DESC:FIELD OF INVENTION:

[0001] The present invention generally relates to a method that reduces cycle time for shaft sighting by 50 % compared to the conventional methods. More particularly, the present invention relates to a method for installing fixed points (dock points) at the AFT of a ship.

BACKGROUND OF THE INVENTION:
[0002] Ships have shafts that connect their engines to their propellers. The translational motion of the pistons induces a rotatory motion on the crankshaft, which is in turn, coupled to the propulsion shaft. Afterward, the shaft passes through the stern tube. At the aft end of the shaft and outside to the stern tube is coupled by the propeller. The centerline of the crankshaft must be along the centerline of the propulsion shaft and the propeller. If that fails, the propeller will wobble about its position during the running condition. Even a few millimeters of wobbling can result in the development of high stresses in the shafting arrangement, leading to structural failure.

[0003] In order to prevent structural failures, shipbuilders follow a method called Boring and Sighting of the stern tube, which is done to establish the centerline of the shafting. The stern tube consists of two bearings, one at its forward end, called the forward bush bearing, and the other at its aft end, called the aft bush bearing. It is through the aperture of these bearings that the propulsion shaft passes. The clearings between the bearings and the shaft are very minute, and hence the shaft center line is to be correctly established in line with the centers of the bearings.

[0004] However, the method usually takes time, which further makes the entire method costly. A novel method is introduced herein which reduces the cycle time for shaft sighting at different stages and eases the installation of bearings.

SUMMARY OF INVENTION:

[0005] Accordingly, the present invention discloses a method for installing fixed points (dock points) at the AFT of a ship.

[0006] In an embodiment of the present invention, the dock points are installed at the AFT of the last shaft bearing, keeping the clearance of bearing length sufficient to insert between the shaft bracket & dock point.

[0007] In another embodiment of the present invention, the dock points for shaft sighting are installed on the slipway at FR 88, which is far away from the AFT bracket. Hence, the clearance between the docking point & AFT Face of the bracket measures 4000 mm, which is higher than the bearing length i.e. 2200 mm.

[0008] In still another embodiment of the present invention, the method reduces the cycle time for shaft sighting by 50 % compared to the conventional methods.

DETAILED DESCRIPTION OF THE INVENTION:

[0009] While the invention has been disclosed with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the invention without departing from its scope.

[0010] 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.

[0011] The figures and protocols have been represented where appropriate by conventional representations in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

[0012] To overcome the aforementioned problems, the present inventors disclose a method that reduces cycle time for shaft sighting by 50 % compared to that of the conventional methods.

[0013] In an embodiment of the present invention, the method includes installing fixed points (dock points) at the AFT of the ship.

[0014] In another embodiment of the present invention, the dock points are installed at the AFT of the last shaft bearing, keeping the clearance of bearing length sufficient to insert between the shaft bracket & dock point.

[0015] In still another embodiment of the present invention, the dock points for shaft sighting are installed on the slipway at FR 88, which is far away from the AFT bracket i.e. ‘A’ bracket AFT face which is at FR 86-500. Hence, the clearance between the docking point & AFT Face of the bracket measures 4000 mm, which is higher than the bearing length i.e. 2200 mm.

[0016] In yet another embodiment of the present invention, the dock point need not to be removed during bearing installation which further helps to reduce the cycle time for re-sighting.

[0017] In still another embodiment of the present invention, the method helps to ease the shaft sighting activity pre & post of stern and further reduce the cycle time to 50 %, compared to the existing conventional method.

ADVANTAGES OF THE INVENTION

[0018] The present method reduces cycle time for shaft sighting by 50 %.
[0019] Compared to the existing methods the following operations are not required in the present method:-
(a) Cutting of AFT target point channel
(b) Use of proof circle for re-sighting.
(c) Re-erection & installation of target point.
(d) Re-sighting for target points.
[0020] The present method requires only less cycle time for re-sighting.
[0021] Ease in the installation of bearings.
,CLAIMS:1. A method of installation of docking points at an AFT of a ship comprises installing plurality of docking points at the AFT of a last shaft bearing, thereby keeping the clearance of bearing length sufficient to insert between a shaft bracket and a dock point position.

2. The method as claimed in Claim 1, wherein the dock points for shaft sighting are installed on the slipway at FR 88.

3. The method as claimed in Claim 1, wherein the dock point remains intact during bearing installation.