Author Archives: Engr. Shafiul Bari

About Engr. Shafiul Bari

Shafiul Bari is a seasoned Marine Engineer with extensive experience in ship design, maintenance, and marine propulsion systems. With a deep technical knowledge of ship engineering and a passion for advancing maritime technology, Shafiul shares practical insights and expert advice to help marine professionals and enthusiasts better understand the complexities of ship systems. Through his website, he aims to bridge the gap between technical theory and real-world application, fostering a community of informed and skilled maritime engineers. When not immersed in ship engines and technical manuals, Shafiul enjoys exploring the latest innovations in marine technology and mentoring aspiring marine engineers.

Desirable Properties of Marine Refrigerants

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Desirable Properties of Marine Refrigerants

When selecting refrigerants for shipboard use, the following properties are considered ideal:

  • Low Specific Volume: Reduces the size requirements for compressors and piping.
  • High Critical Temperature: Allows condensation at higher temperatures, which is beneficial in varying marine climate.
  • High Latent Heat of Vaporization: Ensures efficient heat absorption during the evaporation process.
  • Chemical Stability: Resists decomposition under operating conditions.
  • Environmental Friendliness: Low ODP and GWP values are preferred to minimize ecological impact.
  • Non-Corrosive: Prevents damage to system components.
  • Non-Flammable and Non-Explosive: Enhances safety aboard ships.
  • Compatibility with Lubricants and Materials: Ensures smooth operation and longevity of the system.
  • Easy Leak Detection: Facilitates maintenance and prevents environmental harm.

Key Refrigerant Properties Comparison

Refrigerant ODP GWP Pressure Level Flammability Typical Use
R-134a 0 1,430 Medium Non-flammable Marine AC
R-404A 0 3,922 High Non-flammable Freezers
R-407C 0 1,774 Medium-High Non-flammable AC/Refrigeration
R-410A 0 2,088 Very High Non-flammable High-efficiency AC
-744 (CO2) 0 1 Extremely High Non-flammable Eco-friendly systems

Note: The critical temperature of a substance is the highest temperature at which it can exist as a liquid, regardless of the pressure applied. Above this temperature, the substance cannot be liquefied by pressure alone and will exhibit properties of both gases and liquids.

 

MPA Singapore Approved Class

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MPA approved class

The Maritime and Port Authority of Singapore (MPA) has authorized the following eight classification societies to act as Recognized Organizations (ROs). These societies are empowered to perform statutory surveys, certifications, and audits on behalf of the Singapore flag administration for vessels registered under the Singapore Registry of Ships (SRS).

MPA-Approved Classification Societies:

1.      American Bureau of Shipping (ABS)

2.      Bureau Veritas (BV)

3.      China Classification Society (CCS)

4.      Det Norske Veritas (DNV)

5.      Korean Register of Shipping (KR)

6.      Lloyd’s Register (LR)

7.      Nippon Kaiji Kyokai (ClassNK)

8.    Registro Italiano Navale (RINA)

These classification societies are also designated as Recognized Security Organizations (RSOs), authorized to conduct security assessments and issue International Ship Security Certificates (ISSC) in accordance with the International Ship and Port Facility Security (ISPS) Code.

 

Certificates and supplements required to carry on board.

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What are the certificates and supplements required to carry on board.

MARPOL

1.      International Oil Pollution Prevention Certificate MARPOL Annex I Supplement:

Record of Construction and Equipment for Ships Other Than Oil Tankers (Form A) or Record of Construction and Equipment for Oil Tankers (Form B

2.      International Pollution Prevention Certificate for the Carriage of Noxious Liquid Substances in Bulk (NLS Certificate) MARPOL Annex II

3.      International Sewage Pollution Prevention Certificate MARPOL Annex IV, reg

Supplement:

•         Description of sewage treatment plant or holding tank system

•         document of approval for the rate of sewage discharge.

4.      Garbage Management Plan MARPOL Annex V, reg 10

5.      International Air Pollution Prevention Certificate MARPOL Annex VI

Supplement:

•         Technical details of engines and equipment for NOx, SOx, and particulate matter control

•         EIAPP Certificate (Engine-specific NOx certificate) may also accompany

6.        International Energy Efficiency Certificate MARPOL Annex VI,- validity lifetime

Suppliment: seemp

7.        International Ballast Water Management Certificate; BWM convention

•         Supplement:

•         Ballast Water Management Plan and system details

SOLAS

1.              Passenger ship safety certificate SOLAS 1974, supplement: form P

2.              Special Trade Passenger Ship Safety Certificate

3.              Special Trade Passenger Ship Space Certificate STP 71, rule 5

4.              Cargo Ship Safety Certificate SOLAS 1988, reg I/12 supplement: form C

5.              Cargo Ship Safety Construction Certificate SOLAS 1974, regulation I/12

6.              Cargo Ship Safety Equipment Certificate SOLAS 1974, reg I/12 supplement:

•      Form E

•      Inventory of life-saving appliances, Radio installations and fire-fighting appliances

7.       Cargo Ship Safety Radio Certificate SOLAS 1974, reg I/12 supplement:

                                              Form R

8.      Document of authorization for the carriage of grain and grain loading manual SOLAS 1974, reg VI/19

9.      Document of compliance for ships carrying dangerous goods SOLAS chap 2 reg 19

Supplement:

                                  •    Types of dangerous goods permitted and safety measures in place

10.    Document of compliance SOLAS, ISM Code

11.    Safety management certificate SOLAS, ISM Code

12.    International Ship Security Certificate (ISSC) or Interim International Ship Security Certificate SOLAS 1974

Suppliment: SSP

13.    Continuous Synopsis record SOLAS

14.    Minimum safe manning document SOLAS

15.    Voyage data recorder system – certificate of compliance SOLAS 1974, reg 5

Other

1.               International Tonnage Certificate (1969); Tonnage convention – lifetime validity Supplement:

Details of gross and net tonnage calculations

2.               International Load Line Certificate; LL convention Supplement:

•      Freeboard assignment details

•      Conditions of assignment (closing appliances, machinery space openings, etc.)

2.  International Load Line Exemption Certificate ;LL Convention 4.        International Anti-fouling System Certificate ,AFS Convention

Supplemented: Record of Anti-fouling Systems,

5.       Declaration on antifouling system AFS Convention, reg 5 6.          Certificates for masters, officers or ratings STCW 7. MLC (Maritime Labor Convention) Certificate: supplements:

•      DMLC Part-1 (issued by Flag state)

•      DMLC Part-2 (issued by Company)

8.      International Certificate of Fitness for the Carriage of Dangerous Chemicals in Bulk IBC code

9.      International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk IGC Code

10.  Certificate of insurance or other financial security in respect of civil liability for oil pollution damage CLC 1969, article VII

11.  Certificate of insurance or other financial security in respect of civil liability for bunker oil pollution damage Bunker convention 2001

12.  Certificate of Registry

13.  Certificate of class

14.  P&I Certificate of Entry

A Supplementary Certificate for a Statutory Certificate is an additional document issued alongside a main statutory certificate to provide specific details or conditions not covered directly in the primary certificate.

 

Anti fouling System Convention

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Anti-Fouling Convention


Q. Anti Fouling Convention

The International Convention on the Control of Harmful Anti-Fouling Systems on Ships, commonly called the
Anti-Fouling Convention (AFS Convention), is an IMO treaty aimed at protecting the marine environment from the harmful effects of anti-fouling paints and coatings used on ships’ hulls.

●Purpose of the AFS Convention
  • Prohibit the use of harmful anti-fouling paints.
  • Ensure environmentally safe alternatives are used.
  • Prevent contamination of marine ecosystems and protect marine life.
Applies to
  • It applies to all ships of 400 gross tonnage and above engaged in international voyages, excluding fixed or floating platforms, FSUs, and FPSOs constructed before 1 January 2003 and not dry-docked since then.
  • Ships between 24 meters in length and 400 GT must carry a Declaration on Anti-fouling Systems confirming compliance.
📦What Are Anti-Fouling Systems?

Anti-fouling systems are coatings or paints applied to a ship’s hull to prevent the growth of:

  • Barnacles
  • Algae
  • Mollusks
  • Marine organisms

These organisms increase hull resistance, leading to:

  • Higher fuel consumption
  • Reduced speed
  • More emissions
⛔Harmful Substances Banned
  • Tributyltin (TBT): Banned from 1 Jan 2008. Highly toxic to marine life (e.g., causes imposex in snails).
  • Cybutryne (Irgarol 1051): Banned from 1 Jan 2023. Ships must remove or seal it by 60 months after entry into force (by 1 Jan 2028).
✎Compliant Anti-Fouling Systems

Modern anti-fouling systems include:

  • Biocide-free coatings
  • Silicone-based foul-release coatings
  • Copper oxide (Cu2O)-based (still allowed, though monitored)
  • Electrolytic and ultrasonic systems
📝Certification Requirements
  • International Anti-Fouling System Certificate (IAFSC)
  • Record of Anti-Fouling System

    • Describes type of system used
    • Must include evidence of compliance


Types of bulk carrier

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Bulk carrier ships are specialized merchant vessels designed to transport unpackaged bulk cargo such as grain, coal, ore, steel coils, and cement in their cargo holds. They come in various types and sizes, categorized mainly by their deadweight tonnage (DWT), dimensions, and operational design. Here is a detailed overview of the types of bulk carrier ships:

    • Capacity: 1,000 to 10,000 tons

    • Length: 100 to 130 meters

    • Draft: Less than 10 meters

    • Usage: Often used on rivers and for short international distances7.

    • Capacity: 15,000 to 40,000 DWT

    • Features: Can berth and operate in most ports worldwide due to smaller size and shallower draft

    • Usage: Versatile for various cargoes and routes17.

    • Handymax Capacity: 40,000 to 50,000 DWT

    • Supramax Capacity: Up to 60,000 DWT

    • Length: Around 150–200 meters

    • Features: Equipped with cranes for self-loading/unloading; suitable for longer voyages and diverse cargoes

    • Usage: Popular for transporting coal, grain, cement, steel, fertilizer, and more

    • Capacity: 65,000 to 89,999 DWT

    • Dimensions: Designed to fit the old Panama Canal locks

    • Usage: Common for iron ore, grain, and coal transport; can access many global ports

    • Capacity: 80,000 to 200,000 DWT (commonly 130,000 to 170,000 DWT)

    • Length: Approximately 230 to 290 meters

    • Draft: Around 17 to 18 meters

    • Features: Too large for Panama and Suez Canals; must navigate around Cape Horn or Cape of Good Hope

    • Usage: Mainly for coal, ore, and other raw commodities; includes subtypes like Very Large Ore Carriers (VLOC) and Very Large Bulk Carriers (VLBC)

    • Capacity: 180,000 to 400,000 DWT

    • Length: Up to 360 meters

    • Draft: 20 meters or more

    • Usage: Specialized for iron ore transport, especially on routes between Brazil, Europe, and Asia; Valemax is a specific class owned by Vale mining company

    • Capacity: Up to 400,000 DWT

    • Length: About 360 meters

    • Width: 65 meters

    • Draft: 25 meters

    • Usage: Largest bulk carriers designed for Asia-Europe routes; capable of passing through the Strait of Malacca and Suez Canal with suitable infrastructure

    • : Largest vessel able to transit the Suez Canal with draft limits around 18.9 meters (planned increase to 21.95 meters)

    • : Largest vessel for St Lawrence Seaway locks (max 226 m length, 7.92 m draft)

    • : Largest vessel passing through the Strait of Malacca (~330 m length, 20 m draft)

    • : Maximum size for ports in the Setouch Sea, Japan

    • : Max beam 45 m for Dunkirk harbor lock

    • : Max size for port Kamsar, Equatorial Guinea

    • : Usually Capesize, max beam 47 m for Newcastle port2.

    • Equipped with hatch covers and their own cranes for loading/unloading

    • Number of holds varies with size (5 to 9 holds)

    • Can carry multiple cargo types and operate worldwide4.

    • Designed to carry both bulk cargo and oil

    • Feature pipelines and pontoons on deck

    • More expensive and specialized4.

    • Depend on port facilities for loading/unloading

    • Typically larger vessels designed for high-volume cargoes1.

    • Equipped with conveyor belts or other mechanisms to unload cargo without shore equipment

    • Useful in ports lacking infrastructure4.

Type DWT Range Length (m) Draft (m) Key Features/Usage
Mini Bulk 1,000 – 10,000 100 – 130 <10 River/short international trade
Handysize 15,000 – 40,000 Variable Shallower draft Versatile, most ports accessible
Handymax 40,000 – 50,000 150 – 200 Moderate Equipped with cranes, diverse cargo
Supramax Up to 60,000 ~190 Moderate Larger handy class, long-distance trade
Panamax 65,000 – 89,999 ~230 ~12 – 16 Fits Panama Canal, common bulk cargo
Capesize 80,000 – 200,000 230 – 290 ~17 – 18 Too large for canals, coal/ore transport
VLBC/Valemax 180,000 – 400,000 Up to 360 20+ Very large ore carriers, specialized routes
Chinamax Up to 400,000 ~360 25 Largest bulk carriers, Asia-Europe routes

This classification helps in understanding the operational scope, cargo capacity, and port accessibility of bulk carriers in global maritime trade

In conclusion, bulk carriers are classified by size (from mini to Chinamax), by design (conventional, combined, gearless, self-discharging), and by their ability to navigate specific waterways or ports (Panamax, Suezmax, etc.), reflecting their diverse roles in transporting dry bulk commodities worldwide.

Differences between MC/MC-C and ME/ME-C engines

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The electrohydraulic control mechanisms of the ME engine replace the following components of the conventional MC engine:

  • Chain drive for camshaft
  • Camshaft with fuel cams, exhaust cams and indicator cams
  • Fuel pump actuating gear, includiismng roller guides and reversing mechanism
  • Conventional fuel pressure booster and VIT system
  • Exhaust valve actuating gear and roller guides
  • Engine driven starting air distributor
  • Electronic governor with actuator
  • Regulating shaft
  • Engine side control console
  • Mechanical cylinder lubricators.

The Engine Control System of the ME engine comprises:

  • Control units
  • Hydraulic power supply unit
  • Hydraulic cylinder units, including:
    • Electronically controlled fuel injection, and
    • Electronically controlled exhaust valve activation
    • Electronically controlled starting air valves
    • Electronically controlled auxiliary blowers
    • Integrated electronic governor functions
    • Electronically controlled Alpha lubricators

     

    types of Marine Oxygen Analysers:

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    .oa .o2 analyser .oxygen analyzer .oxygen analyser

    Regardless of the type of inert gas system – flue gas system, inert gas generator, nitrogen generator, etc – the data from oxygen analyzers ensures that the oxygen level of the product gas fulfils the required setting (typically 5% or less), which is the safety requirement to prevent cargo explosions. It also monitors the fuel to air ratio during combustion, which can be used to attain combustion and boiler efficiency.

    There are three main types of marine oxygen analyzers available:

    Zirconia Oxygen Analyzers

    The main components of zirconia oxygen analyzers are a zirconia tube, porous platinum electrodes, and a DC voltmeter.

    The platinum electrodes are both on the inner and outer side of the zirconia tube. One – either the inner or outer – side of the tube is in contact with the process/sample gas while the other is exposed to the surrounding air for reference. Because of the difference in concentrations of both gases, oxygen makes its way through the electrodes and tube from the more concentrated side to the less concentrated. During this process, the platinum acts as a catalyst by helping oxygen molecules to split into ions, allowing them to pass through the zirconia.

    The DC voltmeter is then attached to the inner and outer electrodes for a potential difference reading. This measurement lets the analyzer accurately display the oxygen concentration in the gas being tested.

    One of the main benefits of the zirconia oxygen analyzer is that it doesn’t require a sealed reference gas, which means that it can be utilized in any environment, even those with high temperatures and pressures. This is because instead of directly measuring the concentration of gas, it measures the partial pressure of the oxygen in a sample.

    However, one major disadvantage of the system is that the temperature within the analyzer needs to be high for the oxidation process to occur. This causes changes in the sample gas temperature and high power consumption.

    Galvanic Oxygen Analyzers

    Galvanic oxygen analyzers are fuel cell based and thus involve an anode, often lead (Pb), and a cathode, often silver (Ag), reaction, similar to a battery. Both the anode and cathode are in an electrolyte solution of potassium chloreate. The cell contains a  Teflon membrane that allows the oxygen to penetrate and gain the electrons emitted by the anode at the cathode, proportional to the rate of oxygen pressure. 

    The flow of electrons from this process creates a current that is proportional to the oxygen concentration, resulting in an oxygen measurement.

    This type of oxygen analyzer is low cost and accurate within 0.1% of its oxygen percentage display, detecting any oxygen level from 0% to 100%. It is also very compact and doesn’t require any external power as the reaction it uses naturally occurs.

    Paramagnetic Oxygen Analyzers

    These types of oxygen analyzers make use of magnetic fields to measure oxygen levels. Because oxygen molecules are attracted by magnetic fields, as the gas being tested passes through this field, its rate of flow is impacted in proportion to the level of oxygen in the gas. This rate is then used to calculate the amount of oxygen present.

    The device can detect oxygen levels from 0.5% to 100%. Though these analyzers are relatively uncommon, they are very stable and aren’t impacted by mechanical shock. Still, an issue with paramagnetic analyzers is that their readings can be affected by other gases that may mix with the test sample.

    Aft End Structure:

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    .aft structure .aft end structure .aftend structure .aft end construction .aft construction   .aec

    Considerable attention is paid to the overall design of the stern in order to improve flow into and away from the propeller. There are two types of stern. Cruiser stern, Transom stern. Cruiser stern used previously, but today most of these vessels have a transom stern. A cruiser stern presents a more pleasant profile and is hydrodynamically efficient, but the transom stern offers a greater deck area aft, is a simpler construction, and can also provide improved flow around the stern. Many forms of rudder are available, depending on the manoeuvering needs. Both the shape of the stern and the rudder type will determine the form of the stern frame, and this will be further influenced by the required propeller size. The propeller shaft and the rudder stock  pierce the intact watertight hull, so particular attention should be given. The safety of the ship may depend on these arrangements.

    Stern Construction:

    .Stern Construction

    Flat stern plating stiffened with vertical stiffeners. Deep floors and a centre line girder are provided at the lower region of the transom stern construction. Panting arrangements at the aft end are provided.

    Stern Frame

    .stern frame construction   .sfc

    The form of the stern frame is influenced by the stern profile and rudder type. To prevent serious vibration at the after end there must be adequate clearances between the propeller and stern frame, and this determines its overall size.

    The stern frame of a ship may be cast, forged, or fabricated from steel plate and sections. On larger ships it is generally either cast or fabricated,
    the casting done by a specialist works outside the shipyard. Larger stern frames cant be casted easily due to its bigger size. Also the transportation is a problem .So it may be cast in more than one piece and then welded together after bringing the pieces to the shipyard. Fabricated stern frames are produced by the shipyard itself, plates and bars being welded together to produce the stern frame.

     Forged stern frames are also produced by a specialist manufacturer. And may also be made in more than one piece where the size is excessively large or shape is complicated. Sternpost sections are made streamlined form, in order to prevent eddies being formed behind the posts. Eddies can lead to an increase in the hull resistance.

    Welded joints in cast steel sections will need careful preparation and preheating. Both the cast and fabricated sections are supported by horizontal webs. The connection of the stern frame to the hull structure is very important, the rotating propeller supported by the stern frame may set up serious vibrations. The rudder post is carried up into the main hull and connected to the transom floor which has an increased plate thickness. Also the propeller post may be extended into the hull and connected to a deep floor, the lower sole piece is carried forward and connected to the keel plate. Side shell plates are directly welded to the stern frame.

    Fore end structure: FWD Construction, Forward Construction

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    .FWD Construction .forward construction .fwdc .fore end construction

    • FWD construction is forward of the collision bulkhead.
    • The chain locker is included as it is usually fitted forward of the collision bulkhead below the second deck or upper deck, or in the forecastle itself
    • On the forecastle deck the heavy windlass seating is securely fastened and given considerable support. The deck plating thickness is increased locally, and smaller pillars with heavier beams and a centre line pillar bulkhead, may be fitted below the windlass.

    Stem

    • On many conventional ships a stem bar, which is a solid round bar, is fitted from the keel to the waterline region, and a radiused plate is fitted above the waterline to form the upper part of the stem.
    • This forms a ‘soft nose’ stem, which in the event of a collision will buckle under load, keeping the impact damage to a minimum.
    • The solid round bar is welded inside the keel plate at its lower end, and inside the radiused stem plate at its upper end,
    • the shell is welded each side to the radiused plate.
    • breast hooks’ is used to support that part of the stem which is formed by radiused plates between the decks and below the lowest deck, to reduce the unsupported span of the stem.
    • Panting stringer provided to counteract the panting stress. Panting stringer are triangular shape. Panting stringer are situated 2 meter above the keel and every 2 meter apart one panting stringer is fitted.
    • Where the plate radius is large, further stiffening is provided by a vertical stiffener on the centre line.
    • The thickness of these plates is greater than the forward side shell, but the thickness may taper near the side shell at the stem head.

    Floors and Different Types of Floors

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       Unlike structures on land where a floor refers to something horizontal that you can stand on, floors on ships are the transverse stiffeners mounted vertically on the ship’s bottom. Floor structure is continuous from the centre to the side plating and supports the inner shell (tank top). They may either be solid plates (no cut holes except small half round drain holes at the bottom part) or plates with cut lightening holes.

    Solid Floors

     It is the easiest to comprehend, and consists of a solid plate, with no lightening holes cut into it (they lessen the weight of the plate and allow for the free flow of any liquids stored in the space). Normally it form a tank, below watertight bulkheads these floors are using

    Plate Floor

    Plate Floor is the one if the stiffener / floor plate is made of a solid plate with openings. This is done to optimize weight and also to allow free flow of fluids based on the purpose of the floor plate / part of the ship (Like a tank)

    Bracket Floor

    Bracket floor is the one if the stiffener / floor plate is made of a built-up section with a large opening. This is also done to optimize the weight, provided where much strength / structural integrity is not required and also on the purpose of the area of the ship

    Ship floor:

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    .ship floor .ship floor .floor construction .plate floor

    Ship floor construction:

    Double bottom, transversely framed floor construction:

    →this type of floor construction used in ships of length less than 120 meters.

    →Vertical transverse plate floors are provided both where the bottom is transversely and longitudinally framed.

    →Watertight and oiltight plate floors are provided → At the ends of bottom tank spaces and under the main bulkheads

    → These are made watertight or oiltight by closing any holes in the plate floor and welding collars around any members which pass through the floors.

    →The bracket floors form the transverse stiffeners at every frame, and

    →solid plate floors are used at every 3 to 4 frame space, or 1.8 meters intervals, to strengthen the bottom transversely and support the inner bottom

    → intercostal side girders

    → run longitudinally fastening the transverse members of the floor,

    → it reduces the span of the plates.

    →Side girders are continuous members,

    →where there is an intersection between a plate floor and a side girder,

    →the plate floor is cut and welded on both the sides of the girder

    → it is done to reduce the span of the plate floors,

    → the girders will act as supporting members to the plate floors.

    → Keels are flat plated.

    →Intercostal girders or side girders, and plate floors

    → will have lightning holes at regular intervals to reduce the structural weight and

    →will have flanged manholes to provide access.

    → Plate floors have drain holes to help drainage of liquids.

    →Plate floors are

    →further stiffened by flat bar stiffeners, and bracket floors, by angle struts to prevent warping.

    In Water Survey:

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    .in water survey .inwater survey .iws


    It is an examination of ship’s underwater portion & fittings of the hull instead of intermediate dry docking.

    It is carried out by a team of qualified divers employed by a firm, which is approved by the classification society.
    IWS survey is to provide the information normally obtained from a docking survey, so far as practicable.

    The class will accept an IWS in lieu of the intermediate docking between special surveys required in a five-year period.

    IWS notation: in water survey.

    IWS notation is a must before conducting. If the vessel has an IWS already, the condition of the high resistant paint is to be confirmed to maintain the notation.
    If the vessel needs IWS notation to be assigned by the class, plans & means are to be provided for ascertaining:
    → the rudder pintle & bush clearances to verify the security of the pintles in their sockets with the vessel afloat.
    → The clearance in the stern bush with the vessel afloat.

    Eligibility of ship for IWS:
    (1) Age of the ship not greater than 15 years.
    (2) Ships are not subjected to ESP.
    (3) Ships must have class IWS notation.
    (4) High quality paint coating for (7.5 years) extended dry docking.
    (5) Ships must be fitted with effective ICCP & ECCP.
    (6) Access arrangements for sea v/v, rudder bearing & pintle clearance
    (7) Stern tube wear down measurement, bow & stern thruster sealing checking arrangements.

    Preparation:
    (1) Application to classification society’s ship-safety division for an IWS program.
    (2) Approval from the class for IWS.
    (3) Appoint a diving company approved by the class.
    (4) Meeting & agreement between owner, surveyor & diving firm about the equipment & procedures for both observing & reporting the survey.
    (5) A copy of plans showing the hull & attachments below the water line should be provided to both surveyor & diving firm. One copy retained onboard.
    (6) Class (Ship safety office) should be informed about the date, time & location of the survey.

    Documents to be prepared by C/E before survey:


    (1) IWS notation
    (2) Permission for IWS
    (3) Risk assessment
    (4) Diving checklist fill up
    (5) Last DD reports (maintenance & hull painting)
    (6) Propeller report
    (7) Stern tube report
    (8) Rudder clearance report
    (9) Last stern tube L.O. analysis Lab report
    (10) Reports on anti-fouling system
    (11) Anode plan
    (12) Statement related damaged condition.

    Safeties:
    (1) Ship is safely anchored (Preferred weather with min current).
    (2) Weather forecast good & suitable for next 3 days.
    (3) Toolbox meeting carried out; ship’s crew must be well informed about survey. Risk assessment done.
    (4) Lock out, tag out of the main propulsion system. T/G engaged.
    (5) Steering Gear motor power should be switch off and lock out, tag out for no rudder movement
    (6) Bow & stern thruster same power off & LOTO.
    (7) ICCP & MGPS power off.
    (8) No discharge during survey
    (9) Good underwater visibility
    (10) Diving company pre-dive to confirm cleanliness of hull, rudder, propeller & chest gratings.
    (11) Sea chest suction notified in E/R & ready to change over as per diver’s request.

    During Survey:


    (1) Diving supervisor, ship’s representative (C/E or master), and surveyor should gather @ CCTV station.
    (2) A good two-way communication between divers & surveyor should be provided.
    (3) Surveyor should be satisfied by the pictorial presentation of the divers
    (4) Inspection area →


    (i) Hull condition from fwd to aft
    (ii) Hull painting condition
    (iii) Any damage, corrosion, deformation of hull
    (iv) All underwater hull marking
    (v) Bilge Keel condition
    (vi) Sea chest condition
    (vii) S/T seal condition, clearance & wear down of S/T bearing measurement.
    (viii) Propeller condition & propeller nut
    (ix) Rudder bearing clearance, intact pintle bearing.


    (5) Audio video recording of whole survey.

    Reports:


    Diver’s reports with colored photographs & video recordings should be provided to surveyor, ship safety headquarters (classification society), Owner, and one copy should be readily kept onboard.
    S/T bearing clearance & rudder carrier bearing clearance report should be verified by the maker’s reading.

    If the IWS reveals damage or deterioration that requires early attention, the surveyor may require that ship to be dry docked. So that a detailed survey can be undertaken & necessary repairs carried out.

    After IWS:
    (1) Confirm all divers are out of water
    (2) Diver supervisor to confirm approval to remove LOTO.
    (3) Diver boat cast off.
    (4) C/E prepare M/E ready.

    Drydocking Preparation and Procedure for Chief Engineers

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    .drydock for chief engineer

    Pre-Drydock Planning (3-6 months before)

    1. Review classification society requirements and survey status
      • Identify due surveys and inspections
      • Note any outstanding conditions of class
    2. Prepare comprehensive repair specification
      • Review previous drydock reports
      • Compile defect list from ship staff reports
      • Include planned maintenance items
      • Add statutory/class requirements
    3. Coordinate with superintendent
      • Finalize repair specification
      • Discuss budget and timeline
      • Arrange for spare parts and specialist services
    4. Prepare vessel
      • Plan tank cleaning and gas freeing (for tankers)
      • Arrange for riding crew if needed
      • Review stability and trim requirements

    Mechanical and Structural Preparation

    1. Hull and structure
      • Inspect hull, identify areas needing repair
      • Check for corrosion, cracks, deformation
      • Measure hull thickness if required
    2. Propulsion system
      • Inspect propeller, shaft, stern tube
      • Check rudder clearances
      • Plan any overhauls of main engine, gearbox
    3. Auxiliary machinery
      • Inspect sea overboard valves, sea chests, anodes.
      • Check the condition of heat exchangers.
      • Plan overhauls of pumps, compressors etc.

    Documentation and Safety

    1. Compile necessary documents
      • Classification certificates
      • Previous survey reports
      • Machinery history and manuals
    2. Safety preparations
      • Review yard safety procedures
      • Brief crew on safety precautions
      • Check firefighting and lifesaving equipment
    3. Environmental considerations
      • Plan for proper disposal of sludge, bilge water
      • Arrange for shore reception facilities if needed (for scrap metals

    Drydock Entry Procedure

    1. Pre-arrival checks
      • Change over to MDO/MGO fuel
      • Secure all overboard discharges (4E)
      • Prepare for shore power connection (ETO)
    2. Docking process
      • Coordinate with pilot and dockmaster
      • Monitor vessel’s position on blocks
      • Connect shore services (power, water, etc.)
    3. Initial inspections
      • Conduct underwater hull inspection
      • Check propeller, rudder, sea chests
      • Mark areas for repair/maintenance

    During Drydock Period

    1. Daily routines
      • Attend yard meetings
      • Supervise ongoing work
      • Liaise with class surveyors
    2. Key responsibilities
      • Monitor work progress against schedule
      • Approve any additional work
      • Ensure quality control of repairs
    3. Testing and trials
      • Oversee pressure tests of valves/pipes
      • Conduct sea trials if major work done
      • Verify all systems operational before undocking

    Undocking and Post-Drydock

    1. Final checks
      • Ensure all work completed satisfactorily
      • Obtain class and statutory certificates
      • Close out all repair items
    2. Undocking procedure
      • Prepare vessel for refloating
      • Monitor vessel condition during undocking
      • Conduct alongside trials
    3. Documentation
      • Complete drydock report
      • Update vessel’s maintenance records
      • Plan follow-up actions if needed

    By covering these key areas, a Chief Engineer demonstrates comprehensive understanding of the drydocking process, from preparation through completion, showcasing the technical and managerial skills required for this critical aspect of vessel maintenance.

    Dry Dock

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    .dry dock preparation .drydock  .ddp .drydock preparation

    Dry Dock Preparation: Drydock prep

    The main objective in carrying out dry docking is to ensure ships are operational and to maintain their class license. Structural machinery and various components are subjected to inspection and maintenance to ensure sea worthiness. Dry docking is also required if a ship has sustained damage to the underwater structure due to grounding, collision or any other damage which will affect the water integrity of the ship’s hull.

    Preparation for Dry Docking

    Planning:

    1. To brief engine room staffs before docking and ensure they understand their respective duties.
    2. Preparation of machinery survey in dry dock
    3. Preparation of dry dock list.
    4. Study previous dry dock reports and note clearance to be measured.
    5. Ensure all tools and spares are ready for use.
    6.  Prepare necessary spares and store, drawings, Manuals, Certificates, special tools and measuring equipment.
    7. Safety meeting to be carried out.

    As a second engineer

    1. Make a repair and maintenance list, create or obtain a dry-dock handbook if required, and assign responsible ship staff to their duties on the list. Divide staff into groups to observe the work carried out by yard gangs.
    2. All spare parts must be checked, and repair items kept ready for use.
    3. Previous dry dock reports should be studied, and previous clearance measures noted.
    4. Clean engine room tank top and bilges.
    5. Prepare sewage treatment tanks, dirty oil tanks and bilge tanks.
    6. Flushing of bilge lines is to be carried out prior to dry dock.
    7. For tankers, all cargo tanks are cleaned and gas freed.
    8. Minimum bunkers (Fuel Oil and Fresh water) and ballast carried
    9. All tanks and cofferdams must be sounded and recorded.
    10. The oil-water separator filter element should be renewed, and the system checked for satisfactory operation.
    11. Fill up Settling and Service Tanks.
    12.  Press up Air Bottles and Emergency Air Bottle and shut the valves tightly.
    13.  ME crankshaft deflections to be taken and recorded.
    14. All heavy weights secured prior to dry dock.
    15. Firefighting plans and safety measures discussed before dry dock
    16. Firefighting equipment on board should be checked and kept ready for use.
    17. Emergency lighting and generator should be tested before entry.
    18. Escape routes must be clearly marked.
    19. All valves and sea chests to be overhauled must be clearly marked.
    20. Shore connections for cooling water and fire line are to be readied.
    21. Main engine, generators, and boiler are changed over to diesel oil.
    22. CO2 total flooding systems are secured and locked before entry.
    23. Vessel must approach dock with even keel.

    Trouble/Damage if Dry Docking is Unprepared:

    1. Dangerous confusion if no proper defects list is made and staff not briefed.
    2. Explosion hazards when hot work is done on a tank not emptied of volatile substances.
    3. Engine room bilges may become fire hazards if not cleaned.
    4. If spares are not checked, arranged properly, work will be delayed due to time wasted finding or waiting orders.
    5. Leakage due to draining must be pumped to the empty drain/bilge tanks if not empty prior to dry dock.
    6. Extra unplanned work needed in shore reception required in dry dock costs time and money.
    7. Wrong frequency and power supply information given to dry dock will cause machinery to overheat and eventually fail.

    Procedures Adopted to Ensure Safety During Dry Dock:

    1. Firefighting equipment ready at all times.
    2. Fire detectors and fire alarm in good working condition.
    3. Fire officer at site of work and extinguishers available.
    4. Fire line is always ready with 2 hydrants open if no hull work is carried out.
    5. CO2 total flooding system door is locked to prevent accidental actuation.
    6. Acetylene and oxygen bottles are properly stored and secured.
    7. Proper working permits obtained before carrying any work on board; e.g. hot work permit, enclosed space entry permit.
    8. Safety gear worn while working- safety shoes, helmet, overalls, safety goggles, ear mufflers, and gloves.
    9. All lifting gears checked to be in good working condition.
    10. Safety lamps are used – never use a naked lamp.
    11. Escape routes should be clearly marked.
    12. Co-ordination of work, so no chemical cleaning and hot work around boiler area is done at the same time.
    13. No transfer of oil carried out in dry dock.
    14. No boiler blow downs; in emergency, necessary notice given.
    15. No unauthorized personnel or chemicals allowed on board.
    16. Ship properly grounded to shore earth.
    17. Safety meetings should be carried out every morning before stating the work in dry dock.

    During Docking:

    1. Discuss with the superintendent and dockyard repair manager about repair jobs.
    2. Assist Surveyor and record the survey items.
    3. Witness all alignment works and clearance measurements.
    4. Take and record propeller shaft wear down, rudder wear down and jumping clearance.
    5. Check oil tightness of stern tube.
    6. Check all completed underwater jobs, done by dockyard.
    7.  Check all sea valves, shipside valves and cocks, after overhauling.
    8. Check all repaired jobs done by ship staff, and used spares and store.
    9. Make daily records.

    Undocking:

    1. Check all repair and underwater jobs in accordance with repair list.
    2.  Check all measurement data are correct and completed. Make price negotiation.
    3. When sea water level covers the sea chest, each sea valve should be opened and checked for any leakage.
    4. Test run the ship generators, until satisfactory, and cut out shore supply, cut in ship generator, disconnect the shore connection, restart seawater pump, record the time and read watt meter.
    5. Purge air from cooling seawater pumps, run the pumps and check pressure.
    6. Prepare for ME.
    7. All sea valves, shipside valves, repaired pipes, repaired jobs must be finally checked, before leaving the dock.  
    8.  All DB tank soundings checked.  

    After Leaving the Dock.

    1. checked ME crankshaft deflection and compare with former record.
    2. Prepare for Docking Report.

    2/E should be instructed to perform the followings:  

    a) Label all sea valves, all shipside valves and cocks. Mark the positions of items to be repaired, with tags or color code.

    b) Keep Emergency Fire Pump, Emergency Generator, Air Compressors, Emergency Air Bottle, and portable Fire Extinguishers in good order.

    C) Lock Fixed Fire Fighting Installation, as per shipyard rules.

    d) Shut down Boiler, OWS, and Sewage Plant if dockyard does not allow.

    e) Lock overboard discharge valve in closed position.

    f) Fill up Settling and Service Tanks.

    g) Press up Air Bottles and Emergency Air Bottle, and shut the valves tightly.

    h) ME crankshaft deflections to be taken and recorded.

    I) Hose down tank tops, and empty Bilge Holding Tank, Sludge Tank, Waste Oil Tank.

    j) Prepare for receiving of Shore Power Supply, International Shore Connection, cooling arrangement for Air Conditioning and Provision Plants.

    k) Provide fire watch in ER at all times, and follow Dockyard Fire and Safety Regulations.

    l) Adjust required trim and draught, with deck officer.

    m) Take soundings of DB tanks and cofferdam. 

    Stresses in Ships

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    Stresses in Ships

    .stresses in ship    .stress on ship    .stress in ship    .stresses on ship

    A ship at sea is subjected to a number of forces causing the structure to distort. Initially, these may be divided into two categories, as follows:

    Static forces –

     Ship floating at rest in still water.

    Two major forces acting:

    • the weight of the ship acting vertically down
    • buoyancy acting up

    Dynamic forces – 

    due to the motion of the ship and the sea the structural stresses, caused by the above forces, to which the ship structure is subjected may be categorized as:

    1. Longitudinal stresses (hogging and sagging)
    2. Transverse stresses (racking and the effects of water pressure)
    3.  Local dynamic stresses (panting and pounding)

    Longitudinal Stress

    • The forces are two in number, the weight of the ship and all that it carries acting downwards and the vertical component of the hydrostatic pressure.
    • Depending upon the direction in which the bending moment acts the ship will Hog or Sag.
    Hogging
    • If the buoyancy amidships exceed the weight due to loading or when the wave crest is amidships, the ship will Hog, as a beam supported at mid length and loaded at the end.

    Sagging

    • If the weight amidships exceed the buoyancy or when the wave trough amidships the ship will sag, as a beam supported at a ends and loaded at mid length.

    TRANSVERSE STRESSES

    Racking

    When a ship is rolling in a seaway or is struck by beam waves, the ship’s structure is liable to distort in a transverse direction as shown.

    Water Pressure

    Water pressure acts perpendicular to the shell of the ship, increasing with depth. The effect is to push the ship’s sides in and the bottom up. It is resisted by frames, bulkheads, floor and girders.

    LOCAL DYNAMIC STRESSES

     

    The dynamic effects arise from the motion of the ship itself. A ship among waves as three linear motions.

    1. Surging: The forward and aft linear motion (along x) of a ship is called surging.
    2. Heaving: The vertical up and down linear motion (along y) of a ship is called heaving.
    3. Swaying: The side to side linear motion (along z) of a ship is called swaying.
    4. Rolling: The rotational motion of a ship about longitudinal axis is called rolling.
    5. Yawing: The rotational motion of a ship about vertical axis is called yawing.
    6. Pitching: The rotational motion of a ship about transverse axis is called pitching.

    When the ship motions are large particularly in pitching and heaving, considerable dynamic forces can be created in the structure.

    Panting

    .panting

    As wave passes along the ship, they cause fluctuation in water pressure which tends to create in and out movement of the shell plating This in and out movement is called panting.

    This is particularly the case at the fore end. The rules of the classification societies required extra stiffening, at the end of the ship, in the form of beams, brackets, stringer plate, etc. in order to reduce the possibility of damage.

    Slamming or Pounding

    .pounding

    In heavy weather when the ship is heaving and pitching the bows often lift clear of the water and then slam down heavily onto the sea, which is called pounding.

    Extra stiffening require at the fore end to reduce the possibility of damage.

     

    Single Phasing

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    .Single Phasing

    Causes:
    (1) Due to loose connection in any one phase of the supply system.
    (2) Due to loose connection in any one phase of the motor terminal.
    (3) Due to open circuit in any one phase of the supply system.
    (4) Due to open circuit in any one phase of the motor winding.
    (5) Due to short circuit in one phase of the star connected or delta connected motor.
    (6) Due to equipment failure of supply system.
    (7) One or more, out of the 3 back up fuse blows or fuse wire melts (if the fuse is of wire type)
    (8) A wrong or improper setting of any other protection devices provided on the motor can also lead to single phasing.

    How to detect:
    (1) Unusual humming noise coming from the motor.
    (2) The motor is vibrating at a higher frequency than usual.
    (3) The smell of hot or burnt copper
    (4) Visible light smoke & fumes from motor casing.
    (5) Higher amperage of the motor

    Effects:
    (1) If the motor is in stopped condition, it can’t be started due to single phasing. Also due to the safety system provided in 3-phase motor to protect it from overheating.
    (2) If single phasing occurred while the motor is operating, it will continue to run because of the torque produced by the remaining two phases, which is produced as per the demand by the load. As the remaining two phases are doing additional work, they will be overheated which might result in critical damage to the windings.
    (3) It will lead to increase in the current flow 2.4 times the average current value in the remaining two phases.
    (4) Single phasing reduces the speed of the motor and its rpm will fluctuate.
    (5) Almost all the motor system in the ship has st-by arrangement. If the motor is selected for st-by, with single phasing problem – it will not start in emergency which will lead to failure of the related system.
    (6) If the problem is not identified and motor running continues; windings will melt due to overheating or can lead to short circuit or earthing.
    (7) In such condition, if the crew of the ship comes in contact with the motor, he will get an electrical shock. Which can even be fatal.
    (8) It may cause overloading of generator
    (9) Abnormal noise and Vibration.

    Protection devices:
    (1) Electromagnetic overload device.
    (2) Thermistor; sends signals to the amplifiers – detects overheat due to over current flow.
    (3) Bi metal strips.
    (4) Standard motor starter overload protection.

    All motors above 500 kW are to be provided with protection devices or equipment to prevent any damage due to single phasing. But this rule doesn’t apply to the motor of steering gear system of the ship.
    Only an alarm will be sounded for detection of the single phasing.

    But the motor will not stop as the continuous operation of S/G system is essential for safety & propulsion of the ship.
    Especially when the vessel is in congested waters or under maneuvering.

    Ex-d: exd

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    .exd

    Intrinsically Safe Equipment:

    intrinsically safe equipment is defined as “equipment and wiring which is incapable of releasing sufficient electrical or thermal energy under normal or abnormal conditions to cause ignition of a specific hazardous atmospheric mixture in its most easily ignited concentration.”

    Ex-I: Intrinsic Safety():

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    .ise  .intrinsically safe  .exi

    Intrinsically safe equipment:

    Electric arc or spark on flammable vapor increases the energy of the vapor and air locally so that particles are activated and creates a violent chemical reaction which is known an explosion. A weak spark does not have sufficient thermal energy to heat the local flammable mixture. Because energy generation rate is slower than energy dissipation rate. so no explosion occurs.

    An intrinsically safe circuit is one that is designed for a power so low that any spark produced by it is incapable of igniting the flammable gas.

    Intrinsically safe equipment uses such circuit. It is unable to produce strong enough spark to create explosion.

    Intrinsically safe equipment is made into two standards. Ex-I(a) and Ex-i(b). Ex-i(a) is used in more hazardous area while Ex-i(b) used in less hazardous area. This method of protection is suitable for electrical supplies at less than 30 volts and 50 miliamps. It is used for instrumentation and control functions.

    Design:

    The equipment and system design in such a way that capacitance and inductance is kept minimum, to prevent storage of electrical energy which could generate spark. Ex-I devices cables are not permitted to keep in the same tray as other cables.

    The whole system is earthed and protection is provided by shunt diode safety barriers between hazardous and non-hazardous area. The safety barriers have current limiting resistors and voltage by-passing Zener diodes to prevent excessive electrical energies from reaching the hazardous area. Intrinsically safe equipment is needed to be certified by administration.

    Stroboscopic Effect: 

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    .stroboscopic effect .stoboscopic

    The light falling on the moving parts of any machinery causes it to appear either running slow or in reverse direction or even may appear stationary. This effect is known as the stroboscopic effect.

    Reason for Stroboscopic Effect:

    In alternating current, for every cycle of current or voltage waves, the waves pass through zero-crossing twice. In our electrical system, we have lamps supplied with 50 Hz or 60 Hz AC supply.

    Suppose we are supplying an AC supply of 50 HZ. This means that with a supply frequency of 50 Hz, the lamp will turn off 100 times per second because for 50 Hz supply the voltage or current waves passes through zero-crossings 100 times per second. But, due to the persistence of vision, our eyes do not notice this turning off phenomenon which leads to the stroboscopic effect.

    Methods to Avoid Stroboscopic Effect

    This pattern of illusions is not allowed in industries as this may lead to accidents. This is the main reason Fluorescent lamps are not preferred in industries.

    However, this effect occurs in three-phase as well as single-phase supply. It can be avoided by some simple techniques.

    Method to Avoid Stroboscopic Effect in Three-Phase Supply

    If the system is supplied with a three-phase supply, adjacent lamps should be fed with a different phase so that the zero instants of the two lamps will not be the same.

    Method to Avoid Stroboscopic Effect in Single-Phase Supply

    If single-phase supply is only available, then the connection of two adjacent lamps is made such that the two lamps are connected in parallel with the supply.

    In one lamp connection, a capacitor or condenser is kept in series with the choke. This makes a phase shift and eliminate the stroboscopic effect