Auxiliary equipment and systems for marine engine drivers



Ranger Hope © 2008                                                                                             View as a Pdf file

























This text is provided for research and study only on the understanding that users exercise due care and do not neglect any precaution which may be required by the ordinary practice of seamen or current licensing legislation with respect to its use. No copying is permitted and no liability is accepted resulting from use.



Ranger Hope © 2008                                                                                              View as a Pdf file



A well found vessel has equipment sufficient for the trade and seas that she embarks upon.  Modern engineering is very reliable, often incorporating fail safe mechanisms and sophisticated non serviceable components. Expert service engineers can be required to meet a manufacturer’s warrantee. Licensed installers (LPG, electrical, and refrigeration systems) may be required by National regulations. However, the Marine Engineer remains on the spot, responsible to ensure that the vessel is ready, and if systems fail, to repair them sufficient to reach a safe haven.


A basic understanding of maths and science, including calculation, how heat and pressure change material, how forces stress materials and how momentum and gravity affect motion will assist the reader. Engineers use these principles to understand why machinery works and to interpret the signs and symptoms of malfunction. Reference information can be found in the online dictionary at:


The equipment and systems described may not be exactly match that fitted on your vessel. Your manufacturer’s operating manuals must be consulted in practical tasks. Ensuring a safe work practice and applying OH&S is paramount. This includes using the correct tool for the job, use of personnel protective equipment, (loose clothing can become entangled in moving parts) and maintaining a tidy workplace.



Chapter 1: Safe practice

1.1 The standards                                              - Classification, Marine Orders, USL Code, NSCV.

1.2 Survey                                                          - Initial, periodic, NSAMS

1.3 Safety Management                                     - Risk analysis


Chapter 2:  Tanks and fluid management

2.1 Tanks                                                            - Fuel, water, ballast, sullage, safety

2.2 Calculations                                                  - Tank capacity

2.3 Valves                                                           - Screw down, non return

2.4 Pumps                                                           - Positive displacement, dynamic, gravity

2.5 Bilge systems                                                - Survey, piping, operation, faults


Chapter 3:  Fire control systems

3.1 Principles of fire control                                - Fire triangle, transfer, classes, causes

3.2 Fire safety and survey                                  - NSCV Part C Section 4, fire control

3.3 Fire detectors and alarms                             - Types, operation

3.4 Fire fighting equipment                                 - Portable, extinguishers, fixed installations

3.5 Testing fire fighting equipment                      - Hoses, hydrants, shutdown, closures 

Chapter 4:  Deck gear and hydraulic systems

4.1 Steel wire rope, chain and breaking strain    - Operation, splicing, strength

4.2 Blocks, purchases and tackles                      - Types, maintenance, rigs

4.3 Access                                                           - Stages, boson’s chair, rope ladders

4.4 Lifting gear                                                     - Shackles, hooks, slings

4.5 Deck machinery                                             - Winch, windlass, anchoring, safety, maintenance  

4.6 Hydraulic power units                                    - For winch application


Chapter 5:  Steering gear

5.1 Survey requirements                                     - Performance, NSCV

5.2 Rudders                                                         - Passive, active

5.3 Steering systems                                           - Direct drive, hydraulic, power assisted

5.4 Troubleshooting                                             - Pre-departures, faults


Chapter 6:  Gearing, shafting and propellers

6.1 Gears and clutch mechanisms                      - Selection, clutches, torque converter

6.2 Reverse and reduction gear boxes                - Operation, epicyclic, maintenance

6.3 Couplings and intermediate shaft                  - Muffs, flange, flexible, alignment

6.4 Stern tubes, shafts and alignment                 - Water, oil, mechanical, tailshafts

6.5 Propellers                                                       - Theory, calculations, removal & fitting


Chapter 7:  Marine DC electrical systems

7.1 Basic principles, units and simple circuits     -Theory, series, parallel

7.2 The battery                                                    - Lead acid, alkaline, installation, safety

7.3 Charging, generators and starter motor        - Types, tests

7.4 DC circuit protection                                      - Devices, shorts, stray current



Chapter 8:  Marine AC electrical systems

8.1 Electrical safety with AC                                 - DC, AC

8.2 Single and three phase                                  - Wiring, transformers

8.3 AC circuit protection                                       - Faults, isolation, earth, devices

8.4 The genset (engine driven alternator)            - Distribution, shore power, calculations

8.5 Motor starter isolation and fuses                    - Decommissioning, systems



Chapter 9:  Refrigeration

9.1 Principles of refrigeration                                -Terms, latent heat

9.2 The vapour compression refrigeration cycle  - Operation, components, safety

9.3 Refrigerants                                                    - Regulations, types, pressure

9.4 Common faults                                                - Compressor, pressure


Chapter 10: Slipping, inspection and repair  

10.1 Forces and stress                                         - Hog, sag, rack, pant, point

10.2 Structures of a vessel                                   -Timber, steel, GRP

10.3 Materials and preservation                           - Attributes, deterioration, surface coatings

10.4 Slipping operations                                       - Methods, preparation, checklist

10.5 Maintenance, inspection and repairs            - Tests, tools, repairs, confined spaces



Chapter 1: Safe practice

1.1 The standards

An historical perspective

To ensure safe vessels that would enjoy low insurance rates and higher resale value seafaring nations in the past developed Classification Societies to keep registers (lists of approved safe vessels). Those remaining today still determine rules (specifications) for construction, equipment and maintenance for each vessel class (the trade and sea area of operations).


American Bureau of Shipping AB                              Det Norske Veritas NV 

Lloyds Register of Shipping LR                                 Germanischer Lloyd GL

Bureau Veritas                                                          Nippon Kaiji Kyoka

                                 China Classification Society


For a new vessel, a classification society such as those above will approve the design plans and check the quality of materials and workmanship of all stages of the construction process at what is called the Initial Survey. Seafarers are additionally protected by their assignment of the vessel’s load line to show minimum freeboard (preventing overloading) appropriate to the intended sea area and by mandatory minimum safety equipment. To ensure maintenance to the survey standards, regular ongoing thorough examinations are scheduled, called Periodic Surveys.


Subsequently, concern from nations that unregistered and unsafe foreign ships could sink in their home waters, blocking their ports and polluting their seas resulted in forming the International Maritime Organisation as a forum to promote sea safety. The IMO now encourages conformity in their Conventions that include:


Safety of life at sea conference (SOLAS)

Loadlines conference (LOADLINES)

Marine pollution conference (MARPOL)

Standards of training and certification of watchkeepers (STCW)

International Safety Management Code (ISM)


These conventions, the World’s best practice, are supported in domestic legislation in the jurisdictions of the Commonwealth of Australia and its States and Territories.

Marine Orders and Australian Maritime Regulations

The Commonwealth of Australia’s jurisdiction operates to 200 nm offshore, the States’ to within 3nm offshore, but extensions may cover zones of particular State interest. Where State and Commonwealth Laws are incompatible, the latter can override. Like Class Societies, the Australian Maritime Safety Authority (AMSA) registers large vessels to Australian standards, and the State Authorities manage small vessels to their regulations.


Marine Orders are body of delegated legislation from the Commonwealth Navigation Act 1912 and Protection of the Sea (Prevention of Pollution from Ships) Act 1983 that update rules for commercial vessel construction, operation and manning. They incorporate reference to Australian Standards (AS) for materials and components.




Water -           Emerald Green                        Fire lines -           Signal Red


Steam -          Silver Grey                               Air -                       Arctic Blue


Oil -                Golden Brown                         Gas -                       Light Beige


Hazardous  -  Golden Yellow                        Acids /Alkalis-        Violet


Electricity -    Light Orange                           Communications - White


Other fluids, including drainage pipes, bilge lines -                  Black
















The examples below show some of the Marine Orders of particulars relevance to Marine Engineers for commercial vessel construction and operations. The full list of Marine Orders currently in force can be accessed at the AMSA website.


Marine Order 11    Substandard ships

Marine Order 12    Construction-Subdivision & stability, machinery and electrical installations

Marine Order 14    Accommodation

Marine Order 15    Construction-fire protection, fire detection and fire extinction

Marine Order 16    Load Lines

Marine Order 17    Liquefied gas carriers and chemical tankers

Marine Order 23    Equipment-Miscellaneous and Safety Measurements,

Marine Order 25    Equipment - Life-saving

Marine Order 31    Ship surveys and certification

Marine Order 32    Cargo Handling Equipment

Marine Order 34    Solid bulk cargoes

Marine Order 41    Carriage of dangerous goods

Marine Order 42    Cargo stowage and securing

Marine Order 43    Cargo & Cargo Handling-Livestock

Marine Order 49    High Speed Craft

Marine Order 58    International Safety Management Code

Marine Order 91    Marine Pollution Prevention – Oil


Smaller vessel registration and survey is devolved to the State Authorities, including:


New South Wales NA                             Queensland QA 

Tasmania TA                                          Victoria VA

South Australia SA                                  Western Australia WA

                               Northern Territory NT



Australian Standards and the USL/NSCV are increasing maritime uniformity nationwide and negotiations are ongoing to form a Single National Jurisdiction for conformity in maritime standards and law enforcement.


The Uniform Shipping Laws Code (USL)

The geographic zones under the authority of Australian States range from the balmy Tropics to the wind swept Southern Ocean. Not surprisingly, locally focused State determined standards were different, creating barriers for vessels trading inter-state.


The voluntary Uniform Shipping Laws Code (USL) was devised to promote uniformity in commercial vessel manning and construction regulations for small vessels (< 35 metres). Five of the Codes’ eighteen Sections, directly affected the day-to-day operations of Marine Engineers, specifically:


Section 1   - Definitions and General requirements

Section 10 - Life Saving Appliances

Section 11 - Fire Appliances

Section 13 - Miscellaneous Equipment

Section 15 - Emergency Procedures


The Code lists the classes of vessels and prescribed standards that shall be met.


Class 1 – Passenger vessels (i.e. carrying more than 12 passengers).

Class 2 – Non-passenger vessels (workboats of 12 or less passengers).

Class 3 – Registered commercial fishing vessels (passengers not allowed).

Class 4 – Hire & drive vessels


Each class of vessel includes an operational area as follows:


A – Unlimited seagoing

B – Offshore to 200 nautical miles

C – Offshore to 30 nautical miles

D – Sheltered smooth and partially smooth waters (wave height <1.5 metres)

E – Sheltered smooth waters only (wave height <0.5 metres)


From the 1990’s the USL Code was incorporated into States’ regulations while accommodating existing arrangements of vessels operating to earlier standards. Being voluntary it was implemented more completely in some States than others. It continues to have a profound influence on small vessel regulations and safety nationwide.


The USL code lists prescribed standards. For every vessel class there is a tabulated specification that “shall be met”. In some operations (novel and fast craft), industry found it stifled the use of equivalent or better modern technological innovations.



National Standards for Commercial Vessels (NSCV)

A newer National Standards for Commercial Vessels has been drafted. While drawing from the USL code, the NSCV updates and provides the flexibility required by marine developers and operators. It retains a prescriptive approach to compliance in its “deemed to satisfy” standards (standards that shall be met) but also provides a flexibility with performance based “equivalent solutions” (that can be proven to be as effective as those deemed to satisfy). The Standards, accessed at the AMSA website are:


Part A: Safety Obligations

Part B: General Requirements

Part C: Design & Construction

          Section 1: Arrangement, Accommodation and Personal Safety

            Section 2: Watertight and Weathertight Integrity

                             2a-Load Line Vessels

                             2b-Non Load Line Vessels

            Section 3: Construction


                             3b-Design Loadings

                             3c-Aluminium Construction

                             3d-FRP Construction

                             3e-Steel Construction

                             3f-Timber Construction

            Section 4: Fire Safety

            Section 5: Engineering



                             5c-LPG for Appliances

                             5d-LPG for Engines

            Section 6: Stability

                             6a-General Requirements

                             6b-Intact Stability

                             6c-Buoyancy and Stability after Damage

            Section 7: Equipment

                             7a-Safety Equipment

                             7b-Communication Equipment

                             7c-Navigation Equipment

                             7d-Anchoring and Mooring Equipment

Part D: Crew Competencies

Part E: Operational Practices

Part F: Special Vessels

           Section 1: Fast Craft

                             1a-General Requirements

                             1b-Category F1 Fast Craft

                             1c-Category F2 Fast Craft

             Section 2: Hire and Drive

             Section 3: Novel Vessels

             Section 4: Special Purpose Vessels


Another difference from the USL code is that the principles of risk management outlined in the International Safety Management Code (ISM) are adopted by the NSCV (particularly in Section 4, Fire Safety) where a risk factor based on vessels class and operations determines survey requirements.



National Standards for the Administration of Marine Safety (NSAMS)

These newest Standards are intended to be applied through a single national jurisdiction reform under Commonwealth legislation. It envisages a single national Authority with multiple survey organisations that may be operated by private industry or by State or Territory Government agencies. There are three possible models specified in the Regulatory Impact Statement for National Approach to Maritime Safety Reform (NAMSR). No decision had been taken about the service delivery model at the time of publication of this standard.

1.2 Survey


This text primarily refers to the standards of NSCV. Your commercial vessel may be in Class, AMSA or State survey and you must consult their standards and rules to ensure survey compliance. However, some general principles apply.


To approve a vessel authorities and/or classification societies survey their vessels (a thorough examination by a surveyor or approved person). Some items may be just require inspection (be visually checked by an approved person) or some may require a test (be subject to meeting a performance criteria).


Initial survey and load lines

A vessel brought into survey for the first time is required to undergo an initial survey to approve the plans and check that the quality of materials/workmanship meets the safety parameters appropriate to the trade and sea state (vessel class) likely to be encountered. Most vessels require a Load Line Certificate, other than small vessels less than 24 metres or those operating solely on sheltered waters with passenger restrictions or fishing vessels (that would not be able to read their marks at sea).


At the construction stage, hydrostatic particulars are worked out by the naval architect and are verified in an inclining experiment (the vessel is heeled by weights to proof test its ability to safely return to the upright). The vessel is then subjected to the Load Line regulations. Freeboards (height from waterline to deck) are computed on the basis of the Conditions of Assignments (usage instructions). A five year valid Load Line Certificate is then issued subject to annual checks.


The initials of the survey authority are marked on the load line (as shown in the Det Norske Veritas registered vessel below) and a Certificate of Survey is issued.

Text Box:   


Periodic survey and survey schedule

A vessel’s structure, machinery and fittings are surveyed at specified intervals called the periodic survey (usually annually). However, a surveyor may board a vessel at a reasonable time to make an inspection. The owner of the vessel is required to inform the authority of changes which may alter the vessel or survey requirements such as change of trade, alteration to structure or machinery, collision, fire or grounding. An alteration may initiate further inspection. A current Certificate of Survey must always be prominently displayed on board.

In the periodic survey the surveyor checks the position of the load line marks, that the hull retains its water tight integrity and remains sound, the condition of the fittings/appliances for the protection of openings, guard rails, freeing ports and means of access to crew's quarters. The hull and superstructure will be inspected for any alterations and that the vessel has the Stability Information Booklet and the Conditions of Assignment on board. The surveyor uses a Survey Schedule (a list of items to be inspected and/or surveyed) to enable owners to slip and prepare their vessels for the checks.




USL SURVEY SCHEDULE vessels < 35 metres in length (Sect. 14 of the USL Code) is listed  below:

Annual Surveys


Running trial of each main engine and associated gearbox.

Operational test of bilge pumps, bilge alarms and bilge valves

Operation test of all valves in the fire main system.

Operational test of all sea injection and overboard discharge valves and cocks.

Operational test of main and emergency means of steering.

Running trial of all machinery essential to the safe operation of the vessel.

Inspection of all pipe arrangements.

General examination of machinery installation and electrical installation.

All safety and relief valves associated with the safe ops of vessel set at required working pressure.

Pressure vessels & mountings for generation of steam under pressure or heating of water to >99º C

Inspection of the liquefied petroleum gas installation.

Inspection of escapes from engine room and accommodation spaces

Inspection of personnel protection arrangements in machinery spaces.

Inspection of cargo handling, fishing and trawling gear.

Inspection of casings, superstructures, skylights, hatchways, companionways, bulwarks and guard rails, ventilators and air pipes, together with closing devices.

Inspections of ground tackle (anchors and chains).

Two Yearly Surveys

Hull externally and internally except in way of tanks forming part of the structure.

Sea injection and overboard discharge valves and cocks.

Inspection of propellers, rudders and under water fittings.

Pressure vessel & associate mountings of air pressure/salt water sys - working pressure > 275 kPa.

Four Yearly Surveys

Each screw and tube shaft.

Anchors and cables to range.

Chain locker internally.

Tanks forming part of the hull, other than oil tanks, internally.

Void spaces internally.

Compressed air pressure vessels having a working pressure of more than 275 kPa and mountings.

Pressure vessel and associated mountings of an air pressure/fresh water system having a working pressure of more than 275 kPa.

Cargo handling, Fishing and trawling gear.

Insulation test of all electrical installations above 32V A.C. or D.C.

All safety and relief valves associated with safe ops of vessel set at the required working pressure.

Eight Yearly Surveys

Each rudder stock and rudder stock bearing

Each rudder stock and rudder stock bearing

Steering gear.

Hull in way of removable ballast.

Selected sections of internal structure in way of refrigerated space.

Twelve Yearly Surveys

Fuel oil tanks internally


During the course of a survey or inspection, the surveyor may require the opening up for examination of any other part or parts of the vessel including removal of linings and

ballast. After a survey a list of repairs/ deficiencies is handed to the Master. The survey is not complete until all repairs and/or deficiencies have been made good. After a subsequent survey the registering authority issues a new certificate.


Under exceptional circumstances a Certificate of Survey extension may be granted if the authority is satisfied that the immediate survey of the vessel is impracticable (three months extensions may be granted but an interim inspection may be required). An authority may suspend a Certificate of Survey if the requirements are not being met. The owner will be advised and must not operate the vessel without the approval of the authority. An owner is also required to advise the authority of its sale or withdrawal from commercial operations.


National Standards for the Administration of Marine Safety and Survey

The NSAMS envisages that a single national authority will oversee surveys with a frequency determined by risk level. Risk factors include age, attributes, operational area and nature, incident history of vessel class and performance of the operator. Greater risk category vessels include:


Class 1A, 2A, and 3A vessels;

Class 1 > 35m in measured length;

Class 1B/1C that berth one or more pax or berth >12 persons or carry more >36 pax;

Class 1D/1E that berth one or more pax or berth >12 persons or carry >75 pax;

Class 2B vessels > 35m in measured length;

Class 2 tankers, dangerous goods or tug boats.




Survey Regime for Commercial Vessels (Table F.1)

Vessel Class

Class 1

(pass. vessels)

Class 2

(trading vessels)

Class 3

(fishing vessels)

Class 4

(hire and drive)


Survey Level 1 Vessels

Full Initial & Periodic surveys

Class 1 – all operational areas

Non-propelled barges of high risk



Ferries in chains






2B and 2C > 7.5mt

3C > 7.5mt




2D, 2E and 2C < 7.5mt of high risk




Survey Level 2 Vessels

Full Initial & Partial Periodic Survey


2C < 7.5mt with pax



4C ( both o/night & not o/night)


2D with pax


4D o/night



2E with pax


4E o/night



Survey Level 3 Vessels

Initial Survey Only


2C < 7.5mt with no pax


3C < 7.5mt




2D < 7.5mt with no pax


3D > 7.5mt


4D > 7.5mt (not o/night)



2E < 7.5mt with no pax

3E > 7.5mt


4E > 7.5mt (not o/night)


Compliance to NSCV required (no pre-determined survey)


Non-propelled barges (sheltered, < 24mt)**

(excl. spudded)




Other Compliance with level floatation standards, rec. boat equipment standard or ABP and/or NSCV Part E


2D < 7.5mt no pax*


3D < 7.5mt*


4D < 7.5mt (not o/night)


Sailing school - AYF


2E < 7.5mt no pax*

3E < 7.5mt*


4E < 7.5mt (not o/night)



The extract above specifies various survey level categories of vessels based on the risk factors.



Survey cycles -The periodic survey inspections of a vessel shall be arranged in survey cycles of 5 years as shown in the extract below from Table E1 (for vessels determined as level one). Table E.2 refers to level two vessels and E.3 refers to vessels with steam machinery.  An intermediate survey having both in-water and out of water components is carried out during the third year of the survey cycle however, the interval between two consecutive out of water surveys is not to exceed 36 months. The last survey in a cycle shall be in the nature of a renewal survey that verifies the safety systems on the vessel essential for ensuring continuity in meeting the applicable safety standards required by legislation. For small vessels that is planned to refer to the NSCV specifications.



Scope and depth of survey - NSAMS Tables E.1, E.2 and E.3 specify the scope and depth of periodic survey of a vessel. These periodic surveys are not intended to confirm the vessel’s compliance with every requirement but to identify and verify the continued existence and functionality of components, equipment and safety systems.



Ten yearly surveys -In addition to the items specified in Tables E.1, E.2 and E.3, the following inspections shall be carried out every tenth year:


Ultrasonic thickness for vessels having metallic hull;

Withdrawal of sample fastening for vessels having wooden hull;

Hull in way of removable ballast;

Internal foam buoyancy if not inspected in fifth year because of inaccessibility;

Internal hull inspection if not inspected in fifth year because of inaccessibility;

Pressure test all sea water pipes;

Non-destructive testing of shaft/rudder stock especially keyway, taper and threads;


The NSAMS term to examine means a process that commences with a visual inspection that identifies the evidence of damage, deterioration and/or modification (may require dismantling if deficiencies are found).


The NSAMS term to test means the physical gauging of properties with the objective of ascertaining continued readiness to function, condition or conformance with standards. E.g. hammer tests, ultrasonic thickness measurements, oil analysis, starting of machinery, turning of handles


The NSAMS term to trial means a specific type of rest of a system or component to ascertain functional performance and/or compliance with applicable standards. E.g. machinery trials, emergency generator trials, steering trials, fire hydrant appliance trials, anchoring trials, evacuation trials.


The NSAMS term to verify means to ensure that an item exists and is as per the plan, meets an applicable standard or has been declared as meeting an applicable standard by a recognised organisation or an Authority.


Survey Schedule Level 1 vessels

Extract from Table E.1 - General Survey Year of 5-Year survey cycle

Year 1

Year 2

Year 3

Year 4

Year 5


Annual in-water survey

Annual in-water survey

In and out of the water survey

Annual in-water survey

Renewal in/out

of water

General Items

Hull markings & signage






Equipment marked






LPG sys alarms/sensors

Examine + Verify + Test

Examine + Verify + Test

Examine + Verify + Test

Examine + Verify + Test

Examine + Verify + Test







Sewage sys/holding tanks (external)









Examine + Verify


Examine + Verify

Lightship verification (draft or weight check, re-incline or roll period test as appropriate)


Operational management

Safety management plan












Maintenance records


Examine + Verify + Test




Training/drills record




Examine + Verify + Test









Class certification






Stability documents






Vessel survey record book






Compass deviation card






IOPP certificate






Electrical installation test results including insulation test






Fire detection & smothering system test certificates






Radio survey certificate






Load line certificate (where issued)






Safety Equipment                

Lifejackets, stowage & signage

Examine + Verify

Examine + Verify

Examine + Verify

Examine + Verify

Examine + Verify

Lifejacket lights

Examine + Verify

Examine + Verify

Examine + Verify

Examine + Verify

Examine + Verify


Examine + Verify

Examine + Verify

Examine + Verify

Examine + Verify

Examine + Verify

Lifebuoy self igniting lights

Examine + Verify + Test

Examine + Verify + Test

Examine + Verify + Test

Examine + Verify + Test

Examine + Verify + Test

Lifebuoy buoyant line






Buoyant appliance(s)

Examine + Verify

Examine + Verify

Examine + Verify

Examine + Verify

Examine + Verify

Internal buoyancy (where accessible)





Life raft

Examine + Verify

Examine + Verify

Examine + Verify

Examine + Verify

Examine + Verify

Rescue boat & launching arrangements

Examine + Verify

Examine + Verify + Trial

Examine + Verify + Trial

Examine + Verify + Trial

Examine + Verify + Trial

Dinghy (if counted for lifesaving purposes)

Examine + Verify

Examine + Verify + Trial

Examine + Verify + Trial

Examine + Verify + Trial

Examine + Verify + Trial

Hydro release

Examine + Verify

Examine + Verify

Examine + Verify

Examine + Verify

Examine + Verify

List of further items continues:


1.3  Safety Management

The process of documented management plans for standing orders, bridge, engine room, restricted visibility has long been implemented by sound Masters. The IMO International Regulations for Preventing Collision at Sea in Rule 2 stipulate that the safety of the vessel is the responsibility of the owner, master or crew to ensure all precautions which may be required by the ordinary practice of seamen, or by the special circumstances of the case.

The hell of the “Piper Alpha” Oil North Sea oil rig fire and the equally devastating “Marchioness” (a ferry mown down in London’s Thames River whose passengers were washed into the rescuing crafts’ propellers), were wake up calls that preventable accidents waiting to happen keep happening. An overall management plan therefore includes all parties (with the statutory authority) and needs a pro-active approach where the responsibility for coordination is allocated. In 2002 the IMO published the International Safety Management Code (ISM) to address this problem.

The designated person or persons is tasked to maintain, document and report, the Safety Management System using a SMS Manual format (see the accompanying text SMS manual for a small vessel). It should be available at work stations, remain current and be audited systematically for effectiveness. A SMS manual includes:


Company information including job descriptions and responsibilities

Information necessary for a safe workplace

Risk analyzed plans for operations and contingency plans for emergencies

Information necessary to ensure effective maintenance, documentation & review

Staff training, inclusion in safety planning and the valuing of safe attitudes are encouraged in order to develop safe procedures. In this context, examining “case studies” (such as the Piper Alpha and Marchioness) and relating them to your own operations are a key concept from ISM 2002. 


The risk analysis process

The process of ensuring that hazards are identified, recorded, investigated, analyzed, corrected (eliminated or controlled) and that this process is verified can be summarised by the four steps:

1. Identification of all potential hazards.              What could happen?

2. Assessment of the risk of each hazard.          How likely is it to happen?

3. Elimination or a control plan.                           How to stop it happening.

4. Monitor & re-evaluation.                                  To improve/update the plan.

1. Hazard Identification:

Hazards to persons are associated with:

Gravitational                                   Striking

Electrical                                         Chemical

Work environment                          Manual handling


Hazards to persons may include:

Text Box:


Hazards to vessels are Navigational, Structural or Environmental, and may include:


Text Box:


The identification of hazards can carried out by the designated person in a number of ways including:


Systematic walk around inspection. (of the vessel)


Task analysis


Consultation and interview of the workforce /customers and staff meetings.


The compilation and review of safety information including, Material safety data sheets, AMSA Marine Notices , OH&S advisories and OH&S safety alerts and the study of other ships incidents & accidents (case study).


Audit by an independent expert.


If hazards are recognized, then their risk (significance) must be determined. This is to ensure that corrective measures are targeted and timely. For these determinations the risk assessment process is used.

2. Risk assessment

Risk assessment may be informal (intuitively reached) or formal (by audit) and needs to consider the following factors:


Risk   Level   =        Consequence     X           Exposure      X   Probability

                              (outcome severity)    (frequency/duration)        (likelihood)                

The level of risk from a hazard will determine the scale and priorities of control measures required. Low risk activities may be addressed over a period of time, whereas high risk activities will require ceasing operations until the deficiency is rectified. If a formal assessment is appropriate, the matrix shown below with supportive documentation should be researched by the designated person.


                        View a printable copy of this simple risk assessment template

Text Box:


3. The Control plan

Solutions to minimise or eliminate the risk may include:


Engineering controls-

Get the design right in the first place or redesign

Removal at source



Administrative controls-


Entry permits

Segregation / Isolation


Record keeping

Work practice controls-

Safe work practices

Passenger and crew briefing

Personal protective equipment and rescue equipment

Drill and musters

Training and staff development


4. Monitoring and re-evaluation:

This is coordinated by the designated person whose audits will include:


Vessel’s record books, incident/accident books and record of drills and musters

The currency of staff qualifications and in-service training

The appropriateness of the vessel’s operational & emergency plans to current operations and equipment

Update of the SMS to meet changed circumstances and regulation


Training & staff development:

The cooperation of the staff is essential in implementing an effective control plan. While the necessity to monitor and document places an immediate burden on staff, their engagement in the safety plan will encourage safe attitudes and develop workable safe practices. In the long term this foundation will repay the efforts many fold.




Tanks, Valves, Pumps and Bilge Systems


2.1 Tank arrangements


A vessel’s tanks, in addition to storing fuel and fresh water, can provide a second skin that increases the watertight spaces (limiting in-flooding) and increases stability (by loading cargo or ballast water low in the vessel).The tank arrangement below shows day tanks from which fuel is gravity fed to the motors. Port and starboard tanks 1 are dedicated to the fuel oil needs the vessel’s passage, and are regularly pumped to press up (fill) the day tanks. Tanks 2-3 can be used for ballast or fresh water cargo, and tanks 4 & 5 are suitable for oil cargo. The latter tanks are separated by a void that can be filled with water to limit the spread of fire (a coffer dam).






















Tank Components


The following comments refer specifically to fuel tanks, but the same components are often incorporated in other tank systems.


Breathers- Fuel tanks, containing flammable liquids, are required to be vented to atmosphere (not into the vessel). This breather pipe will terminate in a gooseneck or swan neck (a cranked pipe), which limits rain and spray from entering. If the vent pipe is greater than 18 mm in diameter, the outlet is fitted with a wire gauze for a flame trap.


Filler pipes- Filler pipes are arranged so spillage will not enter the vessel. The inlet or delivery end of the pipe is located outside the vessel and will have a valve and fuel tight cap. The pipe between the deck and the top of the tank may be flexible, but must be reinforced and secured with twin corrosion resistant clips.


Sounding and sight gauges - Float fuel gauges are unreliable due to a vessel’s changing trim, so checking the contents of the tank can utilise poking a calibrated stick (sounding rod) down the filler pipe until it hits the bottom of the tank and reading off the height of fuel that coats the retrieved rod (sounding the tank). An alternative is to read the dry end of the retrieved rod showing the airspace above the fuel (an ullage). If the tank’s pressed up capacity is known then its remaining fuel can be calculated. Whether a filler pipe or a dedicated sounding pipe is fitted, at the tank bottom a reinforcing striker plate is welded to prevent a hole being eventually battered into the tank bottom.


An alternative measuring technique is a transparent sight glass spanning top to bottom whose fuel level reflects that of the main tank. This clear plastic/glass tube is more vulnerable to fire and impact than the main steel tank, so survey regulations specify that a self closing valve be fitted in case of rupture. Under no circumstances must these valves be left open. A recent variation is a non ferrous sight gauge containing a steel float whose height (and tank volume) can be determined by magnetic sensors. Tanks may be fitted with an overflow pipe which leads to an overflow tank or relief double bottom fuel tank. These overflows can be fitted with a sight glass and audible alarm. When re-fuelling, a safety managed procedure that utilises pollution and spill control devices must be operated to prevent spillage or fire. The only way to prevent accident is to ensure that personnel are trained and competent in the refuelling operation.



























Shut off valves - All fuel supply lines have shut off valves fitted as close as possible to each tank (preferably on the tank). In case of fire these can be closed from outside the engine room on the upper deck (remotely) by a non-flammable linkage of steel wire or rod.

Multiple tanks can have a cross over valve fitted to either the fuel supply or return lines enabling the engines to be run from either tank or in the event of contamination, to isolate an offending tank. Care must be taken if redirecting a fuel return line to one tank only as this effective fuel transfer can be rapid and may affect the vessels stability or even overflow the tank.  Some vessels may have two day tanks, thus the fuel return from the engines injectors should be changed over when the delivery is changed. Similarly, it is wise to close cross over fuel supply lines when refuelling from a high pressure fuel pump. The thrust of fuel entering the port tank filler pipe may depress the fuel in the tank and even force fuel up to overflow the starboard tank. The reverse will occur when the filling stops as fuel from the starboard tank can surge back to spill out from the port filler pipe.

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Baffles – Perforated baffles (or not continuous baffles) are fitted inside the tank to allow limited liquid movement but minimise free surface area effects of liquids sloshing around as the vessel moves. Normally spaced not more than 1 m apart, those fitted longitudinally will reduce free surface caused by the vessel rolling and transverse baffles will reduce that caused by the vessel pitching.


Sludge box & drain - Sediment contaminants of water, algae and debris will gather at the tank bottom where they must be periodically removed through a self closing sludge valve. In the event of the tank rupture or for periodic inspections, all fuel tanks which are not double bottoms must be fitted with a method of draining them into another storage tank (not the bilge).


Save all – Tanks that are fitted above machinery must have drip trays (savealls) fitted to prevent leaks onto moving parts. Fillers, engines and gearboxes are similarly fitted to stop oil reaching the bilge. Save alls also need drainage arrangements.


Inspection port- The top or bottom of tanks, where water and condensation accumulate, are prone to corrosion and need regular inspection. The bottom of the sounding pipe can corrode or even jam the sounding device. Consequently fuel tanks of more than 800 litres capacity require opening up and inspecting at periods of not more than 12 years through a manhole or inspection port. A larger tank may also have modified vent pipes or fitted purging (by inert gas) pipes to ensure tanks are evacuated of flammable gasses before opening up. The precautions of entering a confined space must be applied.

Double bottom and void tank tops are equally prone to corrosion but must be more regularly inspected. A weep of water entering a double bottom tank through damage to the outer hull will suddenly become a flood if the tank’s resisting internal air pressure fails due to the tank top watertight seal corroding away. 


Strums, Strainers, and Mud Boxes - Strums are boxes of perforated metal plate are mounted at the suction end of pipes from bilges and tanks to prevent larger objects entering and damaging the pumps while not entirely clogging the piping. They can be constructed with brass bolts or tongues and split brass pins so they can be periodically dismantled for cleaning. 


















                     Strum box                                                                                       Strainer


Strainers are used where frequent or constant cleaning is required and so must be mounted for easier access. The body and lid are usually of cast iron to provide an air-tight suction seal. Other parts are mild steel. The strainer plate is removable for cleaning.


A mud box is created by a (cement) dam around the base of the strainer plates. Solids that drop off the strainer plates are retained in the dam and prevented from flowing further back into the lower bilges. The mud box needs to be cleaned out periodically.













For NSCV specifications for piping see Section 1.5, bilge piping.


Fuel tank arrangements


Fuel systems are more fully described in the accompanying text Marine engine and propulsion systems for Marine Engine Drivers. Fuel arrangements must take into account its highly flammable nature, particularly in the critical operations of loading, unloading and refuelling. Safety considerations for refuelling should include but not be limited to the following:


Training all personnel to understand the systems and operate the safety procedures.

Understand and comply with all port regulations and ensure incoming fuel is clean.


Moor the vessel securely, secure fuel lines and pad where there are sharp edges.

Pipe bends should be smooth, not leak and if necessary be earthed.


Isolate naked flames or smoking and have fire-fighting appliances in readiness.

Plug scuppers on deck, ensure tank vents are clear and have clean up gear ready.


Maintain a constant watch to monitor flow and prevent spills, close filler caps after fuelling and clean any spills on deck.


Refuelling is more fully described in the accompanying text Refuelling and transfer operations”.



Fresh Water Systems 


Fresh water must be stored in a designated tank as it can take on an unpleasant taste or worse still become polluted and a risk to health. It should not be possible to pump fuel or ballast into fresh water tanks or vice versa. Those other tanks should be separated by a cofferdam so that if there is a leak it does not contaminate the fresh water. Fresh water tanks were traditionally coated internally with a cement wash in order to limit corrosion and maintain the water quality. More effective modern coatings are now available but tanks should still be inspected at regular intervals and renewed as required.


Water stored in a cooler area is preferred but as water quality will deteriorate over time it is common practice to flush periodically and filter drinking water. It can be additionally treated with chlorine or by UV sterilisation to kill bacteria. 


Water usage demand will be created as soon as a tap is turned on. In any arrangement other than a gravity feed a pump is required. To prevent the fresh water pump from starting and stopping constantly, a pressure tank system is usually incorporated. It uses a buffer tank of compressed air that allows water to be continuously supplied under pressure, with the pump operating only intermittently to top up the pressure in the tank.


The most common cause of poor drinking water quality is from loading contaminated water from the wharf. It is wise to examine a test sample of water closely before any loading takes place.

Ballast Water Systems


Ballast, or heavy weight such as rock or gravel, can be loaded into a vessel to improve her stability by adjusting her trim or lowering/raising her centre of gravity. Water ballasting allows a larger vessel to more conveniently achieve the same ends by pumping sea water in or out of dedicated ballast tanks. These are typically the double bottom tanks low down in the hull. Smaller vessels may use water ballasting to improve their operations, such as tugs loading ballast to immerse their large propellers to gain greater thrust or landing craft to pin the bow on the beach after landing.


Ballast arrangements

Each ballast tank is provided with means of filling, venting, sounding and emptying. Tanks can be filled by transfer pumps or gravity by opening the tank inlet valves directly to the sea. Filling or emptying by gravity saves the fuel that would normally be used to drive the pump. When gravity is used for filling there is no danger of over-pressurising the tank. The sea connections or sea cocks with their grates prevent debris from entering the system.

On the inboard side of the seacock a strainer filters out the finer solids to protect the system from blockage or damage. An isolating valve enables the inboard strainer to be opened up for the regular cleaning needed without flooding the vessel. Care is required when servicing to ensure that the filter screen is clean and undamaged, that the seals are in good condition and that any sacrificial anodes are inspected and replaced as required. All need to be inspected and repaired whenever the vessel is on the slip.


The transfer pump, typically an electrically driven centrifugal type, can direct sea water to each of the ballast tanks. (Impeller general service pumps may be used on small vessel). In the schematic drawing below, by the opening the relevant valves, water is pumped to the port and starboard aft ballast tanks through the common ballast main pipe. Similarly, by opening and closing the relevant valves, if flow can be reversed to empty from the ballast main to the overboard discharge.


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The simple ballast arrangement shown may alternatively use a general service pump with a common manifold for bilge pumping operations (shown below)


As centrifugal pumps are not self priming it is not advised to run a pump dry. With centrifugal pumps, common practice at the latter stages of pumping is to have the sea water inlet slightly open to act as a pump lubricant and coolant, and to maintain priming.


Ballasting operations


Before operations physically check that all valves on the suction and discharge manifolds of the fire and bilge and general service pump are shut.


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Note: Schematic drawing only. NSCV Part C Section 4 Fire Safety allows some vessels non-dedicated main fire pumps (doubling with deck hose or ballast) provided they are not used as bilge pumps.



Ballasting a tank by gravity

Open the sea inlet valves at the vessel’s side. At the suction manifold of the general service pump, open the sea suction and ballast suction valves. Open the valve to the tank to be filled. Sea water will then flow by gravity from the sea inlet along the manifold through the ballast suction into the ballast main, and to the tank to be filled.


Using gravity, the tank fills only to the draft the vessel is floating at. If the top of the tank being filled is higher than the current draft of the vessel, it will be necessary to complete filling by pumping.


Ballasting a tank by pumping

Open the sea inlet valves. Open the sea suction valve at the suction manifold and close the ballast suction valve. Open the ballast line on the discharge side of the general service pump.  Open the valve for the tank to be filled. Start the pump. Ballast water will now pump from the sea inlet to the selected ballast tank.


Note: With impeller positive displacement pumps, all valves should be open before starting the pump.


When filling, soundings of the tank should be taken at intervals. The pump should be shut down and all valves closed when the tank is full. In some vessels it remains standard practice to allow the tank to fill until water overflows from the tank air vents that are a minimum of 1.25 times the area of the filler line. This practice should be treated with caution particularly with older vessels.



De-ballasting by pumping out (emptying a ballast tank)

Check that all valves on the suction and discharge manifolds of the fire and bilge fire and bilge and general service pump are shut. Open the valve on the tank to be emptied. Check that the shipside overboard discharge valve for the general service pump is open. On the general service pump, open the ballast suction valve.

Start general service pump and open the overboard discharge. The tank will start to empty. Take soundings at regular intervals. When the tank is empty close all valves.


The transfer of ballast from sea and river water and discharging on the other side of the world has led to the unintended importation of pests and exotic species. There are now tight laws worldwide regulating discharge of ballast and larger ships may incorporate sophisticated water ballast handling systems to limit pollution like that shown below.


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Ballast management system drawing Courtesy of Wikipedia



Whether a gravity feed of pressurised system is used, any holding tank will have to be heavily reinforced to withstand at least the pressure of a shore pump out (a requirement within territorial waters) if not the vacuum from toilet to tank. The small bore vacuum piping common in vessels lends itself to blockage so arrangements are made for internal access for cleaning. Gloves and hygiene precautions must be operated while maintaining sullage systems to avoid illness by contact with faeces including that due to the bacteria e coli and the virus hepatitis.


Most vacuum systems incorporate a one way valve to evacuate air from the tank (to de pressurise). If a tank is allowed to overfill, solid debris will be sucked into the valve preventing its seal fully closing - symptoms will include poor flushing, continuous pump operation and cold or frozen valve housing. Additionally the breathers that carry away the flammable methane and other smelly gases may invade the vessel.

Confined spaces


Tanks are typical confined spaces defined as fully or partially enclosed areas which aren’t designed to be normal places of work, and where entry and exit are restricted. Tanks are likely to have depleted or contaminated atmospheres. Before any internal maintenance OH&S legislation requires confined space (tank) venting/purging to remove contaminants, a gas free test certificate confirming the atmosphere is safe to enter, certificates to enter/ work and an entry management plan that includes a watch sentry, rescue equipment and strategies. More about confined spaces is included in Chapter 10 and the associated texts “Working in confined spacesand “Pollution & prevention


2.2  Calculating tank capacity

In determining the vessel’s fuel, water or loading conditions, gauges are inaccurate due to the rolling and pitching at sea. Using standard mathematical formulas calculations can be made from each tank’s dimensions. These formulas include:


Areas of Common Shapes:      

Area is the measurement of the footprint for a two dimensional object.

Rectangles - The area of a rectangle is measured by multiplying the Length by the Width.


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Example: Find the area of a rectangle measuring 10.2 metres long and 6 metres wide.

AREA  =   L     x  W

            = 10.2  x  6

            = 61.2  mtrs2 (square metres)


Triangles -The area of a triangle is calculated by multiplying half of the base of the triangle by the height of the triangle.  Or equivalently, the base can be multiplied by the height and the result then divided by two.


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Example: What is the area of a triangle with a base of 3.8m and 1.1m high?

Area (A)         = ½  x   B  x  H

               A      = ½  x  3.8 x 1.1

                        = 2.09 mtrs2 (square metres).



Trapeziums - A trapezium is a four sided figure that has only two parallel sides.

Its area is calculated by multiplying half its height by the sum of the two parallel sides.








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Where A & B are the parallel sides and H is the perpendicular (shortest) distance between them, the height. Note: Do not measure up one of the sides.

Example: What is the area of a trapezium having parallel sides of 2.12m and 3.1m which are 1.2m apart.

Area (A)     =   ½ x (A + B) x H

            A     =   ½ x (2.12 + 3.1) x 1.2

           A      =   ½ x (5.22) x 1.2

                  = 3.132  mtrs2 







Circles - The area of a circle is given by using the formula:

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Where:       π = pi       = approximately 3.14, or as given by your calculator.

                   r = radius = half of the diameter of a circle.


Find the area of a circle with a diameter of 2.6cm.  Give your answer to 2 decimal places.

Area = π  x  (½ x 2.6) 2  

         = π  x    1.3 2        

         = 5.309291585       

         = 5.31 cms2

Some prefer to use the alternative formula


Area = π  x  diameter2  



Volumes of common tank shapes

Volume is the capacity measurement for three dimensional objects.


Tanks can be considered to be “regular” or “irregular” in shape:


Regular shaped tanks:

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Irregular shaped tanks:


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Tanks that taper also fit into this category.

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In practical situations you may need to make calculations based on an approximate shape. For example, this curved tank can be approximated as a triangular tank or a quarter of a cylinder depending on the lengths of A and B and the curvature.






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Alternatively, tanks may be considered as composite shapes and the capacity of section each calculated separately. For instance, the tank below is calculated as the composite of a rectangular top section added to the triangular bottom section to give the overall tank volume.







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Rectangular Tanks:

To calculate the volume (and capacity) of rectangular tanks the formula is Length multiplied by the Width multiplied by the Height of the tank.







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Example: If a tank is 3.1m long and 2.24m wide, what would be its volume if the depth of the tank is 1.1m. 

Volume (V)              = L      x   W     x  H

                                    = 3.1  x  2.24   x  1.1

                                    = 7.6384 mtr3

                                    = 7.64  mtr3 (in cubic metres to 2 decimal places)                     






Cylindrical Tanks:


The volume of a cylindrical tank is measured by multiplying the area of the circle by the height or length of the tank.




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Example: A cylinder has a circular base of 1.8m in diameter and stands 2.2m high. What is the capacity of the cylinder?

Volume = π r2 x  h

          V =  π   x 0.92  x 2.2

             = 5.595 mtr3



Trapezoidal tanks:


Given the shape of some vessels and the limited space available below decks, it is often necessary to make fuel tanks in an irregular shape.







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The area of a trapezium is calculated by multiplying half its height H by the sum of the two parallel sides A and B.

Area    = ½(A+B) x H x L

Once you have calculated the area of the side ends, you can calculate the volume of the tank by multiplying it by the length L.

Example: Referring to the above shape, calculate the volume if the dimensions of the tank are:

A = 1.5     B = 3    H = 2     L = 4


Area    = ½ (A+B)  x  H x  L

                        = ½ x (1.5 + 3) x 2 x 4

                        = 4.5 x 4

                        =18 mtr3 or the tank has a volume of 18 cubic metres


For more exercises see the associated text Fuel Usage”.



2.3  Valves


Ball valves

These increasing utilised valves rely on accurate machining in manufacture. They use a ball with a matching nylon seat. Older versions may use a cone shape. With the cock turned on, a hole through the centre of the cone/ball lines up with the pipe and opens a full flow. When not line the pipe is blocked. One advantage is that (if properly fitted) the handle will point in the direction of the pipe when open, allowing a visual check of the status of the valve. A disadvantage is that repair can require specialist tools and spares, so the smaller sizes can be regarded as disposable.


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                        Ball valves                                                             Plug Cock


Gate valve

This traditional full flow shut off valve uses a tapered ‘gate’ which wound down onto a seat in the off position. It can suffer from debris and scale build up if not used regularly that can jam the gate from fully closing, but is easy to service. The spindle gland can be adjusted with a gland nut, to reduce weeping.


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Other screw-down valves

The screw-down valve will give full bore flow and is easily maintained.  In the non-return version the valve washer assembly and the spindle are loosely connected.  A back-flow into the open valve will force the valve washer down against the seat, closing it. In low pressure applications, there may be insufficient ‘head’ at the inlet to lift a valve which may stick to the seat. The screw-lift version can be used in these applications, as the valve is fixed to the spindle and forcibly lifted from the seat. There will be no non-return function

with this variation on the standard valve. (This non return problem can be overcome by placing a non-return check valve in the line before the screw lift valve.)

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                A screw down non return valve


Other non return valves

Some non-return valves use pivoting flaps and some spring loaded plungers to allow one way flow. They are used to limit back flow. The flap type is mounted so that gravity closes the flap when flow stops. Back pressure then holds them closed.


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Non-return flap valve                                                           Use as exhaust cover


The check or plunger type is spring activated and will open only when under pressure from the inlet side. If debris collects around the seal then it will not fully close. This can happen if vacuum storage tanks (sullage) are allowed to overfill and back flow.


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Non-return check valve                                                 Use to limit bilge water back flow

The pull lift globe valve for overboard discharges, is opened by a straight pull-lift. The wedge inserted through a slot in the shaft will hold the spindle in the raised position. The valve will move freely while water is discharged, but when the water stops flowing, sea pressure will close the non-return valve.


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                           The pull lift globe valve



L port cock

The L port cock is a modification of a plug valve machined with a Morse taper fit into the valve housing. It allows two different flow pathways. The typical application is for bilge systems where the pump can be directed to the empty the bilge lines or supply the deck hose (from the sea water inlet). The safety feature of the L port cock is that connecting the seawater to the bilge cannot occur. Morse taper valves will stick if left for long periods (usually in the bilge to pump mode). It is advisable to turn the cock on a scheduled basis to avoid this problem occurring when you really need that sea water hose for fighting a fire.



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Butterfly valve

This simple valve is constructed from a flat metal disc attached to a shaft that can be rotated on its central axis to restrict the flow within a circular pipe or housing.

It is often found in low pressure air control systems such as engine room air vents. A more sophisticated version is used in demand air supply systems such as petrol engine carburettors.


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Butterfly valve (courtesy of


High pressure valves

Diesel fuel injector valves are typical examples of where the resistance of a strong (adjustable) spring can be set to open a valve at a precise pressure rating. These valves require very clean fuel in order to operate without blockage by dirt, debris or other contaminants of the fine passageways.

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High pressure injector valve (courtesy of ANTA Publications)



2.4 Pumps


Pumps can be hand (manual) or power driven from the vessel’s main engines, an auxiliary motor, by a hydraulic system or by electrical motors. The pumps on a vessel are known as devices to move water but they also move gasses, other liquids and slurries. Modern vessels use pumps to take the hard work out of many onboard services including fuel, lubrication, steering, machinery, ballasting, plumbing, ventilation and cargo handling.


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On the ship “Zulu” shown above, a reciprocating steam piston turns a rotary paddle wheel


Pumps work in a reciprocating (back and forth) or a rotary action. The first lends itself to pulsing flow and the later to a continuous flow. Common pumps types can use the principles of positive displacement, dynamic (or kinetic) or gravity for their operation.


Positive displacement pumps

These pumps use the principle of expanding and reducing volumes creating pressure difference between sealed chambers (commonly called suction). They are typically self- priming, but air leaks in the suction side will reduce or stop the flow. The suction side seal must be carefully maintained.


Piston pump - A rod raises the piston valve to expand the middle chamber’s volume.

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A stand pipe is a traditional reciprocating piston pump, used here to pump water from a well

The reduced pressure forces water up through the suction valve. On the rod’s down stroke, the raised water is squeezed up through the piston valve and on the next up stroke is further lifted to overflow through the spout. Just as these stand pipes were universally used to access communal village wells a century ago, similar leather valved hollow trunk version served as a bilge to deck pump on old sailing ships.


Twin piston compressor - The modern compressor uses one way metal flap valves to hold pressure in a tank above the twin cylinders. The inlet metal flap valve opens on each piston’s down stroke so gas enters the cylinder. As the piston rises the inlet valve is forced shut and the compression tank valve above opens. Compressed gas is forced up. A shut off or bypass arrangement is needed to avoid over pressurisation of the holding tank and subsequent internal damage. The bottom of the pistons can be splash lubricated from crankshaft action in an oil sump below. As liquids are non compressible, measures need to be taken to avoid water or oil of lubrication entering the cylinders. Typical applications for this type of pump are air compressors and refrigeration pumps.


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A compressor pump


Diaphragm pump - Another positive displacement pump is the diaphragm hand pump, often used as an emergency bilge pump. The flexible rubber diaphragm is squeezed up and down to create suction controlled by the twin valves.  Text Box:

A diaphragm hand pump operated by the reciprocating action of the removable handle

Despite their great advantages of simplicity, low cost, self priming and good flow rate these pumps are reliant on the perishable diaphragm. A spare diaphragm should always be carried. The most common models have plastic housings so are not fire resistant.

The diaphragm principle is also used for small electrical compressors.


Semi-rotary pump - This marine hand pump is made from a housing of cast iron with bronze moving parts. As the handle is moved, the volume of left middle chamber is squeezed as the volume of right middle chamber is expanded. The one-way valves allow liquid in the squeezed chamber to flow up to discharge, while on the other side liquid is sucked into the expanding chamber to await the next stroke’s lift to discharge.


Its self priming capabilities are inferior to the previously described pumps but it is fire resistant and rugged. Consequently it is the commonly approved manual bilge, fire and deck hose pump. Forcing its handle hard over against the stops in an effort to get it pumping can damage internal components. Pouring water down the outlet will be necessary to prime the pump. Unless regularly operated (as required for emergency musters and drills) it can drain dry and debris with rust will seize it. A splash of olive oil poured down the outlet will reduce corrosion and when next used for deck wash will stain them less than the alternative of mineral oil or heavy grease.



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A semi-rotary hand fire and bilge pump



Flexible impeller rotary pump - This rotary positive displacement pump is so widely found in marine engine’s salt water cooling and bilge systems that it is often called by its trade name, “a Jabsco pump”. The casing in which the impeller revolves is not uniformly circular, having a constriction (or cam) over a third of its diameter between the inlet and outlet. As water is carried around the casing the space between the impeller blades expands around the inlet (drawing water in) and contracts around the outlet (pushing water out). Water pumps use rubber or neoprene while oil or fuel pumps use alternative chemical resistant materials for impellers.



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 A rotary impeller positive displacement pump and housing



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Flexible impeller pump construction (Courtesy of ANTA publications)


The engine driven shaft is sealed by packing or a mechanical seal. All suction side connections must also be air-tight as leaks will stop or slow flow through the pump.

A cover plate over a gasket gives easy access to the casing and impeller. The impeller is a drive fit onto a splined shaft or one with a keyway. Although it is a self-priming pump the flexible impellor relies on the pumped fluid for lubrication so it will be damaged if the pump runs dry. Unless an automatic cut-off is fitted this type of bilge pump must therefore be constantly monitored while operated.


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Stripped blades of flexible impellers damaged by debris drawn into the pump

Other failures of flexible impellers result from chemical attack (from polluted bilge water), water flow cavitations (from narrow piping or over speed pumps) or more traumatically solid materials that evade the inlet gratings and screens and are drawn into the pump. A sudden increase in wet exhaust engine noise is a sign that salt water cooling has dramatically failed, and the impeller is a prime suspect. Pumps that are not used for extended periods can develop misshapen and brittle impellers that need to be replaced and can adhere to the pump cover.


With a clean bilge and effective strainers a bilge pumping impeller pump will give years of service, but in a commercial vessel the raw water Jabsco works continuously and will require regular servicing. Spare impellers sets should always be onboard so timely replacement can be carried out by:

Removing pump cover and gasket beneath and sliding the impellor off the splined drive shaft to inspect for damage. They can be reluctant to let go and may have to be carefully prised off with levers. Check for broken blades, impeller end clearance, worn casing wear plate and leaking seals. The end plate and impeller must be a good fit to pump and self prime. Old end plates may have become grooved so will have to be honed flat again. Repairs may include attention to the gasket or replacing a worn bearing.  To separate the bearings from the shaft use a wood block to support the unit while tapping out the shaft.


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Drawing courtesy of ANTA Publications



A new impeller can be just as reluctant to squeeze back onto the shaft and into the casing. A smear of soap and the assistance of a rubber mallet may be required.


Before starting the pump ensure that drive belts (if fitted) do not slip. It may be necessary to initially prime the system especially if the pump is fitted high in the vessel. Smaller portable electric pumps are unlikely to pump up to more than one to two metres so outlets may have to be initially positioned by trial and error.


Rotary vane pump - This simple fixed rotor pump below operates by the solid vanes housed in a slotted rotor being flung by centrifugal force into the eccentric (nylon) housing on rotation. The drive direction (by belt, chain, air or hydraulic) determines the flow direction. Modified versions are often used as hydraulic pumps for steering and winches, though the type has limited pressurisation capabilities. It is best suited for clean fluids only.

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The variable rotor pump operates similarly, but the rotor’s position in the housing can be shifted by a control lever so altering flow speed and direction. With constant anticlockwise drive the variable position rotor pump shown above will create full flow from right to left when positioned at the bottom of the housing, decreasing to no flow in the centre and then increasing to full flow from left to right at the top of the housing.



Gear pumps -These use intermeshed cogs, screw threads or helical gears and are used as lubricating oil pumps. They withstand heat and will pump relatively viscous liquids at medium to high pressure.



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An intermeshed cog gear pump


The roots air blower is a variation of this principle using intermeshed elongated fan blades. A typical application is the supercharger blowers on Detroit engines.



All positive displacement pumps are best operating with an open outlet and the more powerful can sustain internal damage if piping or valves are shut off while the pressure of pumping is allowed to continue building. High pressure pumps are fitted with over pressure relief or bypass valves.

Dynamic or Kinetic pumps


Dynamic pumps use the principle of picking up the gas, liquid or slurry and moving it as in a conveyor belt. Unlike the positive displacement pumps they are not as easily damaged by working against a closed valve, so do not have to be closely monitored to shut down as soon as they suck the tank dry.


Archimedes screw – This ancient water pump is turned within a barrel or trough. It is ideal for slurries and is found adapted for farm machinery and for bulk cargo handling conveyor systems. It is the forerunner of the modern propeller.


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Archimedes screw lifting slurry



Centrifugal pump – This pump type is also resistant to damage by a closed outlet as it will cease to draw in further material. However cavitations and erosion will cause longer term damage. It uses a rotor (solid or flexible impeller) with swept back blades to push material down onto the central rotor, spin it around the “volute” shaped casing and throw it to the outlet. They are suitable for moving less viscous liquids, air and (with sufficiently robust rotor blades) will suck up and spit out solids such as sawdust and shavings.


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A centrifugal pump

Centrifugal pumps are not self-priming so air locks must not be introduced when laying out and installing piping. A short distance between inlet and rotor is critical. Typical applications of this pump include fresh water engine cooling pumps, ballast transfer pumps, blower fans and domestic vacuum cleaners.


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Cutaway of a turbocharger courtesy of ANTA Publications


The specialised turbocharger uses the kinetic energy (energy of movement) of the exhaust gasses to spin a turbine to push more air into engine. It spins very fast and gets hot. Its bearings can be cooled by the engines oil pump, so if the engine is shut down suddenly the turbo continues spinning and will suffer damage. This is typically at the rotor blade bases where the solid hub and thin blades cool at different rates.


Gravity pumps

Gravity pumps or hydraulic rams work by using a large liquid flow rate (high pressure) to lift a smaller quantity of the whole at a lower flow rate (lower pressure). This is achieved by using the “water hammer” effect to sustain a pressure head in a vacuum reservoir. A limited flow can continuously be drawn off and up. Not commonly found on small vessels these pumps are restricted to mining and scientific applications.


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A hydraulic ram

A variety of the type is the mineral extraction water cannons of New Zealand. Piping was laid from a high dam to a nozzle way below. In subsequent use as a water cannon, the pressure from the dam’s head of water supplied a jet of water sufficient to break up the clay and gravels of the mountain sides to allow panning for the gold content in the slurry created.


High pressure and metering pumps

In the jerk fuel pump shown below, an engine driven cam pushes the plunger against a sturdy spring to deliver pressurised fuel injection.  As the plunger forces the fuel up it is squeezed through a helical grove. This is rotated in the housing by a rack and pinion gear to meter the amount of fuel and provide throttle control. 

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Fuel pumps are more fully described in the accompanying text Marine engine and propulsion systems for Marine Engine Drivers”.


For NSCV specifications for piping see Section 1.5, bilge piping.




2.5  Bilge systems


It is said that “a desperate man with a bucket is most motivated to fight a fire or save his sinking ship”. The critical need to maintain floatation and control fire is recognised in Class Rules, the NSCV and USL codes. These rules specify that an effective method must be provided. In small vessels fire buckets with lanyards (to reach the water) and more effective manual and/or mechanical pumps are specified.


A bilge system removes unwanted water and liquids from within the vessel in order to maintain its reserve buoyancy and stability. It is cost effective to share pipes and pumps. Water being pumped in to fight fire will eventually need to be pumped out before it sinks the ship. Consequently shared bilge/fire systems are common in small vessels. Reliable equipment and alarms are vital, particularly in the engine room where water ingress may stop the motors, power supply and the pumps themselves. The new NSCV Part C Section 4 Fire Safety however does not allow fire pumps to be used as bilge pumps, so fire systems are dealt separately in the next chapter.

Survey Requirements

Class Rules, the NSCV and USL codes determine requirements for construction and operation by vessel trade, size and plying zone. For brevity, where requirements are stated, this text refers to the NSCV Part C Section 5 “Machinery”. If your vessel is larger or not surveyed to these standards, the relevant Class rules or your State’s survey regulations must be sought.


The NSCV provides two methods for builders and owners to gain survey compliance. “Deemed to comply” solutions are prescribed in the rules and prefaced by the word “shall”- they are not negotiable.  Equivalent” solutions may be approved by a survey authority if they can be shown to effectively meet the intentions of the rules.


NSCV Part C Section 5 Chapter 5 specifies requirements for seawater and bilge systems of vessels less than 35 m in measured length. Vessels “shall” be fitted with a pumping system capable of draining any bilge or watertight compartment. Open vessels less than 5 metres with access for bailing may be provided with a bucket.



Class 1B vessels of 15 metres and over shall permit pumping and draining from every space in the vessel while any one watertight compartment is flooded.





Manual pumps

Powered pumps


Measured length



capacity in kLitres/hour



capacity in kLitres/hour

<5      undecked

Bailing bucket & ready access to bilge






> 7.5  and < 10





>10    and <12.5





>12.5 and <17.5





>17.5 and <20





>20    and  <25





>25    and  <35






Note; Pumps should be self priming or have a suitable priming device.


Where two pumps are required, each power pump shall not be dependent on the same source of power. The pumps and piping systems shall be arranged to enable simultaneous pumping of each machinery space bilge by both pumps on all vessels of 20 metres and more in length. For vessels other than Class A, one of the two pumps may be a portable pump provided it can be operated at full capacity within 5 minutes of flooding becoming known.


The pump is the heart of the system, dependent on the piping and the valves described in earlier sections being in good order and in the correct position for the intended operation. These also are specified in the NSCV.


Bilge piping (and seawater)

All piping that may come into contact seawater shall be corrosion-resistant. Metal pipes shall be copper, stainless steel, suitable grade of aluminium alloy or carbon steel which is protected against corrosion (galvanised). The thickness of piping shall be sufficient to withstand the likely maximum pressure allowing for corrosion and erosion. Piping shall be protected from mechanical damage arising from the cargo stowage or from other causes. Pipe fittings shall not be made of malleable iron.


Flexible piping for vibration damping or to accommodate machinery movement shall be in short lengths of less than 760 mm and be readily visible and located so as to prevent mechanical damage or contact with hot surfaces. At least two corrosion-resistant clips shall be fitted to secure flexible piping of 25 mm internal diameter and above. Flexible piping may be used in vessels less than 12.5 metres in length, provided that its join to a fitting shall be appropriate for the nature of fluid carried and the risks of fluid leakage.


Rigid plastic bilge piping may only be used in vessels less than 12.5 metres in measured length except in locations of high fire risk.


The minimum diameter of bilge piping in vessels less than 10 metres in length shall not be less than 25 mm, in vessels of 10 metres and over in length shall be determined by formulas from the NSCV, which shall in no case be less than 32 mm,


Suction lines

Bilge suctions shall be located to facilitate the drainage of water from within each compartment over a range of list not less than +5°. Limber holes shall be provided to allow water to drain to the bilge suctions.


A watertight compartment less than 7% of the total under deck volume may be drained into an adjacent compartment by means of a self-closing valve. The adjacent compartment shall itself be served by the bilge system.

Where a pipe pierces a collision bulkhead, it shall be fitted with a suitable valve at the bulkhead that clearly indicates whether the valve is open or closed. Where the valve is fitted on the after side of the bulkhead and is readily accessible at all times, it need not be controllable from the bulkhead deck.



Grids or gratings are fixed to the exterior of the vessel’s hull over sea inlets as initial coarse strainers to prevent large pieces of foreign matter being drawn into the pipes.

Each of the bilge suctions in a machinery space shall be fitted with a mudbox and metallic tail pipe. All bilge suctions in vessels of 20 metres and over are required to be fitted with strum, strainer or mud boxes to prevent solids from entering and either blocking or damaging the system. Strainer holes shall not be greater than 10 mm in diameter, and the total area of the holes shall not be less than twice the suction pipe area.


Isolating and non return valves

All sea inlet and overboard discharge pipes (including sanitary discharges) shall be fitted with valves or cocks. Isolating valves are screw down valves used to isolate a section of piping. Non-return valves prevent liquid flowing back in the opposite direction. They can be uncontrolled (they do not have a positive means of closing) or controlled (they have a spindle and hand wheel to positively close the valve).

In the latter case they are called screw down non-return valves.


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The >10 metre and <12.5 metre vessel shown relies on manifold height, non return lines and good practice to avoid backfooding from sea to bilge.




Bilge manifold

Vessels of 25 metres and over shall be provided with an accessible bilge distribution manifold with non-return valves. This is dedicated main pipe with a line of valve connections that are selected to direct the required suction to the chosen pump.



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Non return valves are incorporates in the >10 metre and <12.5 metre vessel manifold shown.




Backflooding and downflooding

The bilge system shall be arranged to prevent water back-flooding from the sea into watertight compartments or machinery. The bilge connection to any pump that also draws from the sea shall be either a screw down non-return valve, or a cock that cannot be opened at the same time to the bilge and to the sea.


Backflooding- Bilge pumps are often used for other duties such as ballast, fire and wash deck which draw from the sea. If sea water can flood back, or one bilge space can flood into another this undesirable situation may lead to the vessel sinking. Non return valves are fitted to prevent water entering the bilge line and L-port cocks are used that prevent bilge and sea water lines being simultaneously selected. Yet sometimes a malfunction such as a jammed valve or dirty valve seat could admit water into the bilge line. To reduce the possibility of such occurrences regular maintenance should be followed, including:


Avoid trailing deck hoses that may siphon sea water back to the manifold.

Clean all bilge wells, mud boxes and strainers.

Put some water in each bilge well and pump out each in turn to confirm operation.

Open up and service bilge suction non-return valves in scheduled maintenance.

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Larger vessels use L port cocks and screw down non return valves to prevent backfooding from sea to bilge.


Down-flooding- If a vessel heels over sufficiently for the deck edge to be immersed the sea can spills over into the spaces below decks, or down-flood. This will result in loss of buoyancy and a reduction in the righting moment (the ability of a vessel to return to the upright position from a heeled position) and can result in the loss of the vessel due to progressive flooding and capsize.


Entry points for down-flooding are door openings, hatch coamings, ventilators and vent pipes. All hatches should be closed and secure prior to leaving port, vents must have means for closing and doors should be kept closed in heavy weather.


Note: The International Load Line Regulations specify minimum requirements for strength, height and method of closure of doors, hatches, ventilators and air pipes. The Regulations require higher standards for vessels under 100 metres.


A flexible suction hose bilge pumping system may be fitted to service compartments in Class C, D or E vessels of measured length less than 12.5 metres. Where there is a risk of down flooding if hatches or other weathertight or watertight covers leading to a void compartment are opened, void compartments should also be provided with a deck-mounted cam lock fitting connected to a suction pipe permanently mounted within the compartment.




On decked vessels, a bilge level alarm shall be fitted in the propulsion machinery space and all other compartments that contain seawater pumping systems. The alarm shall be clearly audible at a continuously manned control position with the machinery operating under full power conditions and the power supply for the alarm shall be available at all times there is a person on board.


Bilges in engine rooms and compartments must be ventilated by fans and open vents.  These will remove any build-up of vapours and gases.  The fans must be stopped and vents closed if a fire occurs.


Typical Arrangement


The drawing below shows a bilge system fitted on a vessel of between 17.5 metres and 20 metres in length. 

The sea water connection acts as a primer for the flexible impeller pump and is used to flush the system after pumping bilges. The forward bilge suction is into the chain locker beyond the collision bulkhead. Consequently it has a self closing valve in case water can enter the main compartments of the vessel after a collision. Each bilge suction line is fitted with a strum box and a non return valve. If the vessel is not fitted with a separate oily waste tank, the oily bilges should be pumped into a large drum or container on deck for disposal ashore at a later stage.


A key safety feature of this system that prevents back-flooding is the L port cock. It cannot be turned to direct from the sea water inlet towards the bilge, yet allows the same power pump to be used for bilges, deck hose and fire hose.


Because the bilge manifold is in the engine room, remote handles are provided above the deck for access in an emergency.



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The >17.5 metre and <20 metre vessel shown uses an L port to avoid backfooding from sea to bilge




To operate

On the bilge pump check that the sea suction valve and discharge to deck hose valve are shut and the suction valve to the bilge manifold open. If oily water separation is fitted, also shut the oily bilge suction valve discharge and oily water separator valve.

Check that the ship side overboard discharge valve for the fire and bilge pump is open. If the bilge pump is a positive displacement pump, open the overboard discharge. If a centrifugal pump, the valve should be closed.

Start pump (in the case of a centrifugal pump, open up the overboard discharge). Each bilge can now be pumped out. A rattling noise in the bilge valve is an indication that the well is empty. The pump can then be stopped. If vacuum gauges are fitted on the suction side of the pump, a zero reading on the gauge is an indication that the well is empty. To confirm the well is empty it should be sounded. When the well is confirmed as empty, close all valves that are open.

Combined bilge pump & fire main systems

As it is cost effective to share pipes and pumps shared bilge/fire pump systems are common in older non NSCV compliant vessels as described below.









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It includes:

Manifolds on both the suction and discharge side of the pump. (See Section 1.1 Ballast operations Schematic drawing only).

 A screw down non-return valve connecting the suction manifold to the bilge prevents water from flowing back from pump to bilge.

A screw lift valve connecting the suction manifold to the sea suction piping allowing the pump to direct sea water into the fire pumping system.

A screw lift valve connecting the discharge manifold to the overboard discharge. (The valve is opened when the bilge system is being used) and a screw lift valve connecting the discharge manifold to the fire main.  (The valve directs water to the fire main).

The USL code specifies emergency fire and/or portable pumps (hand or power dependent on vessel size). The specifications of a portable emergency fire pump include compatibility for use as a bilge pump. Operated as a fire pump, its flexible suction hose is lowered into the sea while a fire hose is connected to the pump’s discharge. Alternatively, for bilge duty, the flexible hose is lowered into the flooded space and the fire hose directed overboard. Hand operated bilge pumps can be adapted for emergency use on small craft.


The new NSCV Part C Section 4 Fire Safety however does not allow fire pumps to be used as bilge pumps, so fire systems are dealt separately in the next chapter.



Common faults


Mechanical Failure of Pump

Pump not turning - check power source switch is on and cable etc in good repair.

If the pump is driven from an engine it is possible that the clutch is slipping or not engaging properly. Flexible impeller pumps shed their vanes either through old age or having been run dry.  If this is the case then the impeller will need to be replaced according to manufacturer’s instructions (see the previous section on pumps).


Air Leaks

Air sucked into the bilge system reduces the efficiency of the pump and the amount of water which it can be discharge.  Excess air in the system may damage the pump itself. This common suction side problem may be caused by:


Leaking glands on pump drive shafts, valves or cocks;

Holes in the pipe work caused by mechanical damage or corrosion;

Empty compartment valves being opened or leaking to drawing air into the system.


Blocked Bilges

Strum boxes and strainers are provided to prevent debris such as rags and other waste from entering the system. They are prime areas for a blockage can be difficult to get at to clear, hence keep the bilges clean at all times.  High level bilges can lead to dangerous situations including:


Poor stability due to effect on trim, heel and draft and free surface effects;

Oil and water splashing on machinery and dangerous slippery work environment;

Fire hazard due to oil or explosive gases in the bilges

Corrosion, lack of cleanliness and unpleasant odours

Impaired visibility the vessels structure covered by bilges

Periodic Survey Requirements

As per the NSCV/USL Code, for vessel less than 35 metres in length, pumping systems are to be surveyed as follows:


Annual Survey:         Operational test of bilge pumps, bilge alarms and bilge valves.  General examination of machinery installation.  Inspection of all pipe arrangements.


2 Yearly Survey:       Sea injection and overboard discharge valves and cocks.


4 Yearly Survey:       Tanks forming part of the hull except fuel tanks, internally.


12 Yearly Survey:     Fuel tank internally.


Pollution Prevention


Oily bilges must only be discharged into a proper mobile or shore based facility.  It is an offence under State and Commonwealth law to pump oil into the water.


Vessels over 400 Gross Tonnage are allowed to discharge oily bilges into the sea if certain strict conditions are met.  To comply with these conditions, vessels must be fitted with oily water discharge monitoring equipment, oily water separators and sludge holding tanks.  Penalties for breach of pollution regulations are very high.


Fire Control Systems


3.1 Principles of fire control  


Flash point

In order to catch on fire, a material must be heated sufficiently to cause it to partially vaporize. The temperature that a material releases flammable vapor is called its flash point.  Technically petrol and diesel are cocktails of hydrocarbons of different flash points. Commonly from - 40°C to 0°C for petrol and 60°C for diesel is the temperature that they will burn if heat is applied.  (Diesel’s higher flash point means it is safer to use than petrol). If a fire is cooled below its flash point then the flame will not be sustained.


The fire triangle

The three elements necessary for a fire to start to burn and continue to burn are:


Oxygen      +           Heat         +        Fuel  =         The chain reaction that is fire

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The heat of the fire vaporizes the fuel and maintains the chemical chain reaction. Remove at least one of the elements to break the chain reaction and so control the fire.


Heat transfer, the spread of fires

Heat moves (transfers) in three ways:


Convection              Heat moving in a liquid or gas.

Conduction             Heat traveling through a solid.

Radiation                Heat energy traveling out as heat rays (direct heat).


Hot air and flame that experience convection move upwards, overcoming escapees that cannot climb quicker than the fire, or become trapped above it.


Conducted heat may transfer through steel bulkheads or pipes from welding or flame into another compartment remote from the fire itself.

Radiated heat may char material that is close enough or even set it alight. Cooling the exterior of compartments that are on fire (boundary cooling) and removing surrounding flammable materials (boundary clearance) are essential to limit fire spread by radiation.

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Classes of fire

The six classes of fire are defined the type of material burning.






Class A

Solids containing carbon

Wood, paper, cloth, plastic


Class B

Combustible liquids

Petrol, oil, tar, paint.


Class C

Combustible gases

LPG (liquid petroleum gas).


Class D

Combustible metals

Aluminium, sodium, potassium.


Class ‘E’

Live electrical equipment

Switchboards, generators.


Class F

Cooking oils and fats

Sunflower oil, olive oil.



An electrical fire highlights risk of electrocution by use of water based extinguishers when the current is on. Switch it off and the fire reverts to another classification.



Causes of fire


Situations that result in increased fire hazard include fuel and explosive gas transfers (LPG being heavier than air collects in the bilge), engine friction, battery sparking, use of flammable cleaning fluids, accumulation of oily rags, poor and careless housekeeping.


Bad maintenance - Loose tools, untidy work habits, build up of litter, improper disposal of oils, dirty bilges, lack of engine servicing and make shift repairs can all cause fires.


Matches and cigarettes - Limit and sign the areas where persons can and cannot smoke.


Oily rags - The cloth can be oxidised by the oil to generate heat, just like a garden compost heap.  If the heat cannot escape then the cloth may burst into flame in

spontaneous combustion.  It is important to dispose safely of oily rags and other fire hazards, including swarf and dross waste produced in cutting and machining metals.


Fats and oils - In rough weather, cooking fats and oils may slop out of the pan into the stove to ignite. Accumulated grease in overhead fume extractors build up and may catch on fire.  Such areas should be checked and kept clean. Spirit stoves in smaller boats are a similar risk. 


Overloaded power points and circuits - Tightly coiled or partially broken/kinked electrical cable can have increased resistance that may cause local heating leading to fire.  Incorrect installation and electrical protection devices (fuses and circuit breakers) are major causes of fire on vessels. All equipment should be installed by a licensed electrician. 


Cleaners and solvents - Labelling warns of most cleaner, paint and solvent hazards and their safe use is further described in the manufacturers Hazardous Material Data Safety Sheets. Paint lockers can contain a cocktail of serious fire hazards.  Incorrectly stowing non compatible chemicals together can lead to fire. The classification of materials and advice for separation can be found in the IMDG code.


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3.2  Fire Safety and Survey (NSCV Part C Section 4)

The NSCV (Fire Safety) prescribes a defence-in-depth strategy based on a series of measures applicable to different states of a fire as it progresses from ignition to fully developed state. These are illustrated in Table 1 of Section 4 that lists:


Ignition & incipient fire           featuring     Control of heat sources, fuels, interactions

First item development          featuring     Material properties, Fire detection

Spread to secondary items    featuring     Fire detection, Fire suppression

Full space Involvement          featuring     Fire suppression, Ventilation control

Spread to other spaces          featuring     Fire resistance, Manual suppression

Spread to essential systems  featuring     Fire resistance, Manual suppression, Redundancy


The functional requirements for fire control therefore require passive and active fire protection measures by the avoidance of all fire hazards, the restricted use of combustible materials and the minimisation of ignition potential from flammables liquids. Early

detection, containment and extinction in the space of origin is the next line of defence. Separation of spaces by thermal and structural boundaries (to limit spread by smoke & fire) with access protection for escape and fire-fighting are required in addition to the ready availability of fire appliances.


The NSCV also assigns risk categories in Table 2 (not SOLAS vessels) based on class, operations and carriage of day or overnight passengers to determine survey stringency.


Fire Risk Category I (lowest risk)


Fire Risk Category II (moderate risk)


Fire Risk Category III (high risk)


Fire Risk Category IV (highest risk)




Extracts of Table 2 –

Fire Risk Category



Unlimited domestic operations


Offshore operations


Restricted offshore operations


Partially smooth waters


Smooth waters



Class 1- Length of vessel

< 35 m (1)

<35 m (1)

All lengths

All lengths

All lengths


Class 1: 13 to 36 day pax







Class 1: 37 to 200 day pax







Class 1: 201 to 450 day pax







Class 1: 451 or more day pax

NA (2)

NA (2)





Class 1: 13 to 36 berthed pax







Class 1: 37 or more berthed pax

NA (2)

NA (2)





Class 2- Length of vessel