seawater to naturally flow into a cargo hold/ballast and a partial double bottom tank of the tandem ship when floating the ship to be launched by introducing seawater into the dock; and continuing construction work for the tandem ship at the same position after the floated ship to be launched is towed out of the dock by a tugboat and a dock gate is closed. In order to achieve the second object, according to another aspect of the present invention, there is provided a sinking method used in a tandem shipbuilding process in which a plurality of ships is sequentially constructed in a single dock through assembly and floating steps, the method comprising the steps of: constructing ship blocks according to a general tandem shipbuilding process in a dock; mounting at least one of main mounting parts to a tandem ship as a target to be sunk or partially sunk, before a ship to be launched is floated in the dock; lashing portion's on both sides of the tandem ship to be sunk or partially sunk, to a bottom of the dock; sinking or partially sinking the tandem ship at the same position by allowing seawater to naturally flow into a cargo hold/ballast and a partial double bottom tank of the tandem ship when floating the ship to be launched by introducing seawater into the dock; releasing the lashing between the portions on both sides of the tandem ship which is sunk or partially sunk and the bottom of the dock, after the floated ship to be launched is towed out of the dock and a dock gate is closed; and continuing construction work for the tandem ship at the same position. According to another aspect of the present invention, in the step of mounting at least one of main mounting parts to a tandem ship to be sunk or partially sunk, the main mounting parts include a main engine, tail and intermediate shafts, an aft block, a lashing bridge and a hatch cover. According to still another aspect of the present invention, the lashing step is a step in which portions on both sides of at least one selected from among a fore block, an aft block and an Intermediate block of the tandem ship to be sunk or partially sunk are lashed to a bottom of the dock; and the releasing step is a step in which the lashing between the portions on both sides of at least one selected from among the fore block, the aft block and the intermediate block of the sunk or partially sunk tandem ship and the bottom of the dock is released. According to a still further aspect of the present invention, the lashing step is a step in which lashing lugs are formed on portions on both sides of at least one selected from among a fore block, an aft block and an intermediate block of the tandem ship to be sunk or partially sunk, lashing fasteners are formed on a bottom of the dock to correspond to the lashing lugs, and the lashing lugs and the lashing fasteners are connected with each other by lashing chains; and the releasing step is a step in which the connection by the lashing chains between the lashing lugs formed on the portions on both sides of at least one selected from among the fore block, the aft block and the intermediate block of the sunk or partially sunk tandem ship and the corresponding lashing fasteners formed on the bottom of the dock is released. Thanks to the features of the present invention, the advantages described below are realized. In a tandem shipbuilding process, since a deck house can be mounted in an early stage to a tandem ship due to the mounting of shafts and a main engine before a ship to be launched is floated, the time for receiving shore power (supplied from facilities on the ground) can be secured. Also, in the tandem shipbuilding process, because final sighting is permitted on the tandem ship due to the mounting of an aft block before the ship to be launched is floated, the time for mounting a propeller and a rudder can be secured. Further, in the tandem shipbuilding process, due to the fact that main mounting parts are mounted before the ship to be launched is floated, the mounting load on a goliath crane after the ship to be launched is floated can be considerably decreased. Moreover, even in the case that the entire ship blocks cannot be sunk to the bottom of a dock since a certain ship block has a part which must not be sunk or it is structurally impossible to completely sink the ship block, so that a certain level of buoyancy is generated in that ship block, the ship block can be safely fixed in place in the dock through lashing. In addition, even in the case in which the amount of seawater flowing into the dock is much greater than the amount of seawater needed for sinking the ship blocks, so that a certain level of buoyancy is generated in the ship blocks while sinking the ship blocks, the positions of the ship blocks can be safely fixed in the dock through lashing. Besides, even in the case in which the movement of the ship block sunk to the bottom of the dock occurs due to the inflow of seawater or the flow of seawater in the dock due to towing of the ship to be launched, the positions of the ship blocks can be safely fixed in the dock through lashing, whereby the times for constructing or mounting main parts in the tandem shipbuilding process can be significantly decreased. As a consequence, the industrial applicability of the present invention can be anticipated. [Description of Drawings] FIG. 1(a) is a flow chart illustrating a tandem shipbuilding process in which a sinking method in accordance with an embodiment of the present invention is used; FIG. 1(b) is a flow chart illustrating a tandem shipbuilding process in which a sinking method employing lashing in accordance with another embodiment of the present invention is used; FIG. 2 is a view illustrating the unchanged position of a ship to be sunk when the ship is constructed according to the present invention; FIG. 3 is a view illustrating a conventional tandem shipbuilding process and the present tandem shipbuilding process, in which the sinking method is used; FIG. 4 is a plan view illustrating positions on a ship's hull block at which lashing is conducted according to the present invention; FIG. 5 is sectional views taken along the lines A-A, B-B and C-C of FIG. 4, illustrating lashed states at the respective positions on the ship's hull block; and FIG. 6 is a view illustrating the structure of a lashing part. Drawings> 1: lashing lug 2: lashing fastener 3: lashing chain [Mode for Invention] Reference will now be made in greater detail to a preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. FIG. 1(a) is a flow chart illustrating a tandem shipbuilding process in which a sinking method in accordance with an embodiment of the present invention is used. Referring to FIG. 1, the sinking method used in the tandem shipbuilding process, in which a plurality of ships is sequentially constructed in a single dock through assembling and floating steps, comprises the steps of: constructing ship blocks according to a general tandem shipbuilding process in a dock (S100); mounting at least one of main mounting parts to a tandem ship as a target to be sunk, before a ship to be launched is floated in the dock (S200); sinking the tandem ship at the same position by allowing seawater to naturally flow into a cargo hold/ballast and a partial double bottom tank of the tandem ship when floating the ship to be launched by introducing seawater into the dock (S400a); and continuing construction work for the tandem ship at the same position after the floated ship to be launched is towed out of the dock by a tugboat and a dock gate is closed (S600) . In the step of mounting at least one of main mounting parts to a tandem ship to be sunk, the main mounting parts include a main engine, tail and intermediate shafts, an aft block, a lashing bridge, and a hatch cover. FIG. 1(b) is a flow chart illustrating a tandem shipbuilding process in which a sinking method employing lashing in accordance with another embodiment of the present invention is used. The sinking method according to the present embodiment is basically the same as the sinking method shown in FIG. 1(a), except that a partial sinking step is included in a sinking step and lashing is employed to reinforce the force for fastening the tandem ship to be sunk or partially sunk. In detail, the method comprises the steps of: constructing ship blocks according to a general tandem shipbuilding process in a dock (S100); mounting at least one of main mounting parts to a tandem ship as a target to be sunk or partially sunk, before a ship to be launched is floated in the dock (S200); lashing portions on both sides of the tandem ship to be sunk or partially sunk, to a bottom of the dock (S300); sinking or partially sinking the tandem ship at the same position by allowing seawater to naturally flow into a cargo hold/ballast and a partial double bottom tank of the tandem ship when floating the ship to be launched by introducing seawater into the dock (S400b); releasing the lashing between the portions on both sides of the tandem ship which is sunk or partially sunk and the bottom of the dock, after the floated ship to be launched is towed out of the dock by a tugboat and a dock gate is closed (S500); and continuing construction work for the tandem ship at the same position (S600). In the step of mounting at least one of main installed parts to a tandem ship to be sunk or partially sunk, the main installed parts include a main engine, tail and intermediate shafts, an aft block, a lashing bridge and a hatch cover. The lashing step is a step in which portions on both sides of at least one selected from among a fore block, an aft block and an intermediate block of the tandem ship to be sunk or partially sunk are lashed to a bottom of the dock; and the releasing step is a step in which the lashing between the portions on both sides of at least one selected from among the fore block, the aft block and the intermediate block of the sunk or partially sunk tandem ship and the bottom of the dock is released. Concretely speaking, the lashing step is a step in which lashing lugs are formed on portions on both sides of at least one selected from among a fore block, an aft block and an intermediate block of the tandem ship to be sunk or partially sunk, lashing fasteners are formed on a bottom of the dock to correspond to the lashing lugs, and the lashing lugs and the lashing fasteners are connected with each other by lashing chains; and the releasing step is a step in which the connection by the lashing chains between the lashing lugs formed on the portions on both sides of at least one selected from among the fore block, the aft block and the intermediate block of the sunk or partially sunk tandem ship and the corresponding lashing fasteners formed on the bottom of the dock is released. FIG. 2 is a view illustrating the unchanged position of a tandem ship to be sunk or partially sunk when the tandem ship is constructed according to the present invention. It is to be readily understood that a main engine, tail and intermediate shafts, an aft block, etc. are mounted to the respective blocks of a ship as a target to be sunk, in the rear part of a dock before the ship is floated. A lashing bridge and a hatch cover are omitted for the sake of convenience of illustration. It is to be appreciated that the ship is constructed at an original position even after the ship is floated and therefore, the position of the ship is not changed. FIG. 3 is a view illustrating a conventional tandem shipbuilding process and a present tandem shipbuilding process, in which the sinking method is used. Referring to FIG. 3, it is to be understood that, in the conventional tandem shipbuilding process, main installed parts, such as a main engine, tail and intermediate shafts, an aft block, a lashing bridge and a hatch cover are not mounted. On the contrary, it is to be understood that, in the present tandem shipbuilding process, in which the sinking method is used, as main installed parts, a main engine is mounted in an engine room, tail and intermediate shafts are mounted to the lower part of a ship, an aft block is mounted above a rudder, and a lashing bridge and a hatch cover are mounted to the upper part of the ship. Therefore, in the present tandem shipbuilding process, it is to be noted that the main installed parts are mounted to their corresponding ship blocks. Describing in detail the shipbuilding process according to the present invention, when the construction of a ship, which is first put into a dock, is primarily completed and the ship is ready to be launched according to the first-in first-out principle of the tandem shipbuilding process, before the ship to be launched is floated, all main installed parts are mounted to the remaining ships or ship blocks which are under construction in the dock, and a cargo hold/ballast and a partial double bottom tank are naturally sunk to the bottom of the dock when the ship to be launched is floated so that the remaining ships or ship blocks are not floated. As a consequence, in the present shipbuilding process, because the number of installed parts to be mounted to the remaining ships or ship blocks after floating is decreased, an additional time of about 8 days for constructing the tandem ship in the dock can be secured after the ship to be launched is floated. FIG. 4 is a plan view illustrating positions on a ship's hull block where lashing is conducted according to the present invention, FIG. 5 is sectional views taken along the lines A-A, B-B and C-C of FIG. 4, illustrating lashed states at the respective positions on the ship's hull block, and FIG. 6 is a view illustrating the structure of a lashing part. Referring to FIGs. 4 through 6, in order to lash a tandem ship, lashing lugs 1 are formed on portions on both sides of at least one selected from among a fore block C, an aft block A and an intermediate block B of the tandem ship to be sunk or partially sunk, lashing fasteners 2 are formed on the bottom of a dock to correspond to the lashing lugs 1, and the lashing lugs 1 and the lashing fasteners 2 are connected with each other by lashing chains 3. While FIG. 6 illustrates only the aft block A of FIG. 4 for the sake of convenience of illustration, it is to be readily understood that the lashing lugs 1, the lashing fasteners 2 and the lashing chains 3 are arranged in the fore block C and the intermediate block B. When releasing the lashed state, it is sufficient to remove the lashing chains 3. At this time, the tension of the lashing chains 3 can be adjusted by pulling the lashing chains 3 from the positions of the lashing fasteners 2 or by using turnbuckles and the like on predetermined positions on the lashing chains 3. The reasons why the lashing is conducted are as described below. That is to say, even in the case in which the entire tandem ship cannot be sunk, the entire ship blocks cannot be sunk to the bottom of a dock since a certain ship block has a part which must not be sunk, or it is structurally impossible to completely sink a ship block, meaning that a certain level of buoyancy is generated in that ship block, the tandem ship or the ship blocks can be safely fixed in place in the dock through lashing. Moreover, even in the case in which the amount of seawater flowing into the dock is much greater than the amount of seawater needed to sink the tandem ship, so that a certain level of buoyancy must be generated in a ship block while sinking the tandem ship, the position of the tandem ship can be safely fixed in the dock through lashing. In addition, even in the case in which the movement of the ship block sunk to the bottom of the dock occurs due to the inflow of seawater or the flow of seawater in the dock attributable to the towing of the ship to be launched, the positions of the ship blocks can be safely fixed in the dock through lashing. Although preferred embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. [CLAIMS] [Claim l] A sinking method used in a tandem shipbuilding process in which a plurality of ships is sequentially constructed in a single dock through assembling and floating steps, the method comprising the steps of: constructing ship blocks according to a general tandem shipbuilding process in a dock (S100); mounting at least one of main installed parts to a tandem ship as a target to be sunk, before a ship to be launched is floated in the dock (S200); sinking the tandem ship at the same position by allowing seawater to naturally flow into a cargo hold/ballast and a partial double bottom tank of the tandem ship when floating the ship to be launched by introducing seawater into the dock (S400a); and continuing construction work for the tandem ship at the same position after the floated ship to be launched is towed out of the dock by a tugboat and a dock gate is closed (S600). [Claim 2] A sinking method used in a tandem shipbuilding process in which a plurality of ships is sequentially constructed in a single dock through assembling and floating steps, the method comprising the steps of: constructing ship blocks according to a general tandem shipbuilding process in a dock (S100); mounting at least one of main installed parts to a tandem ship, which is a target to be sunk or partially sunk, before a ship to be launched is floated in the dock (S200) ; lashing portions on both sides of the tandem ship to be sunk or partially sunk, to a bottom of the dock (S300); sinking or partially sinking the tandem ship at the same position by allowing seawater to naturally flow into a cargo hold/ballast and a partial double bottom tank of the tandem ship when floating the ship to be launched by introducing seawater into the dock (S400b); releasing the lashing between the portions on both sides of the tandem ship which is sunk or partially sunk and the bottom of the dock, after the floated ship to be launched is towed out of the dock and a dock gate is closed (S500); and continuing construction work for the tandem ship at the same position. (S600) . [Claim 3] The method according to claim 2, wherein the lashing step (S300) is a step in which portions on both sides of at least one selected from among a fore block, an aft block and an intermediate block of the tandem ship to be sunk or partially sunk are lashed to a bottom of the dock; and wherein the releasing step (S500) is a step in which the lashing between the portions on both sides of at least one selected from among the fore block, the aft block and the intermediate block of the sunk or partially sunk tandem ship and the bottom of the dock is released. [Claim 4] The method according to claim 1 or 2, wherein, in the step of mounting at least one of main installed parts to a tandem ship, the main installed parts include a main engine, tail and intermediate shafts, an aft block, a lashing bridge and a hatch cover. [Claim 5] The method according to claim 2 or 3, wherein the lashing step (S300) is a step in which lashing lugs are formed on portions on both sides of at least one selected from among a fore block, an aft block and an intermediate block of the tandem ship to be sunk or partially sunk, lashing fasteners are formed on a bottom of the dock to correspond to the lashing lugs, and the lashing lugs and the lashing fasteners are connected with each other by lashing chains; and wherein the releasing step (S500) is a step in which the connection by the lashing chains between the lashing lugs formed on the portions on both sides of at least one selected from among the fore block, the aft block and the intermediate block of the sunk or partially sunk tandem ship and the corresponding lashing fasteners formed on the bottom of the dock is released.

Full Text

[DESCRIPTION]
[invention Title]
INUNDATION METHOD USED IN TANDEM SHIPBUILDING PROCESS
[Technical Field]
The present invention relates to a sinking method used in a tandem shipbuilding process, and more particularly, to a tandem shipbuilding process using a method in which the hull of a tandem ship is sunk by mounting at least one mounting part on the tandem ship or a method in which lashing is employed in addition to complete sinking or partial sinking of a tandem ship to increase the force for holding the tandem ship so that shipbuilding tasks can be finished at an original position without moving the hull of the tandem ship.
[Background Art]
As is generally known in the art, in a traditional shipbuilding yard, rails are laid on an inclined surface, and a ship is constructed on the rails, so that, when the construction of the ship is completed, the ship can slide down the inclined surface on the rails into the seawater. This type of launching system is called an inclined launching platform. The inclined launching platform is still employed in small and mid-sized shipbuilding yards and in some large scale shipbuilding yards. However, recently, in order to ensure safety and improve efficiency when constructing large ships, the general trend is to construct a ship in a shipbuilding dock. In this case, a ship is constructed in a dock, and when launching the ship, the dock is filled with seawater and a dock gate is opened

so that the constructed ship can be towed out of the dock and remaining shipbuilding tasks can be conducted outside the dock. In detail, this method is implemented in a manner such that a ship that is shorter than the dock is constructed and floated by introducing seawater into the dock, the dock gate is opened, the floated ship is towed out of the dock using a tugboat, and the remaining shipbuilding tasks are conducted outside the dock. Nevertheless, this method has a problem in that space utilization efficiency in the dock is poor, and therefore, the method is inefficient for the mass production of ships. In order to solve this problem, a tandem shipbuilding process has been proposed in the art. In this process, by improving space utilization efficiency in a dock, two to four ships can be simultaneously constructed in one dock. In the tandem shipbuilding process, when a constructed ship is floated and towed out of the dock, a partially constructed ship, for which some construction tasks have been conducted, is necessarily floated together with the constructed ship to be launched. Then, after the constructed ship to be launched is towed out of the dock, a dock gate is closed to position the partially constructed ship in place, and seawater is discharged out of the dock. Thereafter, other construction tasks are conducted in a moved position or in an original position.
[Disclosure]
[Technical Problem]
The conventional tandem shipbuilding process has the drawbacks described below. In the case that a tandem zone
has a length no greater than 55% of the LOA (length

overall) of a ship due to the limitations in the specification of a dock, since floating is implemented in a manner such that the number of mounting parts to be mounted on a tandem ship is limited in order to secure a draft (of 7.1 m at the maximum) for floating a ship, the time for performing construction work in the dock is decreased, which impedes the tandem shipbuilding process and makes it necessary to rush the construction work, thereby causing problems due to the simultaneous implementation of an increased number of working steps. In the conventional tandem shipbuilding process, the mounting parts, which are not mounted on the tandem ship before the floating is conducted, includes a main engine, tail and intermediate shafts, an aft block, a lashing bridge, a hatch cover, and so forth.
Due to the limitation in the number of mounting parts that can be mounted on the tandem ship before the floating, when construction work is performed on the tandem ship in the dock after it is floated, problems are caused as described below. Since the mounting of a deck house is delayed due to the mounting of the tail and intermediate shafts and the main engine after the floating, the supply of shore power (from facilities on the shore) is likely to be difficult. Also, since a final sighting task as an operation for inspecting the verticality of a rudder is delayed due to the mounting of the aft block after the floating, less time is available for mounting a propeller and the rudder.
Further, floated ship blocks are not securely held but move so that they are likely to collide against each other or against the wall of a dock, whereby the ship blocks

under construction may be broken or damaged. Moreover, it is difficult to float the ship blocks while maintaining the balanced states of the ship blocks. In addition, after the ship blocks are floated, when the ship to be launched is towed out of the dock, seawater must be discharged from the dock so that the floated ship blocks can be placed in a position for performing construction work. In this regard, lots of time and labor are required to place the ship blocks in an original position or a moved position.
Accordingly, the present invention has been made in an effort to solve the problems occurring in the related art, and an object of the present invention is to provide a tandem shipbuilding process using a sinking method in which at least one of a main engine, tail and intermediate shafts, an aft block, a lashing bridge and a hatch cover is mounted to a tandem ship such that, when a ship to be' launched is floated in a dock, the tandem ship is not floated but is sunk to the bottom of the dock, and such that, after the ship to be launched is towed out of the dock, construction work can be performed at the same position so that the construction of the tandem ship in the dock can be completed within a short period.
Another object of the present invention is to provide a tandem shipbuilding process using a sinking method in which at least one of a main engine, tail and intermediate shafts, an aft block, a lashing bridge and a hatch cover is mounted to a tandem ship such that, when a ship to be launched is floated in a dock, the tandem ship is sunk to the bottom of the dock or is not fully floated by sinking the tandem ship to a predetermined depth, with the position of the tandem ship fixed through lashing, and that, after

the ship to be launched is towed out of the dock, construction work can be performed at the same position so that the construction of the tandem ship in the dock can be completed within a short period.
[Technical Solution]
In order to achieve the first object, according to one aspect of the present invention, there is provided a sinking method used in a tandem shipbuilding process in which a plurality of ships is sequentially constructed in a single dock through assembling and floating steps, the method comprising the steps of:
constructing ship blocks according to a general tandem shipbuilding process in a dock;
mounting at least one of main mounting parts to a tandem ship, which is a target to be sunk, before a ship to be launched is floated in the dock;
sinking the tandem ship at the same position by allowing seawater to naturally flow into a cargo hold/ballast and a partial double bottom tank of the tandem ship when floating the ship to be launched by introducing seawater into the dock; and
continuing construction work for the tandem ship at the same position after the floated ship to be launched is towed out of the dock by a tugboat and a dock gate is closed.
In order to achieve the second object, according to another aspect of the present invention, there is provided a sinking method used in a tandem shipbuilding process in which a plurality of ships is sequentially constructed in a single dock through assembly and floating steps, the method

comprising the steps of:
constructing ship blocks according to a general tandem shipbuilding process in a dock;
mounting at least one of main mounting parts to a tandem ship as a target to be sunk or partially sunk, before a ship to be launched is floated in the dock;
lashing portion's on both sides of the tandem ship to be sunk or partially sunk, to a bottom of the dock;
sinking or partially sinking the tandem ship at the same position by allowing seawater to naturally flow into a cargo hold/ballast and a partial double bottom tank of the tandem ship when floating the ship to be launched by introducing seawater into the dock;
releasing the lashing between the portions on both sides of the tandem ship which is sunk or partially sunk and the bottom of the dock, after the floated ship to be launched is towed out of the dock and a dock gate is closed; and
continuing construction work for the tandem ship at the same position.
According to another aspect of the present invention, in the step of mounting at least one of main mounting parts to a tandem ship to be sunk or partially sunk, the main mounting parts include a main engine, tail and intermediate shafts, an aft block, a lashing bridge and a hatch cover.
According to still another aspect of the present invention, the lashing step is a step in which portions on both sides of at least one selected from among a fore block, an aft block and an Intermediate block of the tandem ship to be sunk or partially sunk are lashed to a bottom of the dock; and

the releasing step is a step in which the lashing between the portions on both sides of at least one selected from among the fore block, the aft block and the intermediate block of the sunk or partially sunk tandem ship and the bottom of the dock is released.
According to a still further aspect of the present invention, the lashing step is a step in which lashing lugs are formed on portions on both sides of at least one selected from among a fore block, an aft block and an intermediate block of the tandem ship to be sunk or partially sunk, lashing fasteners are formed on a bottom of the dock to correspond to the lashing lugs, and the lashing lugs and the lashing fasteners are connected with each other by lashing chains; and
the releasing step is a step in which the connection by the lashing chains between the lashing lugs formed on the portions on both sides of at least one selected from among the fore block, the aft block and the intermediate block of the sunk or partially sunk tandem ship and the corresponding lashing fasteners formed on the bottom of the dock is released.
Thanks to the features of the present invention, the advantages described below are realized. In a tandem shipbuilding process, since a deck house can be mounted in an early stage to a tandem ship due to the mounting of shafts and a main engine before a ship to be launched is floated, the time for receiving shore power (supplied from facilities on the ground) can be secured.
Also, in the tandem shipbuilding process, because final sighting is permitted on the tandem ship due to the mounting of an aft block before the ship to be launched is

floated, the time for mounting a propeller and a rudder can be secured.
Further, in the tandem shipbuilding process, due to the fact that main mounting parts are mounted before the ship to be launched is floated, the mounting load on a goliath crane after the ship to be launched is floated can be considerably decreased.
Moreover, even in the case that the entire ship blocks cannot be sunk to the bottom of a dock since a certain ship block has a part which must not be sunk or it is structurally impossible to completely sink the ship block, so that a certain level of buoyancy is generated in that ship block, the ship block can be safely fixed in place in the dock through lashing.
In addition, even in the case in which the amount of seawater flowing into the dock is much greater than the amount of seawater needed for sinking the ship blocks, so that a certain level of buoyancy is generated in the ship blocks while sinking the ship blocks, the positions of the ship blocks can be safely fixed in the dock through lashing.
Besides, even in the case in which the movement of the ship block sunk to the bottom of the dock occurs due to the inflow of seawater or the flow of seawater in the dock due to towing of the ship to be launched, the positions of the ship blocks can be safely fixed in the dock through lashing, whereby the times for constructing or mounting main parts in the tandem shipbuilding process can be significantly decreased. As a consequence, the industrial applicability of the present invention can be anticipated.
[Description of Drawings]

FIG. 1(a) is a flow chart illustrating a tandem shipbuilding process in which a sinking method in accordance with an embodiment of the present invention is used;
FIG. 1(b) is a flow chart illustrating a tandem shipbuilding process in which a sinking method employing lashing in accordance with another embodiment of the present invention is used;
FIG. 2 is a view illustrating the unchanged position of a ship to be sunk when the ship is constructed according to the present invention;
FIG. 3 is a view illustrating a conventional tandem shipbuilding process and the present tandem shipbuilding process, in which the sinking method is used;
FIG. 4 is a plan view illustrating positions on a ship's hull block at which lashing is conducted according to the present invention;
FIG. 5 is sectional views taken along the lines A-A, B-B and C-C of FIG. 4, illustrating lashed states at the respective positions on the ship's hull block; and
FIG. 6 is a view illustrating the structure of a lashing part.
Drawings>
1: lashing lug 2: lashing fastener
3: lashing chain
[Mode for Invention]
Reference will now be made in greater detail to a preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings.
FIG. 1(a) is a flow chart illustrating a tandem

shipbuilding process in which a sinking method in accordance with an embodiment of the present invention is used. Referring to FIG. 1, the sinking method used in the tandem shipbuilding process, in which a plurality of ships is sequentially constructed in a single dock through assembling and floating steps, comprises the steps of:
constructing ship blocks according to a general tandem shipbuilding process in a dock (S100);
mounting at least one of main mounting parts to a tandem ship as a target to be sunk, before a ship to be launched is floated in the dock (S200);
sinking the tandem ship at the same position by allowing seawater to naturally flow into a cargo hold/ballast and a partial double bottom tank of the tandem ship when floating the ship to be launched by introducing seawater into the dock (S400a); and
continuing construction work for the tandem ship at the same position after the floated ship to be launched is towed out of the dock by a tugboat and a dock gate is closed (S600) .
In the step of mounting at least one of main mounting parts to a tandem ship to be sunk, the main mounting parts include a main engine, tail and intermediate shafts, an aft block, a lashing bridge, and a hatch cover.
FIG. 1(b) is a flow chart illustrating a tandem shipbuilding process in which a sinking method employing lashing in accordance with another embodiment of the present invention is used. The sinking method according to the present embodiment is basically the same as the sinking method shown in FIG. 1(a), except that a partial sinking step is included in a sinking step and lashing is employed

to reinforce the force for fastening the tandem ship to be sunk or partially sunk. In detail, the method comprises the steps of:
constructing ship blocks according to a general tandem shipbuilding process in a dock (S100);
mounting at least one of main mounting parts to a tandem ship as a target to be sunk or partially sunk, before a ship to be launched is floated in the dock (S200);
lashing portions on both sides of the tandem ship to be sunk or partially sunk, to a bottom of the dock (S300);
sinking or partially sinking the tandem ship at the same position by allowing seawater to naturally flow into a cargo hold/ballast and a partial double bottom tank of the tandem ship when floating the ship to be launched by introducing seawater into the dock (S400b);
releasing the lashing between the portions on both sides of the tandem ship which is sunk or partially sunk and the bottom of the dock, after the floated ship to be launched is towed out of the dock by a tugboat and a dock gate is closed (S500); and
continuing construction work for the tandem ship at the same position (S600).
In the step of mounting at least one of main installed parts to a tandem ship to be sunk or partially sunk, the main installed parts include a main engine, tail and intermediate shafts, an aft block, a lashing bridge and a hatch cover.
The lashing step is a step in which portions on both sides of at least one selected from among a fore block, an aft block and an intermediate block of the tandem ship to be sunk or partially sunk are lashed to a bottom of the

dock; and
the releasing step is a step in which the lashing between the portions on both sides of at least one selected from among the fore block, the aft block and the intermediate block of the sunk or partially sunk tandem ship and the bottom of the dock is released.
Concretely speaking, the lashing step is a step in which lashing lugs are formed on portions on both sides of at least one selected from among a fore block, an aft block and an intermediate block of the tandem ship to be sunk or partially sunk, lashing fasteners are formed on a bottom of the dock to correspond to the lashing lugs, and the lashing lugs and the lashing fasteners are connected with each other by lashing chains; and
the releasing step is a step in which the connection by the lashing chains between the lashing lugs formed on the portions on both sides of at least one selected from among the fore block, the aft block and the intermediate block of the sunk or partially sunk tandem ship and the corresponding lashing fasteners formed on the bottom of the dock is released.
FIG. 2 is a view illustrating the unchanged position of a tandem ship to be sunk or partially sunk when the tandem ship is constructed according to the present invention. It is to be readily understood that a main engine, tail and intermediate shafts, an aft block, etc. are mounted to the respective blocks of a ship as a target to be sunk, in the rear part of a dock before the ship is floated. A lashing bridge and a hatch cover are omitted for the sake of convenience of illustration.
It is to be appreciated that the ship is constructed

at an original position even after the ship is floated and therefore, the position of the ship is not changed.
FIG. 3 is a view illustrating a conventional tandem shipbuilding process and a present tandem shipbuilding process, in which the sinking method is used. Referring to FIG. 3, it is to be understood that, in the conventional tandem shipbuilding process, main installed parts, such as a main engine, tail and intermediate shafts, an aft block, a lashing bridge and a hatch cover are not mounted.
On the contrary, it is to be understood that, in the present tandem shipbuilding process, in which the sinking method is used, as main installed parts, a main engine is mounted in an engine room, tail and intermediate shafts are mounted to the lower part of a ship, an aft block is mounted above a rudder, and a lashing bridge and a hatch cover are mounted to the upper part of the ship. Therefore, in the present tandem shipbuilding process, it is to be noted that the main installed parts are mounted to their corresponding ship blocks.
Describing in detail the shipbuilding process according to the present invention, when the construction of a ship, which is first put into a dock, is primarily completed and the ship is ready to be launched according to the first-in first-out principle of the tandem shipbuilding process, before the ship to be launched is floated, all main installed parts are mounted to the remaining ships or ship blocks which are under construction in the dock, and a cargo hold/ballast and a partial double bottom tank are naturally sunk to the bottom of the dock when the ship to be launched is floated so that the remaining ships or ship blocks are not floated. As a consequence, in the present

shipbuilding process, because the number of installed parts to be mounted to the remaining ships or ship blocks after floating is decreased, an additional time of about 8 days for constructing the tandem ship in the dock can be secured after the ship to be launched is floated.
FIG. 4 is a plan view illustrating positions on a ship's hull block where lashing is conducted according to the present invention, FIG. 5 is sectional views taken along the lines A-A, B-B and C-C of FIG. 4, illustrating lashed states at the respective positions on the ship's hull block, and FIG. 6 is a view illustrating the structure of a lashing part. Referring to FIGs. 4 through 6, in order to lash a tandem ship, lashing lugs 1 are formed on portions on both sides of at least one selected from among a fore block C, an aft block A and an intermediate block B of the tandem ship to be sunk or partially sunk, lashing fasteners 2 are formed on the bottom of a dock to correspond to the lashing lugs 1, and the lashing lugs 1 and the lashing fasteners 2 are connected with each other by lashing chains 3. While FIG. 6 illustrates only the aft block A of FIG. 4 for the sake of convenience of illustration, it is to be readily understood that the lashing lugs 1, the lashing fasteners 2 and the lashing chains 3 are arranged in the fore block C and the intermediate block B. When releasing the lashed state, it is sufficient to remove the lashing chains 3.
At this time, the tension of the lashing chains 3 can be adjusted by pulling the lashing chains 3 from the positions of the lashing fasteners 2 or by using turnbuckles and the like on predetermined positions on the lashing chains 3.

The reasons why the lashing is conducted are as described below. That is to say, even in the case in which the entire tandem ship cannot be sunk, the entire ship blocks cannot be sunk to the bottom of a dock since a certain ship block has a part which must not be sunk, or it is structurally impossible to completely sink a ship block, meaning that a certain level of buoyancy is generated in that ship block, the tandem ship or the ship blocks can be safely fixed in place in the dock through lashing.
Moreover, even in the case in which the amount of seawater flowing into the dock is much greater than the amount of seawater needed to sink the tandem ship, so that a certain level of buoyancy must be generated in a ship block while sinking the tandem ship, the position of the tandem ship can be safely fixed in the dock through lashing.
In addition, even in the case in which the movement of the ship block sunk to the bottom of the dock occurs due to the inflow of seawater or the flow of seawater in the dock attributable to the towing of the ship to be launched, the positions of the ship blocks can be safely fixed in the dock through lashing.
Although preferred embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

[CLAIMS]
[Claim l]
A sinking method used in a tandem shipbuilding process in which a plurality of ships is sequentially constructed in a single dock through assembling and floating steps, the method comprising the steps of:
constructing ship blocks according to a general tandem shipbuilding process in a dock (S100);
mounting at least one of main installed parts to a tandem ship as a target to be sunk, before a ship to be launched is floated in the dock (S200);
sinking the tandem ship at the same position by allowing seawater to naturally flow into a cargo hold/ballast and a partial double bottom tank of the tandem ship when floating the ship to be launched by introducing seawater into the dock (S400a); and
continuing construction work for the tandem ship at the same position after the floated ship to be launched is towed out of the dock by a tugboat and a dock gate is closed (S600).
[Claim 2]
A sinking method used in a tandem shipbuilding process in which a plurality of ships is sequentially constructed in a single dock through assembling and floating steps, the method comprising the steps of:
constructing ship blocks according to a general tandem shipbuilding process in a dock (S100);
mounting at least one of main installed parts to a tandem ship, which is a target to be sunk or partially sunk,

before a ship to be launched is floated in the dock (S200) ;
lashing portions on both sides of the tandem ship to be sunk or partially sunk, to a bottom of the dock (S300);
sinking or partially sinking the tandem ship at the same position by allowing seawater to naturally flow into a cargo hold/ballast and a partial double bottom tank of the tandem ship when floating the ship to be launched by introducing seawater into the dock (S400b);
releasing the lashing between the portions on both sides of the tandem ship which is sunk or partially sunk and the bottom of the dock, after the floated ship to be launched is towed out of the dock and a dock gate is closed (S500); and
continuing construction work for the tandem ship at the same position. (S600) .
[Claim 3]
The method according to claim 2,
wherein the lashing step (S300) is a step in which portions on both sides of at least one selected from among a fore block, an aft block and an intermediate block of the tandem ship to be sunk or partially sunk are lashed to a bottom of the dock; and
wherein the releasing step (S500) is a step in which the lashing between the portions on both sides of at least one selected from among the fore block, the aft block and the intermediate block of the sunk or partially sunk tandem ship and the bottom of the dock is released.
[Claim 4]
The method according to claim 1 or 2, wherein, in the step of mounting at least one of main installed parts to a

tandem ship, the main installed parts include a main engine, tail and intermediate shafts, an aft block, a lashing bridge and a hatch cover.
[Claim 5]
The method according to claim 2 or 3,
wherein the lashing step (S300) is a step in which lashing lugs are formed on portions on both sides of at least one selected from among a fore block, an aft block and an intermediate block of the tandem ship to be sunk or partially sunk, lashing fasteners are formed on a bottom of the dock to correspond to the lashing lugs, and the lashing lugs and the lashing fasteners are connected with each other by lashing chains; and
wherein the releasing step (S500) is a step in which the connection by the lashing chains between the lashing lugs formed on the portions on both sides of at least one selected from among the fore block, the aft block and the intermediate block of the sunk or partially sunk tandem ship and the corresponding lashing fasteners formed on the bottom of the dock is released.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=qNaf2zib0bZcT/NFjzM2cg==&loc=egcICQiyoj82NGgGrC5ChA==

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Patent Number

272660

Indian Patent Application Number

2228/CHENP/2008

PG Journal Number

17/2016

Publication Date

22-Apr-2016

Grant Date

18-Apr-2016

Date of Filing

05-May-2008

Name of Patentee

HYUNDAI HEAVY INDUSTRIES CO., LTD.

Applicant Address

1 JEONHA-DONG, DONG-GU, ULSAN 682-792.

Inventors:

#	Inventor's Name	Inventor's Address
1	KIM, BYUNG-MOON	ILSHIN EILEEN-GARDEN APT 115-401, NAMOE-DONG, 1B-1L, JUNG-GU, ULSAN 681-270.
2	YEO, UN-HACK	BYUCKSAN UJIN APT 101-1801 HWAJEONG-DONG, DONG-GU ULSAN 682-090

PCT International Classification Number

B63B9/06

PCT International Application Number

PCT/KR07/05765

PCT International Filing date

2007-11-16

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10-2007-0096679	2007-09-21	Republic of Korea
2	10-2006-0137604	2006-12-29	Republic of Korea