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Bank Effect on Ships

BANK EFFECT:-

A vessel navigating close to a gently shelving bank will experience forces pushing the bow away from and drawing the stern towards the bank. If the forces are strong enough, it may cause the vessel to roll towards the obstruction which, because the draught has now increased on that side, may cause grounding on the low side.

Bank Effect on Ships
Bank Effect on Ships

It is often thought that it is the repelling action of the forward positive pressure area which is the sole cause of the bow being pushed away from the obstruction.

Inspection of the forces involved clearly show that this is not always the case. In certain circumstances there can be a greater suction area at the stern created by the faster flowing water in that area, which in turn creates a negative pressure area acting on a much greater turning lever.

Bank Effect on Ships
Bank Effect on Ships

It need not be a river or canal bank, the same effect can be observed where there is a shoal area which is significantly less on one side of the vessel than on the other or where a vessel is navigating near say a dredged channel where the depth is significantly deeper on one side.

The effect can only be controlled by constantly correcting the applied helm and through judicious adjustment of ship speed.


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Ship to Ship (STS) Operations

Ship to Ship (STS) operations plan:

ARRIVAL

OPERATIONAL PROCEDURES BEFORE MANOEUVRING

Preparation of Ships – Preparation before manoeuvres begin:

1. Ensure that the crew is fully briefed on procedures and hazards, with particular reference to mooring and unmooring.

2. Ensure that the oil tanker conforms to relevant guidelines, is upright and at a suitable trim.

3. Confirm that all essential cargo and safety equipment has been tested.

4. Confirm that mooring equipment is prepared in accordance with the mooring plan.

5. Fenders and transfer hoses are correctly positioned, connected and secured.

6. Cargo manifolds and hose handling equipment are prepared.

7. Obtain a weather forecast for the STS transfer area for the anticipated period of the operation.

8. Agree the actions to be taken if the emergency signal on the oil tanker’s whistle is sounded.

The following information should be exchanged between the two ships – Information to be exchanged between ships:

1. Mooring Arrangements.

2. Quantities and characteristics of the cargo (es) to be loaded (discharged) and identification of any toxic components.

3. Sequence of loading (discharging) of tanks.

4. Details of cargo transfer system, number of pumps and maximum permissible pressure.

5. Rate of oil transfer during operations (initial, maximum and topping-up).

6. The time required by the discharging oil tanker for starting, stopping and changing rate of delivery during topping-off of tanks.

7. Normal stopping and emergency shutdown procedures.

8. Maximum draught and freeboard anticipated during operations.

9. Disposition and quantity of ballast and slops and disposal if applicable.

10. Details of proposed method of venting or inerting cargo tanks.

11. Details of crude oil washing, if applicable.

12. Emergency and oil spill containment procedures.

13. Sequence of actions in case of spillage of oil.

14. Identified critical stages of the operation.

15. Watch or shift arrangements.

16. Environmental and operational limits that would trigger suspension of the transfer operation and disconnection and unmooring of the tankers.

17. Local or government rules that apply to the transfer.

18. Co-ordination of plans for cargo hose connection, monitoring, draining and disconnection.

19. Unmooring plan.

  • Navigational Signals

The lights and shapes to be shown, and the sound signals made are those required by the

International Regulations for Preventing Collisions at Sea (COLREGS) [8], and local

regulations. These lights and shapes should be checked and rigged ready for display prior to

the STS operation.

Dangers associated with STS operation:-

  1. Collision risk in the vicinity
  2. Cargo vapour pressure
  3. H2S content

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Piracy & Armed Robbery

Piracy is the act of boarding or attempting to board a ship with hostile intentions. Once pirates have boarded a ship and taken control by suppressing the crew, the ship is  said to be hijacked.

Hijacking is mainly of two types:

  1. By terrorists – to gain world attention, to release someone in captivity or for ransom or a combination of these.
  2. For financial gains – it can be for ransom money or for theft of cargo.

Actions prior to entry:

  1. Prepare the vessel as per guidelines given in BMP4.
  2. Provide additional lookouts for each watch, especially night watches.
  3. Emphasize on a careful radar watch and use of nigh vision optics.
  4. Place several dummies at visible locations to give an impression of a large number of persons on watch.
  5. Give enhanced protection to the bridge by covering glass windows with steel gratings or metal plates, making a wall of sandbags, double layer of chain link fence, anti-RPG screens, etc.
  6. Keep Kevlar jackets and helmets for the bridge team. If possible, these should be of non-military colour.
  7. Many operators provide armed security guards for HRA transits.
  8. All doors and accesses must be securely shut and only one access must be used throughout the HRA transit.
  9. Physical barriers such as razor wires or electrified barriers must be used to prevent pirates from boarding the vessel or at least delaying their boarding.
  10. Water cannons must be fixed in place and foam monitors pointed to the ship side and use in order to deter or delay the pirates boarding attempt.
  11. A unique alarm must be decided upon and sounded in case of a pirate attack.
  12. A citadel must be in place and drills must be carried out prior entry into HRA so that all crew members are aware of the alarm signal and action to be taken on hearing the alarm.
  13. Emergency contact list with all important numbers such as CSO, MSCHOA, UKMTO, etc must be readily available.
  14. SSAS must be tested and confirmed as operational.

During HRA transit:

  1. Proper look out must be kept for suspicious crafts or movements.
  2. Vessel must participate in the UKMTO and MSCHOA reporting schemes and must proceed at maximum available speed while transiting the HRA.
  3. When suspicious boats are sighted, the vessel must commence various monoeuvres in order to determine whether the boat is concern or not.
  4. The vessel must sound the ship’s whistle to warn the pirates that they have been noticed. The armed guards will fire warning shots.
  5. The Master must be called on the Bridge well in time and once boats are approaching, the emergency alarm must be raised so that all crew proceed to the designated area and later move to the Citadel.
  6. Pumps must be started for the water cannons and foam monitors so as to delay the boarding.
  7. Master must call UKMTO well before pirates have boarded. When pirate boarding is imminent, the Master should also send the SSAS alert.
  8. Once the pirates have boarded, the Master must stop engines and proceed to Citadel with the Bridge Team. Engine Room team must black out the vessel and proceed to the Citadel.
  9. If all crew members are available in Citadel and no one is missing, then there are high chances of the Navy / Military forces to come for rescue.
  10. If caught by the Pirates, crew members must not retaliate with aggression, but be calm and patient.

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Risk Assessment

Risk Assessment of Damage & Control Measures after Stranding:

  • Prior to transiting the HRA, ship operators and Masters should carry out a thorough Risk Assessment to assess the likelihood and consequences of piracy attacks to the vessel, based on the latest available information.
  • The output of this Risk Assessment should identify measures for prevention, mitigation and recovery, which will mean combining statutory regulations with supplementary measures to combat piracy. It is important that the Risk Assessment is ship and voyage specific and not generic.
  • Factors to be considered in the Risk Assessment should include, but may not be limited to, the following:-
    1. Crew Safety – When trying to prevent prate boarding, it must be ensured that crew members will not be trapped inside and should be able to escape in the event of another type of emergency, such as for example fire. A Safe Muster Point or Citadel should be considered. Adequate ballistic protection should be given to the crew who may be required to be on the bridge during a pirate attack, as pirates fire at the Bridge to try to force the ship to stop.
    2. Freeboard – Pirates try to board the ship at the lowest point above the waterline, making it easier for them to climb onboard. These points are often on either quarter or at the vessel’s stern. Experience suggests that vessels with a minimum freeboard greater than 8 metres have a much greater chance of successfully escaping a piracy attempt than those with less. This also depends on the construction of the ship. A large freeboard alone may not be enough to deter a pirate attack.
    3. Speed – One of the most effective ways to defeat a pirate attack is by using speed to try to outrun the attackers and / or make it difficult to board. Ships are recommended to proceed at Full Sea Speed or maximum safe speed throughout their transit of the HRA. If a vessel is part of a ‘Group Transit’ within the IRTC, speed may be required to be adjusted.
    4. Sea State – Pirates mount their attacks from very small craft (skiffs), even where they are supported by ‘Motherships’, which tends to limit their operations to moderate sea states. It is difficult to operate small craft effectively in sea state 3 and above.
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Muster List

Muster List

Emergency planning of the ship and onboard training are closely related.  The ship’s crew is divided into teams and all are allocated duties to perform in response to emergencies and to ensure personnel safety.  On board ship this is achieved through muster lists.

All ships engaged on international voyages and ships of Classes II(A) and III must have muster lists.  It is the duty of the Master of the ship to compile the muster list and keep it up to date.  Copies of the muster list must be exhibited in conspicuous places throughout the ship and must be exhibited in the wheelhouse, engine room and crew accommodation.

The format of muster lists is usually prepared by the company under the SMS.  For ships of Classes I, II, II(A) and III, the muster list should be approved by the Flag State Administration (MCA in the case of the UK).

The following is an example of a muster list.

MUSTER LIST – PART A

Name of vessel:……………………………………………………..

Emergency SignalDescription of Signal
General emergency alarmSeven or more short blasts/rings followed by one long on vessel’s whistle and internal bells
Withdraw to boats/raftsSeries of long blasts/rings on vessel’s whistle and internal bells
Abandon shipVerbal command from Master or Officer in Charge
Man overboardThree long blasts on vessel’s whistle, repeated as necessary.  This signal may be supplemented as required on internal bells and/or public address announcement
Automatic fire alarmContinuous ringing of internal bells
Emergency SignalAction on Hearing Signal
General emergency alarmAll crew proceed to their emergency station, wearing suitable and sufficient clothing, footwear and protective headgear, carrying lifejacket, survival suit and hand-held VHF radios (where allocated), closing all doors behind them as they go.  Team Leaders check off personnel and report to Bridge Team.  Bridge Team ensures automatic fire doors closed (where fitted) and ventilation stopped (as appropriate).  Specific duties are defined in Muster List – Part B.  Additional duties will be allocated depending upon the nature of the emergency.
Withdraw to boats/raftsAll crew proceed immediately to their allocated boat/raft station, donning survival suits and lifejacket.  Master or Officer in Charge arranges distribution of GMDSS VHF radios, SARTs, EPIRT and vessel’s current position.
Abandon shipAll survival craft launched, followed by evacuation of crew.
Man overboardMaster and deck officers to wheelhouse.  Chief Engineer and motorman to engine control room.  All other crew to their emergency station.  (Refer to appropriate ship contingency plan)
Automatic fire alarmDuring unmanned operation, either at sea or in port, protected space to be examined by two persons including a responsible officer.  During manned operation, bridge or duty deck officer to be advised immediately of the situation.  General emergency alarm shall thereafter be activated if the fire confirmed, or at any time if there is doubt as to the safety of the vessel or crew.
Emergency StationLocation for Muster
Bridge TeamWheelhouse
Engine Room TeamLocation
Deck TeamLocation
Back-up TeamLocation

The Second Officer is responsible for ensuring that all life-saving appliances (LSA) and portable fire fighting equipment (FFE) are maintained in good condition and ready for immediate use.  The Chief Engineer is responsible for ensuring that all fixed fire fighting equipment (FFE) is maintained in good condition and ready for immediate use.  Any deficiencies and/or defects discovered must be reported to the appropriate officer immediately.

All crew members must familiarise themselves with the content of the vessel’s muster list (Parts A and B) and with their emergency duties assigned therein before the commencement of each voyage.  All officers must familiarise themselves with the content of Shipboard Contingency Plans.

Any member of crew unsure as to the content of the muster list and/or their duties must consult a superior officer.

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Contingency Planning

Composition of Emergency Teams in the Contingency Plan:

  1. The Command Team – will be on the Bridge ( called Command Center) and take overall charge of all operations. Hence, frequent feedback, short and crisp, is necessary from each team to the Command Center. Navigation, communication, maintenance of records of all actions and their timings, etc. will be carried out at the Command Center.
  2. The Emergency Team – would be divided into two, depending on the emergency. Where the emergency is in the E/R, the second engineer will be the leader of the Primary Team and Chief Officer will lead the back-up team. If the emergency is elsewhere, the Chief Officer will be the leader of the Primary team and the Second Engineer will lead the backup team.
  3. The Support Team – also called the medical team, will look after administration of first aid, if and when required. They will prepare the patients for evacuation, prepare lifeboats in case of necessity to abandon the ship,  shut watertight doors and vents, provide assistance to other teams as directed by the Command Team, etc.
  4. Engine Room Team – also called Roving Team, will be under the charge of Chief Engineer. They will attend to E/R systems, services and controls, start emergency fire pump when required, isolate electricity from compartments on fire, shut off ventilation systems to compartments on fire and provide assistance to other teams as directed by the command team.
  5. Crew for Rescue Boat – This team is mainly for man overboard or for picking up survivors from the water. They will prepare the rescue boat and on specific instructions from the command team, lower and launch the rescue boat, rescues the man or survivors and get hoisted back on board.

IMO for preparing Contingency Plans for Various Emergencies:

All crews are familiar with a system of procedures and guidelines for performing potentially hazardous and safety related operations.  For example:

  • Entry into enclosed spaces.
  • Actions after collision.
  • Abandonment.

The majority of these procedures and guidelines have been well documented in publications such as the Code of Safe Working Practises for Seamen, SOLAS, MARPOL, MGNs etc.  However they relied on the Master, officers and crew remembering them from their studies.  The additional problem lay with them being ‘generic’ rather than vessel-specific.  Other procedures were developed from the experience of the Master on board at a particular time, which caused confusion amongst officers and crews when the Master was relieved.

This was one of the reasons for the introduction of ISM and, in particular, the vessel’s SMS.

Since 1 July 2002 all vessels of 500 gross tonnes and above must carry a SMC and will be the subject of internal and external audits to verify that the documented procedures are being followed.  It is true to say that a large number of companies delayed the production and subsequent approval of their SMSs until very close to the implementation date.

Company SMSs were developed utilising a range of resources, for example quality managers appointed from both within the company and externally, consultancy companies and ‘off the shelf’ SMS models.  This led to a proliferation of differing methods for producing SMSs and the ways in which they were presented, particularly at shipboard level.

The Maritime Safety Committee (MSC) of the International Maritime Organisation (IMO) identified this as a problem area and stated that they were “concerned that the presence on board ships of different and non-harmonized emergency plans may be counter-productive in case of an emergency” hence the adoption of Resolution A.852(20), on 27 November 1997, of Guidelines for a Structure of an Integrated System of Contingency Planning for Shipboard Emergencies.

These guidelines will be the basis for your study in preparing emergency and damage control plans.  They may vary from the system on board your vessel/s but the essential elements will be similar, namely : Planning, Preparing, Training, Response actions, Reporting.


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Squat

Description Method of Calculation & Application:

  • In figure 6-3 the ship is running on even keel with a small under keel clearance and, therefore, water which would normally pass under the ship is now severely restricted.
Squat - Shallow Water

This result in two things, firstly the build of water ahead of the ship, longitudinal resistance pushes the pivot point back from P to PP and the steering lever is reduced. Secondly the water being forced under the bow, at a higher speed than normal, creates a low pressure and loss of buoyancy. The ship will now ‘Squat by the Bow’ which in turn makes the problem even worse. Several cases have been reported of large ships running in shallow water and experiencing bow sinkage of up to 2 metres!

Squat - The effect of Squat (water pressure)

In addition to the possibility of grounding forward there also exists the possibility of losing control and sheering violently out of a channel. If the helmsman allows a small swing to develop, longitudinal resistance ahead of the ship will be brought round onto the exposed bow, (as in figure 6-5) which in turn will encourage a violent swing in the same direction as the helm. Counter helm to correct the swing may be sluggish because as we have seen, the steering lever is reduced. Once the ship does respond, it may now sheer violently the other way. A chain reaction then sets in, with the ship sheering badly from one side to the other and failing to respond correctly to the helm. The effect can be extremely rapid, with the ship out of the channel and aground in just a few minutes. Excessive speed is the main contributing factor under such circumstance; reduced speeds are essential to avoid such violent forces building up.

Squat - The effect of Squat (helm response)
  • Trim is also important and in some districts the pilotage authority may refuse to handle certain ships if they are trimmed by the head and may even request a small trim by the stern. The latter does, in any case, improve the steering lever and therefore the handling of a ship, it may also be intended as an allowance for squat by the bow and very much a decision based upon local knowledge and experience.

Effect:-

  • Water displaced by the hull is not easily replaced.
  • Bow wave and stern wave increase in height.
  • Trough becomes deeper and after part is drawn downwards.
  • Under keel clearance decreases.

Squat varies on the following factors:-

Ship’s speed: – Squat is directly proportional to the square of speed.

                                                Squat a V2 (V = speed in knots)

Block co-efficient: – Squat directly varies with CB.

                                                Squat a CB

Blockage factor (S):- it is the ration between cross section of the vessel and cross section of the canal or river. Squat varies with blockage factor as.

                                                Squat a S0.81

So, in confined water, squat is more than in open water.

Squat may be calculated by the following simplified formulae:

                                                Squat = (CB X V2) / 100                        (In open waters)                     

                                                Squat = 2 X (CB X V2) / 100                  (In confined waters)


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Navigation in Ice

Preparations & Precautions while Navigating in Ice:

  1. A large area of floating ice formed over a period of many years and consisting of pieces of ice-driven together by wind, current, etc. also called as ice-pack.
  2. Ice is an obstacle to any ship, even an ice-breaker, and the inexperienced navigation officer is advised to develop a healthy respect for the latent power and strength of ice in all its forms.
  3. However, it is quite possible, and continues to be proven so far well-found ships in capable hands to navigate successfully through ice-covered waters.
  4. The first principle of successful ice-navigation is to maintain freedom of man oeuvre.
  5. Once, a ship becomes trapped, the vessel goes where-ever the ice goes.
  6. Ice Navigation requires great patience and can be a tiring business with or without ice-breaker escort.
  7. Experience has proven that in ice of higher concentration, four basic ship-handling rules apply :
    • Keep moving – even very slowly, but try to keep moving,
    • Try to work with the ice-movement,
    • Excessive speed almost always results in ice damage,
    • Know your ship’s manoeuvring characteristics.
  8. Navigation in pack ice after dark should not be attempted without high-power search-lights which can be controlled easily from the bridge.
  9. In poor visibility, heave to and keep the propeller turning slowly as it is less susceptible to ice damage than if it were completely stopped.
  10. Propellers and rudders are the most vulnerable parts of the ship, ship’s should go astern in ice with extreme care – always with the rudder amid-ship.
  11. All forms of glacial ice / ice-bergs, bergy bits, growlers in the pack should be given a wide berth, as they are current driven whereas the pack is wind driven.
  12. When a ship navigating independently becomes beset, it usually requires ice-breaker assistance to free it. However, ships in ballast can sometimes free themselves by pumping and transferring ballast from side-to-side, and it may require very little change in trim or list to release the ship.
  13. Masters who are in-experienced in ice often find it useful to employ the services of an ice-pilot / advisor for transiting the Gulf of St. Lawrence in winter or an Ice-navigator for voyages into the Arctic in the summer.

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IAMSAR Introduction

The purpose of the International Aeronautical and Maritime Search and Rescue Manual for Mobile Facilities, which is intended for carriage aboard search and rescue units, and aboard civil aircraft and vessels, is to provide guidance to those who:

* operate aircraft, vessels or other craft, and who may be called upon to use the facility to support SAR operations

* may need to perform on-scene coordinator functions for multiple facilities in the vicinity of a distress situation

* experience actual or potential emergencies, and may require search and rescue (SAR) assistance.

Responsibilities and Obligations to Assist:

Under long-standing traditions of the sea and various provisions of international law, ship masters are obligated to assist others in distress at sea whenever they can safely do so.

The responsibilities to render assistance to a distressed vessel or aircraft are based on humanitarian considerations and established international practice. Specific obligations can be found in several conventions, including the following:

· Annex 12 to the Convention on International Civil Aviation

· International Convention on Maritime Search and Rescue

· Regulation V/1 0 of the International Convention for the Safety of Life at Sea, 1974 (SOLAS 1974). (See appendix A).


National and Regional SAR System Organization:

Many States have accepted the obligation to provide aeronautical and maritime SAR co-ordination and services on a 24-hour basis for their territories, territorial seas, and where appropriate, the high seas.

• To carry out these responsibilities, States have established national SAR organizations, or, joined one or more other States to form a regional SAR organization associated with an ocean area or continent.

• A search and rescue region (SRR) is an area of defined dimensions associated with a rescue co-ordination center (RCC) within which SAR services are provided.

1. SRRs help to define who has primary responsibility for coordinating responses to distress situations in every area of the world, but they are not intended to restrict anyone from assisting persons in distress

2. the International Civil Aviation Organization (ICAO) regional air navigation plans (RANPS) depict aeronautical SRRs 3. the International Maritime Organization (IMO) Global SAR Plan depicts maritime SRRS.


Search and Rescue Region (SRR) and its purpose:

A Search and Rescue Region (SRR) is an area of defined dimensions associated with a rescue co-ordination centre (RCC) within which SAR services are provided.

Purpose:-

  • SRRs help to define who has primary responsibility for co-ordinating responses to distress situations in every area of the world, but they are not intended to restrict anyone from assisting persons in distress.
  • The International Civil Aviation Organization (ICAO) regional air navigation plans (RANPs) depict aeronautical SRRs.
  • The International Maritime Organization (IMO) Global SAR Plan depicts maritime SRRs.

SAR co-ordination to be carried out on the scene of distress in search and Rescue operation:

SAR Co-ordination:

The SAR system has three general levels of co-ordination:

  • SAR co-ordinators (SCs)
  • SAR mission co-ordinators (SMCs)
  • On-scene co-ordinators (OSCs).
  • SAR Co-ordinators:
    • SCs are the top level SAR managers; each State normally will have one or more persons or agencies for whom this designation may be appropriate.
    • SCs have the overall responsibility for:
      • Establishing, staffing, equipping and managing the SAR system.
      • Establishing RCCs and rescue sub-centres (RSCs).
      • Providing or arranging for SAR facilities.
      • Co-ordinating SAR training.
      • Developing SAR policies.
  • SAR Mission Co-ordinator:
    • Each SAR operation is carried out under the guidance of an SMC. This function exists only for the duration of a specific SAR incident and is normally performed by the RCC chief or a designee. The SMC may have assisting staff.
    • The SMC guides a SAR operation until a rescue has been effected or it becomes apparent that further efforts would be of no avail.
    • The SMC should be well trained in all SAR processes, be thoroughly familiar with the applicable SAR plans, and:
      • Gather information about distress situations.
      • Develop accurate and workable SAR action plans.
      • Dispatch and co-ordinate the resources to carry out SAR missions.
    • SMC duties include:
      • obtain and evaluate all data on the emergency
      • ascertain the type of emergency equipment carried by the missing or distressed craft
      • remain informed of prevailing environmental conditions
      • if necessary, ascertain movements and locations of vessels and alert shipping in likely search areas for rescue, lookout and/or radio watch
      • plot the areas to search and decide on methods and facilities to be used
      • develop the search action plan and rescue action plan as appropriate
      • co-ordinate the operation with adjacent RCCs when appropriate
      • arrange briefing and debriefing of SAR personnel
      • evaluate all reports and modify search action plan as necessary
      • arrange for refuelling of aircraft and, for prolonged search, make arrangements for the accommodation of SAR personnel
      • arrange for delivery of supplies to sustain survivors
      • maintain in chronological order an accurate and up-to-date record
      • issue progress reports
      • determine when to suspend or terminate the search
      • release SAR facilities when assistance is no longer required
      • notify accident investigation authorities
      • if applicable, notify the State of registry of the aircraft
      • prepare a final report.
  • On-Scene Co-ordinator:
    • When two or more SAR facilities are working together on the same mission, one person on-scene may be needed to co-ordinate the activities of all participating facilities.
      • The SMC designates an OSC, who may be the person in charge of a:
      • Search and rescue unit (SRU), ship, or aircraft participating in a search, or
      • Nearby facility in a position to handle OSC duties.
    • The person in charge of the first facility to arrive at the scene will normally assume the OSC function until the SMC arranges for that person to be relieved.

Also Check out:-

Man overboard preferred Manouevre

IAMSAR Search Pattern


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Towing

GUIDELINES FOR EMERGENCY TOWING ARRANGEMENTS ON TANKERS:

1. PURPOSE:

1.2 The present Guidelines are intended to provide standards for the design and construction of emergency towing arrangements which Administrations are recommended to implement.

1.3 For existing tankers fitted with the emergency towing arrangements in accordance with resolution A.535 (13), the existing towing arrangements forward of the ship may be retained, but the towing arrangements aft of the ship should be upgraded to comply with the requirements of the present Guidelines.

Typical Emergency Towing Arrangements
Typical Emergency Towing Arrangements

2. REQUIREMENTS FOR THE ARRANGEMENTS AND COMPONENTS:

2.1 General:

The emergency towing arrangements should be so designed as to facilitate salvage and emergency towing operations on tankers primarily to reduce the risk of pollution. The arrangements should at all times be capable of rapid deployment in the absence of main power on the ship to be towed and easy connection to the towing vessel. Figure shows arrangements which may be used as reference.

2.2 Towing Components:

 Forward of Ship*Aft of Ship*Strength Requirements
Pick-up gearOptionalYes
Towing PennantOptionalYesYes
Chafing gearYesDepending on designYes
FairleadYesYesYes
StrongpointYesYesYes
Rolling PedestalYesDepending on design

The major components of the towing arrangements should consist of the following:

2.3 Strength of the towing components:

2.3.1 Towing components as specified in 2.2 for strength should have a working strength of at least 1,000 kN for tankers of 20,000 tonnes deadweight and over but less than 50,000 tonnes deadweight and at least 2,000 kN for tankers of 50,000 tonnes deadweight and over(working strength is defined as one half ultimate strength). The strength should be sufficient for all relevant angles of towline, i.e. up to 90° from the ship’s centerline to port and starboard and 30° vertical downwards.

2.3.2 Other components should have a working strength sufficient to withstand the load to which such components may be subjected during the towing operation.

2.4 Length of towing pennant:

The towing pennant should have a length of at least twice the lightest seagoing ballast freeboard at the fairlead plus 50 m.

2.5 Location of strongpoint and fairlead:

The bow and stern strongpoint and fairleads should be located so as to facilitate towing from either side of the bow or stern and minimize the stress on the towing system.

2.6 Strongpoint:

The inboard end fastening should be a stopper or bracket or other fitting of equivalent strength. The strongpoint can be designed integral with the fairlead.

2.7 Fairleads:

2.7.1 Size:

Fairleads should have an opening large enough to pass the largest portion of the chafing gear,   towing pennant or towing line.

2.7.2 Geometry:

The fairlead should give adequate support for the towing pennant during towing operation which means bending 90°to port and to starboard side and 30°vertical downwards. The vending ratio (towing pennant bearing surface diameter to towing pennant diameter should be not less than 7 to 1.)

2.7.3 Vertical location:

The fairlead should be located as close as possible to the deck and, in any case, in such a position that the chafing chain is approximately parallel to the deck when it is under strain between the strongpoint and the fairlead.

2.8 Chafing Chain:

Different solutions on design of chafing gear can be used. If a chafing chain is to be used, it should have the following characteristics:

2.8.1 Type

The chafing chain should be stud link chain.

2.8.2 Length

The chafing chain should be long enough to ensure that the towing pennant remains outside the fairlead during the towing operation. A chain extending from the strongpoint to a point at least 3 m beyond the fairlead should meet this criterion.

2.8.3 Connecting limits

One end of the chafing chain should be suitable for connection to the strongpoint. The other end should be fitted with a standard pear-shaped open link allowing connection to a standard bow shackle.

2.8.4 Stowage

The chafing chain should be stowed in such a way that it can be rapidly connected to the strongpoint.

2.9 Towing connection

The towing pennant should have a hard eye-formed termination allowing connection to a standard bow shackle.

2.10 Prototype test

Designs of emergency towing arrangements in accordance with these Guidelines should be prototype tested to the satisfaction of the Administration.

3. READY AVAILABILITY OF TOWING ARRANGEMENTS:

3.1 To facilitate approval of such equipment and to ensure rapid deployment, emergency towing arrangements should comply with the following criteria:

3.1.1 The aft emergency towing arrangement should be pre-rigged and be capable of being deployed in a controlled manner in harbour conditions in not more than 15 min.

3.1.2 The pick-up gear for the aft towing pennant should be designed at least for manual operation by one person taking into account the absence of power and the potential for adverse environmental conditions that may prevail during such emergency towing operations. The pick-up gear should be protected against the weather and other adverse conditions that may prevail.

3.1.3 The forward emergency towing arrangement should be capable of being deployed in harbour conditions in not more than 1 h.

3.1.4 The forward emergency towing arrangement should be designed at least with a means of securing a towline to the chafing gear using a suitably positioned pedestal toller to facilitate connection of the towing pennant.

3.1.5 Forward emergency towing arrangements which comply with the requirements for aft emergency towing arrangements may be accepted.

3.1.6 All emergency towing arrangements should be clearly marked to facilitate safe and effective use even in darkness and poor visibility.

3.2 All emergency towing components should be inspected by ship personnel at regular intervals and maintained in good working order.


Tractor Tug:

Tractor Tugs: The design of tractor tugs is unlike that of conventional tugs. The propulsion units are fully turning controllable pitch blades, able to give thrust in any direction and act as steering units or azimuthing fixed or controllable pitched propellers. The propulsion units are placed far ahead of the towing point, close to the pivot point thereby producing a large turning momentum. This potentially gives a poor steering performance, which is overcome by fitting a large centreline skeg. Their general characteristics are:

  • Full power available in all directions
  • Quick response to engine movements.
  • Very maneuverable, especially in tight sea space.
  • Reduced risk of girting / girding.
  • Reduced maneuverability if towing from forward at higher speeds.
  • Reduced directional stability, particularly in open waters.
  • Reduced bollard pull per kilowatt output.
  • Relatively deeper in draught therefore increased risk of bottom damage from grounding.
  • Increased training required for tug masters.


Tow Plan:

Planning and preparation before a Tow commences might include:

  • Assessing the size and type of vessels or barges to be towed and any limitations of the tow.
  • Confirmation that the tug is of suitable; size, manning, sea-keeping, horse power (HP) and bollard pull (BP).
  • Tow wire and towing equipment is suitable for the planned tow.
  • Route to be taken and passage planned, including safe transit times (day/night transits), times when passing through narrows, under bridges or areas of high traffic density, tight bends in rivers and adjacent river berths.
  • Noting: and areas of reduced depth, tidal limitations and currents expected during the voyage.
  • A list of bridges with maximum and minimum height; tide height for each arch to be passed under showing the bridge’s maximum air-drafts.
  • Weather forecasts to include outlook for at least 48 hours.
  • Confirmation of sufficient fuel, water, spares on board.
  • Navigational information and warnings.
  • Recommended speeds to comply with river regulations.
  • Connection and disconnection arrangements.
  • Stability of the tug and towed unit.
  • Emergency contingency plans.

Preparations on board the Tug:

It is essential that checks should be completed on board the tug and vessel or barge to be towed, which should include:

  • All water / weathertight openings are securely closed with signs indicating that they should remain closed for the duration of the voyage. It is a reality that tugs have capsized as a result of doors and ports being left open when in difficulty, e.g. girting. Down flooding is a real danger to small tugs.
  • Life-saving and fire-fighting appliances must always be operational.
  • Navigational equipment, wheelhouse whistles, horns, shapes for day signals and communication gear are fully operational.
  • All critical machinery prior to commencing a towing operation should be confirmed as operational – this would include; main engine, steering gear and towing equipment (winches, wires) etc.
  • All personnel are fully familiar with the intended towage plan and their responsibilities.
  • Any change of fuel and ballast to the tug and/or tow have been fully calculated and the crew are aware of any factors of concern.

Checks on board the towed vessel or barge:

The tow should not proceed until a satisfactory inspection of the tow has been carried out by a competent party.

Checks should include:

  • Condition of the towing arrangements
  • Condition of the anchoring equipment if fitted. If not fitted some authorities require a temporary anchor to be supplied of an adequate weight.
  • Condition of tow including an inspection of the peaks and buoyancy spaces to check for water ingress.
  • Watertight integrity of the unit to be towed; obvious signs of damage, especially in the hull and deck plating. Hatchways, ventilators, doors, scuttles, manholes and other openings are closed and sea valves shut.
  • Fore and aft drafts, appropriate freeboard for the voyage and no evidence of a list. Generally a slight trim by the stern ensures that the tow is laterally stable when towed.
  • Air draft of the tow, appropriate for the voyage and bridge transits.
  • Power is available for navigation lights.
  • Safe method of boarding available (portable or fixed rungs).
  • Emergency towline rigged.
  • Life-saving and fire-fighting appliances are in good condition and in the regulatory number required.
  • Cargo, whether it is bulk cargo (within the holds), containers or break bulk cargo can shift causing the barge to capsize and sink and therefore stowage and securing arrangements must be verified as adequate for the intended voyage prior to departure.
  • Some bulk cargoes pose a serious hazard, including spoil and certain ore cargoes which are liable to liquefaction e.g. spoil cargoes can contain a high amount of moisture which can assume a liquid state in a seaway and can cause the barge to lose stability, list and even capsize.
  • Reference should be made to the IMO International Maritime Solid Bulk Cargoes (IMSBC Code). When it is suspected that cargoes with high moisture content have been loaded onto a barge advice should be sought.
  • If cargo is liable to move e.g. vehicles and timber, the lashing arrangements and sea fastenings should be inspected.