Handling a ship in congested or high traffic areas is not an easy task. Congested waters are high-density traffic areas where a vessel is likely to collide with another vessel if ship navigation is not carried out in the right manner.
Navigation out in open sea isn’t easy either but by virtue of lesser traffic and ample sea room, it doesn’t pose as much of a threat as that posed in congested waters. Approaches such as that in Singapore or China have dense traffic in the form of fishing boats, small crafts in addition to larger merchant vessels which, by default, means that a higher degree of precaution, situational awareness, and decision making is to be exercised under such circumstances.
Factors such as the state of sea, weather, proximity of vessels, status of the ship (underway or making way, laden or under ballast condition etc), interaction with other vessels causing difference in pressure at the bow or stern, proximity to the land, steering gear effectiveness, effectiveness of the aids to navigation, rudder movement, effect of shallows are among many things that are to be adhered to. All of that aforementioned are to be applied in conjunction with COLREGs to ensure that the vessel is safely navigated into and out of the congested area. Rule 18 of COLREGs explicitly state as to which vessel is to be kept out of the way of another, which basically means that a vessel cannot bypass pre existing rules with regard to vessel responsibility.
As there are several vessels present in the vicinity, chances of a collision or any other form of an accident are very high; adherence to COLREGs in such cases is imperative in order to negate any legal liabilities that might arise due to vessel mishandling. In such conditions, the officer on watch and the ship’s master must take all the necessary precautions to avoid any kind of accident. Even in the presence of a Pilot who is, most of the times, thorough with the existing local navigational landscape, the onus of the safety of the vessel lies with the Master; to make it clearer, the presence of a Pilot does not relieve the Master and his bridge team of the obligations to keep clear of other vessels. A comprehensive passage plan along with information pulled from the Admiralty publications (prepared by the 2/O under the authority of the Master) including the presence of Aborts & Contingencies for emergency situations ensures that the whole process of safe navigation runs efficiently.
For navigating through congested waters, the officer on watch must know his duties well and be aware of the positions of ships in the vicinity and other fixed structures. He must make full preparations to sail through such areas. Practical ship handling is a skill acquired with experience, and the OOW must never hesitate to call the Master in case of the slightest doubt. After all, the Master is termed as a ‘Master’ for obvious reasons! Having said that, the following points are laid out to assist the OOW with regard to his decisions in congested waters:
Comply with COLREGs at all times
Be thorough with the ship’s maneuvering characteristics such as the UKC, Squat, stopping distance etc. Such details are laid out concisely in the wheelhouse poster
Change over to hand steering
Post additional lookouts. As stated by Rule 5 of ROR “Every vessel shall at all times maintain a proper look-out by sight and hearing as well as by all available means appropriate in the prevailing circumstances and condition so as to make a full appraisal of the situation and of the risk of collision.” (Know what are the duties of ship lookout here)
Always keep the Master informed about the current situation and action plans. Call him if in the slightest doubt with regard to the existing situation or action to be taken
Give the Engine Room adequate notice with regard to any requirements (maneuverability) that shall be necessary during the course of the vessel movement
Reduce the vessel’s speed to a safe speed for navigation. Refer to Rule 6 of ROR for more clarity on ‘Safe Speed’
Run parallel power units for steering gears for additional safety. This is to ensure that the navigation of the vessel does not come to a standstill in case one steering gear system fails. Preparedness to ensure that equipment is not liable to failure are gauged with a prior control test. The same should be applicable to the ship’s whistle which is used more often when in congested waters to warn the vessels in the vicinity of one’s own approach or presence
Adhere to the company’s ISM checklist for navigation in confined waters
Use all available resources including all aids to navigation and cross verify with the chart (use largest scale chart for that area) to check depths, distances, bearings etc. Monitor the position of the vessel continuously with the help of parallel indexing, ARPA etc
Coordinate with the VTS as well as with the other ships in the vicinity using the VHF
Record the vessel movement in the Bell Book
In case the vessel is in congested areas in restricted visibility, the associated risks increase. Rule 19 of COLREGs lays out mandatory rules with regard to navigation in RV which must be adhered to at all times. In addition to the above guidelines, the appropriate light and fog signals for a vessel in RV must be applied as well. For further reading on RV, refer to this article.
About a century ago no one would have heard about a marine engineer, but today it is a profession which is as established as any other famous ones. Over the last 100 years, engineering as a field of study has developed and diversified far beyond what could have been imagined prior to this period. Not only this, it has also branched out into various specialised fields that have achieved great progress. Most of these new fields are aligned to any of the basic engineering branches like mechanical, electrical, civil, electronics, computers etc and have something or the other incorporated from them. One such branch is called marine engineering
Marine engineering is the branch of study that deals with the design, development, production and maintenance of the equipments used at sea and on board sea vessels like boats, ships etc. As a matter of fact, it is quite a vast field and it also has many sister arenas like naval architecture and nautical science.
A marine engineer is a professional who is responsible for the operation, maintenance and repair of all major mechanical and engineered equipments on board a ship. There are many mechanical systems that help in the operations of any vessel like the propulsion mechanics, electricity and power generation system, lubrication, fuel systems, water distillation, lighting and air conditioning system etc. These are all included in the technical responsibilities of a marine engineer.
A variety of marine programs, conducted by engineers also fall under this area of study, like an underwater vehicle research, cable laying work, renewable energy production in marine areas etc. In the latter half of the 19th century, marine engines for propulsion arrived and revolutionised the sea traveling vessels. It was about this time that the marine engineer began to stamp his importance over the scheme of work and transformed from a ‘stoker’ to an engineer.
In recent years, there have been many new introductions to the marine technologies that have further enhanced the machines and the services like the fuel cells and magneto hydrodynamics etc. Further research and development is also in progress and newer details emerge every now and then. It would thus be safe to state that marine engineering is a very dynamic field.
A marine engineer can opt for different types of vessels, depending upon his/her background training and expertise, which can be categorised to :
Foreign going dry vessels
Foreign going tanker vessels (oil, gas , chemical etc)
Coastal trading dry and tanker ships
Passenger vessels
Dynamic position vessels
Offshore platforms and ships
Port assisting boats and ship (Tugs, barges etc)
In recent times, this field of study has caught on the imagination of many around the world. The interest shown by students of various countries and the response at the concerned departments in the universities bears testimony to this. The increase in the employment opportunities in this field has added to the lure of a job as a marine engineer. Both merchant navy and armed navy have immense opportunities for the students of this field. In addition to this, various manufacturing industries and units that produce shipping equipments and machines also hire these professionals to work in their production houses.
In some countries, a marine engineer can switch over to armed navy (after giving physical and medical fitness exams) as the technical qualification requirement are already achieved by a sea going engineer.
Also, budding field jobs as trainers and teachers at various institutions are available and suitable candidates are very much in demand. Judging by the developments and the interest it would not be wrong to assume that this field of study would continue to leave an indelible mark on the world.
Career Path after Marine Engineering.
The above graph is a brief overview of hierarchy and job opportunities for Marine engineering candidates. The Shore Job entirely depends on the capability/ experience of the candidate and requirement of the shore company. After marine engineering, a candidate has to do various advance courses and management studies to opt for shore job even having sailed as a chief engineer.
10 Things Marine Engineers Must Do To Know Their Machinery Inside Out
If you are a marine engineer working on ships, you would know that there is a massive difference between the theoretical knowledge provided in the maritime books and the practical skills that are acquired by getting one’s hands dirty in the engine room. Though there is no substitute to the knowledge that is acquired through years of experience working in the engine room, a marine engineer wouldn’t be able to survive if ignores the bookish knowledge completely.
A ship’s engine room is installed with different types of machinery systems, each requiring specific approach while carrying out maintenance and troubleshooting. It is only through a healthy combination of knowledge and practical skills can a marine engineer understand his machinery inside-out.
So what exactly does it take for a marine engineer to know his machinery systems inside-out?
Mentioned below are few key points which can help marine engineers for understanding their machinery and systems in a better way.
1. Understand Starting / Stopping Procedures
Every ship is different and so are its machinery systems. Though the basic type of machinery systems remains the same for all ships, the operating and maintenance procedures would differ according to the manufacturer of the machine and the ship type.
It is imperative for a ship’s engineer to understand the starting and stopping procedures of his machinery extremely well before doing everything else. This can be done by using the operating manual of each machinery system and asking questions to fellow engine room colleagues/seniors. (Most of the times, engineers are afraid to ask seniors or colleagues for help as they feel that it would make them look inexperience and dumb. Though people on board ships have a tendency to judge a person’s knowledge by the kind of questions he or she asks, it is always better to get over such apprehensions and gather as much details about your machinery as possible. Moreover, there are always officers on board who would be more than happy to share their knowledge when asked. It is always better to know everything about your machinery before hand than to regret and slog during breakdown or emergencies.)
Note: The operating manuals would teach the basic steps for starting/stopping a machinery. But it’s only through experience that an engineer will be able to understand how his machinery works, what are their common issues, and how he can troubleshoot them quickly.
2. Read The Machinery Manual Thoroughly
As mentioned above, the manual of every machinery is the bible to understanding that particular system. As an engineer, you must know your machinery manual like the “back of your hand”. It’s the knowledge base on which you will be able to build the foundation of your maintenance schedules and troubleshooting techniques. Without knowing the construction/design of your system and understanding how it works, you will be shooting “arrows in dark” while dealing with an emergency situation.
A marine engineer therefore must read, understand, and memorise his machinery manual to the best of this abilities.
3. Learn From The Machinery Records
Every engine room machinery has a history which should be studied thoroughly by the marine engineers. This history will tell you about the all the things that the machinery has gone through in the past including major accidents, problems, and overhauling operations. Based on these records, a marine engineer will also be able to plan his routine maintenance procedures and prepare the troubleshooting approach with utmost ease.
Go through the records of the past few months to find out when and how did your machinery got stuck or confronted a problem. The data therein would help you to learn a lot about your machine.
4. Find out Details on All Major Maintenance
Past maintenance reports helps engineers to understand the main problems that the machinery has faced and what are the issues that have been experienced frequently. The maintenance reports would also include all important comments and tips that needs to be considered while handling that particular machinery system. Marine engineers must study the maintenance reports not only to understand the past problems but also to learn how the machinery will behave under different conditions.
5. Keep a Track of Running Hours
Depending on the running hours of the machinery, the ship’s engineer will plan and perform the next maintenance procedure. Keeping a track of the running hours is extremely important to prevent any kind of sudden failure or breakdown of machinery. Marine engineers must properly maintain and monitor the running hours as stated by the manufacturer or the company to ensure smooth running of their machinery systems. They would also help to plan any major maintenance of the machinery in the next scheduled dry dock.
6. Know Your Machinery Clearances
Routine maintenance is an integral part of marine engineers’ duties on board ships. One of the important aspects of the machinery which engineers must be aware of are the different types of clearances. A ship’s engineer must keep a close watch on the clearances of different parts of engine room machinery such as bearing and bumping clearances in compressors, crank pin and piston ring clearances in generator etc. as they are an important part of any planned maintenance system. These data would help to plan out and schedule the next maintenance operation.
7. Check If There is any Alteration Done in the Used Parts by Referring Past Records
Ship’s machinery systems are constantly going through regular maintenance procedures which often involves major repair works. During such procedures some of the machinery parts are to be altered to perform repair jobs. For e.g. whenever any major repair is done on the crank shaft pin of the marine engine (through grinding), the dimensions of the adjoining parts like the shell bearings are also altered. It is therefore important for engineers to look through the past records to find out if any alteration of machinery parts done in order to ensure that the right kind of spare parts are used during any pending or future maintenance or repair work.
8. Know the Required Spare parts
A marine engineer must have the knowledge of all the spare parts that are required for his machinery. It is imperative that these spare parts are available in the ship’s inventory especially during sudden break down and while planning machinery overhauling. Go through the manuals to know what all parts will be required to carry out maintenance and repair work. Cross-check the ship’s inventory to keep a track of the number of spare parts left on board ships. Raise a requisition whenever required.
9. Know All Important Tests
All important engine room machinery and systems have some kind of tests attached to them for their smooth operations. As a ship’s engineer, it is important to understand these tests and learn how are they performed and what are the procedures involved to send the required sample shore. Tests such as boiler water tests, generator lube oil test etc. require engineers to know about their contents, chemicals involved and common impurities found. Learn the purpose and procedures of these tests to ensure smooth running of your machinery.
10. Find Out Past 3 months Log Book Parameters
Log book is one such reference on board that marine engineers have to refer every single day. Apart from this, they must take out time to go through the log book parameters of their machinery, especially from the past three months, in order to understand common problems or any major changes that have taken place in their usual operations. If an engineer is new to the ship, log book is the best and quickest reference which would help to know and understand his machinery system.
Bow Thrusters: Construction and Working.
Bow thrusters are a type of propeller-shaped system fitted either on the bow (forward part) and stern part (known as stern thruster) of the ship. They are smaller in size as compared to the ship’s propeller and help in better manoeuvrability of the vessel at lower speeds.
Bow thrusters are generally used for maneuvering the ship near the coastal waters, channels or when entering or leaving a port while experiencing bad currents or adverse winds.
Bow thrusters help in assisting tugboats in berthing the ship to avoid unnecessary wastage of time and eventually money because of lesser stay of the vessel in the ports. The presence of bow thrusters on a vessel eradicates the need of two tugs while leaving and entering the port, and thus save more money. Nowadays ships have both bow and stern thruster, which makes them independent of the tugboats for manoeuvring in the port limits (if the port regulation does not make it compulsory to use tugboats).
Generally, side thrusters are transverse thrusters placed in a duct located at the forward and aft end of the ship. The thruster set in the forward end is known as the bow thruster and the one placed in the aft end is known as the stern thruster. The requirement for the number of thrusters to be installed depends on the length and the cargo capacity of the ship. The route of the vessel also plays an important factor as many countries have local regulations of compulsory use of tugboats to enter or leave their port limits.
For the installation of the side thrusters, following things are important:
The thruster compartment, also known as bow thruster room, should be easily accessible from the open deck by the ship’s crew
As most of the seagoing vessels use an electric motor for the thruster, which is a heat generating machinery and must, therefore, be positioned in a dry and well-ventilated area
The bow thruster room should be fitted with a high-level bilge alarm and the indication to be provided in engine control room and bridge
The thruster room should be well lit
The room should be provided with at least one light supplied from the emergency source
In the case of installation of more than one panel, make sure to operate the thruster from only one panel at the time
The thruster room should not be used to store flammable products in the area of the electric motor
The installation of the tunnel or conduit containing the propeller must be positioned perpendicular to the axis of the ship, in all the directions
The propeller should not protrude out of the conduit
Grid bars may or may not be fitted at both ends of the tunnel (taking into account of how much debris the ship bottom will experience in its voyage). The number of bars for them to be kept at a minimum as they tend to reduce the thrust force and overall performance of the bow thruster (or stern thruster)
Sharp edges on the grid bars to be avoided. Trapezoidal shape with no sharpness is a good choice of design for grid bars installed perpendicularly to the direction of the bow wave
The design and position of the thruster tunnel should not interfere with the water flow under hull or should not add to hull resistance
Ensure that the material used for the installed thruster does not foul existing equipment inside the ship such as steering links etc.
The bow and stern thrusters are placed in the through-and-through tunnels which open at both sides of the ship. There are two such tunnels – at forward and aft ends of the ship. The thruster takes suction from one side and throws it out at the other side of the vessel, thus moving the ship in the opposite direction. This can be operated in both the directions, i.e. port to starboard and starboard to port. The bow thrusters are placed below the water line of the ship. For this reason, the bow thruster room should be checked for water accumulation at regular intervals of time.
The bow and the stern thrusters can be electrically driven or hydraulic driven or diesel driven. However, the most commonly used are electric driven, as in hydraulic driven thrusters there occur many leakage problems. Also, with diesel driven bow thrusters, the amount of maintenance required is more and every time before starting someone needs to go to the thruster room to check the thrusters.
The thruster used are usually of CPP type, i.e. the blades on the propeller boss can be moved to change the direction of the thrust. The boss which carries the blades is internally provided with a movable shaft (operated by hydraulic oil) also know and Hydraulic Pod Motor driven Thrusters. Once the signal is given to change the pitch, the hydraulic oil will be supplied to operate the internal shaft (within the boss) to change the blade angle of the thruster (as shown in the video).
The motor shaft drives the shaft of the thruster via pinion gear arrangement. The sealing gasket is provided in the motor casing which holds the water which is in the tunnel.
The Thruster assembly consists of the following components:
The electric motor with safety relays
The flexible coupling between motor and thruster
Mounting and casing for the electric motor
The connecting flange and shaft
Motor casing seal
The tailpiece with shaft seal
Bearings
The propeller shaft
The zinc anodes
Grid with bars at both ends of the tunnel
Operation:
Bow thruster consists of an electric motor which is mounted directly over the thruster using a worm gear arrangement. The motor runs at a constant speed, and whenever there is a change required in the thrust or direction, the controllable pitch blades are adjusted. These blades are moved, and the pitch is changed with the help of hydraulic oil which moves the hub on which the blades are mounted. As the thruster is of controllable pitch type, it can be run continuously, and when no thrust is required, the pitch can be made to zero.
The thruster is controlled from the bridge, and the directions are given remotely. In case of remote failure, a manual method for changing the pitch is provided in the thruster room and can be operated from there.
Usually, the hydraulic valve block which controls the pitch of the blades is operated in the BT room for changing the blade angle in an emergency.
When the Bow Thruster is operated alone, and the signal is given to operate the pitch at port side, the thrust will result in turning the ship towards starboard side from the forward part.
Similarly, when the Bow Thruster is operated alone, and the signal is given to run the pitch at starboard side, the thrust will result in turning the ship towards the port side from the forward part.
When the stern thruster and bow thruster are operated together at the same side, the ship will move laterally towards the opposite side.
As seen in the above diagrams, the bow thruster and the stern thruster provides excellent manoeuvrability to the ship.
Following things to be kept in mind when operating the Side Thrusters:
Ensure to start the motor well ahead of the thruster operation and open the hydraulic lines
Never operate the thruster beyond its rated load else it may lead to tripping of the motor
Gradually increase the capacity and shift the pitch. Avoid sudden changes in the BT movement
The side thrusters are considered as an “on load” starting device, i.e. they should only be operated when they are submerged in water
Before operating the thruster, check for small craft, swimmers, boats and tugs adjacent to the thruster tunnel
Never touch any moving parts or the electric motor in operation
In the case of installation of more than one panel, ensure the thruster is operated from only one panel at a time
Maintenance Required
1) The insulation needs to be checked regularly and should be kept dry. This is done because bow thrusters are not used frequently and thus there are chances of damages by moisture. Moreover, because of the frequent idle state of the bow thrusters, there can be a reduction in the insulation resistance, especially in colder regions.
2) The space heater is checked for the working condition so that the insulation can be kept dry.
3) The bearings of the motor and the links are to be greased every month.
4) The condition of hydraulic oil is to be checked every month for water in oil and samples should be sent for lab analysis for further checking.
5) The thickness of the contactors is to be checked from time to time.
6) Checks are to be made for any water leakages in the bow thruster room which is an indication of seal leaking.
7) The flexible coupling between the motor and thruster should also be checked.
8) Check and inspect all the cable connections for the cleanliness and tightness
9) Vacuum or blow clean the motor grid for removing the carbon grid which may increase the operating temperature
Major Maintenance
The major overhauling and maintenance of the bow and stern thruster are done during the dry dock when the ship’s hull is out of the water, and the thruster blades and tunnel can be easily accessed.
Following maintenance are usually done in the dry docking:
Replacement of the O’ rings and the sealing rings
Removal of the pinion shaft
Inspection and maintenance/ replacement of gear set
Replacement of the bearings
Repairs, cleaning and replacement of the blades
Inspection of hub and repair if needed
Inspection and overhauling of the oil distribution box (for operating propeller blades)
Advantages
1) Better manoeuvrability at low speeds of the ship.
2) Safety of the ship increases when berthing in bad weather.
3) Saves money due to the reduction of stay in port and less usage of tugboats.
Disadvantages
1) A very large induction motor is required, which takes a lot of current and load, and thus large generator capacity is required.
2) Initial investment is high.
3) Maintenance and repairs are costly when there is damage.
The thrust force produced by the motor to move the ship will depend on various parameters such as; hull design, power source, the design of tunnel, use of grids, draft and load of the vessel etc.
The condition of the weather and state of the water also plays a vital role in BT performance..
Manjeet Vishwakarma 