DESC:FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

Title of invention:
A RUDDER CLEARANCE MEASUREMENT SYSTEM FOR IWS VESSELS AND METHOD THEREOF

Applicant:
GOA SHIPYARD LIMITED
(A Govt. of India Undertaking-Ministry of Defense)
Having addressed as:
GOA SHIPYARD LIMITED
Vasco-Da-Gama, Goa - 403802, India

The following specification particularly describes the invention and the manner in which it is to be performed
CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY
[001] The present application claims priority to Indian Patent Application No. 202221055698 titled “RUDDER CLEARANCE MEASUREMENT SYSTEM FOR THE IWS VESSELS” filed on September 28th, 2022, the entity of which is hereby incorporated by reference.
FIELD OF INVENTION
[002] The present subject matter described herein, in general, relates to measuring the rudder clearance during in water survey without docking the vessel and more specifically relates to measuring the rudder bush clearance by providing a socket and allen bolt to rudder head box.

BACKGROUND OF THE INVENTION
[003] For ships with IWS (In water survey) notation less than 15 years in age the examination of the outside of ship's bottom and related items of ships may be carried out while the ship is afloat (in water survey) in lieu of the required intermediate docking between special surveys. The In-Water Survey is to be carried out at an agreed geographical location under the surveillance of a Surveyor, with the ship at a suitable draught in sheltered waters and with weak tidal streams and currents. The in-water visibility and the cleanliness of the hull below the waterline is to be clear enough to permit a meaningful examination which allows the Surveyor and diver to determine the condition of the plating, appendages and the welding. The in-water survey is to provide all the information normally obtained from a docking survey. However, special consideration may be given to ascertaining rudder bearing clearances and stern bush clearances of oil stern bearings based on a review of the operating history, on board testing and stern tube oil sample reports. During the In water survey, vessel will be positioned at forward trim so that the rudder head box at aft will come above the water level which will enable diver to take the rudder clearance measurements.
[004] A rudder is one of the most important components in any marine vessel. It enables to steer, control, and direct the ship in the sea. Rudder, part of the steering apparatus of a boat or ship is fastened outside the hull, usually at the stern.
[005] Main components of rudder system are as follows:
a) Rudder stock
b) Trunk tube
c) Rudder blade
d) Seals
e) Bearings: (Upper bearing and neck bearing)
[006] During in water survey of the vessel, diver goes into the water and takes measurement of bush wear out for stern gear and rudder system. For rudder system measurements can be taken by feeler gauge to understand the clearance between neck bearing and rudder stock. For the rudder stock assembly with o ring, the feeler gauge readings can be taken by removing a jumping collar and retaining ring. However rudder assembly with Lip seals cannot be measured with feeler gauge during in water survey by removing jumping collar and retaining ring.
[007] Thus, as an alternative solution has been developed to measure the rudder clearance without removing the jumping collar and retaining ring.

OBJECTS OF THE INVENTION
[008] Main object of the present invention is to provide a rudder bush clearance measurement system without docking the vessel.
[009] Another object of the present invention to provide a rudder clearance measurement system for measuring the rudder stock clearance with neck bearing during in water survey when lip seals are provided for rudder system
[0010] Yet another object of the present invention is to provide a rudder clearance measurement system for measuring the rudder stock clearance with the jumping collar and retaining ring in mounting position.
[0011] Yet another object of the present invention is to provide a rudder clearance measurement system to measure the rudder stock clearance where use of feeler gauge is impracticable during in water survey.

SUMMARY OF THE INVENTION
[0012] Before the present system is described, it is to be understood that this application is not limited to the particular machine or an apparatus, and methodologies described, as there can be multiple possible embodiments that are not expressly illustrated in the present disclosures. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope of the present application. This summary is provided to introduce aspects related to rudder clearance measurement system for IWS vessels and method thereof, and the aspects are further elaborated below in the detailed description. This summary is not intended to identify essential features of the proposed subject matter nor is it intended for use in determining or limiting the scope of the proposed subject matter.
[0013] The present subject matter described herein, in general, relates to measuring the rudder bush clearance during in water survey without docking the vessel by providing a socket and allen bolt to rudder head box. A hole is made in the rudder head box and along the same lateral axis a hole is made in the neck bearing through the bush housing. Allen bolts are placed at both the holes to avoid leakage of water. While measuring the clearance both the allen bolts are removed and the clearance is measured with a Vernier caliper through the hole.

STATEMENT OF INVENTION
[0014] Accordingly, the present invention discloses a rudder clearance measurement system for in-water survey (IWS) vessels comprising a rudder head box (12) configured with at least one aperture (6), at least one bush housing (3) configured with at least one aperture (7), at least one neck bearing (2) configured with at least one aperture (7) and plurality of bolts (16) and (18) configured for closing the apertures for avoiding water leakages.
[0015] The present invention also discloses a method for measuring rudder clearance comprising of the steps of: Removing the bolt (16) mounted on the rudder head box (12). Removing the bolt (18) mounted on the neck bearing using a T type allen key. Inserting a back end of the Vernier caliper inside the aperture till it reaches the rudder shaft (15). Measuring the clearance between the rudder shaft (15) and neck bearing (2). Plugging the apertures (6,7) with the bolts (16, 18).

BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The foregoing summary, as well as the following detailed description of embodiments, is better understood when read in conjunction with the appended drawing. For the purpose of illustrating the disclosure, there is shown in the present document example constructions of the disclosure, however, the disclosure is not limited to the specific methods and apparatus disclosed in the document and the drawing:
[0017] The detailed description is described with reference to the accompanying figure. In the figure, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawing to refer like features and components.
[0018] Figure 1 illustrates a front orthographic view of the prior art of the rudder system with O ring seal.
[0019] Figure 2 illustrates a front orthographic view of the rudder system with Lip seals of the present invention.
[0020] Figure 3 illustrates a schematic view of the rudder system with O ring.
[0021] Figure 4 illustrates schematic enlarged image of the rudder system with O ring with feasibility to measure clearance with feeler gauge.
[0022] Figure 5 illustrates a schematic full view of the rudder system with Lip seals.
[0023] Figure 6 illustrates schematic enlarged image of the rudder system with Lip seals without feasibility to measure clearance with feeler gauge.
[0024] Figure 7 illustrates schematic view of arrangement of Lip seals on rudder stock.
[0025] Figure 8 illustrates a schematic view of the rudder head box and the allen bolt mounted on it.
[0026] Figure 9 illustrates a schematic view of the rudder system and removal of the measuring device bolt with a T type allen key.
[0027] Figure 10 illustrates a schematic view of the rudder system and measuring of the rudder clearance with a Vernier caliper.
[0028] The figures depict various embodiments of the present disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION OF THE INVENTION
[0029] Some embodiments of this disclosure, illustrating all its features, will now be discussed in detail. The words "comprising", “having”, and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. Although any systems and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the exemplary, systems and methods are now described. The disclosed embodiments are merely exemplary of the disclosure, which may be embodied in various forms.
[0030] Various modifications to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. However, one of ordinary skill in the art will readily recognize that the present disclosure is not intended to be limited to the embodiments illustrated, but is to be accorded the widest scope consistent with the principles and features described herein.
[0031] Rudder is a device used for steering and manoeuvring a vessel. Rudders are hydrofoils which are pivoting on a vertical axis. They are located normally at the stern behind propeller(s) to produce a transverse force and steering moment about the ship centre of gravity by deflecting the water flow to the direction of the foil plane. The rudder consists of a shaft and neck bearing (2) wherein, the shaft rotates inside the neck bearing (2). The wear and tear of the bearing has to be checked at regular intervals to avoid malfunctioning of the rudder.
[0032] The present subject matter relates to measuring the rudder bush clearance during in water survey without docking the vessel by providing a socket and allen bolt (16) to rudder head box. Here rudder head box (12) is a structure fitted on top of the rudders integrating with hull in the aft region to minimize the drag caused due to unstable flow in the stagnation region behind the top of the rudder provided. For measuring the rudder bush clearance without removing the jumping collar (5) and retaining ring (13) a hole (6) is made in the rudder head box (12). Along the same lateral axis of the hole another hole (7) is made in the neck bearing (2) through the bush housing (3). Both the holes are closed by using allen bolts (16) and (18) respectively in order to avoid water leakage. In in-water survey (IWS) for vessel the diver goes into the water and measures the rudder clearance. For measuring the rudder clearance the diver has to remove the allen bolt (16) mounted on the rudder head box first using an allen key. Later a T type allen key is used to remove the measuring device bolt (18) mounted on the neck bearing (2). As the allen bolt (18) is removed the clearance between the rudder shaft (15) and the neck bearing (2) is measured by using a Vernier caliper (17). Here during construction of ship i.e. before launching ship in the water, initial value of rudder bush clearance is measured with this Allen bolt and socket arrangement. At later stage i.e after few years of vessel operations, during the In water survey the obtained vernier caliper readings for rudder bush clearance needs to be compared with the initial readings taken during construction to obtain the exact wear and tear.
[0033] By using this method it reduces the efforts of the diver to remove Jumping collar (5) and retainer ring (13) for the rudder systems with O ring (14). Measurement can be taken by calibrated digital Vernier caliper (17) for accurate output for rudder system with Lip seals (10).
[0034] Here during construction of the ship, air pressure test is carried out for the Rudder head box after providing the holes (6,7) and Allen bolts (16, 18) to check its integrity to avoid water ingress in the rudder head box (12) and trunk tube (1) of the ship. Upon sustaining the Air pressure test, vessel will be launched in water with this Allen bolt and socket arrangement. Thus this arrangement can be used during in water survey as it will not allow water ingress inside the rudder head box (12) and trunk tube (1).
[0035] Accordingly, the present invention discloses a rudder clearance measurement system for in-water survey (IWS) vessels comprising a rudder head box (12) configured with at least one aperture (6), at least one bush housing (3) configured with at least one aperture (7), at least one neck bearing (2) configured with at least one aperture (7) and plurality of bolts (16) and (18) configured for closing the apertures for avoiding water leakages.
[0036] The aperture (6) and aperture (7) are configured to be sealed with bolts (16) and (18) respectively. The aperture (7) and aperture (6) are configured to be retained in same lateral axis adapted for measuring the rudder bush clearance. A vernier caliper (17) is configured to be inserted in the apertures (6) and (7) to measure the clearance between the rudder shaft (15) and the neck bearing (2).
[0037] The method for measuring rudder clearance is performed in the following steps:
• Removing the bolt (16) mounted on the rudder head box (12).
• Removing the bolt (18) mounted on the neck bearing using a T type allen key.
• Inserting a back end of the Vernier caliper inside the aperture till it reaches the rudder shaft (15).
• Measuring the clearance between the rudder shaft (15) and neck bearing (2).
• plugging the apertures (6,7) with the bolts (16, 18).
[0038] Further, the invention can be used, but not limited to, in the following applications.
[0039] Exemplary embodiments discussed above may provide certain advantages. Though not required to practice aspects of the disclosure, these advantages may include the following:
[0040] Some embodiments of the present subject matter provide a measurement system for measuring the rudder bush clearance.
[0041] Some embodiments of the present subject matter provide a rudder bush clearance measurement system for measuring the rudder stock clearance with neck bearing during in water survey.
[0042] Some embodiments of the present subject matter provide a rudder bush clearance measurement system for measuring the rudder stock clearance with the jumping collar and retaining ring in mounting position.
[0043] Some embodiments of the present subject matter provide a rudder clearance measurement system to measure the rudder stock clearance where use of feeler gauge is impracticable during in water survey.
[0044] Although implementations for rudder clearance measurement system for IWS vessels and method thereof have been described in language specific to structural features and/or system, it is to be understood that the appended claims are not necessarily limited to the specific features or described. Rather, the specific features are disclosed as examples of implementations
[0045] Figures 1-10 are now described using the reference numbers stated in the below table.
Reference Numeral Description
1 Trunk tube
2 Neck Bearing
3 Bush housing
4 Locking plate
5 Anti jumping collar
6 Socket with allen head bolt
7 Measuring device slot
8 Lip seal
9 Pressure plate
10 Lip seal
11 S.S Liner
12 Rudder head box
13 Retaining ring
14 ‘O’ ring
15 Rudder shaft
16 Allen bolt on rudder box
17 Vernier caliper
18 Allen bolt on bush housing and neck bearing

,CLAIMS:
1. A rudder clearance measurement system for in-water survey (IWS) vessels comprising:
a rudder head box (12) configured with at least one aperture (6);
at least one bush housing (3) configured with at least one aperture (7);
at least one neck bearing (2) configured with at least one aperture (7); and
plurality of bolts (16) and (18) configured for closing the apertures for avoiding water leakages.

2. The rudder clearance measurement system for IWS vessels as claimed in claim 1 wherein, said aperture (6) and aperture (7) are configured to be sealed with bolts (16) and (18) respectively.

3. The rudder clearance measurement system for IWS vessels as claimed in claim 1 wherein, said aperture (7) and aperture (6) are configured to be retained in same lateral axis adapted for measuring the rudder bush clearance.

4. The rudder clearance measurement system for IWS vessels as claimed in claim 1 wherein, a vernier caliper (17) is configured to be inserted in the apertures (6) and (7) to measure the clearance between the rudder shaft (15) and the neck bearing (2).

5. A method for measuring rudder clearance comprises of:
• removing the bolt (16) mounted on the rudder head box (12);
• removing the bolt (18) mounted on the neck bearing using a T type allen key;
• inserting a back end of the Vernier caliper inside the aperture till it reaches the rudder shaft (15);
• measuring the clearance between the rudder shaft (15) and neck bearing (2); and
• plugging the apertures (6,7) with the bolts (16, 18).