 Narrow passageways and fairways in rivers and canals with a navigable depth and width comparable small in relation to the draft and the breadth of passaging ships are called restricted waters. The maneuverability of ships navigating through such restricted waters will be affected by high hydrodynamic effects that are different from those when ships navigate in broad and deep waters. These peculiar hydrodynamic effects are the shallow water effects, ship squat, interaction and bank effect. Let us have a look into the shallow water effect and ship squat.
When a ship proceeds, the surrounding water is displaced toward the sides and bottom, making a relative flow against the ship’s advance. Advancing hull submerges deeper compared to when she is dead in the water; this changes the trim because the water  around the hull flows a little faster compared with the ship’s speed and the hydraulic pressure decreases. This phenomenon is called ship squat; but why does this take place?
In shallow water, when the bottom clearance is comparatively small, the ratio of the horizontal flow along both sides of the ship increases because the current towards the bottom is restricted. The hydraulic pressure along both sides of the hull decreases, as the nearer hull is to the surface flow, the faster the rate accelerates and the water level around the ship drops considerably. For this reason, sinkage of the bow and stern and subsequent trim change become larger in shallow water than in deep water. We should be careful that sinkage of the bow and change of trim become greater when a ship  runs in shallow water.
Now let us see how the depth of water affects the turning capability of the ship in shallow water. We will have a look at the data of the turning capability of the large ships. Every curve indicates the tactical diameter of a specific ship by the multiples of the ship’s length. There is another graph illustrating how the turning track of the ship differs as the depth of the water changes. Note that in both cases, the ratio of the water depth to draft is changed with all other parameters remaining same. Thus, we can estimate the tactical diameter of a ship running in restricted water as the multiples of its length, although the presented data are taken from the test results of the large ships, this method can also be applied to smaller ships.
 In view of the maneuverability of a ship, the depth of water also affects course stability like the effects on turning ability. We shall study the difference of the effects on course stability in deep water and in shallow water from the results of the zigzag maneuver tests. In the zigzag maneuver test a ship’s rudder starts to swing alternately to port and starboard when the ship is set on the steady straight course. At first, the rudder is put to starboard ten degrees until her head swings starboard ten degrees from her original course. Immediately after the ship’s head swings ten degrees starboard, the rudder is changed to port ten degrees until her head appoints ten degrees port from her original course.
This alternate rudder operations are repeated several times making a ship run in a zigzag course. On the picture you can see the results of the zigzag tests conducted in deep and shallow water. The required time to turn a ship’s head port or starboard to a settled angle in shallow water become shorter with a smaller overshoot angle than that in deep water. This means that we can expect quicker rudder effect in shallow water compared to that in deep water.
A well-remembered case among several cases reported in the past is that of a large passenger ship navigating in shallow water without reducing the speed that hit her bottom severely on the rocks. When running in restricted water, it is essential to keep enough underkeel clearance to avoid the deterioration of the maneuverability and touch bottom damage.
Underkeel clearance means the space between the ship’s bottom and the sea bed. It equals the value when the ship’s draft is subtracted from the sum of chart datum and  height of tide at that time. To maintain enough underkeel clearance, we have to consider the factors affecting the sinkage of the hull such as squat allowance, wave response allowance, possible error of chart datum, meteorological and oceanographic conditions, and other environmental conditions, and secure a safety allowance that eliminates ship handling difficulties.
The effects of sinkage and change of trim when a ship navigates in shallow water greatly affect the ship’s maneuverability. Enough knowledge of these effects in restricted waters will prevent accidents.
 Working offshore is demanding – the work is specialized and often technical, the schedules are intense, fatigue and tiredness represent potential problems for everyone on board. Tiredness is due to long and hard physical effort – it is resolved by rest and sleep. This is not always easy on a constantly moving vessel.
Fatigue builds up over time and includes both physical and mental effects and results in reduced physical and mental capacity. It can be difficult to recover. The effects of fatigue are dangerous – it affects everyone regardless of experience, skills, age, knowledge and training. It can affect the individual’s reaction time, coordination and decision making. The senior officers on board need to be aware of this possibility which is especially likely towards the end of the shift or the tour.
Deck crew can be involved in hard physical work and so are affected by tiredness. Over time, this can also build up into fatigue . Those on the bridge are at risk of fatigue when maneuvering the vessel for long periods while close to installations. To avoid tiredness and fatigue, all personnel must use their off-duty time to relax and sleep.
There is international legislation that restricts working hours on ships and so helps to combat fatigue. Everyone on board must comply with the working hours requirements set out in the STCW Convention and the Maritime Labor Convention.
Occasionally, installations will ask for more working hours than the vessel is chartered for. Masters should put the welfare of their crews first. If they believe that crew fatigue will increase the hazards of any requested operation, they must say no and give their reasonsю
As well as knowing the legislation, the human element is equally important. Everyone must make the best use of their off-duty time to get enough rest. Senior officers must ensure that everyone including themselves does that. Tired and fatigued crew members are more likely to suffer personal injuries and make poor decisions with the potential to endanger the crew, the vessel, installations and the marine environment.
Everyone needs to aware of the effect of continual heavy weather on personnel’s ability to sleep. During safe job analysis, toolbox meetings, senior officers should watch out for any signs of fatigue in their personnel. But everyone should know how to  recognize the signs of fatigue in themselves and their colleagues. The danger signs include:
- Difficulty staying awake
- Difficulty concentrating
- Slowness & clumsiness
- Forgetfulness
- Headaches
Other signs show the psychological effect of fatigue. People become unusually irritant and less talkative. They can become depressed and show anti-social behavior. If anyone believes that fatigue is affecting them or a colleague, they should do all they can to get themselves or individual some rest. The person concerned must use their maximum allowance of rest time to sleep and relax.
Crew members should inform their supervisor if they believe that fatigue is lowering their effectiveness. In the longer term, reducing fatigue is helped by eating healthily, smoking less and reducing coffee consumption.
Fatigue is dangerous offshore because it leads to slower responses and poor judgment of distance, speed, time and risk. Individuals can become pre-occupied with a single task and overlook more important issues. They become less vigilant.
Officers should ensure that everyone including themselves gets enough rest and makes best use of their off-duty time to minimize fatigue. Everyone needs to be aware of the symptoms of fatigue. Remember that if you are suffering from fatigue, you have the potential to engender yourself, your colleagues, your vessel, and the marine environment.
 Working on deck of the offshore vessel requires good safety awareness by both the deck crew and those on the bridge controlling the operation. The risk of personal injury is always present. The first defense against this is keeping to proper planning procedures. Personal protective equipment, or PPE, is also important. This includes a hard hat with a chin strap, safety footwear, high visibility jackets, and gloves. It can also include eye protection. Flotation devices will be required on the vessels with open decks. These must be put on correctly so that they do not come off should the wearer fall into the water.
There is often water on deck, so slips, trips and falls and a constant hazard. The deck crew should look out for each other’s safety and be prepared to stop the operation if their safety is jeopardized. Generally, for hooking up the pre-slung cargo requires a team of two is required. Deck crew must go to a position of safety during actual lifting. One crew member is designated as banksman and signals to the crane operator on the installation.
When working cargo, or anchor handling, the vessel will usually be working down weather – even a small swell can cause water to come on board and wash the crew off the deck. In difficult weather conditions remember the old nautical say – one hand for yourself and one for the vessel.
When deck operations have to be carried out at night, effective illumination of the working area is essential. In anchor handli ng, towing, and also mooring operations everyone on deck as well as those commanding the deck crew must be aware that ropes and wires can break, so when equipment and lines are under tension, everyone should be in a position of safety.
Anchor handling involves working with anchors, buoys, wire, chains and there equipment on deck. The mud and water comes on deck with them, makes a deck slippery and increases the risk of slips, trips and falls. For this reason, the deck should be cleaned as soon as possible.
If you are unsure about how to carry out a procedure, do not just carry on. You may be putting yourself and others on board at risk. If you are asked to do something that you consider unsafe, stop the job and speak to a senior officer. The senior officers should plan the operations efficiently and issue their commands in positive and calm manner. Complying strictly with proper procedures helps to minimize the risk of personal injury. Avoid cutting corners. Always think about where you are standing. Be aware of mooring points, uneven decks and other trip hazards.
In all situations, it is important to work calmly and never rush around. No job is so urgent that is worth risking your life and your safety. You, your colleagues and your vessel will all benefit from you carrying out the work calmly and correctly. Make safety your first priority while working on deck.
 This short article is devoted to the practical use of ECDIS as an aid to navigation and the usage of the common features and functions in a safe and efficient way during the voyage of your vessel. The ECDIS system is only one of many complicated electronic navigation aids found on today’s modern ship bridges. To navigate his vessel safely and efficiently, the navigator must have a good navigational background, sufficient navigational practice, theoretical knowledge about the ECDIS system architecture, functions and features, and practical experience in the use of ECDIS systems.
An ECDIS system is a very impressive system even when seen through the eyes of the professional navigator. But no navigator should ever forget that all systems do have limitations and the fact that these limitations are very often well-hidden and/or not mentioned in the system manuals. The most important thing to know about modern computerized systems is their limitations. Knowledge concerning their functions and features is quickly accessible with a little interest and practice. The only way to get to know the limitations of the system is to study available material about the subject, system manuals, and by practical use under safe conditions.
As of today, the Seafarers Training, Certification and Watchkeeping (STCW) Code does not specify any special training in the use of ECDIS. STCW table A-II/1 considers the ECDIS training to be a part of training in understanding a “chart”. As a modern ECDIS system is just as complicated as ARPA, this lack of detailed training requirements may pose a hazard to ships, sailing with ECDIS operated by untrained operators.
The reduction of presented information or proper selection of only relevant information is often an important task when setting up  an ECDIS system. An ECDIS system which simultaneously presents all available information tends to be overloaded and therefore the important information may be less visible. A basic and very important thing to understand and take into account at all times when using ECDIS is the fact that no system is better than its weakest chain, that is, “rubbish in – rubbish out”. Vital information for any ECDIS system is own ship’s position. Whenever own position is wrong, ECDIS chart information is wrong. Simple as that!
information is wrong. Simple as that! ECDIS systems accept position input from a number of positioning devices as well as dead reckoning. Most ECDIS systems today are connected to a GPS and/or DGPS. This means that stable and good positioning can be expected most of the time. However, the navigator should never forget to check his position as often as practicable by all available means in order to detect any malfunction or inaccuracy in the navigation system used as an input to the ECDIS.
Positions are always referenced to “something” and this “something” is referred to as the chart datum and there are hundreds of different chart datums around. This means that the navigators at all times must know:
- What chart datum does the ship’s positioning system connected to the ECDIS use
- What chart datum does the actual ECDIS chart use
- Whenever the datum used by the positioning system and the chart are different, known corrections must be taken into account.
Today, the ECDIS system is often connected to an integrated bridge system, of forms a part of an integrated bridge system, i.e. a system where the Radar, ARPA, Autopilot, Positioning, Routing, Log, Gyro, ECDIS etc. are connected and work as “one system”. Several options for “automatic sailing” become available to the navigator. Depending on the ship position, i.e. open sea, coastal or restricted waters, the navigator may select between several sailing options. The examples of possible sailing options found on an integrated ship bridge system include course mode, corrected course mode, and track mode.
Course mode is a sailing mode normally used in open waters and for long distance sailing, as this mode will give the shortest distance between two points. No correction for offset is made, but the ship will “home” to the destination.
Corrected course mode is used in waters where it is necessary to correct for wind and current. Correction for offset is made, but no attempt to follow the original planned track is made.
In track mode, the system will calculate the optimal path back to the original planned track. This mode is used in restricted waters whenever it is important to stay exactly on the planned track.
 For a professional navigator, it is a matter of course that the route selected for actual sailing is properly checked before it is activated and used for actual sailing. Parameters used when planning the route must still be valid in order to maintain required safety margins. If not, the route may have to be changed before it can be used safely. Examples of parameters which may have changed after the selected route was programmed are ship draft, available position accuracy, engine and steering gear reliability etc.
Navigation with an ECDIS system, especially when the ECDIS is connected to an integrated bridge system, changes the work situation for the navigator a lot. Conventional navigation with manual plotting of ship position in the chart, heavy traffic, and manual course change in restricted waters is a task that puts a heavy workload on the navigator. A good working ECDIS reduces that workload a lot. So, the navigator’s role has changed from actually doing the tasks to monitoring them. From the safety point of view, this should be very good, as the navigator is given more time to check important parameters and monitor the traffic more closely.
Sailing with ECDIS requires a highly qualified navigator with a sound and positive skepticism towards computerized systems. Take the necessary time and effort to really get to know your ECDIS. This will definitely save you lot of work and trouble in the future; it may someday save your career or even your life.
 Let us talk a bit about the preparations that shall be done by the crew of the supply vessel about to enter the 5000 meter zone of the offshore installation. Before leaving port, the vessel shall ensure that it has most recent field charts and up-to-date information about the installations it is going to. On the way to the field, the vessel must monitor the weather and the weather forecasts. The people on the installation will be doing the same but the final decision for going ahead with any operation will be made by the Master.
Whenever at an hour of way or consistent with field procedures, the vessel notifies the installation of the vessel’s ETA, or estimated time of arrival. After the vessel is instructed to proceed, the pre-entry 500 meter zone checklist must be gone through.
Every vessel will have one as a part of the safety management system. Sometimes the charterers will have one that they will need the vessel to use. Whether the company or charterer checklist, it will include a communication check and a full equipment check including engines, thrusters, and rudders.
All propulsion machinery should be started; steering gear system and changes between control positions and maneuvering modes need to be checked. Some fields require the vessel to be on DP, while others insist that it is not used. The vessel needs to get it right. If required, the DP checklist must be completed and the DP must be running on entry to the zone.
Once all checklists are completed, the vessel can request permission to enter the 500 meter zone. Only when permission is given, can the vessel proceed. Before entering the zone, there must be a toolbox talk. Although time may be limited, it is important that the deck crew members understand the planned operations as well as the hazards on the vessel; there are many external hazards that must be considered.
The most recent field charts will be needed. Check with the OIM or the designated person to ensur e that you have the most recent information. If subsea operations are taking place, it is unlikely that the vessel be allowed inside the 500 meter zone. But this can happen if the installation needs the supplies urgently.
Helicopter operations are another potential hazard. Helicopters almost always land and take off into the wind and the vessel is usually asked to stand off. The vessel will be informed of any helicopter operations.
Other operations that can conflict with the vessel’s activities include overboard discharges, flaring, well testing, seismic work and air venting. The Master must ensure that the installation’s designated person keeps the vessel fully informed about all these operations, both planned and unplanned.
The vessel should first maneuver to a safe position outside the radius of the installation’s cranes and at least fifty meters off the installation. The Master should then assess the situation to ensure that working conditions are safe before proceeding to the position for cargo operations. Inside the zone, the engine room as well as the bridge should be continually manned. It is best practice to work down weather from the installation. If the installation requires vessel to work up weather, a further risk assessment may be needed.
It is possible that the vessel may need to tie up to the installation. This is a challenging procedure. The vessel will be moored either stern-to or alongside. Regular checking of the mooring lines is essential. These situations can cause considerable wear on the mooring ropes.
The personnel on the bridge must maintain a constant listening watch on the field VHF channel. The vessel must be ready to change position or stop operations at short notice. Stopping operations may mean leaving the 500 meter zone. Working inside the  500 meter zone is demanding for everyone on board.
Many operations may be going on at the same time so it is important that anyone is told about any changes to the plan. The deck crew needs to keep alert – they must be prepared to stop or alter what they are doing at short notice, either because the weather has deteriorated or because the installation requires it for any reason.
Proper planning, good communications, and putting the safety of everyone on board as main priority will help to make these operations safe and successful.
 The basic inspection regime for all the MOUs is the IMO conventions. These include the Load Lines, SOLAS, MARPOL, STCW, COLREG and Tonnage conventions. Some MOUs also examine compliance with the relevant ILO conventions. Ships can check each MOU’s website for the further requirements. Complications can arise because for all members of MOUs, their national legislation will take priority over the MOU agreements.
MOUs have different levels of inspection. The initial inspection usually takes about three hours. If there are clear grounds to concern, it may progress to a more detailed inspection, adding another hour or two. Ships with a poor inspection history may be subject to a more detailed inspection. If the Master believes that port state control inspection is likely, he should double check the gangway watch. An ineffective or absent gangway watch will start the inspection badly as it implies poor compliance with the ISM Code. A proper gangway watch must always be in place. The ISPS Code must be strictly kept to. Ships with high target scores, such as old bulk carriers, passenger ships, oil tankers and gas and chemical carriers, will be subjected to an expanded inspection which will take six to eight hours.
MOUs have different levels of inspection. The initial inspection usually takes about three hours. If there are clear grounds to  concern, it may progress to a more detailed inspection, adding another hour or two. Ships with a poor inspection history may be subject to a more detailed inspection. If the Master believes that port state control inspection is likely, he should double check the gangway watch. An ineffective or absent gangway watch will start the inspection badly as it implies poor compliance with the ISM Code. A proper gangway watch must always be in place. The ISPS Code must be strictly kept to. Ships with high target scores, such as old bulk carriers, passenger ships, oil tankers and gas and chemical carriers, will be subjected to an expanded inspection which will take six to eight hours.
Under the Paris MOU, the ship is obliged to inform the port if it believes that it is due for the mandatory annual inspection. The Paris MOU website lists the types of ship for which this is required. Always ensure that the PSC officer is escorted to the Master’s cabin. Be aware that the inspector will be looking around to see the state of the ship.
 What is voyage planning, who is responsible, how do we comply with the rules and how do we utilize the features and functions available in an ECDIS? The purpose of voyage planning is to support the bridge team and ensure that the ship can be navigated safely between ports from berth to berth. A voyage plan should cover ocean, coastal and pilotage waters and according to STCW regulations be planned in advance. The voyage plan aim to establish the most favorable route while maintaining appropriate margins of safety and safe passing distances offshore.
The following factors are amongst those that should be taken into account:
- - The marine environment
- - The adequacy and reliability of charted hydrographic data along the route
- - The availability and reliability of navigation aids, coastal marks, lights and radar conspicuous targets for position fixing along the route
- - The type of cargo can influence route selection
- - Any routing constraints imposed by the ship, e.g. draught, type of cargo, etc.
- - If possible, avoid areas with dense traffic
- - Take into account weather forecasts, current, tide, wind, swell and visibility conditions
- - If possible, avoid areas with onshore set or areas where onshore set can be expected
- - Whenever possible, follow traffic separation schemes and follow ship reporting procedures
- - Check technical systems before departure and if possible, take into account previous experience of their reliability
- Take into account your own experience with the planned route and type of ship.
There are four main stages in the planning of a safe voyage:
- - Appraisal, i.e. the collection of information and validation of all relevant information;
- - Planning, i.e. the presentation of the raw data -into information and the strategy to be used;
- - The execution of tracking, voyage and communication control;
- - Monitoring, i.e. ensuring that the voyage plan is being followed.
 Cargo operations are probably the most important ship operations. They vary enormously from petrochemicals where the discharge is controlled by the ship’s officers to containerships where the discharge and loading is organized and largely carried out by the shore stuff. From your training and experience you will know the requirements of your own ship’s cargo operations but, whatever the cargo, many of the principles remain the same.
Prompt and accurate reporting of any damage must be done within twenty-four hours. Cargo condition, speed of loading or discharging, any delay in operations all can have commercial consequences. The chief officer will know what is critical in your cargo operations and you should discuss the procedures with him. Much of the time cargo operations proceed according to pre-determined plan. It is when the unexpected occurs that the skill of the deck officer is really tested. By responding in the right way you can make a big difference to the commercial performance of your ship.
Make sure you know what can go wrong, what to do and whom to contact if it does. Good situational awareness is the basis for any effective response. Make sure you know what is going on at all times in port. This means being on deck most of the time, keeping your eyes open and communicating with the terminal staff. This will also help with another major task – making sure that the ship is safe.
Current, tide and the cargo operations can all move the ship in relation to the shore if the mooring ropes are slack.  The ropes need to be checked regularly for tautness. If your ship has self-tensioning winches, these are best left on the brake and not left in tension once the ship is secured alongside. In an emergency, never release the brakes and attempt to pull a ship back alongside using the power of the winches alone. You must know the ship’s mooring equipment and be familiar with its operation and capabilities including the type of winch and brake, the size, type and length of lines.
Make sure you are aware of the tidal changes and keep an eye on a weather forecast. Sudden changes can have a big impact on cargo operations and additional mooring arrangements may be needed. Be aware of nearby ship movements, check the lines after any ship has arrived or left the next berth.
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