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Conference Proceedings Vol. I, II, III

 事業名 海事シミュレーションと船舶操縦に関する国際会議の開催
 団体名 日本船舶海洋工学会 注目度注目度5


SALVAGE SIMULATION OF GROUNDED TANKER
Marko Perkovic (Faculty of Maritime Studies and Transportation, Slovenia)
Dusan Fabe (Faculty of Maritime Studies and Transportation, Slovenia)
Valter Suban (Faculty of Maritime Studies and Transportation, Slovenia)
 
 Abstract: After several decades of successful work on simulators for education and training of automatic radar plotting, even the most prominent critics of simulators have finally realised their advantages and contribution to the safety at sea. Since with up-to-date performance of the computer hardware and after several years of software development and the integration of different models, like: ships handling, engine room, cargo handling and communication more advanced education and training was enabled.
 
 Our Faculty has together with the 》Istituto tecnico nautico di Trieste《 carried out a PHARE Cross-border Corporation Project, co-financed by the EU. The project aimed to improve the salvage process, which may be necessary in case of a grounded tanker in the small Gulf of Trieste. Namely, through the Gulf about 50 million tons of crude oil is transported per year by VLCCs. The sea in this enclosed part of the Adriatic Sea is very shallow, with weak steams and minimum degree of self-cleaning. Organisers of the project invited all concerned parties to take part in carrying out a salvage simulation with the integration of the said simulators. Following were the participants in the project: Port Authorities, Marine Police, Navy, Civil Defence, Fire Brigade, Towing Service, Pollution Protection Service and Oil Terminal Loading Masters.
 
 Organisers believe that the project was successfully completed, the present paper, however, presents various problems encountered during the project.
 
1. INTRODUCTION
 Protection against natural and other disasters is the responsibility of national bodies, municipalities, professional and scientific research organisations, public rescue services, and humanitarian and other non-governmental organisations, as well as of every single individual. The common objective of all these factors is to prevent disasters, or at least to mitigate their consequences.
 
 Safety at sea has significantly improved in recent years. Also the number of oil spills has been reduced compared to the past, e.g. in the year 1974 there were 26 heavy spills (more than 700 tons of oil) and in the year 2000 only 3 [1]. The improved safety at sea is the result of passing and enforcing of several international conventions, regulations and codes. The conventions covering safety at sea are as follows: SOLAS (safety), MARPOL (pollution) and STCW (training, certification and watchkeeping). Besides, circulation of information has become more transparent referring to the ships condition, the reliability of the ships propulsion has improved and more sophisticated navigational systems have been introduced. Last but not least, mandatory implementation of the International Safety Management Code has had a great contribution.
 Modern teaching and training centres, using simulators, raise the level of seamen's knowledge and skills. Apart from that, at the MARSIM, IMLA, ICERS and INSLC conferences a lot has been presented referring to training on simulators [2], [3], [4], [5] , [6] , [7]. The authors shared experience, advantages and disadvantages of working with crew, management personnel and pilots, rarely, however, with other participants in the sea transport. [8].
 
 Therefore our Faculty of Maritime Studies and Transportation attampted to fill the said gap by a simulator training involving all other potential participants in the rescue of a grounded tanker.
 
 In 2001 we tendered for the research project of cross-border cooperation, co-financed by the EU and we succeeded. It was a ten-months project encompassing eight-week simulation workshops on rescue of a grounded tanker. Simulations were carried out separately on the nautical, engine room, communication and cargo handling simulators. 75 participants from Italy and Slovenia were divided in eight groups. The project involved all institutions potentially involved in rescue operations from Slovenia: Maritime Directorate, Civil protection, Environmental protection, Fire brigade, Navy, Coastal Municipalities, Terminal Operator, and from the Italian side the employees from the Coast Guard, Fire Brigade, Salvage Association, Civil Protection, Tug Boat Company and Coastal Municipalities. The project also included a follow up study. [9].
 
2. MARITIME ACCIDENT RISK, MARINE POLLUTION AND THE CORRESPONDING RESCUE OPERATION
 Often, and particularly since the accident of the tanker Prestige, journalists have been eager to know how high is the risk of oil spillage from a tanker in the Gulf of Trieste. The answer to this question mainly depends on either optimistic or pessimistic views. Considering the fact that our sea is is a relatively closed aquatorium any pollution represents a serious danger to Slovenia, Italy and Croatia, no matter where exactly it takes place. Further, tankers are not the only potential oil polluters. There are also other smaller vessels, like barges and yachts during the tourist season. For a serious pollution several hundred tons of oil stored in a ship's double bottom would suffice. We were witnesses of such a pollution already in 1952 from the Italian prestigious passanger ship REX, while she was cut into pieces, after being bombarded during the WW2. Oil from that spillage remained at some parts along the coast for four more years, causing severe problems to the post-war flourishing tourism.
 
Table 1 Rounded average tanker traffic in the last years
Tanker type Koper (SI) Trieste (I)
Oil tankers   300
Product carriers 100 100
Tanker barges 100 100
Chemical tankers 40  
 
 We, being somehow part of the maritime industry, are all very well familiar with the miserable condition of the world tanker fleet. Also at the Slovenian tanker terminal are berthing old and badly maintained tankers. All these tankers have almost by rule classical propulsion, with one main engine and one steering engine. They are also boarded with a small number of multinational crew, inadequately trained and having communication problems. [10]. Last but not least, we do not know, whether such crew is familiar with emergency procedures like grounding, collision or even oil spillage. Imagine the said tanker is located in the waters of the North Adriatic - the small Gulf of Trieste - with average sea depth 18.6 m. The area has not fixed traffic separation, neither has it established a reporting system and the pilotage is required only on entering ports. All this is a clear evidence of increased danger risks. In addition, the North Adriatic is in winter and early spring exposed to strong winds and sporadic dense fog (from 16 to 32 fog days per year). The direction of water currents is unknown. Daily tanker traffic in the region is relatively high, one supertanker, one smaller tanker and about six other ships carrying dangerous cargo. Apart from the collision risk, there is also a risk of grounding, particularly in case of failure of the propulsion or steering systems.
 
 Due to rocky bottom the risk of tank or double bottom damage is higher. The very geomorfological structure of coastline is varied. The great part of it accessible with difficulty ether from the sea or from the shore, which might greatly prevent rescue or removal of pollution. The Slovenian rescue equipment is very poor and adequate only for minor pollutions. The rescuers have a numerical model available to predict the spreading of the slick, which was made in 1993, however its applicability is uncertain, due to unknown currents in the area.
 
 Comment on the efficiency of rescuers should be avoided, as it is closely related to the equipment available. Rescue operations are also influenced by politics and the insurance companies. We witnessed the inefficiency of the rescue systems in almost all major world pollutions, as the operations did not commence on time. And it is well known that the response time is critical in any grounding or pollution incident.
 
 After the last accident the question also arises who dares undertake the right to confine the leaking tanker in port, instead of taking it to the open sea.
 
 Likewise concern over marine pollution tends to focus on crude oil, but chemicals can cause more persistent damage.
 
 On the other hand, certain optimism is allowed due to the fact that only two incidents recorded in the Mediterranean between 1981 and 2000 resulted in spills of more than 10,000 tonnes. Besides, we have got a national contingency plan for sea pollution....
 
Fig.1 Mediterranean Sea
 
3. CASE STUDY
 Italy and Slovenia have established adequate professional services to take action in case of maritime accidents. Both countries have also a few agreements of joint operation in case of natural and other disasters. The services are trained for large scale operations ashore and at sea, however they are not trained specifically for rescue operations in case of a tanker accident.
 
3.1 Accident scenario
 
 At the frontier line between Slovenia and Italy a tanker ground, the crew of which sounds the alarm. After an adequate response to the alarm, the relevant services find out that no major structural damages of the tanker hull occurred and consequently there was no oil spillage. However, as the tanker is exposed to the sea, the possibility of pollution cannot be excluded. Refloating the tanker would require transfer of certain amount of cargo to the barges.
 
 The stress of the simulation drill is on each service to find its proper role in the search and rescue operation, however, maintaining the overall prospective of the operation in order to be able to recognize eventual difficulties that other services are facing. Following is a brief presentation of theoretical origins of the rescue operation [16][17].
 
Fig.2 Grounding position
 
3.1 Tanker grounding
 
 The leakage of pollutant can be relatively small, at least during the first few hours, while the structure of the vessel is not affected. The crew can try to limit the consequences of the accident by taking, for example, one of the following actions:
・transferring the cargo, if it is liquid, from damaged to intact tanks, using normal piping in an attempt to refloat the vessel;
・jettisoning possibly a part of the cargo on the sea, if this may help to relieve the perilous situation of the vessel aggravated either by grounding during periods of high tide or by worsening of the sea state;
・depressurizing damaged tanks in order to reduce leakage of pollutant below the water-line.
The efficiency of assistance will mainly depend on:
・meteorological conditions;
・availability and proximity of lightering equipment, towing vessels and storage capacities.
 
3.2 Assessment of the situations
 
 Every accident presents a hindrance to the navigation of other vessels. These should be warned immediately and instructed on safety measures (Notice to mariners). If necessary, the zone of accident should be marked by buoys.
 
 Proximity to shore and bases of personnel and materials will determine the promptness of the intervention. Meteorological conditions may delay the possibilities of action. Specialized lightering tankers are generally not operational if wind exceeds 25-30 knots and sea state exceeds Force 5 (wave heights up to 3 metres).
 
 If oil is already spilled on the sea, evaporation of hydro-carbons may create an explosion risk and prevent temporarily the access to the site. Measurements made during various past accidents suggest that a delay of 2 hours is sufficient for the light breeze to dilute the atmosphere below the explosion limit of 1%, obviously providing that the leakage has been stopped. Nevertheless, the risk of intoxication of personnel, which may persist, necessitates precautions and use of safety equipment during the access.
 
3.3 Ship's capabilities
 
 The following check-list indicates information which should be known:
 
Table 2 Ship's capabilities check-list
a) Situation of the ship
afloat; damaged; aground
empty;laden(characteristics of cargo)
Bunker(quantity/nature)
b) Crew:
Evacuated; on board
qualifications; specialization
c) Available means:
Propulsion engine/steam.
Steering gear.
Capstans, cable holders, windlasses, etc...
Electric current supplies: main, auxiliary.
Steam supplies: main, auxiliary.
Pump room.
Fire fighting system.
Tanks' heating system
d) Stability:
Length; Breadth; Displacement
List; Trim
Computer on board; Computer on shore
e) Buoyancy:
Empty Full Quantity
Forward:
Midships:
Aft:
 
3.4 Lightering vessel in peril
 
 Considering the difficulties and cost of oil pollution combating both at sea and on shore, it is necessary to remove the potential pollutant from a vessel in peril if there is a threat of its spillage. This obviously concerns the cargo of tankers as well as fuel oil of all other types of vessels.
 
 All lightering operations involving a vessel in peril should be preceded by a rapid legal action. Practically it means that rights and responsibilities of ship owners, ship managers, crew and particularly the master, insurers and finally the State should be defined. Once the decision to lighter the vessel has been taken, either the national means (equipment) can be used, if the country involved disposes of them, or the means of specialized (salvage) companies under the supervision of (national) maritime authorities. The contract should include the responsibilities of the State and of the contractor for the general safety of the operation and precise the terms of co- ordination of various actions.
 
 Checklist for commercial lightering operations should be used and modified for each particular case of emergency operation.







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更新日: 2019年8月10日

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