Preface

The journey began in 1884, with a small factory on the Eastern Bank of river

Hooghly. It was named as Garden Reach Workshop (GRW) in 1916. Later,

on 19th April 1960, it was taken over by the Government of India.

Garden Reach Shipbuilders & Engineers Ltd (GRSE) is the premier Warship

building Company in India, under the administrative control of Ministry of

Defence. GRSE, since 1960, has built 94 warships for various roles, starting from

state of the art Frigates & Corvettes to Fast Patrol Boats. GRSE has played a very

important role in the defence preparedness of the country and has always risen to

the occasion in the national mission of design and construction of warship

indigenously. In addition to warships, GRSE has also built & supplied close to 700

vessels to carry men and materials as well as for surveillance of the Coast Line by

the Police Forces. Apart from ship building and ship repair, GRSE is one of the

few versatile shipyards having its own Engineering and Engine Division. On 05

Sep 2006, GRSE was accorded the status of Mini Ratna Category 1.

GRSE is currently building four Anti-Submarine Warfare Corvettes (ASWCs) for

Indian Navy. The 1st of the class ship, INS Kamorta was commissioned by

the Honorable Raksha Mantri, Shri Arun Jaitley in Aug 2014.

GRSE is making persistent efforts to set itself firmly on a growth trajectory. Firm

foundation being laid today is aimed at enabling GRSE to further consolidate on its

strengths and emerge as a leading shipyard with multi-dimensional engineering

capabilities, in the years to come.

2

Acknowledgement

I had my training from 4th May, 2015 to 1st June, 2015 in Garden Reach

Shipbuilders & Engineers Ltd (GRSE). I was posted in various unit of the

organization viz. Modern Hull Shop, Ship Building Shop, Plate Preparation Shop,

Yard-3019, and Central Design Office during my training. Therefore, I wish to

express my heartiest gratitude to Garden Reach Shipbuilders & Engineers Ltd.

(GRSE) for allowing me to undergo a vast and thorough training on various fields

related with ships and surroundings. I am grateful to Mr. M.K. Pandey (DGM,

PPS, MAIN, GRSE), Mr. M K Rath (DGM, SBS, MAIN, Mr. R.L Banerjee (SM,

MHS, MAIN, GRSE), Mr. Gulshan Ratan (DGM, Outfit, CDO, GRSE). My

sincere thanks to Mr. Tanmoy Mondal (DM, SBS,MW), Mr. Ajit Vikram, Mr.

Umesh Pashwan, Mr. K.K Chakravarthy, Mr. Nibir Mandal, Mr. Palla Narendre,

Mr. Anand Rup, Mr. Kundu, Mr. Sourav Kumar who guided me at the different

units and all other helping hands for their valuable guidance, direction and intent

supervision at every stage of my work. I am pleased especially because of the

friendly behavior of the people of the Units who helped me to know different

techniques of Production and Design.

At last but not the least I would like to express my gratitude to the whole of GRSE,

helping personals and my friends those who helped me in collecting information

for the project.

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Table of Contents

1. Modern Hull Shop...........................................................4

2. Dry Docking....................................................................9

3. Ship Building Shop ……………………………………..11

4. Plate Preparation Shop …………………………………17

5. Yard 3019……………………………………………….22

6. Central Design Office…………………………………...28

4

Modern Hull Shop

It is one of the shops in GRSE where hull fabrication along with edge preparation

is done. MHS has infrastructure to build large pre outfitted blocks of upto 200

tonnes. It has a gantry of capacity 40 tonnes to move plates from one place to other

within the shop. Gas Metal Arc Welding (GMAW) and Shielded Metal Arc

Welding (SMAW) are used for welding (for fabrication of blocks).

Currently, GRSE is working mainly on two projects namely LCU (Landing Craft

Utility) and Corvette. All the plates used in the hull fabrication of these ships are

made of steel alloy named DMR 249A. It is a low carbon low alloy steel developed

in Bokaro Steel Plant, for strategic applications by Indian Navy.

5

Operations:

1. Hull Fabrication

Hull fabrication is a process of making panels and assemblies out of plates coming

from Plate Preparation Shop and combining them to form a hull block. Hull blocks

are fabricated on a skid structure as they are huge and need support as they are

built. But before starting the process, every plate’s edge preparation is done so that

welding of plates is consistent and there is no defect in the structure as whole when

fully built.

Blocks are fabricated in an inverted fashion on the skid structure i.e. the deck is

laying on the skid structure. This is done as all the stiffening arrangements are

under the deck and it is not possible to weld from under the skid structure. To

support the plates to be welded together, strong bars are used. (Note: Strong bars

are used to hold the plates together till they are welded together. These also take

care of the possible distortions which may occur if welding is done without any

support.) These bars are removed by gas cutting after the structure is completed.

In the stiffening arrangement, at the intersection of longitudinal stiffeners with

transverse stiffeners, longitudinals run from the small cut-outs called scallops made

in the transverses. And the connections of transverse with the longitudinals are

done with plates named lugs.

Here in GRSE, all the blocks are fabricated according to frame-wise plan provided

by the Indian Navy. All the scantlings of stiffeners and details of manholes,

compartments and decks are provided in that plan.

2. Skid Structures

These are low platform structures designed to support or elevate any bulk structure

(in this case, a block of a ship or a rudder). The skid structure elevation is such that

it fits the exact curvature of the corresponding bulk structure to be fabricated on it.

While the structure over the skid is fabricated, it is attached to the skid with tack

welds.

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3. Edge Preparation: The process consists of removing the material

along the edges of metal plates. It is very important for welding when parts and

assemblies require certain strength. It also ensures full opening welding

penetration. Edge preparation is done with the help of a semi-automatic oxy-

acetylene gas cutting machine.

Types of edge preparations available are:

—One side root —V-groove angle cut

—Bevel-groove angle cut —V-groove angle cut with root

opening

—Both sides root opening —Bevel-groove angle cut with

root opening

Figure shows the edge cutting parameters:

1) Groove angle

2) Depth

3) Root Opening

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4. Rudder Construction: A rudder of a ship is a hydrofoil surface used

to navigate the ship. It is fitted in the aft region of a ship, in front of propeller

blades. A rudder is has a hollow but highly stiffened structure as it has to bear

severe bending moment and torque in the water. Its construction is also done on a

skid structure designed according to its curvature. It is also made of DMR 249A

plates( in this case) and plate sides are stiffened by internal webs. Where the rudder

is fully fabricated, one side plate is prepared and the vertical and horizontal

stiffening webs are welded to this plate. The other plate, often called the ‘closing

plate’, is then welded to the internal framing from the exterior only. This may be

achieved by welding flat bars to the webs prior to fitting the closing plate, and then

slot welding the plate.

The hollow body of a rudder filled with oil to protect it from corrosion. At the

same time, weight of the structure is also under control.

Rudder Stock- Rudder stock may be of cast or forged steel, and its meter is

determined in accordance with the torque and any bending moment it is to

withstand. At its lower end it is connected to the rudder by a horizontal or vertical

bolted coupling, the bolts having a cross-sectional area which is adequate to

withstand the torque applied to the stock. This coupling enables the rudder to be

lifted from the pintles for inspection and service.

Jumping Plate- It’s a bump stop in case if rudder hits the bottom of the ship to

avoid damage to the bottom shell.

Welding Techniques Used In MHS:

1. GMAW

It is a welding process in which an electric arc forms between

consumable wire electrode and the workpiece metal(s), which heats the workpiece

metal(s), causing them to melt, and join. A gaseous mixture is used as a shielding

medium and is semi-automatic.

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It is called MIG (Metal Inert Gas) when the shielding gas mixture used is of

Argon and Helium or Argon and Helium separately. And it is called MAG

(Metal Active Gas) when shielding medium used is CO2.

With DMR 249A, MIG welding gives the desired quality.

In GMAW, there is continuous supply of electrode and hence consistency of

welding profile and heat content of the product is better than SAW and

SMAW.

Power supply used is DC.

2. MMAW:

It is a welding process in which weld pool is shielded by the flux coated around the

electrode itself. It is completely manual.

Power source is again DC for consistency.

Metal transfer mechanism is globular. For thick plates, welding is done in

multiple number of rounds using CBS (Ceramic Backing Strip) on other side

of the plates.

Flux from the electrode burns to form a gaseous shielding medium and slag.

Slag provides shielding to the molten metal.

Gaseous shielding medium protects the arc column from atmosphere.

Note: Drooping Power source is used in both the welding techniques. Therefore,

there is no fluctuation in current due to small voltage fluctuations.

9

Dry Docking

A dry dock is a narrow basin or vessel that can be flooded to allow a load to be

floated in, and then drained to allow that load to come to rest on a dry platform.

Dry docks are used for the construction, maintenance, and repair of ships, boats,

and other water crafts.

GRSE has three dry docks:

1. Dry Dock No.1: This particular dry dock is 185M long and 25 M wide and

6.4M depth. This dry dock can accommodate ship having a draft facility of 1.9

M

2. Dry Dock No. 2: This dry dock is 160M long, 25M wide and 9M depth. This

dry dock can accommodate ship having a draft of 4M. This particular dry dock

is made of all weather dry dock having portable cover.

3. Dry Dock No. 3: This dry dock is 107M long, 25M wide and 6 M depth and is

under repair.

Infrastructure in dry docks:

Goliath Crane- A big gantry crane of 250 tonnes capacity is installed to lift the

gates or heavy items like plates, chains propellers which covers Module Hall, Dry

Dock and Inclined Berth.

Portable Shelters- There are portable shelters over the Dry dock and Incline

Berth.

Fenders- Fenders are installed on the side walls of the dry dock so that they

protect a ship from banging into the walls while dry docking or undocking.

Capstons- These are spinning spindles to pull the vessels or to guide them outside

the dock.

Bollards- Bollards are small vertical posts used for mooring.

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Gates- Big gates are there to stop water from entering the dry dock or the Building

Berth. These gates are opened when a ship has to be docked or undocked or to be

launched. Dry dock 2 has a gate weighting 90 tonnes and the building berth

adjacent to it has a gate weighting 40 tonnes.

Gates cannot be lifted directly while the pressure difference is huge on both sides.

E.g. one side is water and other side is air pressure. This is due to the fact that gate

gets jammed due to the uneven pressure. So, firstly the gate openings are opened

so that sufficient water comes in and there is enough pressure on both sides to lift

the gate.

Gates are only lifted when there is high tide in the river.

Wet Basin: GRSE has117.80 X 25 X 8 M fully covered non-tidal wet basin with 2

X 10T EOT Cranes is ideally suited for all weather fitting-out of medium and

small ships

Building Berth: In addition to Dry Dock, GRSE’s facility includes one Building

Berth, measuring 180m X 25m. This is equipped with 2 X 40/10 T Cranes and

supporting fabrication shops to facilitate faster job turnaround.

Recent Activities in the Docks:

Recently, Corvette 3020 (Kavaratti) was successfully launched in the old dry dock.

One of the ships of Corvette series Corvette 3019 (Kilton) is docked in the dry

dock 2 for repairs and new installations.

LCU 2095 is also docked in the same dry dock.

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Shipbuilding Shop

Welding

Positions of welding:

1G Plate- which is flat position

2G Plate- which is horizontal position

3G Plate- which is vertical position

4G Plate- which is overhead position

1G Pipe (rolled)- which is flat position

2G Pipe (fixed)- which is horizontal position

5G Pipe (fixed)- which is vertical position

6G Pipe (fixed)- inclined position at 45 degrees

6GR Pipe (fixed)- inclined position with restriction ring

Types of Joints:

1. Butt Joint

A butt weld, or a square-groove, is the most common and easiest to use. Consisting

of two flat pieces that are parallel to one another, it also is an economical option. It

is the universally used method of joining a pipe to itself, as well as flanges, valves,

fittings, or other equipment.

Types of Butt Joints:

Single V

Double V

Single J

Double J

Single U

Double U

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2. Tee Joint

Tee joints, considered a fillet type of weld, form when two members intersect at

90° resulting in the edges coming together in the middle of a component or plate. It

may also be formed when a tube or pipe is placed on a baseplate.

3. Lap Joint

This is formed when two pieces are placed atop each other while also over lapping

each other for a certain distance along the edge. Considered a fillet type of a

welding joint, the weld can be made on one or both sides, depending upon the

welding symbol or drawing requirements. It is most often used to join two pieces

together with differing levels of thickness.

4. Edge Joint

Edge welding joints, a groove type of weld, are placed side by side and welded on

the same edge. They are the most commonly replaced type of joints due to build up

accumulating on the edges. They are often applied to parts of sheet metal that have

edges flanging up or formed at a place where a weld must be made to join two

adjacent pieces together.

Welding using ceramic backing strip

Weld joints are done from one side, the tape is opposite. The ceramic backing tape

acts like a mold for the electrode to fill. Weld quality improves and tape requires

less skill. We save time with ceramic backing tape when we use it to convert two-

sided projects into a single-side weld. The tape will not cause chemical or

metallurgical changes.

The ceramic backing strip is fixed with the joint by Aluminium tape and U-clamp

(welded to the plates) with packing in between.

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Welding Defects in a Fillet Joint

Convexity – due to over-deposition of weld metal

Concavity – due to lack of deposition of weld metal

Unequal Leg-lengths

Overlapping –when the throat of the weld is greater than the leg-lengths

Under cut - when there is a depression at the edges of the weld bead

Notches – in case of multiple runs of welding

Defects of Welding

External Defects:

Hair Crack

Slag inclusion

Porosity / Blow Holes

Overlapping

Excessive Convexity

Excessive Concavity

Undercut

Notches

Over penetration

Internal Defects

Hair Crack

Slag inclusion

Porosity/Blow holes

Root Run Crack

Electrode:

In arc welding an electrode is used to conduct current through a workpiece to fuse

two pieces together. Depending upon the process, the electrode is either

consumable, in the case of gas metal arc welding or shielded metal arc welding, or

non-consumable, such as in gas tungsten arc welding. For a direct current system

the weld rod or stick may be a cathode for a filling type weld or an anode for other

welding processes.

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Electrode specifications:

The "E" stands for arc welding electrode. Next will be either a 4 or 5 digit number

stamped on the electrode. The first two numbers of a 4 digit number and the first 3

digits of a 5 digit number indicate the minimum tensile strength (in thousands of

pounds per square inch) of the weld that the rod will produce, stress relieved.

Examples would be as follows:

E60xx would have a tensile strength of 60,000 psi E110XX would be 110,000 psi

The next to last digit indicates the position the electrode can be used in.

EXX1X is for use in all positions

EXX2X is for use in flat and horizontal positions

EXX3X is for flat welding

The last two digits together, indicate the type of coating on the electrode and the

welding current the electrode can be used with. Such as DC straight, (DC -) DC

reverse (DC+) or A.C.

Types of flames used in Gas (Oxy-Acetylene) cutting

Neutral (1:1 ratio of Oxygen and Acetylene) - more frequently used in

cutting

Carburising (more Acetylene) – For cutting plates with high carbon content

Oxidising (more oxygen)

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Welding Symbols

Dye Penetration Test

Dye Penetration Test (DPT), is a widely applied and low-cost inspection method

used to locate surface-breaking defects in all non-porous materials. DPI is used to

detect welding surface defects such as hairline cracks, surface porosity, leaks in

new products, and fatigue cracks on in-service components.

Inspection steps:

1. Pre-cleaning:

The test surface is cleaned to remove any dirt, paint, oil, grease or any loose scale

that could either keep penetrant out of a defect, or cause irrelevant or false

indications.

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2. Application of Penetrant:

The penetrant is then applied to the surface of the item being tested. The penetrant

is allowed "dwell time" to soak into any flaws (generally 5 to 10 minutes). The

dwell time mainly depends upon the penetrant being used, material being tested

and the size of flaws sought. As expected, smaller flaws require a longer

penetration time.

3. Excess Penetrant Removal:

The excess penetrant is then removed from the surface.

4. Application of Developer:

After excess penetrant has been removed a white developer is applied to the

sample. Developer should form a semi-transparent, even coating on the surface.

The developer draws penetrant from defects out onto the surface to form a visible

indication, commonly known as bleed-out. Any areas that bleed-out can indicate

the location, orientation and possible types of defects on the surface.

6. Post Cleaning:

The test surface is often cleaned after inspection and recording of defects.

Fabrication of blocks

According to the modern shipbuilding practice, ships are constructed by erecting

prefabricated blocks. The blocks are fabricated strictly according to the shell

expansion of production drawings prepared for a particular yard/class of ship by

the Central Design Office (CDO).

The production drawing consists of every specifications regarding all the

bulkheads, decks, floors, girders, lightening holes, pads (for connecting

longitudinals to bulkheads), stiffeners and their types of connection. The Welding

method used is Shielded Metal Arc Welding (SMAW) using ceramic backing

strips. The seam and butt lines of the under-water hull are given special attention.

Their root runs are inspected using Dye Penetrant Test. In case any welding defect

is detected the concerned area of the Root run is gouged and re-welded and again

inspected using Dye Penetrant Test.

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Plate Preparation Shop

A shipyard consists of a large number of shops in which various processes of

building of any ship (Only for Defense) are carried out. Plate Preparation Shop is

one of them, where plate is straightened, shot-blasted, painted and cut into various

desired shapes and sizes as per requirements & send to the vendors for

fabrications. After it is being fabricated (block) processed materials are being

delivered to the GRSE ship yard.

There are mainly three types of plates that are being processed in this shop:

Types of plates Carbon

percentage Strength Longevity

DMR-249 A

grade MS steel

plates

Low High High

IS – 2062 grade

MS steel plates High Low Low

Aluminum plates - Medium High

Now the two main classes of ships for which the plates are being prepared are:-

1. Anti-Submarine War Craft (ASWC)

YD: 3017, YD: 3018, YD: 3019

2. Landing Craft Utility (LCU)

YD: 2092, YD: 2093, YD: 2094, YD: 2095, YD: 2096, YD: 2097,YD: 2098,YD:

2099.

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The machines that are being used in the Plate Preparation Shop are –

1. CNC – Plasma cutting Machine.

2. CNC–Oxy cutting Machine.

3. Hydraulic shearing Machine.

4. (a) Strengthening Machine.

(b) Shot Blasting Machine.

(c) Painting Machine.

5. PUG Machine.

6. Electronic weight Machine.

7. EOT cranes (Max.10 Ton Capacity)

The uses of the above machines are described as follows:

1. CNC – Plasma cutting Machine

The machine here used is being made by the company named as Hypertherm

(series HT 2000). The word CNC here stands for Computer Numerical Control

programs. The design of the plate cutting which is done through the software

AUTO CAD, is being transformed into a CNC program. This program is then sent

to the plasma cutting machine through wireless communication (CISCO-WAP 54G

Switch).

The machine has two sub divisions mainly. There are one cutter and as well as one

marker for each set. There are two sets for a machine. All are controlled by power

thyristor and feedback path via Master controller.

The plasma machine is being processed to make block, skid, flat bar types of

materials.

The plate thickness that is being maintained for cutting is in between 3.0 MM to

12.0 MM.

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2. CNC – Oxy cutting Machine

The design of the plate cutting which is done through the software AUTO CAD, is

being transformed into a CNC program. This program is then sent to the Oxy

cutting machine using wireless communication.

Here both Oxygen and Acetylene is being used under certain pressure to cut plates.

Material which are being processed or made like blocks, Flat Bars, Flange, PAD

etc.

The plate thickness that is being offered through, maintains a range in between

7millimetre to 130 millimetres.

Flange is a special type of processed material which is used in ship. Processed

material having thickness of 15 mm to 130 mm. The materials are being sent to the

machine shop for machining work as per the requirement.

3. Hydraulic shearing Machine

This a manual control machine where cutting teeth/blades upper portion only

moves up and down and lower portion is fixed.

There are total six blades in this Machine.

Among the six blades the guard distance could be maintained manually for upper

portion only as per the requirement.

Flat bar and sheet materials are being processed with the help of this manual

controlled distance.

The plate thickness that is being processed through it lies in between 3 millimetre

to 12 millimetres.

4. (a) Straightening Machine

The DMR or IS steel plates or Aluminium plates may not be straight. There may

be some unevenness in the plates but that tolerance is being removed by the

straightening machine. When the plates are moved in between the straightening

machine, the plates become fully straight.

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(b) Shot Blasting Machine. (Made by M/s Wheelabrator)

After the plates are being made straight, it might be corrosive in nature or it may

have rust on it. To remove this rust or corrosiveness, the plates are then processed

through shot blasting machines where steel shot are used.

(c) Painting Machine

After removing the corrosiveness, the plates are being painted in the painting

machine. There are two pointed guns above and below the plates which move

horizontally. Spray painting technology is used here.

5. PUG Machine

PUG machine helps in fabrication (Flat Bar and Plates) and for precision jobs like

TSB & OSB purpose. This machine is manually handled. The machine can process

maximum thickness up to 45 millimeters of sheets dimensions like (400x800x7) to

(900x1000x45).

6. Electric weight Machine

The electronic weighing machine is placed near Gate no-2 of PP Shop. It is used to

measure the weight scrap materials for delivery purpose.

7. EOT cranes (Capacity/Safe Working Load-10 Ton)

The Electrically operated Overhead Cranes are being used for loading and

unloading purpose. There are 3 EOT cranes in plate preparation shop. These also

help for material loading and unloading purpose.

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Material Flow Chart

Plan for making AUTO CAD drawing

+ CNC Nesting Programming. + CAD

MEMO PLANNING

DEPARTMANT

CENTRAL

DESIGN

OFFICE

(CDO)

Sent to vendors

For block fabrications

Plate Processing Techniques

Plate incoming

Plate Requirement

Input Data

Work

Plan

Priority

PLATE

PREPARATION

SHOP

STEEL STOCK

YARD

(SSY)

INTERNAL

VENDORS

EXTERNAL

VENDORS

PLASMA

CUTTING

PPS - STORE

Blocks after fabrications are delivered to GRSE

ship yard

PUG

MACHINE

HYDRAULIC

SHEARING M/C OXY CUTTING

22

YARD 3019

Skeg: A skeg is a sternward extension of the keel of boats and ships which have

a rudder mounted on its centre line. This term also applies to the lowest point on

an outboard motor. It also adjusts the boat’s centre of lateral resistance.

Sea chest intake: A sea chest is a rectangular recess near the bottom of a

vessel from which piping systems draw raw water for cooling or other uses. It acts

in much the same way as distilling basis or distilling well, offsetting the affects of

vessel speed and providing an intake reservoir. Their size can vary from 1.5 sq ft

for a small inland tug up to several square feet for a larger vessel.

Sacrificial Anode: From the main body of the ship to the smallest equipment

used in operations, iron makes its presence felt in almost every type of equipment

used on board the ship. The ship is continuously in contact with water and moisture

laden winds which make it highly susceptible to corrosion. The sacrificial anodes

are used to protect the parent material, mainly hull.

Sensors: Various sensors are fitted to the hull of the ship for different purposes:

1. Sensor for measuring dielectric field

2. Wind speed sensor-temperature

3. Echo sounder-depth

4. Speed log-speed of ship

Bilge keel: The main purpose of bilge keel is to reduce a ship’s tendency to

roll. It helps in increasing hydrodynamic resistance to rolling, that is, provides

lateral resistance to water. Thus, it acts as passive stability system.

Sonar dome: Sonar domes are located on the hulls of submarines and surface

ships. Their purpose is to house electronic equipment used for navigation,

detection and ranging. Sonar domes on Navy ships are made of rubber. Sonar

domes can be filled with fresh and/or sea water to maintain their shape and design

pressure. Components and materials interior to sonar dome can include piping,

sacrificial anodes, paint and the interior material surface of the sonar dome itself.

23

Materials on the exterior surface of the sonar dome consist of the exterior material

surface of the dome itself, any paints or coatings applied to the dome, and in some

cases, sacrificial anodes.

Sonar domes are emptied for sonar dome maintenance or replacement, and are

always emptied when the vessel is in dry dock. Sonar domes are emptied by first

pressurizing them with air, to force as much water as possible through the installed

educator piping. Once this step is complete, educators are used to remove all

remaining water in the dome. The total volume of water discharged, exceeds the

sonar dome volume because the sea water used to operate the educators is

discharged along with water from the sonar dome.

Controllable Pitch Propeller: A controllable pitch propeller or variable

pitch propeller is a type of propeller with blades that can be rotated along their long

axis to change the blade pitch. A CPP can be efficient for a full range of rotational

speeds and load conditions, since its pitch will be varied to absorb the maximum

power that the engine is capable of producing. When fully loaded, a vessel

obviously needs more propulsion power than when empty. By varying the

propeller blades to the optimal pitch, higher efficiency can be obtained, thus saving

fuel. A vessel with a VPP can accelerate faster from a standstill, and can decelerate

much more effectively, making stopping quicker and safer. A VPP can also

improve vessel maneuverability by directing a stronger flow of water onto the

rudder.

Most vessels use a reduction gear to reduce the engine output seed to an optimal

propeller speed. While n fixed-pitch propeller (FPP) equipped vessel needs either a

reversing gear or a reversible engine to reverse, a VPP vessel may not. On a large

ship the VPP requires a hydraulic system to control the position of the blades.

Compared to an FPP, a VPP is more efficient in reverse as the blades’ leading

edges remain as such in reverse also, so that the hydrodynamics cross-sectional

shape is optimal for both forward and reverse.

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Measures for Rolling Control:

1. Bilge keel

2. Moderate GM

3. Outriggers

4. Anti-roll tanks

5. Stabilizer fins for towed winged(hydrofoil) object

6. Water kites

Compartments Visited:

1. Diesel Generator room

It contains 3 diesel generators, 2 of 500 KW and one of 1000 KW. International

maritime regulations require at least two generators for a ship’s main electrical

power system. The generators are normally driven from their own dedicated diesel

engine but this can be expensive, taking up additional space that could be used for

other purposes. International maritime regulations also require at least one

electrical generator to be independent of the speed and rotation of the main

propellers and shafting and accordingly at least one generator must have its own

prime mover.

If a minimum of two generators is provided, one of which is driven from the

propeller shaft, failure of one of the generators could make the ship non-complaint

with the international regulations. For this reason many owners opt to provide three

generators. One is used for the normal sea load (e.g. the shaft generator), leaving

two available to meet any unusually high loads or to provide security when

manoeuvring. Alternately, the third is retained as a standby set able to provide

power should one set fail in service or require specific maintenance work.

2. Engine room

The engine room (ER), is the propulsion machinery spaces of the vessel. To

increase a vessel’s safety and chances of surviving damage, the machinery

necessary for operations may be segregated into various spaces. The engine room

is one of these spaces, and is generally the largest physical compartment of the

25

machinery space. The engine room houses the vessel’s prime mover, usually some

variations of a heat engine- diesel engine, gas or steam turbine. On some ships, the

machinery space may comprise more than one engine room, such as forward and

aft, or port or starboard engine rooms, or may be simply numbered. On a large

percentage of vessels, the engine room is located near the bottom, and at the rear,

or aft, end of the vessel, and usually comprises few apartments.

Here, we have a total of 4 engines in 2 rooms, 2 in forward engine room and other

2 in aft engine room. The output from each room is given to each propeller shaft.

The output of the 2 engines is combined using GRM (gear box raft mounted) and

given to a propeller shaft.

MFMB and MFRB

Mineral Fiber Marine Board and Mineral Fiber Resin Board are an appropriate

certified Insulation material that helps in creating and sustaining an environment of

human comfort in the ships while these ships are subjected to extreme ambient

conditions (temperature/humidity).

MFMB/MFRB boards are used for exposed structural boundaries such as the shell,

bulkheads, and decks (which are critical paths of heat flow) and also to thermally

separate the compartments.

Stealth Ship

Every ship has her own unique signature. There are three types of signatures for a

vessel:

Electromagnetic:

1. The electricity running in the whole ship creates an electromagnetic field

around the ship.

2. If a ship’s bilge is corroded, there is a formation of electrolytic cell

between bilge and propellers (made of brass), bilge being the anode and

propeller being the cathode. This results in a flow of current of a range of

milli-amperes which creates a magnetic field of its own.

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Thermal:

1. High power engines having capacity to generate power in range of 2-5

thousands kilowatts and emit huge amount of heat to the surroundings,

leaving a trace.

2. Heat is also generated by huge bulky generators and air conditioners.

Acoustic:

1. Huge power generating engines and generators having motors rotating

more than 1000 rpms make a lot of noise.

2. Vibrations in the structures created by propellers and engines also account

for noise.

Submarines or ships use these signatures to detect and locate enemy ships. So, to

make a ship undetectable, some arrangements are needed to be installed in the ship

making it a Stealth Ship.

Features of a Stealth Ship:

A stealth ship is a ship which employs stealth technology construction techniques

in an effort to ensure that it is harder to detect by one or more of radar, visual,

sonar and infrared methods. Visual masking, reduction of radar cross-section

(RCS), visibility and noise is not unique to stealth ships. One common feature is

the inward-sloping tumblehome hull design that significantly reduces the RCS.

In designing a ship with reduced radar signature, the main concerns are radar

beams orienting near or slightly above the horizon (as seen from the ship) coming

from distant patrol aircraft, other ships or sea-skimming anti-ship missiles with

active radar seekers. Therefore, the shape of the ship avoids vertical surfaces,

which would perfectly reflect any such beams directly back to the emitter. A

stealthy ship shape can be achieved by constructing the hull and superstructure

with a series of slightly protruding and retruding surfaces.

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To make a vessel electromagnetically undetectable:

Gauging is done i.e. Reverse current carrying wires run parallel to the main

network of wires. This nullifies the magnetic field around the ship

significantly.

Sacrificial Anodes are installed in the ships so that bilge is protected from

corrosion.

To make the vessel thermally undetectable:

Coolant system is installed before the exhaust. So that all the heat is

absorbed by the coolant and exhausting gases cannot be traced by the enemy

infrared waves detecting instruments.

To make the vessel acoustically undetectable:

Extensive rubber mounts are used to avoid mechanical noises that could

reveal the location of the vessel.

To make the vessel visibly masked

Paint or other materials are used to colour and break up the lines of the

vessel.

Vessel shapes are modified in a complex way to deviate the waves coming

from enemy radars or sonar systems.

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Central Design Office

CDO is the centre for ship modeling and design in GRSE. The softwares used by

the company for modeling and design of vessels are Tribon and AutoCAD. CDO is

the backbone of GRSE, no work can be done in production department till plans

and designs are been prepared. It is divided mainly into 6 departments for working

on different parts of the design:

Outfit

Computer Aided Design (C.A.D)

Hull

Forward Design

Electrical

Engineering

Outfits

This department is mainly handles the responsibility of designing hull outfits.

Preparing General Arrangement drawings, details of hatches, manholes, bollards,

davits, ladders, racks, doors and plans of mooring, insulation, berthing and

launching arrangements come under outfit department.

General Arrangement Drawings (GA): GA is a set of schematic diagrams of

different views of the vessel in 2-D. It includes:

Silhoutte

Profile View

Body Planes at Different Frames

Super Structure Deck Plans

Deck plans

Tankage Plan

Principle Particulars

GA is prepared prior to the bidding for a getting a particular contract to build a

vessel. As GRSE comes under Defence Ministry on India, it only gets orders from

Indian Navy or the government for building warships. The GA is to be shown to

the Navy to be approved so that they can open the bidding.

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Analyzed G.A. Drawings:

Corvette 3019: Corvette Series Warship installed with high-tech

stealth features.

Principal Particulars :

Length Overall = 109.1m with 13 bulkheads

Length Between Perpendicular = 100.0 m

Breadth Moulded at 1 No Deck = 13.7 m

Breadth at waterline = 12.8 m

Breadth (Max) Knuckle = 14.17 m

Frame Spacing = 1.2 m

Depth Moulded at 1 Deck = 8.5 m

Draught (Deep, Design) = 3.7m

Displacement (Deep , Design) =2500 tonnes

LCU 2095

Principal Particulars:

Length Overall = 62.8 m with 10 bulkheads

Length (In Waterline) = 60.0 m

Breadth (Moulded) at 1 No Deck = 11.0 m

Frame Spacing = 650 mm

Depth (Moulded) at 1 No Deck = 4.0 m

Draught (Deep , Design) = 1.7 m

Citadels: They are the chambers within a vessel to hide the entire crew in case any

nuclear weapon is used by the enemy. Citadels are perfectly detached from

atmosphere and air inside doesn’t get contaminated.

Build Specifications: It is a document specifying each and every detail regarding

the structure and functionalities of the vessel to be constructed. It is provided to

GRSE by the Navy after the contract for the construction is signed. Build

Specifications have every detail of each part of the ship including the material

composition of different parts to be installed. If the company fails to satisfy certain

criteria, it has to report to the Navy so that different solution is found. Here is the

list of some details specified in Build Specs:

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Role of Ship

Special Features of Amphibious operation

Principal Particulars

Sea Worthiness

Military Lift

Approval of equipment’s

Photographs

Inspection ,Tests and Trials

Stability

Instant Stability

Damaged Stability

Inclining Test

Weight Recording

Docking

Test and Trials

Basin Trials and Sea Trials

Basin Treats

Heeling Trials

Contractor Sea Trials

Progressive Speed Trials

Full Power Endurance Trial

Contractual Speed Trial

Turning / Manoeuvring Trial

Crash-Stop Trial

Final Machinery Trials

Naval Stores

Guarantee

ILMS (Documentation)

Applicability of Latest Rules & Regulations

Project Monitoring System

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Statement Of technical Requirement: It is a document asking the vendor to

supply a particular order e.g. a D-type Fender. List of specifications and details

specified in SOTR is:

Scopes of Supply

Requirement along with accessories

Brief Specification

Design

Types

Material Specification

List of material used

Quality Requirements of the Material

Guarantee

Inspection and Test

Instructions to the Bidders

Need to make a brief G.A

Model Testing

Powering

Resistance

Build Specifications

G.A.

Costing Document

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Inclining Experiment

Purpose To Determine the Lightship Weight

To Determine the Coordinates of CG of the lightship weight

References Taken

General Arrangement Diagram

Hydrostatic Curves

Cross Curves of Stability

Tank Calibration Charts

Draught Mark Plan

Preparations

Date of experiment

Location

Responsible Person

Inclining Weight (With Positions)

List of Items to be Added/Removed(Along with their weight and

C.G)

Ship should be in following condition as far as possible:

Hull Structure should be complete

Fitting out practically complete

There should be no Crew and Effects on the board

Only personal participating in the experiment should stay on board.

Hydrostatic and waterline particulars as inclined:

Specific Gravity of Water

Extreme Displacement

Vertical Centre of Buoyancy

Longitudinal Centre of Buoyancy

Longitudinal Centre of Gravity

Water Plane Area

Longitudinal Centre of Floating

Tons per immersion (cm)

Moment to change Trim

KM (transverse)

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Calculation of GM (from inclining experiment)

GM = Moment .

Displacement (extreme) * Average of mean Tangents

,where Moment = Total moment by inclining weights, Tangent = d/l, d=

displacement of pendulum, l= length of pendulum.

We need to do some adjustments to the ‘as inclined condition’:

Items to be added

Items to come off

Tank contents

VCG of fluid

,to calculate the light weight, LCG, TCG, VCG and Free Surface Moment.

Hull Modeling

CAD is used in designing the General Arrangement and also the system drawings

like galley, JS mess, SS mess, toilet, dining hall.

Tribon: Tribon is ship-designing software used to prepare composite layouts. It

works in different modules separately, but these modules are synchronized together

so as to simultaneously design different divisions, like Hull, outfit, Electricals,

system drawings. Even multiple projects can be handled together using Tribon.

Model selection specifies the shell profile (bulb sections in shell), panels and

plates.

Model Drawing uses all the model selections of a particular block and shows all

the stiffening arrangements, butt joints, scallops and slugs.

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Nesting Plan:

Tribon generates

Plate/Material list- plate generated items

Profile list- bulb sections, bars, channels, tubes.

Every plate/profile item has a POS number. Maximum items of same thickness are

placed in nesting plan. POS numbers help in identifying the location of every item

in block fabrication. Every item of a panel has a different code as a .cnc file which

acts as a scheme drawing. The cnc code contains all details of flanges, openings,

slugs and scallops. Every panel is designed with reference to other panels. Items

with same POS number have exactly same scantlings.

A cnc file has a unique number.

Viz.: wju2-flr-fr-1250-1-p

,where wj :- water jet (name of project)

u2:- block number

flr:- floor

fr:- frame

1250:- 12.5 mm

1:- 1st part

P:- port side

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SAP:

SAP is a widely used software used in procurement issues. It is used in generating

indents. There are two groups responsible for preparing the indent:

1) Purchase department

2) NCM or New Construction Machinery

The indent consists of details regarding the material, its quality, units, delivery

date, etc.

After the indent is prepared two committees namely TNC (Technical Negotiating

Committee) and PNC (Price Negotiating Committee) interact with the vendors. In

case there is a single vendor, the purchase amount is limited to 10 lacs under the

authority of the GM.

Then the purchase order is placed and a SOR (indenting) indicating the items with

material code is prepared. A technical clearance with the firms is done and the L1

is decided. Then SOR (ordering) is prepared with a RFQ (Request for Quotation).

A General material code is used, not particular to a class of ship. In case of repeat

orders (within 1 year), cost remains same and processing time is less.

Cost Estimation Cell uses prices of previously purchased items from price booklets

to estimate the prices. Prices are already fixed by the bidders but not disclosed,

they are sealed in boxes and the bidder with lowest price becomes L1.

SORs include pre-launching materials and consist of:

Scope of supply

Drawings

Material specifications

Inspection and test

General requirements