DESC:FIELD OF INVENTION:
[001] The present invention generally relates to ship building. More particularly, the present invention relates to a novel method of retractable thruster installation.

BACKGROUND AND PRIOR ART:
[002] The strategy for building the vessel is primarily decided based on the method and sequence of Thruster installation during in situ construction. Conventionally, the Retractable Thruster Installation is one of the precision and critical activities which has ever been installed by Indian Shipyards for a Diving Support Vessels. The Thruster installation conventionally will be with the lowering on the Foundation on Blocks using the overhead crane. Once the Thruster is lowered, subsequent blocks above it could be lowered. This conventional procedure can be planned and a suitable erection strategy could be adopted in the Build strategy. The other construction activities such as blocks erection and integration are sequenced accordingly. Head Room for Thruster retraction is a no-go for this design as there is no dock floor space from bottom of the hull with proper installation and alignment. This is the challenge to overcome. Some developers suggested to dig the pit in the dock floor for accommodating the Thruster in retracted position. This would also delay the progress of the planned concurrent activities and will impact the time lines of the ship building. This leads to loss of time and cost of projects and may affect the economy & security of any country.

[003] Few prior arts are listed herein. WO2015160306A1 discloses a self elevating work platform above which an oil rig is put so that it can be transferred from one position to other. US4281615A discloses generally to floating platforms for tending marine operations, and in particular to a column stabilized, self-propelled semi-submersible vessel for servicing offshore petroleum production and drilling operations in severe ocean environments.

[004] For the in-situ installation and checking of the retractable thruster unit, a pit is required to be dug in the dock floor, which demands massive concrete structure excavation involving high labour and cost. As stated before, the in-situ installation is the most critical activity in this entire process chain. With the innovative approach of the present invention, the time and cost would be reduced, yet meeting the required timeline for the vessel’s launch.

SUMMARY OF THE INVENTION:
[005] An object of the present invention is to provide a method of retractable thruster installation that reduces labour work, time, and risk factors.

[006] Another objective of the present invention is to a method of Retractable Thruster Installation that minimizes the cost involved during the execution.

[007] Yet, another objective of the present invention is to a method of Retractable Thruster Installation that eliminates the necessity for in situ installation of retractable thrusters.

[008] In an aspect, the method for installing the retractable thruster unit 200, comprising removing a block 330 from the hull, supporting block 330 on an elevated platform 340, machining the foundation face of block 330 to achieve the desired tolerance for aligning the retractable thruster unit 200, drilling holes in block 330 for precise alignment of the retractable thruster unit 200, lowering the retractable thruster unit onto block 330, installing a retractable thruster unit 200 in block 330, aligning a retractable thruster unit 200 with a laser tool to achieve perpendicularity and parallelism during installation, fitting and bolting the retractable thruster unit 200 securely onto block 330, retracting thruster trials both downward and upward with rotation checks of the propeller, reintegrating block 330 with the installed retractable thruster unit 200 into the vessel.

[009] In an aspect, the block is removed from the hull through an overhead crane system.

[010] In an aspect, the system for installing the retractable thruster unit comprises a block situated on the hull, an elevated platform configured to support the block during the installation of the retractable thruster unit, and a retractable thruster unit installed in the block.

[011] In an aspect, the retractable thruster unit consists an azimuth retractable thruster.

BRIEF DESCRIPTION OF DRAWINGS:
[012] The invention has other advantages and features which will be more readily apparent from the following detailed description of the invention and the appended claims, when taken in conjunction with the accompanying drawings, in which:

Figure 1 illustrates the system for the installation of a retractable thruster unit.
Figure 2 illustrates the conventional system for the installation of a retractable thruster unit.

DETAILED DESCRIPTION OF THE INVENTION:
[013] The invention is described herein in detail with the help of figures appended at the end of the specification. The figures illustrate the preferred embodiment as well as other embodiments that define the scope of the present invention. However, it may be understood that the figures presented herein are intended to exemplify the scope of the invention only. The person skilled in art may note that by no means the figures limit the scope of the invention. Any variation in the drawings by any other person will be falling in the scope of the present invention.

[014] Throughout the specification and claims, the following terms take the meanings explicitly associated herein unless the context clearly dictates otherwise. The meaning of "a", "an", and "the" include plural references. The meaning of "in" includes "in" and "on." Referring to the drawings, like numbers indicate like parts throughout the views. Additionally, a reference to the singular includes a reference to the plural unless otherwise stated or inconsistent with the disclosure herein.

[015] The present invention discloses an innovative method for the installation of retractable thrusters in shipbuilding, specifically tailored for Diving Support Vessels.

[016] As illustrated in Figure 1, the method for installing the retractable thruster unit 200 comprises the steps that commence with the removal of a block 330 from the hull which is then supported on an elevated platform 340 during the installation process. This block 330 undergoes precision machining of its foundation face to achieve desired tolerances, and holes are drilled for accurate alignment of the retractable thruster unit 200. Subsequently, a retractable thruster unit 200 is lowered onto Block 330 and then installed a retractable thruster unit 200 in block 330. The alignment of a retractable thruster unit 200 with a laser tool to achieve perpendicularity and parallelism during installation. The fitted and bolted retractable thruster unit 200 onto block 330 undergoes hydraulic trials to validate proper propeller retraction in both downward and upward directions, along with rotation checks to ensure the overall functionality of the system. block 330 is reintegrated with the installed retractable thruster unit 200 into the vessel.

[017] In an embodiment, the system for installing the retractable thruster unit 200, comprising a block 330 situated on the hull, an elevated platform 340 configured to support block 330 during the installation of retractable thruster unit 200,a retractable thruster unit 200 installed in the block 330.

[018] In an embodiment, the retractable thruster unit 200 having an azimuth retractable thruster.

[019] In an embodiment, the block 330 is removed from the hull through an overhead crane system.

[020] As depicted in Fig.2, the conventional approach for shipbuilding practices may involve digging a pit 310 in the dock floor to provide additional space for the retraction of the propeller of retractable thruster unit 200. In the shipbuilding process related to the designed dock plan, particularly the limited dock block height of 1600mm. This limitation prevents the propeller of the retractable thruster from retracting up and down within the dock floor. The solution to this challenge has been to dig a pit 310 in the dock floor, allowing the necessary space for the movement of the retractable thruster unit 200.

[021] The pit 310 allows the retractable thruster unit 200 to move both downward and upward without constraints. The pit is created to facilitate the alignment and installation of the retractable thruster unit 200. It provides a space where the thruster can be properly aligned using laser tools and then securely fitted and bolted in place. The pit 310 could also offer easier access for maintenance and inspection activities on the retractable thruster unit 200, ensuring that necessary checks can be conducted efficiently. The innovative method of the present invention eliminates the need for digging a pit 310 in the dock floor by introducing an alternative approach that eliminates the need for such excavation of pit 310 while still ensuring the successful installation of retractable thruster unit 200.

[022] Although a particular exemplary embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized by those skilled in the art that variations or modifications of the disclosed invention, including the rearrangement in the configurations of the parts, changes in steps and their sequences may be possible. Accordingly, the invention is intended to embrace all such alternatives, modifications, and variations as may fall within the spirit and scope of the present invention.

[023] The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching.

ADVANTAGES OF THE INVENTION:
[024] The present invention provides a method for installing the retractable thruster unit that eliminates the need for pit digging, streamlining the installation process.
[025] The present invention provides a method for installing the retractable thruster unit that minimizes labour-intensive tasks associated with pit excavation, resulting in significant cost reductions in terms of labour, machinery, and time.
[026] The present invention provides a method for installing the retractable thruster unit that significantly shortens the time required for retractable thruster installation compared to traditional methods.
[027] The present invention provides a method for installing the retractable thruster unit that offers a more efficient and cost-effective solution for retractable thruster installation.
,CLAIMS:1. A method for installing the retractable thruster unit 200, comprising:
a) removing a block 330 from a hull;
b) supporting the block 330 on an elevated platform 340;
c) machining a foundation face of the block 330 to achieve the desired tolerance for aligning a retractable thruster unit 200;
d) drilling holes in the block 330 for precise alignment of the retractable thruster unit 200;
e) lowering the retractable thruster unit 200 onto the block 330;
f) installing the retractable thruster unit 200 in the block 330;
g) aligning the retractable thruster unit 200 with a laser tool to achieve perpendicularity and parallelism during installation;
h) fitting and bolting the retractable thruster unit 200 securely onto the block 330;
i) retracting thruster trials both downward and upward with rotation checks of the propeller;
j) reintegrating the block 330 with the installed retractable thruster unit 200 into the vessel.
2. The method as claimed in claim 1, wherein the block 330 is removed from the hull through an overhead crane system.
3. A system for installing the retractable thruster unit 200, comprising:
a block 330 situated on the hull;
an elevated platform 340 configured to support block 330 during the installation of retractable thruster unit 200;
a retractable thruster unit 200 installed in the block 330.

4. The system as claimed in claim 3, wherein the retractable thruster unit 200 consists an azimuth retractable thruster.