FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"Fixture for Turning Boat Hull"
2. APPLICANT:
(a) NAME: Larsen & Toubro Limited
(b) NATIONALITY: Indian Company registered under the
provisions of the Companies Act-1956.
(c) ADDRESS: Larsen & Toubro Limited
L&T House, Ballard Estate, MUMBAI-400001, Maharashtra State, INDIA
3. PREAMBLE TO THE DESCRIPTION:
COMPLETE
The following specification
particularly describes the invention and
the manner in which it is to be
performed.

Fixture for Turning Boat hull
Field of the invention
The present invention provides a fixture for safe turning of a boat hull, and more particularly, to a fixture for safe turning of a boat hull which maintains stability and integrity of the boat hull structure during turning.
Background of the invention
Generally, a boat hull is manufactured in upside down position. Thereafter, it is turned by 180 degree to bring it in upright position for further fabrication and out-fitting related work. Since the structure of the boat hull is very delicate, turning of boat hull is very critical operation considering structure deformation and safety aspects. Conventionally, turning of the boat hull is carried in air using 2-3 cranes.
In conventional method of lifting and turning the boat hull, 2-3 crawler cranes, and an hydraulic axle is required. Further, the lifting and turning operation is required to be carried out in large open space. Specifically, after the boat hull fabrication is completed on the skid fixture, the boat hull is lifted from the skid with the help of evener beam/crane and placed on the transportation axle. Thereafter, the boat hull taken to open area where turning is possible with the help of two crawler cranes. After turning the boat hull to upright position, the boat hull is then placed on a support fixture(Cradle). The boat hull with cradle is again taken inside the shop with the help of axle for further work of superstructure building.
However, the conventional method of lifting and turning the boat hull requires large open space for turning operation of the boat hull outside shop. Further, the

method requires critical resources like overhead crane, crawler crane, transportation vehicle, and fixture. Furthermore, the method requires handling the boat hull in air - load transfer on structure. Moreover, the boat hull gets jerks during turning which is unsafe for structural stability and safety of people working around.
Accordingly, there exists a need which overcomes the drawbacks of the prior art and provides for safe turning of the boat hull.
Objects of the invention
An object of the present invention is to provide a fixture for boat hull lifting and turning which to maintain stability and integrity of boat hull structure during turning and also avoids distortion of the hull structure.
Another object of the present invention is to provide a method for carrying out turning operation of the boat hull within the confined space of shop area.
Yet another object of the present invention is to provide safety of people involved in boat hull lifting and turning.
Summary of the invention
Accordingly, the present invention provides fixture for turning a boat hull, the fixture comprising:
a first roller assembly and a second roller assembly, the first roller assembly and the second roller assembly placed apart at a predetermined distance and grouted;
a bottom ring assembly having a first bottom semicircular ring placed on the first roller assembly and a second bottom semicircular ring placed on the second roller assembly, wherein the first bottom semicircular ring is detachably

secured to the first roller assembly and the second bottom semicircular ring is detachably secured to the second roller assembly;
a support link connecting the first bottom semicircular ring and the second bottom semicircular ring of the bottom ring assembly thereby holding the first bottom semicircular ring and the second bottom semicircular ring in place;
a top ring assembly having a first top semicircular ring capable of being detachably secured to the first bottom semicircular ring and a second top semicircular ring capable of being detachably secured to the second bottom semicircular ring; and
a second support link connecting the first top semicircular ring and the second top semicircular ring of the top ring assembly thereby holding the first top semicircular ring and the second top semicircular ring in place;
wherein upon detachably securing the bottom ring assembly with the top ring assembly having the boat hull to be turned therewithin and rotating the roller assembly enables turning of the boat hull by a predetermined angle. Brief description of drawings
Figure 1 depicts a front view of a fixture for boat hull before turning operation in accordance with the present invention;
Figure 2 depicts a side view of the fixture of figure 1; and
Figure 3 depicts a front view of fixture for boat hull after turning operation by 180 degree.
Detailed description of the present invention
The foregoing objects of the invention are accomplished and the problems and shortcomings associated with the prior art techniques and approaches are

overcome by the present invention as described below in the preferred embodiment.
The present invention provides a fixture for boat hull turning which maintains stability and integrity of boat hull structure during turning. Further, the fixture provides for boat hull lifting and turning in a confined shop area. Furthermore, the fixture provides for safety of people working during the boat hull lifting and turning activity.
The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the figure. These reference numbers are shown in bracket in the following description.
Referring now to Figure 1 and 3, there is shown a front view and side view of the fixture for boat hull turning, in accordance with the present invention. Specifically, figure 1, figure 2 and figure 3 shows the fixture (100).
The fixture (100) includes a first roller assembly (10a) and a second roller assembly (10b). The first roller assembly (10a) and the second roller assembly (10b) are placed apart at a predetermined distance and grouted. The distance for placing the first roller assembly (10a) and the second roller assembly (10b) is determined based on the size and length of the boat hull(60) to be turned.
The fixture (100) further includes a bottom ring assembly (20). Specifically, the bottom ring assembly (20) includes a first bottom semicircular ring (20a) and a second bottom semicircular ring (20b). The first bottom semicircular ring (20a) is placed on the first roller assembly (10a) and the second bottom semicircular ring (20b)is placed on the second roller assembly. Further, the first bottom semicircular ring (20a) is detachably secured to the first roller assembly (10a) and the second bottom semicircular ring (20b) is detachably secured to the

second roller assembly (10b). In an embodiment, the first bottom semicircular ring (20a) the second bottom semicircular ring (20b) are fitted to the first roller assembly (10a) and the second roller assembly (10b) with ring supporting link (70a, 70b) to avoid the rotational movement on the roller assembly (10a, 10b).
The first bottom semicircular ring (20a) and the second bottom semicircular ring (20b) are connected to each other by a support link (30). The support link (30) also known as distance support link provides for holding the first bottom semicircular ring(20a) and the second bottom semicircular ring (20b) in place.
The fixture (100) furthermore includes a top ring assembly (40) having a first top semicircular ring (40a) and a second top semicircular ring (40b). The first top semicircular ring (40a) is capable of being detachably secured to the first bottom semicircular ring(20a) and the second top semicircular ring (40b) is capable of being detachably secured to the second bottom semicircular ring (20b) to form a complete ring which provides ease of rotation thereof. Further, the first top semicircular ring (40a) is capable of being detachably secured to the first roller assembly (10a) and the second top semicircular ring (40b) is capable of being detachably secured to the second roller assembly (10b), when the top ring assembly (40) is at bottom position after rotating the ring by roller assembly (10a, 10b).
The first top semicircular ring (40a) and the second top semicircular ring (40b) are connected with a second support link (50). The second support link (50) known as second distance support link provides for holding the first top semicircular ring (40a) and the second top semicircular ring (40b) in place.
Upon arranging the bottom ring assembly (20) with the top ring assembly (40) having the boat hull(60) to be turned therewithin and rotation of the roller assembly enables turning of the boat hull(60) by a predetermined degree.

Specifically, the anti-drift mechanism (80a & 80b) is provided on both the sides of the ring (202, 20b) as shown in figure 2 to control the axial drift of fixture (60) during turning operation.
Further, for monitoring of the roller assembly's (10a, 10b) rotation on a digital display, encoders are used to get feedback from the roller assemblies (10a, 10b). However, it may be evident to those skilled in the art to use any contact or non-contact type sensors to detect and measure roller assembly's (10a, 10b) rotation. The feedback received from the roller assembly's (10a, 10b) is given to a control system, wherein the present speed of both roller assembly's (10a, 10b) is displayed and compared with each other. If the speed difference is out of predefined tolerances, the error message is generated and rotation of the roller assembly's (10a, 10b) is stopped for avoiding any damage to the hull structure.
Specifically, in an operation, the roller assembly (10a, 10b) are set on the ground at required distance and the bottom ring assembly (20) is detachably secured with the roller assembly (10a, 10b)by means of the ring supporting link (70), and both the semicircular rings (20a, 20b) of the bottom ring assembly (20) are connected with first support link (30) as shown in figure 2. Further, the top ring assembly (40) is lifted and bolted with the bottom ring assembly (20) and both the semicircular rings (40a, 40b) of the top ring assembly (40)are connected with second support link (50).
Thereafter, the top ring assembly (40)is unbolted with the bottom ring assembly (20) and placed on the ground.
The boat hull(60) is lifted from a deck support fixture with the help of aevener beam/crane and placed on the bottom ring assembly (20). Thereafter, the top ring assembly (40) is lifted from the ground with evener beam/crane and bolted with the bottom ring fixture (20). The top ring assembly (40) and the bottom

ring fixture (20) are then connected to the crane with belt and the locking of the bottom ring assembly (20) from the roller assembly (10a, 10b) is unlocked.
The roller assembly (10a, 10b) rotates together in a synchronized manner thereby causing turning of the boat hull(60) till the boat hull(60) is turned by 180°. Thereafter, the top ring assembly (40) which is now at bottom position is locked with the roller assembly (10a, 10b) using ring supporting link (70) to avoid rotational movement thereof as shown in in figure 3 .
The bottom ring assembly (20) which is on top position now is unlocked from the top ring assembly (40). Thereafter, the bottom ring assembly (20) is lifted and placed on the ground and the turned boat hull is lifted with the help of evener beam/crane and placed on the support fixture for further fabrication and related work.
Advantages of the present invention
1. The fixture (100) of the present invention provides safe turning without any damage to the boat hull (60).
2. The fixture (100) reduces jerks during the turning operation of boat hull(60) which was prevalent in the conventional method.
3. The fixture (100) do not require critical resources like crawler crane, transportation vehicle as in case of conventional method of turning of the boat hull.
4. The fixture (100) does not require welding additional lugs on the structure to be turned.
5. The fixture (100) provides safety of the people working around and do not
require skill person for the operation to carried out.
6. By using this fixture (100) cycle time for turning has been reduced compared
to prior art.

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 present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.

We claim
1. A fixture for turning a boat hull, the fixture comprising:
a first roller assembly and a second roller assembly, the first roller assembly and the second roller assembly placed apart at a predetermined distance and grouted;
a bottom ring assembly having a first bottom semicircular ring placed on the first roller assembly and a second bottom semicircular ring placed on the second roller assembly, wherein the first bottom semicircular ring is detachably secured to the first roller assembly and the second bottom semicircular ring is detachably secured to the second roller assembly;
a support link connecting the first bottom semicircular ring and the second bottom semicircular ring of the bottom ring assembly thereby holding the first bottom semicircular ring and the second bottom semicircular ring in place;
a top ring assembly having a first top semicircular ring capable of being detachably secured to the first bottom semicircular ring and a second top semicircular ring capable of being detachably secured to the second bottom semicircular ring; and
a second support link connecting the first top semicircular ring and the second top semicircular ring of the top ring assembly thereby holding the first top semicircular ring and the second top semicircular ring in place;
wherein upon detachably securing the bottom ring assembly with the top ring assembly having the boat hull to be turned therewithin and rotating the roller assembly enables turning of the boat hull by a predetermined angle.
2. The fixture as claimed in claim 1, wherein the boat hull and the top ring
assembly are lifted from a deck support fixture for placing on the bottom ring
assembly by evener beam/crane.

3. The fixture as claimed in claim ], wherein the boat hull is turned by 180° angle.
4. The fixture as claimed in claim 1, wherein an anti-drift mechanism is provided to control the drift of the fixture while turning operation.
5. The fixture as claimed in claim 1, wherein a monitoring system is provided with digital display for ensuring equal rotation of both roller assemblies.
6. The fixture as claimed in claim 1, wherein the roller is driven by any
one of the manual operation, motor and combination of both.