chapter 01 structure and organization of...

1 සීමාන්විතයි

CHAPTER 01

STRUCTURE AND ORGANIZATION OF ENGINEERING DEPARTMENT

1. Organization – An organization is a social entity that has a collective goal and is

linked to an external environment (a compartment for a particular task).

2. Structure – The typically hierarchical arrangement of lines of authority, rights and

duties of an organization. Organizational structure determines how the roles, power and

responsibilities are assigned, controlled, and coordinated, and how information flows

between the different levels of management.

3. Organization structure of marine, ship wright & automobile engineer officers –

Naval Head Quarters.


DGE – Director General Engineering

DME – Director Marine Engineering

DAE – Director Automobile Engineering

DES – Director Engineering Services

DHR – Director Hull Repairs

DDME (A&O) – Deputy Director Marine Engineering (Auxiliary and Offshore)

DDME (F&I) – Deputy Director Marine Engineering (FAC and Inshore)

DDES – Deputy Director Engineering Services

DDAE – Deputy Director Automobile Engineering

DDHE – Deputy Director Hull Engineering

SSEO (A&O) – Senior Staff Engineer Officer (Auxiliary and Offshore)

SSEO (M&D) – Senior Staff Engineer Officer (Monitoring and Development)

SSEO (NC) – Senior Staff Engineer Officer (New Construction)

SSEO (QA) – Senior Staff Engineer Officer (Quality Assurance)

SSEO (ADM) – Senior Staff Engineer Officer (Administration)

SSEO (AM) – Senior Staff Engineer Officer (Automobile)

SSHEO – Senior Staff Hull Engineer Officer

MANAGER (IPCCP) – Manager (Inshore Petrol Craft Construction Project)

SEO (Ref & AC) – Senior Engineer Officer (Refrigeration and Air Conditioning)

SEO (NC) – Staff Engineer Officer (New Construction)

SEO (FAC) – Staff Engineer Officer (Fast Attack Craft)

SEO (M) – Staff Engineer Officer (Marine)

SEO (R) – Staff Engineer Officer (Repair)

SEO (ILMS) – Staff Engineer Officer (Integrated Logistics Management System)

SEO (ADM) – Staff Engineer Officer (Administration)

SEO (TRG) – Staff Engineer Officer (Training)

SEO (AM) – Staff Engineer Officer (Automobile)

SEO (D) I – Staff Engineer Officer (Design) I

SPE (MECH) – Senior Project Engineer (Mechanical)

SAEO – Staff Automobile Engineer Officer

SPE (IPCCP) – Senior Project Engineer (Inshore Petrol Craft Construction Project)

OIC (HVP) – Officer In Charge (Heavy Vehicle Pool)

EO (M) – Engineer Officer (Maintenance)

PE (IPCCP) – Project Engineer (Inshore Petrol Craft Construction Project)

PE (M) – Project Engineer (Marine)

PE (QA) – Project Engineer (Quality Assurance)

PE (H) – Project Engineer (Hull)

PE (M) MAW – Project Engineer (Maintenance) Malima Auto Works

PE (BR) MAW – Project Engineer (Body Repairs) Malima Auto Works


4. Duties and responsibilities of key appointments are as follows.

a. Director Marine Engineering

(1) Responsible to the Director General Engineering on all matters

pertaining to Marine Engineering including Shipwright matters.

(2) Formulating plans and strategies in all Marine Engineering works.

(3) Forecasting Marine Engineering requirements.

(4) Recommending and monitoring all Marine Engineering purchases,

refits of ships/craft.

(5) Ensuring effective and timely implementation of maintenance and

repair scheduled to achieve optimum performance of SLN ships and

Craft.

(6) Handling of appointments of officers in the Engineering Branch in

consultant DGE.

(7) Direct and monitor the functions of Deputy Director Hull Engineering

(DDHE) and advise DDHE in arranging and coordination of

shipwright works related to Marine Engineering until Director Hull

Repairs (DHR) is appointed.

b. Director Engineering Services

(1) Planning and forecasting departmental requirements on general

engineering matters.

(2) Planning and forecasting of the cadre requirement of engineering

branch.

(3) Selection of engineering personnel for special tasks and for training

consultation.

(4) Formulating academic and Continuous Professional Development

training requirements of Engineering branch personnel.

(5) Making views/recommendations for BOI reports on losses and

damages to machinery, ships/craft and vehicle in consultation DME

and DAE.

(6) Monitor progress of training of Engineering branch Officers and

sailors local and abroad.

(7) Planning and forecasting departmental requirements on general

engineering matters.

(8) Planning and forecasting of the cadre requirement of engineering

branch.

(9) Selection of engineering personnel for special tasks and for training

consultation.


(10) Formulating academic and Continuous Professional Development

training requirements of Engineering branch personnel.

(11) Making views/recommendations for BOI reports on losses and

damages to machinery, ships/craft and vehicle in consultation DME

and DAE.

(12) Monitor progress of training of Engineering branch Officers and

sailors local and abroad.

c. Director Automobile Engineering

(1) Responsible to DGE for all matters pertaining to Automobiles and

transport system in SLN.

(2) Efficient and effective functioning of Automobile Department in SLN.

(3) Projection of annual vehicle machinery requirement and initiate

purchasing action.

(4) Allocation of vehicles to meet SLN requirements.

(5) Maintaining of records on all Automobiles belonging to SLN

including hired vehicles.

(6) Arrangement for registration/insurance of vehicles.

(7) Responsible for maintenance of vehicles in SLN.

(8) Preparing and scrutinizing of specifications of Automobile, Earth

moving vehicles. Land vehicles and other machinery tools related to

automobile field and initiating procurement action.

(9) Make recommendations on spares purchase/ repair files related to

vehicle maintenance and forward for approval.

(10) Administration of warranty and contract repairs to Automobiles and

machinery related to Automobile Engineering Workshop.

(11) Coordination of hiring of vehicles and services rendered from outside

organization.

(12) Proposing improvements on infrastructure facilities, amendments to

current regulations/ orders to improve departmental activities.

(13) Forecasting of man power requirements.

(14) Issuing of Service Driving License.

(15) Supervising of staff under DAE Department.

d. Director Hull Repairs

(1) Responsible to DGE for efficient and smooth functioning of

Shipwright Branch and to consult DME in arranging all kinds of

repairs, related to Marine Engineering and maintenance schedule.

(2) Plan strategies of all shipwright matters.


(3) Forecast manpower, material and equipment requirement for

Shipwright branch.

(4) Preparing all specifications for Shipwright branch requirements in

SLN.

(5) Appointments and Training of officers of Shipwright branch.

(6) Drafting of sailors and Training of offices and sailors of Shipwright

branch.

(7) Forecast, schedule and monitoring of slipping/ docking of shops &

craft.

(8) Monitoring and quality controlling of IPCCP.

5. Structure of marine engineering department – Eastern Naval Area

CSD (E) – Commodore Superintendent Dockyard (East)

CLD (E) – Commodore Electrical Department (East)

DSD (E) – Deputy Superintendent Dockyard (Engineering)


MED (FAC) – Manager Engineering Department (Fast Attack Craft)

MED (F&A) – Manager Engineering Department (FGB & Auxiliary)

MED (YS) – Manager Engineering Department (Yard Support)

MHED (E) – Manager Hull Engineering Department (East)

CAEO (E) – Command Automobile Engineer Officer (East)

SME (FAC) SQ – Senior Marine Engineer (Fast Attack Craft) Squadron

SME (FAC) WS – Senior Marine Engineer (Fast Attack Craft) Workshop

SME (FGB) – Senior Marine Engineer (Fast Gun Boat)

SME (MV) – Senior Marine Engineer (Major Vessels)

SME (DT) – Senior Marine Engineer (Dockyard Tender)

SME (OBM) – Senior Marine Engineer (Out Board Motors)

SME (AM) – Senior Marine Engineer (Auxiliary Machinery)

SME (R&F) – Senior Marine Engineer (Refrigeration and Factory)

SE (QA&T) – Senior Engineer (Quality Assurance & Training)

SHE (DM&R) – Senior Hull Engineer (Dry Maintenance & Refit)

SHE (WS) – Senior Hull Engineer (Work Shop)

SHE (F) – Senior Hull Engineer (Fleet)

ME (FAC) SQ – Marine Engineer (Fast Attack Craft) Squadron

ME (FAC) WS – Marine Engineer (Fast Attack Craft) Workshop

ME (FGB) SQ – Marine Engineer (Fast Gun Boat) Squadron

ME (FGB) WS – Marine Engineer (Fast Gun Boat) Workshop

ME (PC) – Marine Engineer (Patrol Craft)

ME (UC) – Marine Engineer (Utility Craft)

ME (HP OBM) – Marine Engineer (High Power) Out Board Motors

ME (LP OBM) – Marine Engineer (Low Power) Out Board Motors

ME (BG) – Marine Engineer (Base Generators)

ME (MR) – Marine Engineer (Machinery Repairs)

ME (Ref & AC) – Marine Engineer (Refrigeration and Air Conditioning)

ME (F) – Marine Engineer (Factory)

ME (QA&T) – Marine Engineer (Fast Gun Boat)

ME (MTTU) – Marine Engineer (Machinery Trial & Testing Unit)

HE (QA&T) – Marine Engineer (Quality Assurance & Training)

HE (F) – Hull Engineer (Fleet)

HE (RF) – Hull Engineer (Refit)

HE (S) – Hull Engineer (Slipway)

MTE (R) – Motor Transport Engineer (Repairs)

MTE (BR) – Motor Transport Engineer (Body Repairs)

MTE (M) – Motor Transport Engineer (Maintenance)


CHAPTER 02

SI UNITS AND MEASURING INSTRUMENTS

SI Unit

1. The International System of Units (SI) specifies, a set of seven base units of measure

from which all other units of measurement are formed, by products of the powers of base

units. The International System of Units consists of a set of base units, a set of derived units,

some of which have special names and a set decimal-based multipliers that are denoted as

prefixes.

2. Base Units

Name of the unit Symbol Measure

Meter m Length

Kilogram kg Mass

Second s Time

Ampere A Electric current

Kelvin K Thermodynamic temperature

Mole mol Amount of substance

Candela cd Luminous intensity

Derived Unit

3. Derived units are units which are deriving from SI base units. Following units are

derived units from SI units.

Name Symbol Quantity Expression in

terms of SI units

Square meter m2 Area m

2

Cubic meter m3 Volume m

3

Meter per second m/s Velocity ms-1

Newton meter Nm Torque kgm2s

-2

Meter Per second squared ms-2 Acceleration ms

-2

Kilogram per cubic meter kg/m3 Mass density kgm

-3

Hertz Hz Frequency s-1

Radian Rad Angle Dimensionless

Newton N Force kgms-2

Joul J Energy kgm2s

-2

Pascal Pa Pressure kgm-1

s-2


4. The names of SI units are always written in lowercase. The symbols of units named

after persons, however, are always written with an uppercase initial letter (e.g. the symbol of

hertz is Hz; but meter is m).

5. Conversions

Measurement Non-SI unit Metric (SI) unit Conversion

Length Inch (in) Millimeters (mm) 1 in = 25.4 mm

Foot (ft) Centimeters (cm) 1 ft = 30.48 cm

Yard (yd) Meters (m) 1 yd = 0.914 m

Mile Kilometers (km) 1 mile = 1.609 km

Area Square Inch (in2) Square Millimeters (mm

2) 1 in

2 = 645 mm

2

Square Feet (ft2) Square Centimeters (m

2) 1 ft

2 = 929 cm

2

Hectares (ha) Square Kilometers (km2) 1 ha = 0.01 km

2

Volume Cubic Inch (in3) Cubic Millimeters (mm

3) 1 in

3 = 16387 mm

3

Cubic Feet (ft3) Cubic Meters (m

3) 1 ft

3 = 0.028 m

3

Gallon UK Liters (l) 1 gal = 4.55 l

Mass Ounce (oz) Grams (g) 1 oz = 28.35 g

Pound (lb) Kilograms (kg) 1 lb = 0.45 kg

Measuring Instruments

6. Measuring instrument is a device for measuring a physical quantity such as the extent

or amount or degree of something. Established standard objects and events are used as units

(US, UK or Metric) and the process of measurement gives a number relating the item under

study and the referenced unit of measurement.

Calliper

7. A calliper is a device used to measure the distance between two symmetrically

opposing sides. It can be used with inward or outward-facing points to measure either

directly or indirectly as measuring transferring tool.

Outside Calliper

8. Bowlegged outside callipers which clear the

work are used to take outside measurements. Two kinds

of callipers are available: firm jointed calipers, which

are free to move but are held firmly in any position by

friction or spring-jointed calipers which are controlled

by a knurled nut on a threaded rod. The tips of the

calliper are adjusted to fit across the points to be

measured and then measuring distances by a ruler.


Inside Calliper

9. Inside calipers are available in the same size

range as outside callipers. They have straight legs, turned

out at the top and are used to take inside measurements.

They are available with firm or spring joints. As with

outside callipers, it is possible within limits to measure

external dimensions with firm joint inside callipers. The

tips of the calliper are adjusted to fit across the points to

be measured, the calliper is then removed and the

distance read by measuring between the tips with a

measuring tool, such as a ruler.

Odd Leg Calliper

10. These are generally used to scribe a line a set

distance from the edge of a work piece. The bent leg is

used to run along the work piece edge while the scriber

makes its mark at a predetermined distance, this

ensures a line parallel to the edge. Some has a slight

shoulder in the bent leg allowing it to sit on the edge

more securely and other has a renewable scriber that

can be adjusted for wear, as well as being replaced

when excessively worn.

Divider Calliper

11. Divider callipers have a small knurled spigot to facilitate the

scribing of circles. Adjustment is made by means of a knurled nut

on a threaded rod. Dividers normally have two identical flat legs

with hardened points. They are sometimes fitted with removable

points which can be adjusted for equal length and be replaced when

worn.

Vernier Calliper

12. The vernier caliper, named after its inventor, is a development of the slide caliper, but

is graduated to make finer readings. It is capable of measuring internal and external

dimensions and can also be used as a depth gauge. Vernier calipers are available with

imperial and metric graduations. The vernier, dial, and digital calipers give a direct reading

of the distance measured with high accuracy and precision. These calipers comprise a

calibrated scale with a fixed jaw, and another jaw, with a pointer, that slides along the scale.


Vernier Scale

13. A Vernier is a mechanical means of magnifying the last segment on the main scale so

addition subdivisions can be made. The reference point is the „0‟ on the vernier scale. To

read a vernier, the line of coincidence must be located. The line of coincidence (LOC) is the

line on the Vernier that coincides with a line on the main scale.

Micrometer Calliper

14. Micrometers are designed to produce the extremely fine measurements required in

engineering, so that parts of a machine will meet with the minimum tolerance. The

micrometer is used with different types and sizes of frames to provide precise measurements

of many different objects. It is a caliper using a calibrated screw for measurement, rather than

a slide.


15. There are micrometers for measuring depth, inside dimensions and most commonly

outside dimensions. The micrometer has a U-shaped frame with an anvil on one side and an

adjustable spindle extending from the other. The knurled thimble adjusts the spindle to the

required setting, which is then fixed by the lock nut. A ratchet stop is sometimes fitted to the

end of the spindle. If the ratchet is used to adjust the spindle it will click or slip when the

anvil and spindle contact with the work.

Reading Micrometer

16. Micrometer calliper is read at the point where the edge of the thimble crosses the

barrel scale and the last step of measuring is reading the value on the thimble scale.

17. The latest development in micrometers is expensive, but extremely easy to use. When

the spindle and anvil come in contact with the work piece, the measurement can be read

directly from a digital display. It is very accurate and does not involve the computations

needed by a standard micrometer.

18. There are different types of micrometers available which used for different purposes

such as,

a. Outside Micrometer - Typically used to measure wires, shafts, blocks etc.

b. Inside Micrometer - Used to measure the inside diameter of holes.

c. Depth Micrometer - Measures depths of slots and steps.

d. Bore Micrometer - Typically a three-anvil head on a micrometer base used to

accurately measure inside diameters.

e. Tube Micrometer - Used to measure the thickness of tubes.


CHAPTER 03

HEAT ENGINE

Definition of Heat Engine

1. It is a device, which transforms the chemical energy of a fuel in to thermal energy and

uses this energy to produce mechanical work. This means there are two processes involved,

a. Transforming chemical energy of fuel into heat energy

b. Using this heat energy do mechanical work

External Combustion Engine (ECE)

2. The energy developed by combustion process, transfer in to a secondary medium

which produce mechanical power. An EC engine is a heat engine where an (internal)

working fluid is heated by combustion in an external source, through the engine wall or a

heat exchanger. The fluid then, by expanding and acting on the mechanism of the engine,

produces motion and usable work. Example: Steam Engine, Steam Turbine plant.

Internal Combustion Engine (ICE)

3. Chemical energy is converted in to heat energy and heat energy in to mechanical

power. An IC engine is a heat engine in which the combustion of a fuel occurs with an

oxidizer (air) in a combustion chamber. High-temperature and high-pressure gases produced

by combustion applies direct force to some component of the engine, such as pistons, turbine

blades, or a nozzle. This force moves the component and generating useful mechanical

energy. Example: Petrol, Diesel Engines and Gas Turbine.

4. Advantages of ICE over ECE

a. Mechanical simplicity

b. High power to weight ratio

c. Lower initial cost

d. Less requirement of water

e. Less bulky

f. Higher overall efficiency

g. Low maintenance

5. External combustion engine has one major advantage over IC engine is it can use

cheaper fuel including solid fuel. Therefore they are used where cost of power is more

important than size of plant.


Basic components of an IC engine

6. Basic components of an IC engine are as follows.

a. Crank shaft

b. Cam shaft

c. Piston

d. Connecting rod

e. Fly wheel

f. Rocker arm

g. Push rods

h. Piston rings

j. Bearings

k. Inlet & exhaust valves

l. Timing gears and wheels

m. Cylinder head

n. Cylinder liner

p. Cylinder block

q. Crank case

r. Oil sump

s. Spark plug / fuel injector

Two and Four Stroke Engines

7. Based on working cycle of an IC engine, it can be divided into two main types.

a. Four stroke working cycle

b. Two stroke working cycle

Four Stroke Working Cycle

8. The following requirements are common to all internal combustion engines.

a. Filling the cylinder with air or fuel-air charge

b. Compressing this charge to generate high temperature and pressure.

c. Burn the fuel to create the necessary rise in pressure to move the piston.

d. Expelling the burnt gasses from the cylinder in order to draw in fresh charge

to continue the working cycle.

9. These requirements can be met in the following ways by the provision of inlet and

exhaust valves arranged to open and close in a special sequence and relative to the position of

the piston in the cylinder.


10. In a four stroke engine all the above requirements are met by four distinct strokes.

a. Induction Stroke or Intake Stroke In this stroke the piston moves

from TDC (Top Dead Center) to BDC (Bottom Dead Center). The inlet valve remains

open and the exhaust valve remains closed. As the downward movement of the piston

creates a vacuum atmospheric air is sucked in through the inlet valve. This continues

till the inlet valve is closed after the piston reaches BDC.

b. Compression Stroke At the end of the induction stroke both the

valves are closed and the cylinder becomes gas tight. Therefore as the piston moves

from BDC towards TCD the pressure of the air trapped inside rises rapidly due to

reduction of volume. The heat created by the compression will be sufficient to ignite

the fuel, when injected.

c. Power Stroke Towards the end of compression stroke fuel is injected

into the cylinder in atomized form. These fuel partials mixed with air inside the

cylinder, absorb heat from it and ignite. The burning causes rapid increase in

temperature and pressure inside the cylinder. This forces the piston towards the BDC.

As useful power is developed during this stroke it is called power stroke.

d. Exhaust Stroke during the power stroke all useful energy is extracted

from the burning fuel-air mixture. In order to continue the cycle, fresh air is to be

inducted into the cylinder. Prior to that the burnt gases in the cylinder are to be

expelled. This is done during the exhaust stroke as the piston moves from BDC

towards TDC. The exhaust valve is kept opened and the gasses pass through it to the

atmosphere. At the end of the exhaust stroke the exhaust valve is closed.


11. These four strokes occur continuously to develop continuous power. These strokes

occupy two complete revolutions of the crankshaft. Therefore one power stroke is achieved

for every two revolution of the crankshaft.

Two Stroke Working Cycle

12. In this cycle induction, compression, power and exhaust are arranged to take place in

two strokes of the piston, i.e. one revolution of the crankshaft. Ports cut into the cylinder

walls are used instead of valves. These ports are opened and closed by the position of the

piston. Exhaust ports are usually cut higher than inlet ports. Both the ports are cut towards

the bottom of the cylinder.

Compression Stroke (with Intake)

13. When the inlet port is uncovered a mixture of fuel and air is drawn inside the

cylinder. During its upward travel the piston covers both inlet port and exhaust port making

the cylinder gas tight. Therefore the charge in the cylinder gets compressed.

Power Stroke (with Exhaust/Transfer)

14. This charge is the ignited by a spark (in SI engine). This causes a rise in temperature

and pressure inside the cylinder forcing the piston towards BDC. When the piston uncovers

the exhaust port exhaust gases are expelled from the cylinder under their own pressure. When

the inlet port is uncovered fresh charge is inducted making the cylinder ready to continue

cycle. Usually two stroke engines are spark ignited using petrol as fuel, but compression

ignited two stroke diesel engines are also used.


15. Comparison between two strokes and four strokes are as follows.

FOUR STROKE ENGINE TWO STROKE ENGINE

Cycle is completed in four stroke of

piston/ two revolution of crankshaft.

Cycle is completed in two stroke of piston/

one revolution of crankshaft.

Heavy flywheel is needed due to turning

movement is not uniform.

More uniform turning movement and lighter

flywheel is needed.

Engine is heavy and bulky (for the same

power).

Engine is light and compact for the same

power output.

Higher weight-to-power ratio because it is

much heavier.

Lesser weight-to-power ratio because it is

much lighter.

Low environment hazards. Environment pollution is high.

Less wear and longer engine life due to a

good lubricating system.

Faster wear and shorter engine life due to

lack of lubricating system.

Used where efficiency is important. Used where low initial cost, lightweight &

compactness is involved.

High fuel efficiency and mileage. Low fuel efficiency and mileage.

Uses valves for inlet and exhaust. Uses ports for inlet and may use valves for

exhaust.

Thermal efficiency high. Thermal efficiency low.

SI and CI Engines

16. IC engines can be divided into two basic types according to the method of ignition.

a. Spark Ignition Engine – Fuel air mixture introduces to cylinders of the

engine then compressed and ignited with the help of a spark generated by spark plug

and starts the power stroke. (Petrol engines).

b. Compression Ignition Engine – Air drawn into the cylinders and then

compressed. At the end of compression stroke fuel is introduced and starts the power

stroke (Diesel engines).

17. SI and CI engine comparison

SI ENGINE CI ENGINE

Use Petrol, Gas and Kerosene as fuel. Use Diesel as fuel.

Spark plug required for firing. Injectors required for firing.

Use Carburetor to mix air & fuel. Injector use for fuel atomization.

Carburetor control air/fuel mixture Injector pump control fuel amount.

Load / speed controlled by controlling

quantity of air-fuel mixture.

Load / speed controlled by quantity of fuel

injected.


Usually consider as high speed engines. Usually consider as low speed engines.

Low compression ratio. High compression ratio

Light weight. Heavy weight

Low cost. High cost

Good for low & medium power engines. Good for medium & high power engines

Less noise. Noise is comparatively high

Less emission of polluted particles. High emission of polluted particles

Efficiency is low. Efficiency is high

Low fuel economy. High fuel economy

Less reliability. High reliability

Frequent maintenance required. Less maintenance

Less torque. High torque at low rpm

CO2 emission high. CO2 emission low

Higher exhaust temperature. Lower exhaust temperature.

Higher fire hazard. Lower fire hazard.

Lower operating life. Higher operating life.

Classifications of IC engines

18. IC engine can be classified into different types under following characteristics.

a. Basic engine design (reciprocating, rotary)

b. Arrangement of cylinders (inline, v-type, radial)

c. Number of cylinders (single, multi)

d. Method of ignition (spark, compression)

e. Number of strokes or working cycle (two, four)

f. Method of air intake (natural, supercharge, turbocharge)

g. Type of fuel used (gasoline, diesel, gas)

h. Fuel input method (injection, carburetion)

j. Cooling (air, liquid)

k. Application (automotive, marine, power generation)

Systems of a Marine Diesel Engine

Fuel System

19. The fuel oil used by all diesel engines in Navy is called LSHSD (Low Sulphur High

Speed Diesel). Sulphur content is a very important property of the fuel. If the sulphur content

is high it forms sulphur dioxide during combustion process. This sulphur dioxide may be

absorbed by the moisture present in the incoming air to form sulfuric acid. This sulfuric acid

is highly corrosive and result in excessive corrosion of piston, cylinder liner, valves etc.

Therefore low sulphur content of fuel is essential.


20. Quality of the fuel injected into the cylinder has a significant effect on the

performance of engine. Benefits of using low sulphur diesel on the engine and the

environment are as follows.

a. Decreases corrosion in pistons and/or cylinder liner wear.

b. Reduces maintenance costs.

c. Increases overhauling duration (TBO).

d. Potentially extends lubricant life.

e. Reduces exhaust particulate and odor emissions.

f. Reduces visible black smoke.

g. Reduces sulphur oxide emissions which contribute to acid rain, will reduce the

risk of acid rain occurring.

System Components

a. Ready use tank

b. Fuel separator

c. Duplex filter

d. Fuel feed pump

e. Micro filter

f. Fuel injection pump

g. HP lines

h. Injectors

21. Function of marine fuel system

a. Fuel stored at ready use tank.

b. Fuel transferred to fuel injection pump by fuel feed pump.

c. Before it enters to FIP, fuel gets filtered by fuel filters.

d. Fuel injection pump deliver fuel to fuel injectors through high pressure lines

according to firing order.

e. Fuel injectors atomize fuel in to respective combustion chamber.


Fuel Hygiene

22. One of the most common factor affecting the quality of fuel is water particles mixing

with fuel. Effects of water mixing with fuel are as follows.

a. Loss of power

b. Low peak pressure

c. Low exhaust temperature

d. Pitting on piston crown and liner wall

e. Corrosion of parts of fuel injection system

f. Uneven power / fluctuation in speed

Lubrication System

23. Lubrication is an art of admitting a substance (which is softer) between two surfaces

which are in contact and relative motion. It will reduce friction as well as wear from the

surfaces. An IC engine has many metallic surfaces in close contact and moving against each

other. Therefore the friction and resultant heat and wear down will damage the engine unless

lubricated properly.

Purpose of Lubricating System

24. Under mentioned facts can be considered as essential purposes of lubricating oil

system.

a. To cool the surfaces by carrying away heat generated by friction.

b. To reduced friction & wear, by continuous supplying of oil.

c. To clean the surfaces by washing away carbon & metal particles caused by

wear.

d. To provide sealing effect. Example: lub oil helps the piston rings to maintain

an effective seal against the high pressure gases in the cylinder from leaking

in to crank case.

e. To prevent corrosion.

f. To reduce engine noise.

g. To provide dampening effect.

25. Basic Component

a. Lub oil pump

b. Lub oil filter

c. Lub oil cooler

d. Lub oil strainer

e. Lub oil sump

f. Breather


26. There are three main types of lubricating systems associated with IC engines.

a. Mist lubricating Used for 2 stroke engines where 2 to 3% of oil is added

into fuel and the fuel/oil moisture is inducted through carburetor. As the gasoline is

vaporized, oil in the form of mist goes via crankcase into the cylinder. Thus lubricates

crank shaft, piston, piston rings & cylinder. This system is simple, low cost and no

additional components like lub oil pump.

b. Dry sump lubricating system The lub oil is not stored in the sump. As

soon as the lub oil falls into the sump after lubricating various parts of the engine it is

transferred to a circulating tank. There are two pumps used in the system. The

pressure pump takes suction from circulating tank and discharge to gallery. The

Scavenging pump takes suction from sump and discharge to circulating tank thus

keeps sump dry. Advantages of this system are easy access to the crankcase fitting,

low fire/explosion risk, smaller crank case resulting in smaller engine, reduced risk of

contamination and economical. Main disadvantages are high cost and high

maintenance cost.

c. Wet sump lubricating system The oil required by the engine is

contained in the sump at the lower part of crankcase. Pump draws oil from the sump

through strainer, filter and the cooler. From the cooler, oil is supplied to the gallery

and then to main bearings, big-end bearings via drilled passages in the crankshaft and

to small-end bearings via drilled passages in the connecting rod. Tappings are taken

from the gallery to cam shaft, rocker arms, timing gears, auxiliary drives and to

cylinder walls through spray jets. The oil then drains back into the sump. The


advantages of this system are compact, self-contained and reasonably cheap. Main

disadvantages are risk of crank case explosion and increase in crankcase size. Further

this system can be sub divided into following categories.

(1) Splash lubricating system Used in small engine, where sump level

is maintained at high level. The dipper strike in the oil & splash on various

parts of the engine.

(2) Semi-pressure lubricating system In this system oil pump supply

the oil with pressure to main bearings and cam shaft bearings lubrication and

rest other parts are lubricated with the help of splash lubrication.

(3) Full pressure lubricating system In this system engine driven oil

pump supplies oil to the various engine parts (drilled internally) from where

oil flows to piston ring, piston pin, cylinder walls. Oil is also supply to rocker

arms, governor, fuel injection pump, water pump bearing etc.

27. Types of lubrication oil use in SLN

a. Shell Gadinia 40 (SAE 40 grade)

b. Shell Gadinia 30 (SAE 30 grade)

c. Shell Rimula X 15 W 40

d. Shell Rimula Ultra 10 W 40

e. Caltex Lanka Super DS SAE 40

f. Caltex Lanka Super DS SAE 30

j. Quick Silver 2 Cycle Outboard Oil

k. Caltex Super Outboard 3

Cooling System

28. In an IC engine only a part of the heat energy generated by the burning fuel is

converted into mechanical work. Rest of the heat energy accumulates in the cylinder, piston

and associated parts. If this excess heat is note removed it will lead to melting of the parts.

Cooling system of an engine is designed to extract this additional heat and dispose it off so

that the engine can operate continuously without failure of parts.

29. There are two types of cooling systems associated with IC engines. Generally only

small engines use air as a cooling medium and not used in marine engines. In this system an

engine driven fan forces a continuous airflow around the hot cylinder, cylinder head etc. In

water cooled engines, water is circulated through jackets for cooling the parts. Two cooling

circuits are used:


a. Primary Cooling Fresh water is usually used for primary cooling. In this

fresh water pump takes suction from the system and discharges the water into the

cylinder jackets. The water extracts heat from the cylinder, through jackets, during

circulation. From the jackets the water rises through internal passages and reaches the

cylinder head, exhaust manifold and then to fresh water cooler. An expansion tank is

fitted to compensate for the water lost in the form of vapour. A thermostatic valve

ensures certain minimum temperature of fresh water when the engine is in operation.

Pressure and temperature gauges are fitted for efficient monitoring of the system. In

engines where lub oil is cooled by fresh water, fresh water circulates through the lub

oil cooler also.

b. Secondary cooling As the fresh water circulates through the engine it gets

heated up. This heat must be extracted from the fresh water before it is re circulated

through the engine. The secondary cooling system is used for this purpose. In ships

secondary cooling system uses seawater. But the radiator unit of an automobile also

fulfills the same function. A centrifugal pump takes suction from the ship‟s sea water

system and discharges it to the fresh water cooler. In the fresh water cooler heat is

transferred from the hot fresh water to the cooler seawater. This seawater is then

discharged overboard.

30. System Components

Fresh water pump Sea chest

Thermostatic valve Strainer

Expansion tank Sea water pump

Heat exchanger After cooler (Charge air cooler)


Intake Air and Exhaust System

31. The induction system must provide the engine with an adequate supply of clean air

for good combustion for all operating speeds, loads, and operating conditions. To increase

the amount of power that can be developed from an engine the amount of fuel burnt and air

induction in its cylinders have to be increased. Air intake of an IC engine may be natural

aspiration, supercharging or turbocharging.

32. On a naturally aspirated four-stroke-cycle engine, the system includes the air cleaner,

the intake manifold, and the connecting tubing and pipes. On the two-stroke cycle, the

system also includes a blower for scavenging air and for combustion. On a turbocharged

engine, additional air is supplied by means of a turbocharger, which is exhaust gas–driven.

On a supercharged engine a mechanically driven blower is used to supply additional air. The

turbocharger compresses intake air to a density up to four times that of atmospheric pressure.

This greater amount of dense air allows more fuel to be burned, thereby doubling the

engine‟s power output. The turbocharger also reduces exhaust emissions and exhaust noise.

33. An air shutdown valve may be included to allow engine intake air to be shut off

completely for emergency engine shutdown.

34. An intercooler or after-cooler may also be included in the induction system. Since

cooler air is denser, a greater amount of air is in fact supplied if the air is cooled. The

intercooler is mounted to cool the intake air after it leaves the discharge side of the

turbocharger and before it enters the engine.


CHAPTER 04

SHIP’S SYSTEMS

Introduction

1. A set or group of components interconnected to ensure efficient working of

equipment is called a System.

Purpose

2. The purposes of a Ship's system are,

a. To increase the operational efficiency of machinery and ship.

b. To save manpower and time.

c. To save wastage of material.

d. To save duplication of equipment.

3. Various systems fitted onboard ships are as follows.

a. Domestic fresh water system

b. Compressed air system

c. Fuel filling and transfer system

d. Sea water system

(1) Fire main system

(2) Cooling water system

(3) Sanitary system

(4) Pre-wetting system

(5) Bilge system

(6) Magazine spraying and flooding system

(7) Ballasting / de-ballasting system

Domestic Fresh Water System

4. This system is meant for receiving fresh water from another ship or ashore and

storing it in storage tanks and also for distributing water from storage tanks to various

consumers. It can also pump water to other ships or overboard from storage tanks. This

system is provided with clarifiers for mixing chlorine with the fresh water. This system may

be of any of the following types,

a. Gravity fresh water system.

b. Pressurized fresh water system.

c. Direct pumping system.


Sea Water System

5. This system is meant for supplying seawater throughout the ship for various

requirements. The salt water systems onboard are as follows.

a. Fire main system. It is meant for supplying sea water to the fire hydrants

for fighting the fire on board ship. It also supplies sea water to pre-wetting system,

sanitary system, bilges pumping out system, magazine spraying system, ballasting

and de-ballasting system and for anchor washing. Fire main system is fitted with two

or more pumps to maintain the sea water pressure throughout the ship.


b. Cooling water system It is meant for supplying sea water to cool down

the lubricating oil of main engines and auxiliary machinery. All the machinery

require sea water for cooling has separate sea water pump to maintain the sea water

pressure in the cooling system and additional line given to these system via fire main

to use in case of an emergency.

c. Sanitary system It is meant for supplying seawater to the crew's sanitary

spaces and bathrooms for sanitation.

d. Pre-wetting system This system sprinkles the sea water with the use of

sprinklers on the weather-deck to provide a cover for the ship when the ship is

passing through a nuclear fallout area.

e. Bilges pumping out system It is meant for pumping out the bilges with the

use of educators which were operated by the sea water under pressure.


f. Magazine spraying and flooding system This system is used to keep the

temperature of magazines within limits to avoid any explosion, which can cause

heavy damage to ship. This system is normally operated remotely.

g. Ballasting system / De-ballasting This system is meant for filling sea

water by flooding directly through sea cock or through main suction line into empty

fuel tanks or ballasting tanks to maintain ship's stability and emptying the sea water

from filled fuel tanks or de-ballasting tanks by pumping out through main suction line

or by portable/submersible pumps to sea.


Compressed Air System

6. It supplies high pressure and low pressure air through the ship for the following

purposes.

a. Main engine and diesel generator starting system.

b. Gas turbine starting system.

c. Gas turbine liquid firefighting system.

d. For compressed air foam system (CAFS) as a firefighting system.

e. For supplying water to accommodation and various parts of the ship through

hydrophore.

f. For automation and control air for main and auxiliary engine.

g. For different application on the deck side and in engine room such as

chipping, drilling, buffing, pressurized water jet cleaning etc. by use of

pneumatic tools and machinery.

h. Torpedo firing system.

j. Testing of water tight compartments.

k. Compressed air is also used for ships whistle and fog horn.

l. General cleaning purposes

Fuel Filling and Transferring System

7. This system is meant for receiving fuel to fill storage tanks and to transfer fuel from

storage tanks to daily use tanks or other places required within the ship or transferring to

other ship/craft. The fuel filling and transferring system has the tanks, piping and pumps for

loading, storing and transferring fuel internally.


8. Fuel comes onboard at the deck fueling station and then flows by gravity through a

fueling manifold in the machinery spaces to the storage tanks. Fuel is transferred with the

fuel transfer pumps from the storage tanks to daily use tanks prior facilitate to the main

machinery. These tanks are normally above the main machinery level and nearby the

machinery spaces therefore, it provides fuel to the main machinery by gravity. In smaller

craft these tanks are optional and each machinery provided with a suitable fuel pump to take

the required suction from the tank.

9. The fuel oil filling and transfer system provides a means for routing the discharge of

the fuel oil transfer pump to the deck connection so that the ship may be defueled with

installed equipment.

10. The colour code used for systems on board ship stated below.

a. Red – Fire main system, hanger spraying system & firefighting systems

b. Orange – Oils other than fuel

c. Black – Waste media

d. Blue – Fresh water system

e. Brown – Fuel system

f. Green – Sea water

g. Silver – Steam

h. White – Compressed air system & air ventilation system

j. Yellow – Flammable gases


k. Gray – Non-flammable gases

CHAPTER 05

MACHINERY LAYOUT OF AN ENGINE ROOM

01. On a ship the engine room is the propulsion machinery spaces of the vessel. To

increase the safety and damage survivability of a vessel, 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 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 and starboard engine rooms or may be simply

numbered.

02. On a large percentage of vessels, ships and boats, the engine room is located near the

bottom and at the rear or aft end of the vessel and usually comprises few compartments. This

design maximizes the cargo carrying capacity of the vessel and situates the prime mover

close to the propeller minimizing equipment cost and problems posed from long shaft lines.

03. Large engines drive electrical generators that provide power for the ship's electrical

systems. Large ships typically have two or more synchronized generators to ensure smooth

operation. The combined output of a ship's generators is well above the actual power

requirement to accommodate maintenance or the loss of one generator.

04. Besides propulsion and auxiliary engines, a typical engine room contains air

compressors, RO plant, air conditioning plants, refrigeration plants, purifiers, fire pumps,

feed pumps, fuel pumps and electrical instrumentation.

05. Engine rooms are hot, noisy, sometimes dirty, and potentially dangerous. The

presence of flammable fuel, high voltage (HV) electrical equipment and internal combustion

engines (ICE) means that a serious fire hazard exists in the engine room, which is monitored

continuously by the ship's engineering staff and various monitoring systems.

06. If engines are equipped with internal combustion or turbine engines, engine rooms

employ some means of providing air for the operation of the engines and associated

ventilation. If individuals are normally present in these rooms, additional ventilation should

be available to keep engine room temperatures to acceptable limits. The requirement for

general ventilation and the requirement for sufficient combustion air are quite different.

Engines pull sufficient air into the engine room for their own operation. However, additional

airflow for ventilation usually requires intake and exhaust blowers.


07. Machinery layout

01 – Machinery control room 02 – Starboard main engine

03 – Port main engine 04 – Gear box

05 – Starboard generator 06 – Port generator

07 – Air compressor 08 – Forward power board

09 – Hydrophore 10 – Fresh water pump

11 – Air bottle 12 – Fuel transfer pumps

13 – RO plant 14 – Stbd AC plant

15 – Port AC plant 16 – No 1 fire pump

17 – No 2 fire pump


CHAPTER 06

AUXILIARY MACHINERY ONBOARD SHIP

Air Conditioning and Refrigeration Plants

1. Introduction The term refrigeration has been derived from the word

"Freeze" which involves the conversion of a liquid into solid by extraction of heat. Freezing

involves the extraction of sensible heat for lowering the temperature of the liquid followed by

removal of latent heat of freezing for conversion of the liquid to solid at a constant

temperature known as freezing point. A heat pump or a refrigerating machine can be utilized

for the removal of heat from a given body or space. Refrigerators are commonly used for

production of ice, cooling of storage chambers in which perishable food, fruits, drugs etc.

may be stored for liquefying gases and vapour in chemical and pharmaceutical industry, for

cooling water in water coolers and in air conditioning of buildings, milk vans etc.

2. Refrigeration Refrigeration can be defined as the process by which the

temperature of a given space or substance is lowered below that of the surroundings and

maintaining it.

3. Air conditioning Air conditioning can be defined as the process of simultaneous

controlling of temperature, humidity, cleanliness and flow of air or air motion.

4. Basic Laws of A/C & Refrigeration The basic laws of Air Conditioning and

Refrigeration are:-

(a) All liquids while evaporating take heat from their surroundings.

(b) Any vapour can be condensed back to liquid if it is suitably compressed and

cooled.

(c) The temperature at which any liquid will evaporate or boil away directly

depends upon the pressure to which it is subjected.

5. There are several types of Air Conditioning and Refrigeration systems are available

and the most common system using in SLN is vapour compression refrigeration system.

6. Main Components of a Vapour Compression A/C Plant A vapour compression

refrigeration A/C plant consists of four main components.

(a) Compressor

(b) Condenser

(c) Expansion Valve/Regulating Valve

(d) Evaporator


7. Compressor The refrigerant is removed as a gas from the evaporator during

the suction stroke of the compressor. The compression stroke compresses the gas and the

temperature and pressure of gas is increased. The superheated gas is delivered to the

condenser in the cycle.

8. Condenser The purpose of condenser is to extract the heat from superheated

refrigerant and liquefy it. The high pressure refrigerant vapour enters the condenser and heat

flows from refrigerant to cooling medium thus allowing refrigerant to change the state from

gas to liquid.


9. Expansion Valve / Regulating Valve The refrigerant after changing its state is

made to pass through the expansion valve. Here the pressure falls, which causes the state of

refrigerant liquid to change to gaseous form. This change of state causes the cooling to the

temperature required in the evaporator.

10. Evaporator The refrigerant must be completely changed to gas in the evaporator to

avoid liquid being returned to the compressor. In the evaporator the brine, solution/cooling

water rejects the heat to the refrigerant and the refrigerant completely changes to gaseous

form. Thus the refrigerating effect is achieved.

Basic Refrigeration Cycle

11. The refrigeration cycle begins with the refrigerant in the evaporator. At this stage the

refrigerant in the evaporator is in liquid form and is used to absorb heat from the product or

from an area. When leaving the evaporator, the refrigerant has absorbed a quantity of heat

from the product or the area and is a low-pressure, low-temperature vapour. This low-

pressure, low-temperature vapour is then drawn from the evaporator by the compressor.

When vapour is compressed it rises in temperature. Therefore, the compressor transforms the

low-temperature vapour to a high-temperature vapour, in turn increasing the pressure.

12. This high-temperature, high-pressure vapour is pumped from the compressor to the

condenser and it is cooled by the surrounding air, sea water in marine system or in some

cases by fan assistance. The vapour within the condenser is cooled only to the point where it

becomes a liquid once more. The heat, which has been absorbed, is then conducted to the

outside air or sea water. At this stage the liquid refrigerant is passed through the expansion

valve. The expansion valve reduces the pressure of the liquid refrigerant and therefore

reduces the temperature. The cycle is complete when the refrigerant flows into the evaporator

from the expansion valve as a low-pressure and low-temperature liquid.

13. An air conditioning system can be further classified as direct and indirect air

conditioning system plant

(a) Direct expansion system The refrigerant is circulated through the

evaporator coils directly for cooling the space or taking the heat from the products.

There is no secondary refrigerant such as brine or fresh water used in this system.

Therefore, the refrigerant has to circulate in separate evaporators placed for cabins or

the plant is placed at only one location and cooled air will be taken by a blower

through the ducts to the cabins.


(b) Indirect expansion system In this type a secondary refrigerant is cooled by

the primary refrigerant in a chiller and then this secondary refrigerant is circulated

through the coils of the air treatment unit in which heat transfer takes place. This

makes the system bulky as more amount of brine is required to be circulated for the

same refrigerating effect compared to a direct refrigerating system. A separate chill

water pump available to circulate chill water through the system.

14. Applications of A/C & refrigeration plants The air conditioning and

refrigeration applications may be grouped in six general categories.

a. Domestic Refrigeration.

b. Commercial Refrigeration.

c. Industrial Refrigeration.

d. Marine and Transportation Refrigeration.

e. Comfort Air Conditioning.

f. Industrial Air Conditioning.

15. Use of A/C plants on board ships The common uses of A/C plants are as follows.

a. Air Conditioning of mess decks.

b. Sick bay air conditioning.

c. Air conditioning of Machinery Control Room and operations rooms etc. for

better operation of equipment.

d. Air conditioning of missile hangers.

e. Air conditioning of magazine compartment.

16. Uses of refrigeration plant onboard ship The common uses of refrigeration plants

onboard ship are as follows.

a. Preservation of meat, fish etc. (Cold room -7 to -11 0C).

b. Preservation of Vegetables, fruits, milk products etc. (Cool room 15 to 19 0C)

c. Preservation and storage of medicines.

d. Cooling of drinking water

e. Preparation of ice for domestic and medical purposes


RO Plant

17. Principle of Osmosis Osmosis is the natural phenomena, which takes place

when solutions of different concentrations are separated by a semi-permeable membrane. The

solvent flows from the weak solution to the strong solution through the semi-permeable

membrane. Thus osmosis tends to reduce the difference or to equalize concentration of

liquids on both sides. Many phenomenon observed in nature are due to Osmosis. These include

plants taking water from the soil through their roots, the lining of our stomachs accepting the

food and water that we drink.

18. Principle of Reverse Osmosis This osmosis process can be reversed, by

applying pressure (above osmotic pressure) on the strong solution side and is called Reverse

Osmosis process. That is the solvent (pure water) is extracted from seawater. All Reverse

Osmosis plants operate on this principle.

19. In Reverse Osmosis, the pressurized sea water is forced through a semi-permeable

membrane to the fresh water recovery side. The membrane rejects the salt ions present in the

sea water, yet allows the pure water to pass through the thin membrane material. Only about

30% of the sea water actually passes through the membrane as permeate. The remaining 70%

sea water flushes the salt ions and other impurities off the membrane surface, and is

discharged back into the sea as brine. Pressure of up to max of 65 bar is applied to the sea

water to force the pure water molecules through the semi-permeable membrane. The majority

of the dissolved salts and all of the organic material, bacteria and suspended solids are

retained by the membrane and are discharged from the system with the brine.


20. Main Components of RO Plant

(a) Pre-filter Pump

(b) Filter Pump

(c) Sand Filter

(d) Cartridge Filter

(e) De-acidification Filter

(f) High Pressure Plunger Pump

(g) Servomotor Control

(h) DT Module

Function of main components

21. Pre-Filter Pump Pre-filter pump is used to supply Sea Water to the RO plant

filter pump with sufficient pre-pressure and quantity, and consist of centrifugal pump.

22. Filter Pump Filter pump is designed to supply this raw water received from

the Pre-Filter pump to the filter system and thereafter to the high-pressure pump with

designed pressure and quantity. The Filter Pump is also a centrifugal pump.

23. Sand Filter The sand filter contains 3 layers of fine, medium and coarse sand. This

unit is designed for rapid filtration of the raw water with back washing facility. The filter

system is supplied with gauges and diverting valves. The normal flow of water is from top to

bottom. Only the top layer carries out the function of filtering while others are supporting

layers.


24. Cartridge Filter Cartridge filter is designed to remove any suspended matter to

reduce organic or inorganic fouling of the membrane up to 10 microns. Cartridge filter is

supplied with sufficient pre-pressure from the filter pump.

25. High Pressure Pump The high pressure plunger pump system consists of a

slow revolution triplex plunger pump supplied with motor, pulsation damper and pressure

relief valve. The high pressure pump is fitted in a separate frame for alternative installation in

case of space shortage and for easy installation.

26. Pulsation Damper The pulsation damper is fitted on the discharge side of the HP

pump. The pump being triplex plunger type reciprocating pump the discharge pressure of

each cylinder varies over the entire length of its stroke. The pulsation damper evens out the

pressure variations so that the pressure at the DT module is even and steady.

27. De-Acidification Filter The normal sea water contains carbonates in small

percentage. During reverse osmosis process these carbonates break up and generate CO2,

which passes over to the permeate side. This carbon dioxide will combine with water and

form carbonic acid. Hence, to prevent the corrosion of product water flowing coated iron

pipes a de-acidification filter is installed. This filter converts free CO2 back in to Ca++

and

HCO3-1

by the following chemical reaction.

CaCO3 +CO2 + H2O = Ca (HCO3) 2

28. DT Module The DT module consists basically of a disc membrane stack and

pressure vessel. The disc membrane stack is fitted inside the pressure vessel. End flanges

with groove rings close both openings of the pressure vessel. The membrane spacer and the

pure water manifold are designed as an integral part of the hydraulic disc. The integrated

spacer forms the open raw water channel. The extremely short feed water path across the

membrane followed by a 180-degree flow reversal eliminates polarization concentration. The

result is minimum membrane fouling and scaling and a minimum flow path with low

resistance.

29. The membrane cushions are stacked on the center tension rod. Each membrane

cushion is covered at top and bottom by a hydraulic disc to form a separate chamber for each

cushion. Raw water, which flows under high pressure into the membrane module at raw

water inlet on the DT module, enters the membrane stack at the first membrane. On its way

to the next chamber it flows across bottom and top membrane cushion surface. This

permeates drains into the pure water manifold around the tension rod. From there it is

discharged out through permeate line. The brackish water is sealed off with an „O‟ Ring from

the pure water manifold.


Operation of RO plant

30. The sea water is pumped into the system by the pre filter booster pump at the inlet of

the filter pump. The filter pump further ensures that sufficient pressure is maintained in the

system for normal operation. The sea water then filtered by the sand filter and the cartridge

filter which removes the foreign materials down to 10 microns. The filtered water is then

pressurized to 60 bar (normal operating pressure) by the high pressure pump. The water

passes over the membrane cushions in the DT Modules.

31. The high pressure is regulated by the servo motor control valve. About thirty percent

water passes across to the pure water side. The remainder water is called as brine is

discharged back to the sea. The entire operation of the RO plant is automatically controlled

by a stored programme in the microprocessor fitted in the control panel. The control panel

houses all the electronics and the electrical circuits. The pure water is called as permeate

water which is the output of the RO Plant is sent to the storage water tank of the ship.

Purifier

32. When a centrifuge is set up as a purifier, a second outlet pipe is used for discharging

water as shown. In the fuel oil purifier, the untreated fuel contains a mixture of oil, solids and

water, which the centrifuge separates into three layers. While in operation, a quantity of oil

remains in the bowl to form a complete seal around the underside of the top disc and, because

of the density difference, confines the oil within the outside diameter of the top disc.


33. As marine fuel oil normally contains a small quantity of water, it is necessary to

prime the bowl each time that it is run; otherwise all the oil will pass over the water outlet

side to waste. The water outlet is at greater radius than that of the fuel. Within the water

outlet there is a gravity disc, which controls the radial position of the fuel water interface.

34. A set of gravity discs is supplied with each machine and the optimum size to be fitted

depends on the density of the untreated oil. When the fuel centrifuge is operating, particulate

matter will accumulate on the walls of the bowl. If the centrifuge is set as a clarifier, the

particulate matter will be a combination of water and solid material. If it is set as a purifier,

the free water is continuously discharged; therefore, the particulate matter will consist of

solid material. In older machines it is necessary to stop the centrifuge to manually clean the

bowl and disc stack, however, the majority of machines today can discharge the bowl

contents while the centrifuge is running.

Pumps

35. Introduction Pumps form an important part of any engineering system.

Pumps serve as a means of transporting fluids. They convert mechanical energy into

potential, kinetic and thermal energy of the fluid. This mechanical energy may be obtained

from an electrical motor.

36. Water, by far, is the most common fluid handled by pump and serves as a "standard"

fluid for determining pump performance.

37. Pump Pump is a mechanical device used to increase the pressure energy of

liquid.

38. Uses of Pumps Pumps are widely used on board ships for the following

purposes:

a. Domestic fresh water supply to Bathrooms, Wash basins, Galley etc.

b. Fire main/sanitary supply of sea water.

c. Machinery cooling by sea water/fresh water.

d. Embarking/Disembarking of POL.

e. Transfer of POL within the ship.

f. Pumping out bilges and flooded compartments.

g. Supply of fluid for operation of steering gear, stabilizers and hydraulic

machinery.

h. Circulation of brine in Air Conditioning plants.


39. Types of Pumps All pumps can be grouped under the following heads.

a. Positive Displacement Pump Positive-displacement pumps are another

category of pumps. Types of positive-displacement pumps are reciprocating, semi-

rotary and rotary pumps. Positive-displacement pumps operate by forcing a fixed

volume of fluid from the inlet pressure section of the pump into the discharge zone of

the pump. These pumps generally tend to be larger than equal-capacity dynamic

pumps. Positive-displacement pumps frequently are used in hydraulic systems at

pressures ranging up to 5000 psi. A principal advantage of hydraulic power is the

high power density (power per unit weight) that can be achieved. They also provide a

fixed displacement per revolution and, within mechanical limitations, infinite

pressure to move fluids. These pumps do not require to be primed and therefore can

be conveniently used as priming pumps.

b. Dynamic Pressure Pump In this type of pump energy is continuously

added to the fluid within the pump. Dynamic pumps are one category of pumps under

which there are several classes, two of which are: centrifugal and axial. These pumps

operate by developing a high liquid velocity and converting the velocity to pressure in

a diffusing flow passage. Dynamic pumps usually have lower efficiencies than

positive displacement pumps, but also have lower maintenance requirements.

Dynamic pumps are also able to operate at fairly high speeds and high fluid flow

rates.

Reciprocating pump

40. In a reciprocating pump, a volume of liquid is drawn into the cylinder through the

suction valve on the intake stroke and is discharged under positive pressure through the outlet

valves on the discharge stroke. The discharge from a reciprocating pump is pulsating and

changes only when the speed of the pump is changed. This is because the intake is always a

constant volume. Often an air chamber is connected on the discharge side of the pump to

provide a more even flow by evening out the pressure surges. Reciprocating pumps are often

used for sludge and slurry.


41. One construction style of a reciprocating pump is the direct-acting steam pump.

These consist of a steam cylinder end in line with a liquid cylinder end, with a straight rod

connection between the steam piston and the pump piston or plunger. These pistons are

double acting which means that each side pumps on every stroke.

42. Another construction style is the power pump which converts rotary motion to low

speed reciprocating motion using a speed reducing gear. The power pump can be either

single or double-acting. A single-acting design discharges liquid only on one side of the

piston or plunger. Only one suction and one discharge stroke per revolution of the crankshaft

can occur. The double-acting design takes suction and discharges on both sides of the piston

resulting in two suctions and discharges per crankshaft revolution. Power pumps are

generally very efficient and can develop high pressures. These pumps do however tend to be

expensive.

Rotary pump

43. A rotary pump traps fluid in its closed casing and discharges a smooth flow. They can

handle almost any liquid that does not contain hard and abrasive solids, including viscous

liquids. They are also simple in design and efficient in handling flow conditions that are

usually considered to low for economic application of centrifuges. Types of rotary pumps

include cam-and-piston, internal-gear, lobular, screw, and vane pumps.


44. Gear pumps are found in home heating systems in which the burners are fired by oil.

Rotary pumps find wide use for viscous liquids. When pumping highly viscous fluids, rotary

pumps must be operated at reduced speeds because at higher speeds the liquid cannot flow

into the casing fast enough to fill it. Unlike a centrifugal pump, the rotary design will deliver

a capacity that is not greatly affected by pressure variations on either the suction or discharge

ends. In services where large changes in pressure are anticipated, the rotary design should be

considered.

Centrifugal pump

45. A centrifugal pump consists of an impeller and an intake at its center. These are

arranged so that when the impeller rotates, liquid is discharged by centrifugal force into a

casing surrounding the impeller. The casing is there in order to gradually decrease the

velocity of the fluid which leaves the impeller at a high velocity. This velocity is converted to

pressure which is needed to discharge the fluid.

46. Some of the advantages of centrifugal pumps are smooth flow through the pump and

uniform pressure in the discharge pipe, low cost, light weight, less maintenance and an

operating speed that allows for direct connection to steam turbines and electric motors. The

centrifugal pump accounts for not less than 80% of the world‟s pump production because it is

more suitable for handling large capacities of liquids than the positive-displacement pump.

Axial flow pump

45. Axial flow pumps are also called propeller pump. These pumps develop most of their

pressure by the propelling or lifting action of the vanes on the liquid. These pumps are

classed with centrifugal pumps, although centrifugal force plays no part in the pumping

action. When sea water has to pass through large condensers, axial flow pumps are used. It

ensures sufficient speed and adequate flow of water. The screw propeller creates an increase

in pressure by causing an axial acceleration of liquid within its blades. This is converted to

straight axial movement by suitably shaped outlet guide vanes.


47. These pumps are used for drainage, sewage, storm water disposal, irrigation and

condenser water circulation. These pumps are marked under the names as propeller, axial

flow and straight flow. In general, vertical single-stage axial and mixed-flow pumps are used

however; sometimes two-stage axial-flow pumps are economically more practical.

Horizontal axial-flow pumps are used for pumping large volumes against low pressures.

47. Comparison of Centrifugal and Reciprocating pumps

Centrifugal pump Reciprocating pump

Simple in construction, because of less

number of parts.

Complicated in construction, because of

more number of parts.

Total weight of the pump is less for a given

discharge.

Total weight of the pump is more for a

given discharge.

Suitable for large discharge and smaller

heads.

Suitable for less discharge and higher heads.

Requires less floor area and simple

foundation.

Requires more floor area and comparatively

heavy foundation.

Less wear and tear. More wear and tear.

Maintenance cost is less. Maintenance cost is high.

Can handle dirty water. Cannot handle dirty water.

Can run at higher speeds. Cannot run at higher speeds.

Its delivery is continuous. Its delivery is pulsating.

No air vessels are required. Air vessels are required

Thrust on the crankshaft is uniform. Thrust on the crankshaft is not uniform.

Operation is quite simple. Much care is required in operation.

Needs priming. Does not need priming.

It has less efficiency. It has more efficiency.


CHAPTER 07

TRANSMISSION OF ENGINE POWER AND SHAFTING

Purpose of Engine Power Transmission

1. Marine propulsion is the mechanism or system used to generate thrust to move a ship

or craft across water. Marine engineering is the discipline concerned with the design of

marine propulsion systems. Most modern ships use a reciprocating diesel engine as their

prime mover, due to their operating simplicity, robustness and fuel economy compared to

most other prime mover mechanisms. The rotating crankshaft can be directly coupled to the

propeller with slow speed engines and via a reduction gearbox for medium and high speed

engines.

2. Power transmission is occurring according to two methods.

a. Direct drive A direct drive mechanism is one that takes the power coming from a

motor/engine without any reductions or without changing the rotational direction.

Generators, slow speed and smaller engines and pumps are examples for this type.

b. Indirect drive The drive mechanisms of most engine powered in ships and of

many boats are the indirect type. With this drive the power developed by the engine is

transmitted to the propeller indirectly, through an intermediate mechanism that

reduces the shaft speed. Speed may be reduced mechanically by a combination of

gears or by electrical means (for example a diesel electric drive).

Reduction Gear

3. The mechanical drives include the devices that reduce the shaft speed of driven unit,

provide a means for reversing the direction of shaft rotation in the driven unit and permit

quick disconnection of the driving unit from the driven unit.

4. Propellers operate most efficiently in a relatively low rpm range. The most efficient

designs of diesel engines however, operate in a relatively high rpm range. In order that both

the engine and the propeller may operate efficiently, the drive mechanism in many

installations includes a device that permits a speed reduction from engine crankshaft to

propeller shaft. The combination of gears that brings about the speed reduction is called a

reduction gear. In most diesel engine installations, the reduction ratio does not exceed 3 to 1.

There are some units, however, that have reductions as high as 6 to 1. The propelling

equipment of a ship / craft must provide astern power as well as forward power.


Gearbox

5. In mechanical drives, the direction of rotation of the propeller shaft is reversed by use

of reverse gears. The drive mechanism of a ship or boat must do more than reduce speed and

change direction of rotation. Most drive mechanisms have a clutch. The clutch disconnects

the drive mechanism from the propeller shaft and permits the engine to be operated without

turning the propeller shaft.

6. Most of ships and craft are normally equipped with a „Thrust Reversing Gearbox‟

which has three gear positions of „Ahead‟, „Neutral‟, and „Astern‟ to navigate and manoeuvre

safely at sea. Main components of a gear box are,

a. Reduction gear wheel

b. Gear wheels (forward and reverse pinions)

c. Reverse driven gear wheel

d. Clutch (forward and reverse)

e. Rubber block drive (Coupling)

7. Reversible Engines These engines are not designed with reversible gear mechanism. For astern movement, engine should shut down and changes the direction of

firing immediately.

Purpose of shafting system

8. It is used to transmit the torque developed by the engine to the propeller and to

transmit the thrust developed by the propeller to the ship's hull. Further it provides support to

the propeller and shafts and safely withstands transient operating loads.


Arrangement of Shafting

9. The shaft line is divided into three main sections coupled together rigidly. Those are,

a. Thrust shaft The thrust of the propeller is transmitted to the ship hull

through the thrust block, which is usually fitted in this length of shafting.

b. Intermediate shaft The length of shafting connecting the thrust

shaft and tail shaft is known as intermediate shaft.

c. Tail shaft The final length of shafting, to which the propeller is attached,

is known as tail shaft.

Main components of Shafting System

10. The main components of shafting system are as follows.

a. Thrust block

b. Plummer block

c. Bulkhead gland

d. Shaft locking gear

e. Loose coupling

f. Stern gland

g. Stern tube bushes

h. A' bracket

j. Eddy plate

k. Rope guard


Thrust Block

11. Its function is to transmit the thrust to the ship's hull. The thrust pads transmit the

thrust to the thrust block body which is rigidly secured to the ship structure.

Plummer Block

12. Its function is to support the length of intermediate shafting. A Plummer Block is

assembled with self-aligning ball bearings or spherical roller bearings to support the load and

weight of the whole equipment and to maintain the rotational movement stably so it is a very

important that requires high degree of precision even at difficult running conditions. Bearings

may be grease lubricated or oil lubricated in large Plummer blocks.


Bulkhead Gland

13. These are fitted where the shaft passes through the watertight bulkheads to maintain

watertight integrity between two adjacent watertight compartments. Further, it has the

capability to withstand shaft movement in vertical, angular and horizontal direction. These

are grease lubricated. There are two main types of bulkhead glands available and those are,

a. Flexible spherical bulkhead gland

b. Self-aligning bulkhead gland

Shaft Locking Gear

14. Shaft locking gears are used to lock the individual shaft to prevent it from rotating

under the following conditions.

a. To lock the shaft at 12 „O‟ clock position before entering into dry dock.

b. To prevent damaged engine or shaft from rotating.

c. To prevent a damaged component of shafting from further damage.

d. When a ship to be towed with damaged shafting.

e. To load an engine when required to sail at slow speed with one shaft engaged.

15. There are two types of shaft locking gears use inboard ships and those are,

a. Positive locking gear type

b. Band brake type


Loose Coupling

16. It is the coupling connecting the intermediate shaft with the tail shaft and the thrust

shaft. This facilitates easy disconnection of the shafting link specially the tail shaft. This

consists of an iron flange or collar which is forced on to a tapered cone at the inboard end of

the tail shaft and secured by keys and rings.

Stern Gland

17. It is fitted in way of shaft passing through the ship structure to sea and avoids water

ingress from sea into the ship. The commonly used sealing arrangement in the stern glands

includes:

a. Conventional stuffing box with turns of soft packing.

b. Facial contact sealing gland.

c. Inboard water lubricated inflatable ET type split deep sea seals.

d. Out board/inboard oil lubricated stern tube seal.


Stern Tube Bushes

18. The Stern tube consists of a shipbuilder‟s tube which is integral with the hull. Stern

tube bushes are fitted inside the stern tube to support the tail shaft in way of shaft passing

through ships structure in to the sea and the stern gland is mounted on the forward inboard

end.

19. The bushes are fitted at each end of the stern tube and consist of gunmetal or steel

bushes made in halves and lined with lignum vitae, hard rubber strips, thordon /feroform

bushes or white metal. Most of ships these bushes are water lubricated and few are oil

lubricated. At the inboard end gland can be of soft packing type or facial contact type.

‘A’ Bracket

20. It is fitted on the outboard side of the ship and adjacent to the propeller to support the

tail shaft and to take the weight of the propeller. The bearings inside the „A‟ bracket may be

hard rubber, thordon or feroform and the bearings are fitted on a gunmetal bush. Generally,

these bearings are water lubricated.


Eddy Plate

20. Eddy plates fitted on aft side of stern tube and forward side of „A‟ bracket. These are

fitted to maintain the stream line profile of the ship and minimize the corrosion and

cavitation effect due to eddies. Therefore these are specially shaped fittings to streamline

flow of water.

Rope Guard

21. A cylindrical steel plate in halves, called rope guard is fitted between the propeller

and the aft end of the „A‟ bracket to prevent ropes, wires, chains from becoming wound

around the shaft.


CHAPTER 08

STEERING SYSTEM

Principle of Steering Gear

1. A ship is steered by a rudder which is power operated by the movement of steering

wheel. The rudder is moved by hydraulic rams mounted on the inboard rudder head and

hydraulic power is supplied from pumps. The delivery of oil from the pumps to the rams is

achieved by the inclusion of Telemotor system/electric motor etc.

2. Steering system is divided into three parts.

a. Control Equipment Control equipment conveys the signal for desired

rudder angle and activates the power unit and transmission system.

b. Power Unit Power unit provides the force to move the rudder to the

desired angle.

c. Transmission System This system is the means by which the

movement of the rudder is accomplished.

Types of Steering Gear

3. The steering gears can be classified into different types depending on the control

equipment used.

a. Manual Rudder turned manually (as operated in a whaler).

b. Mechanical steering gear All transmissions from the steering wheel to

the rudder are by mechanical means through hand operated tiller or rudder operated

by a rope, chain and pulley or rack and pinion.

c. Telemotor steering gear This employs „master and slave‟ principle. The

control and power systems are hydraulic.

d. Electro-hydraulic steering gear In this control system is electrical and

the power system is hydraulic.

e. All electrical Both control and power systems are electrical.


4. Characteristic features of Steering gear are,

a. Dependable and safe operation under any navigating condition.

b. Long service life.

c. Ability to put the rudder over to the required angle at full ship speed.

d. Ability to put the rudder over to the required speed of rudder motion.

e. Possibility of rapid changeover from main type of steering to the auxiliary

system.

f. Possibility of control from several places.

g. Minimum overall size and weight.

h. A simple design with easy maintenance and servicing.

5. Various Positions of Steering

a. Primary Steering position (Bridge)

b. Secondary Steering position (Wheel house)

c. Aft steering position

(1) Local control

(2) Emergency

Rudder

6. The rudder is the fin or spade like projection under the counter and below the water

line, generally placed as far as practicable. It is hung on a circular, solid shaft called a stock

that penetrates the hull through a stuffing box and bearings. It often has a fixed, faired, foil

like sections ahead of it, which is firmly attached to and part of the ship‟s structure. It moved

by hydraulic rams mounted on the rudder head and hydraulic power is supplied from constant

running rotary pump.

Types of Rudders

7. The general types of rudders are as follows.

a. Unbalanced Blade entirely aft of the stock.

b. Balanced Portion of the rudder area disposed systematically throughout

the rudder height, is forward of the stock.

c. Semi Balanced Rudder Area forward of the stock does not extend the

full height of the blade aft of the stock.


Telemotor Steering Gear

8. The Telemotor steering gear consists of the following major units.

a. Steering Wheel - Steering control lever.

b. Telemotor Transmitter - Operates the rack by the steering wheel at bridge

and moves the transmitter plunger. It displaced fluids to receiver.


c. Telemotor Receiver - In which identical movement is conveyed from the

transmitter and then applied to the stroke of the pump. Fitted in steering

compartment.

d. Steering Pump - Variable displacement delivery pumps which can deliver a

reversible flow of liquid to the steering rams.

e. Steering Rams - Moved by the delivery of the fluid from the pumps and

convey the movement to the rudder head.

f. Floating Lever - It gets activated by the movement of the transmitter

plunger.

g. Hunting Rod - To center-up the pump or to bring the pump in non-pumping

position as and when rudder has reached the desired angle.

h. Rudder - Steering controller.

Function of Telemotor System

9. Telemotor transmitter connected to steering wheel by a rack. When the steering wheel

moves Port and Stbd Telemotor piston moves up and down accordingly. Telemotor

transmitter has connected to Telemotor receiver by two hydraulic lines. The displacement of

fluid due to the piston movement thereby causes a corresponding movement of the receiver

plunger. The system is maintained fully charged with fluid, with air release, center balancing

ports and equalizer springs on the receiver to maintain correct relationship of movement.

10. Telemotor receiver has connected to hydraulic pump with the help of floating leaver.

Floating lever activate the hydraulic pump and provides required amount of hydraulic oil to

hydraulic ramps. Because of the oil pressure generated by the ramps, the rudder will turn to

the required directions. Hunting rod de activates the hydraulic pressure pump after achieving

the required rudder angle. The Hunting Gear `centers up‟ the pump when the rudder has

moved over the degrees of helm applied by the steering wheel or if the system without

hunting gear it would be necessary to take the stroke off the pump (center-up) by moving the

wheel back to the central position.

Electro-Hydraulic Steering System

11. In this system the helm (steering wheel) in the bridge or wheel house transmits

orders electrically and executes the orders hydraulically on the rudder through steering gears

located directly above the rudder. Although several different designs of steering gears are in

common use, their operating principles are similar and in this system only transmitter and

receiver are electrical when comparing with the Telemotor system.


12. Modes of Steering

a. Non-follow up In this mode rudder will continue to turn when the

steering wheel or other controller is moved from its control position. Rudder

movement is stopped only when the steering control is centered once again.

b. Follow-up With this system movement of the rudder follows the

movement of the steering controller. If the controller is moved to indicate a desired

rudder position, the rudder will turn until the actual rudder angle is the same as the

desired rudder angle shown on the steering pedestal.

c. Automatic With these systems the steering control circuits are controlled

by signals received from the master compass; so that the ship is automatically held on

to a selected course.


Emergency Steering System

13. An emergency steering system, as the name suggests, is a system which is used

during the failure of the main steering system of the ship. A situation can occur in which the

remote control operation may fail to work and there can be a sudden loss of steering control

from the bridge. This can be due to sudden power failure, any electrical fault in the system or

the control system which includes faulty Telemotor or servo motor which is used for

transferring the signal from bridge to the steering unit.

14. To have control the steering of the ship at such emergency situation with manual

measure from within the steering gear room, an emergency steering system is used.

Procedure for Emergency Steering Operation

15. The following points should be followed for emergency steering operation.

a. The procedure and diagram for operating emergency steering should be

displayed in steering gear room and bridge.

b. Even in emergency situation we cannot turn the massive rudder by hand or

any other means, and that‟s why a hydraulic motor is given a supply from the

emergency generator directly through emergency switch board. It should also be

displayed in the steering room.

c. Ensure a clear communication for emergency operation via VHF or ships

telephone system.

d. Normally a switch is given in the power supply panel of steering gear for

Telemotor; switch off the supply from the panel and change the mode of operation by

selecting the switch for the motor which is supplied emergency power.

e. There is a safety pin at the manual operation helms wheel so that during

normal operation the manual operation always remains in cut-off mode. Remove that

pin.

f. A helms wheel is provided which controls the flow of oil to the rams with a

rudder angle indicator. Wheel can be turned clockwise or anti clockwise for going

port or starboard or vice versa.

g. If there is a power failure, through sound power telephone receive orders from

the bridge for the rudder angle. As soon as you get the orders, turn the wheel and

check the rudder angle indicator.


16. A routine check should always be done for proper working of manual emergency

system and steering gear system. An emergency steering drill should be carried out every

month (prescribed duration - 3 months) in the steering gear room with proper communication

with bridge to train all the ship‟s staff for proper operation of the system so that in

emergency situation ships control can be regained as soon as possible, avoiding collision or

grounding.


CHAPTER 09

DOCKING AND SLIPPING

1. Purpose of docking a ship/craft is as follows.

a. To undertake routine maintenance of underwater hull & components of propulsion system.

b. Repairs to underwater fittings.

2. Types of docks

a. Graving docks b. Floating docks

3. Graving Dock The classic form of dry-dock, properly known as graving dock,

is a narrow basin usually made of earthen berms and concrete closed by gates or by a caisson,

into which a vessel may be floated and the water pumped out leaving the vessel supported on

blocks. The keel blocks as well as the bilge block are placed on the floor of the dock in

accordance with the "docking plan" of the ship. More routine use of dry-docks is for the

cleaning (removal of barnacles and rust) and re-painting of ship's hulls. Modern graving

docks are box-shaped to accommodate the newer boxier ship designs whereas old dry-docks

are often shaped like the ships that are planned to be docked there. This shaping was

advantageous because such a dock was easier to build, it was easier to side-support the ships

and less water had to be pumped away.

4. Floating Dock A floating dry-dock is a type of pontoon for dry docking ships,

possessing floodable buoyancy chambers and a "U"-shaped cross-section. The walls are used

to give the dry-dock stability when the floor or deck is below the surface of the water. When

valves are opened, the chambers fill with water causing the dry-dock to float lower in the

water. The deck becomes submerged and this allows a ship to be moved into position inside.

When the water is pumped out of the chambers, the dry-dock rises and the ship is lifted out

of the water on the rising deck allowing work to proceed on the ship's hull.

Alternative Dry-dock Systems

5. Apart from graving docks and floating dry-docks, ships can also be dry docked and

launched by:

a. Marine railway - For repair of larger ships up to about 3000 tons weight

b. Shiplift - For repair as well as for new building. From 800 to 25000 tons

weight

c. Slipway, Patent slip - For repair of smaller boats and the new building launch

of larger vessels


6. Preparations for docking

a. Remove all ammunitions, guns & explosives.

b. De-bunkering the ship.

c. Ensure that all spare parts & paints are available as per the defect list.

d. All stores those are not mandatory to be kept onboard to empty.

e. All water tanks must be empty.

f. Adjust the trim with consultation of dock master.

g. Zero list and trim according to ship builders‟ standard.

h Ensure that all moving parts & cranes, derricks are properly secured.

j. Educate men about safety precaution to be adhered whilst on dock.

k. Ensure availability of sufficient men onboard.

l. Ensure all defects are included in the defect list & prepare a supplementary

defect list if required.

7. Safety precautions whilst on dock

a. Ensure that the ship is properly earthed.

b. Place safety instructions boards at all necessary places.

c. Ensure that fire sentries are properly placed prior to allowing any

welding/cutting operations.

d. Do not shift or add/remove weight without taking prior precautions.

e. Ensure that all men wearing proper safety gears.

f. No loose electrical wiring to be allowed.

g. Fire party must be ready in all aspects.

h. Temporary ladders & gangways must be properly secured.

j. Ensure that no spillage of oil /oily substances on docks.

k. Cover all equipment whilst carrying out blasting.

l. No consumption of liquor onboard.

m. All the work are properly monitored & attended.

n. Proper precautions are taken prior to entering confined spaces.

8. Routines / Repairs to be attended during the docking/slipping

a. Scrape and clean under water portion of hull.

b. Surveying of hull.

c. Examine under water structure which includes - Hull plate thicknesses,

propellers, shaft brackets, rudders, keel, ship builder‟s tube, eddy plates, zinc

protectors and consumable anodes, gratings of inlets and discharges, ICCP

anodes and electrodes for damages.


d. Check draught marks are in position and paint them.

e. Paint underwater structure of hull.

f. Check the bearing clearances of “A” brackets and replace bearings which

having excessive clearances (max 4mm).

g. Polish the shaft and give protective coating to outboard length.

h. Check the rudder bearing clearances.

j. Alignment of shafting system.

k. Overhauling of all the underwater valves.

9 Prior-Undocking

a. All the underwater valves should be service & proved.

b. All underwater hull repairs to be completed.

c. All Zinc protectors are properly secured.

d. Do necessary calculations & considering the record of weight shifting &

ensure that trim is same as that existed while docking.

e. Ensure that all places, where hull repairs were attended, are properly checked

& proven.

f. Have all underwater compartment manned by competent personnel while

undocking.

g. Stop flooding halfway through and check the performances of the underwater

valves.


CHAPTER 10

OUT BOARD MOTORS

Introduction

1. Out board motor is designed to propel a boat/raft of reasonable size. It can be easily

installed and detached from the boat/raft. OBM is a power plant complete with engine, fuel

supply and starting system. It has a power head and drive shaft extending downwards into the

water to drive the propeller.

2. Main parts of OBM

a. Power Head This part is generating power for the operation of OBM.

This section contains horizontally mounted cylinders, piston, cylinder head, crank

shaft, fly wheel, carburetor, electrical system, fuel pump and starting mechanism.

b. Mid-Section This section contains the drive shaft, bracket, exhaust

manifold, water pump discharge line etc.

c. Lower Unit The lower unit has transmission gears, a dog clutch,

water pump, water pump inlet strainer, anti-cavitation plate, propeller and water &

exhaust outlet.

POWER HEAD

LOWER UNIT

MID-SECTION


Basic working principle

3. The majority of existing outboard motors use two stroke technology. However the

current movement in emissions regulations is pushing the design of current outboards

towards the 4 stroke and direct injection two stroke design. Efforts to build a 4 stroke

outboard in the past have been many and varied, mostly unsuccessful as the design

technology and precision production that can be achieved today were impossible to achieve

then. Resulting motors were bulky and unreliable. Those motors that were viable were for the

most part rejected by the boating public.

4. The two-stroke engine completes its power cycle in only one crankshaft revolution

with two strokes of the piston. There are no valves, camshafts, springs chains, etc. So the

engine is much less complex and lighter. Instead of valves there are a series of strategically

located transfer ports - intake and exhaust, cut into the sides of the cylinder wall. The ports

are on opposite sides of the cylinder. The transfer ports are opened and closed by the up and

down movement of the piston. To accomplish a complete power cycle both sides of the

piston are used; consequently several events occur simultaneously during each stroke.

5. On the up stroke the top side of the piston is compressing an air/fuel mixture in the

cylinder. At the same time the bottom side of the piston pulls another fresh charge of air/fuel

mixture into the crankcase thru a one way valve called a reed valve. Near the top of the

stroke the compressed air/fuel above the piston is ignited by the spark plug and begins to

burn. The rapidly burning fuel expands and begins forcing the piston down.

6. On the down "power" stroke the piston is forced towards the crankcase reducing its

volume and creating a positive pressure. As it continues downward travel it starts first to

uncover the exhaust ports. Exhaust gas begins to rush out of the cylinder. Then the intake

ports are uncovered. The fresh air/fuel charge in the crankcase is forced into the cylinder and

continues to push the remaining exhaust gases out.

Systems

7. Following systems are available in OBM‟s.

a. Electrical system

b. Fuel system

c. Cooling system

d. Power transferring system

e. Lubrication system


Electrical System

8. There are 02 types of electrical ignition system.

a. Contact breaker ignition system.

b. Capacitor discharge ignition system.

Contact Breaker Ignition System

9. This system contains with under mentioned accessories.

a. Fly wheel & magnet.

b. Charger coil

c. Lighting coil

d. Capacitor

e. Ignition coil

f. Spark plug

10. The magnets are fixed on the fly wheel and when fly wheel rotates these magnets are

generating magnetic fluxes. This magnetic flux gets contact with charger coil which is fixed

in stator plate. Because of that 230 AC current will generate. This current converts in to DC

current at rectifier.

11. After converting in to DC current, it will store inside the capacitor. The electrical

circuit will complete through contract breaker. Then stored DC current flows ignition coil.

There are 02 coils inside the ignition coil, those are

a. Primary coil

b. Secondary coil

12. The voltage increases up to 50000, when it passes from primary coil to secondary

coil. Finally this current flows up to spark plug.

Capacitor Discharge Ignition System

13. This system is the most common method of ignition system use in OBMs and it

consists with under mentioned accessories.

a. Fly wheel & magnet

b. Pulsar coil (sensor coil)

c. Charger coil

d. Lighting coil

e. CDI unit (power pack)

f. Ignition coil


g. Spark plug

14. 230 AC current will generate by charger coil by disturbing to the magnetic flux. This

230 AC current will flows to CDI unit. 230AC current converts into 170 DC current by

rectifier inside the CDI unit. This 170 DC current will store inside the capacitor. As piston

moment, the pulsar coil generates 0.3 AC current. This current flows to SCR and complete

the circuit. Stored current at capacitor flows to ignition coil. The voltage will increase up to

50000 DC when current flows from primary coil to secondary coil. Thereafter the produced

current flows to spark plug.

15. Magnetic field is generated around the secondary coil when current passes through

the primary coil. The interruptions of the current flow through the primary coil induce a

current (at 50000VDC) to jump across the electrode.

Lubrication System

16. Mist Lubrication system Mist lubrication system is using to lubricate the

machinery parts. In this system, lube oil mixing with fuel generally in 1:50 ratio.

17. Types of Lubrication oil Using

a. 2T oil

b. Caltex super out board motor oil

c. Caltex TCW 3 out board motor oil

d. Quicksilver two cycle oil


Fuel System

18. The unique feature of the fuel

pump of OBM is that, the pumping

action is taking place inside the pump

by the suction & compression of the

pistons of the engine. The pump

consists of two diaphragms, one inlet &

one out let valves. On the upward

movement of the piston, suction is

created inside the crank case. Due to

this the diaphragm of the pump is

pulled back. In return diaphragm

creates vacuum in its front chamber. It

causes the inlet valve to open & fuel

enters into the front chamber of the

diaphragm because of the atmospheric

pressure.

19. When the piston moves down, it

compresses the intake charge in crank

case. This pressure forces the

diaphragm in the forward direction. There by the fuel in front chamber of the diaphragm is

compressed, inlet valve closes & fuel is forced out to the pulsation chamber and through

outlet valve it goes to the float chamber of carburetor.

20. The carburetor is the metering device for mixing fuel and air. At the idling speed the

engine requires a mixture of about 8 parts of air to 1 part of fuel. At high speed the mixture

ratio is about 12:1. A throttle valve controls the volume of air fuel mixture in to the engine. A

chock valve is placed behind the throttle valve to cater for a rich mixture for starting of the

engine.


Cooling System

21. Cooling system consists of the following components:

a. Water pump

b. Thermostat

c. Water manifold

22. The water pump is located at the top

of the gear case and is driven directly by the

drive shaft. The pump has a rubber impeller.

The cooling system consists of one warning

nipple and one thermostat.

23. Warning nipple is for monitoring

whether the cooling system is functioning

properly or not. If water does not come

through the warning nipple immediately after

starting the motor, at once stop the engine

and rectify the defect. It is prohibited to run

the OBM when water pump is not working.

Thermostat functions at 45°C to 60°C.

Gear Box Construction

24. The gear box consists of one bevel

pinion and two drive gears. The engine

power is transmitted to the propeller

through the bevel pinion and drive gears.

The two drive gears are mounted on the

propeller shaft and are supported on

bearings. A dog clutch mechanism is

adopted to engage the desired gear with

the propeller shaft so as to rotate the

propeller gear shifting lever is provided to

shift the gears for ahead or astern

direction.

25. The bevel pinion and drive gear

teeth ratio is to increase the power at propeller. The propeller is mounted on the splined

propeller shaft. There are double oil seals to prevent oil leakage at the shaft ends.


Classification of OBM’s

26. An OBM can divide in to 03 parts as per the construction.

a. Short tail Centre part of the OBM is short. These kind of OBM‟s are

using for light crafts (Eg. RFD‟s). These OBM‟S are using for shallow water

operations.

b. Long tail Centre part of the machine is longer than short tail OBM‟s.

c. Extra-long tail Mid-section of the machine is longer than long tail

OBM‟s, using for deep sea operations.

27. Types of OBM’s using in SLN

a. Johnson

b. Yamaha

c. Suzuki

d. Evinrude

e. Mariner

f. Mercury

28. Starting Procedure

a. Check the Engine weather it is properly installed.

b. Check the fuel line and fuel level.

c. Ensure oil is mixed with fuel in correct ratio.

d. Check the Engine for any disturbances.

e. Check the propeller blades for any damages.

f. Keep the gear leaver in Neutral position

g. Keep the throttle handle in Start position.

h. Keep the switch at correct position.

29. Points to be checked when started

a. Check the cooling system.

b. Check for any abnormal sounds or vibration.

chapter 01 structure and organization of...

Documents