Correlation Between Human Factor And Ship Stability

CORRELATION BETWEEN HUMAN FACTOR AND SHIP STABILITY

1ANDREI CRISTIAN, 2xxxxxxxxxxxx

1,2 Constanta Maritime University

ABSTRACT

The present paper presents general and particular aspects regarding the impact of human factor on the safety of ships and safety of navigation. The correlation between safety of ship stability and the influence of human factor is presented through real case accidents. Methods of evaluation of human factor upon ship stability are pointed out. The role of human factor from the ship’s stability point of view is clearly identified in relation to critical hazard.

Keywords: human factor, safety, navigation, stability.

1. INTRODUCTION

Since first man went to sea, the human error has been blamed as the cause of accidents. Current wisdom is that human error, attributable to the Master and /or crew of a ship, has been responsible for approximately 80% of maritime accidents, at least in part [5].

Over the last 25 years or so, the main target of shipping industry was to improve the reliability of the ship system as well as the ship structure in order to minimize accidents and increase efficiency and economy. The ship systems became technologically advanced and highly reliable due to important improvements that have been made in hull designs, propulsion system and navigational equipments.

With a growing awareness of safety issues, public tolerance of accidents in shipping has decreased. So even nowadays, despite all of the improvements and advanced technologies, maritime casualties continued to happen, moreover with a high rate. This happen as a result of the fact that ship system reliability and ship structure are only a small component of the safety system. As people are the most important part of the maritime system then the human errors are predominant in casualty situations.

Human error is often described as being an incorrect decision, an improperly performed action, or an improper lack of action [6]. In considering the human contribution to marine accidents, it is most important to analyze two types of errors: active errors, when the effect occur immediately and latent errors whose adverse effects may lie within the system for a long time [8].

Active errors are categorized when the actions of the ship’s crew leading up to and at the time of the incident. Latent errors are categorized that are occurring at an earlier stage of the ship’s building process or in other conditions at different levels of management decisions.

The new developments in ship design and navigation equipment have considerably reduced the rate as well as the grade of severity of shipping incidents. However, the reduction of failures in technology has revealed the underlying level of influence of human error in accident causation [4].

2. CASUALTIES OF SHIP STABILITY FAILURE RELATED TO HUMAN ERROR

TORM ALEXANDRIA – 270 TEU feeder containership

The vessel was under loading and in the same time discharging operations of containers at the port of Monrovia, Liberia. While lifting a container from the berth with the ship’s crane, a suddenly heeling of the vessel ot portside was developed. Then, the master attempted to control the list using the ballast but without the desired effect and the vessel continued to list further until she capsized (fig. 1).

Figure 1. Feeder vessel “Torm Alexandria” capsized along berth [11]

The subsequent official enquiry [11] revealed that the main cause of ship’s capsize was the attempted lift of a heavy container from the berth at a time when ship’s stability was very small or even zero. The ship developed a sudden large angle of heel as a result of suspension the heavy container in ship’s crane. This aspect brought the vessel in a situation that the developed angle of heel was beyond all positive values of righting levers. Nothing could be done to remedy the situation as was also exacerbated by the shifting of containers across the deck and sea water flooding the engine room through an open trap hatch on main deck.

The vessel’s unstable condition and her subsequent capsize was a result of the following factors:

The ship’s staff not paid the importance of preparing the curve of righting levers for the vessel’s actual loading condition.

Vessel’s officers were too much confident in respect of the fact that for the vessel’s transversal stability in all conditions of loading, only the initial metacentric height (GM) represents a criterion.

When the GM of the vessel was calculated, no allowance for free surface effect was made, despite that clearly instructions were stated in the stability booklet in this respect.

Despite the fact that a written letter issued by the owners stated that only 740 tons of cargo has to be loaded on deck, corresponding with loading condition no.7 from ship’s stability booklet, no attention was paid for this issue. At the time of the incident, a quantity of 1150 tonnes were actually loaded on deck that means with 55% in excess. That means the limit for the cargo on deck was breached only by the weight of the first tier of containers loaded on deck.

COUGAR ACE – 55,328 GRT Car Carrier

After the vessel departed from Yokohama port, loaded with 4,703 cars, Chief Officer planned the ballast exchange. Vessel’s Master advised Chief Officer to conduct the ballast exchange in one pair of tanks at the time. Chief Officer informed him that in the worst case scenario, if four tanks were to be deballasted together till they were emptied, the vessel’s GM would be 0.50 m positive. In the next four days, the deballasting and ballasting operations went as planed by Chief Officer. However, during this period of time, a couple of tanks, that were not planed for deballast operations as per ballast water exchange plan drawn by Chief Officer, were deballasted in order to correct the vessel’s list in the same time with the planned ballast tanks. On 24th July, during ballast exchange process, the vessel started to list to port and within few minutes was lying on its portside about 80° list (fig. 2).

Figure 2. MV Cougar Ace lying on its portside [12]

As per investigation report [7] [12], the sequential exchange of water ballast would result in the ship having four of its nine water ballast tanks empty. This aspect, together with additional water ballast being pumped out for the adjustment of list, and correlated with the consumption of fuel from double bottom tanks, resulted in the ship becoming unstable and developing an angle of loll to port side of about 80°.

There were some important inadequacies in the ship’s ballast water exchange operation that came out from the investigation report [7] [12]:

Improper planning and execution of ballast water exchange operations. This fact resulted in insufficient weights in the water ballast tanks below the ship’s waterline;

Ship’s staff in charge with the ballast exchange operations, i.e. Chief Officer and Master, failed to ensure that the ship stability is maintained throughout the operations, at various stages of ballast water exchange;

Failure of Chief Officer and Master as to clearly understood and complied with the IMO recommendations related to safe operations of the ballast water exchange procedure .

GULIZAR ANA – 1,500 GRT, general cargo vessel

Vessel was in ballast voyage from Turkey to Romania, one port on Danube River, for loading steel coils. Before entering the river, vessel de-ballasted all ballast tanks, double bottom and side tanks as well as the fore peak tank. During loading of the 5th steel coil, vessel began to lean on starboard side till the vessel’s accommodation has propped on main deck of the floating crane berthed alongside vessel. The list of the vessel was 51 degrees (fig. 3). Engine room and starboard side crew quarter have been flooded.

Figure 3. Vessel “Gulizar Ana” listed at starboard side, alongside berth [10]

Notwithstanding the list was a result of shifting of coils inside the hold, the main cause of the accident was that the vessel, after de-ballasting all ballast tanks, remained with insufficient weight below waterline thus leading to insufficient stability of ship. This fact was the result of improper planning of de-ballasting and failure of ship’s staff to maintain the ship stability [10].

3. HUMAN FACTOR AND SAFETY OF SHIP

A classical field of ship safety and safety to navigation is without any doubt the intact stability of the vessel. In regard to the ship safety, the intact stability is of paramount concern. The earliest regulatory recognition of this can be traced to before Samuel Plimsoll in the 1860’s. Times have moved on and stability regulations have come on a long way but the concern remains high.

Vessel’s intact stability is a fundamental component of seaworthiness so it is in the interest of all owners/operators to learn about this topic and ensure that their vessel possesses a satisfactory level of stability in order to ensure its safety as well as that of the people on board the ship. Understanding ship's stability, trim, stress, and the basics of ship's construction is a key to keeping a ship seaworthy.

Human factor is also a contributory factor to safety of ship. A Master’s error in applying proper decisions may result in a failure of equal consequences so that of bad design. An incompetent ship’s officer can easily make a fine, seagoing ship unseaworthy, but even the most experienced, prudent and vigilant officer cannot turn a badly designed, unseaworthy ship into a safe one.

Man can be looked upon as apart of the total system and, as with any other physical system, a human being may suffer weakness or fail altogether. This is of great importance when man controls other systems in combination: for example master/ship or pilot/aircraft systems.

The overlap between these basic factors contributing to ship safety in a seaway is schematically shown in figure 4.

Figure 4. Overlap between factors contributing to safety of ship

Following the logic of figure 4, the problems of safety of ship stability are discussed from three different aspects:

Fundamental design features which determine a ship’s behavior in extreme weather conditions and her seaworthiness in terms of intact ship stability failure. Although there seem to be a large number of different ship stability failure situations with different mechanisms involved, their number can be reduced to a few basic modes.

The dynamic aspects of wind and wave forces, particularly relevant to capsize situation.

Human decisions. Good seamanship in heavy weather is not a quality which can be learned from reading books alone. It is, however, reasonable to expect that a man who learns much from his own experience can also gain a little from the experience of others, or from knowledge acquired through scientific experiments. This may help him to make rational decisions regarding seakeeping strategy in particular sea conditions.

A human-ship system is a technical system which is operated by people. The activity of human-ship system is in strong connection with a various categories of problems like operational, technological, human, etc. Human problem is the most important part in consideration with safety of ships.

In ship safety, the influence of human factor is in connection with:

Human resources – recruiting, teaching, training.

Career – qualifications, motivations, experience.

Performance on board ships – adaptation, assimilation.

4. Methods of evaluation of human factor upon ship stability

The human influence upon the ship stability is manifested by the ignorance of information referring to the ship stability, the lack of general marine knowledge, wrong maneuvering during unfavorable weather. The stability casualties resulted mainly from the wrong operation of ship by man.

The influence of human factor upon ship stability can be evaluated by two possible methods: computer simulation tests and full scale investigations.

In our day, when ships are very modern, the man takes the role of a controller-observer. On board vessel the man is connected with receiving, transforming, sending and utilizing information being in the position for fulfilling a variety of functions. In order to accomplish the tasks on board vessel, the man’s behavior is dependent on his knowledge, experience, ability, condition of ship, condition of loading, weather factors, etc.

One of the best method for determining the influence of human factor upon ship stability is the real-time simulation with the help of a simulator. Such a simulator enables improving the ship stability safety due to observation of the actual situation of cargo loaded, condition of loading, weather information or situation of the sea, ship behavior at various angles of heel, variations of stability parameters. Those information to be in a form of an image, numerical data, etc to give the possibility of taking a rapid and correct decision.

Fitness-for-duty and the personnel readiness represents assessments of the crew to safely and reliable perform their duties.

Knowledge, skills and abilities that stem from an individuals basic knowledge and general training.

Task specific maritime training and abilities (certification and licenses).

Placing a person in a position without the requisite skills, training, or tools will reduce safety, efficiency, and increase the potential for error. Often too much reliance is placed on a few highly skilled individuals in senior positions. Safety requires experience.

It is of paramount importance that stability (refresher) courses should be given at regular intervals for those working in the field (i.e. ship designers, crew, operators, managers etc.). The benefit of a highly trained and motivated workforce cannot be over stated. Such a crew is better able to deal with difficult situations when they arise and so prevent or mitigate incidents.

5. Conclusions

In the age of precision navigation and the satellite era, many casualties still occur at sea. Maritime transport safety is being enhanced by introducing numerous technical measures, by building safer ships, developing new and more efficient methods of transportation, investing in human resources, increasing traffic surveillance and control, issuing new regulations, etc. Nevertheless, accident statistics show that these measures are not sufficient and sometimes unable to halt shipping casualties. Casualties with catastrophic consequences still happen.

Stability of ship is a problem in which not only the inherent features of a ship but also the action of its crew determine weather the ship will survive in critical conditions. The correct reaction in dangerous situations and the skills of the crew may well decide between survival and disaster. The human factor should be taken into consideration in the overall analysis of safety against capsizing.

Human factor still remains a decisive factor for the ship stability and safety at sea, despite the growing process of automation to ships. The ship stability casualties shows that human factor is one of the most important elements of the ship safety system. The loss of control over a ship, not only in a critical situation, can be a main cause of casualties. For the safety of ships the human factor and technical factor are equally important. However, the man is the decisive factor.

Human factor issues are therefore complex and need to be carefully analysed, but more importantly, recognized if there are to be any significant improvements in safety at sea. Quality factors, like human factors, are concepts that are frequently talked about but rarely if ever adequately addressed. Seafarers are locked into a system that is very dependent upon them. They are the most important quality factor throughout the life of a ship.

There is a need to adopt humane approach to what is a very human issue. Concentration on satisfying narrow rules of ship construction and operational training is not enough. The ISM Code, while useful, fails to address the issues relating to human factors.

New insights, like concerns of the influence and contribution of the human element to ship stability casualties, have to motivate maritime community, Class societies,, to broaden their role in safety of ship stability in significant ways.

The changing attitude for the connection between stability of ships and human factor is well reflected in the work of the international research community, in particular at IMO. In the Code of Intact Stability of Ships, the stability requirements and standards have been supplemented by some paragraphs related to human factor in operational aspects of stability safety, as for instance: “Compliance with the stability criteria does not ensure immunity against capsizing regardless of the circumstances, or absolve the master from his responsibilities. Masters should therefore exercise prudence and good seamanship having regards to the season of the year, weather forecasts and the navigational zone, and should take the appropriate action as to speed and course warranted by the prevailing circumstances [13].”

6. REFERENCES

[1] Belenky V., Sevastianov – Stability and Safety of Ships: Risk of Capsizing, 2nd Ed., Sname, Jersey City, 2007.

[2] Belev Bl., Information Characteristics of a Man-Operator for Ensuring the Vessel’s Safety of Navigation, Proceedings of ENS GNSS 2010, Braunshweig, Germany.

[3]Clifford B., Kevin.P.McSweeney, Denise B.McCafferty – Human Factors and Ergonomics in Safe Shipping: The ABS Approach, ABS Technical Paper 2002, 7th Annual Conference, Washington, April 2002.

[4] Hetherington C., Flin R., Mearns K., Safety in shipping: The human element, Journal of Safety Research 37, 2001.

[5] Filor K., Marine Accidents: Present Trends and A Perspective of the Human Element, Marine Policy Division, Department of Transport of Comunication, 2009.

[6] Gerigk M., The Human Factor Effect On The Safety of Ship Stability At Sea, Third International Conference on Stability of Ships and Ocean Vehicles, Gdansk, September 1986.

[7] IMO FSI 15/6/2, Information concerning the listing of the vessel “Cougar Ace”, 2 April 2007.

[8] IMO Document SLF54/INF.12, Information collected by Intersessional Correspondence Group on Intact Stability, Submitted by Japan, November 2011.

[9] Kobylinski L. – Stability and Safety of Ships: Holistik And Risk Approach, R&RATA#1 (Vol.1), March, 2008.

[10] Romanian Naval Authority (RNA), Report on the investigation of the incident M/V “Gulizar Ana” September 2006, No. 24-362, 09/09/2006. [11]”***”http://www.cargolaw.com/2001nightmare.heavymetal.html

[12] “***” http://www.fortunes-de-mer.com/old/rubriques/liens%20et%20contacts/detailsactualites/CougarAce2006.htm

[13] IMO, International Code on Intact Stability 2008, London 2009 Edition.

[14] Cristian A., Actual Ship Stability Problems and The Influence on Safety of Navigation, ISBN 978-606-8799-24-7, Editura Digitala, 2016.