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4 Establishing Safe Crew Levels The U.S. Coast Guard relies on a combination of laws, regulations, tradition, and informal policy guidance to set crew levels. This piecemeal approach was effective in the past when technological change was slow and manning scales generous. However, it is not a sound basis for decisions that must accommodate changing technology and minimal manning. Systems engineering techniques are beginning to be used in manning decisions by shipping companies. These techniques include the construction of computer models of vessel operations, so that shipboard functions and tasks can be precisely specified and evaluated for a ship of a given design, trade, and level of technology under normal and emergency conditions. Manning scales can be established accordingly. This chapter reviews current regulatory procedures for Coast Guard manning determinations and discusses the advantages of systems engineer- ing as an alternative. It also presents a functional task analysis model developed and tested by the committee. With appropriate extension and refinement, such a model could offer regulators, owners, and operators the tools for making manning decisions on a sound analytical basis. As ship operating technology and crewcut grow more complex, such an approach will become increasingly necessary. U.S. COAST GUARD CERTIFICATION PROCEDURES The U.S. government controls vessel manning through statutes, which are implemented in regulations and interpreted by judicial rulings. The 59
60 CREW SIZE AND MARITIME SAFETY regulations are promulgated and enforced by the U.S. Coast Guard. In addition, the Coast Guard specifies the minimum complement of licensed and unlicensed persons necessary for safe operation of each vessel; these requirements are set out by each vessel's Certificate of Inspection (COI), as required by the International Convention on the Safety of Life at Sea (SOLAS). Until the late 1970s, most U.S.-flag vessels sailed with crew com- plements well above the levels specified in Coast Guard-issued COIs as necessary for safe navigation. Recent attempts to cut costs have brought dramatic crew reductions, however, with some ships operating at or near their COI minimum. The Coast Guard anticipates that future technical and organizational innovations will result in ships with crews of a dozen or fewer highly trained specialists to operate the vessel and conduct emergency maintenance, and that routine maintenance and cargo operations will be the responsibilities of shore-based personnel (Connaughton, 1987~. Current statutes and reg- ulatory procedures will be inadequate to accommodate these innovations (see Chapter 5~. Regulatory Procedures The owner or operator of any ship that requires a COI must submit an application for inspection to a Coast Guard Officer-in-Charge, Marine Inspection (OCMI). The owner also must submit descriptions of the vessel and the kind of trade in which it will be used. On the basis of these descriptions, the vessel is placed in a particular class or inspection category (e.g., freight vessel, tank vessel, or offshore supply vessel). Depending on its class and intended service, the vessel's design and construction plans are reviewed by either the Coast Guard's Marine Safety Center or the American Bureau of Shipping, acting on behalf of the Coast Guard. Once the vessel's class is determined, the owner or operator can develop a manning plan according to standards set out in the Coast Guard Mann e Safely Manual. The plan is submitted to the OCMI in the region where the vessel is being built. The OCMI then sets a conditional manning level, which is subject to revision if an OCMI later decides a change is necessary for safety reasons. The OCMI, in establishing manning levels, considers applicable statutes (especially Part G. Title 46, of the U.S. Code [U.S.C.~), regulations (46 CFR Part 15), and Coast Guard policies set out in the Mann e Safer Manual and Navigation and Inspection Circulars (NVICs). Special conditions such as shipboard automation and monitoring equipment, route and trade char-
ESTABLISHING SAFE CREW LEVELS 61 acteristics, maintenance and support facilities, and self-imposed operating limitations can also be considered, along with the documented history of any vessel being modified or reflagged. Ordinarily, the OCMI's manning determination is a routine matter. However, if the manning request involves innovation (the first ship of a series, reduced manning on an existing ship, or a ship whose class is not covered in policy guidelines) the OCMI forwards the request to the Merchant Vessel Personnel Division at Coast Guard Headquarters. When the OCMI and headquarters reviews are complete and the vessel has completed sea trials, its manning complement is placed on the COI. The complement specified on the COI represents the minimum number of personnel considered necessary for safe operation, along with the license and document grades and endorsements those personnel must hold. (The COI will also specify the maximum numbers of "other persons in the crew" and "persons in addition to the crew," according to the available accommodations and lifeboat capacity.) The Coast Guard normally does not specify manning levels outside the deck and engineering departments (such as stewards), except for radio officers, which are required by law and international agreement aboard most ocean-going commercial vessels. In 1983, a significant change in the manning statutes was made, partly to accommodate increased number of requests for reduced manning. Pre- viously, the law required manning levels to be determined as the minimum necessary for safe navigation. In that year, a recodification of 46 U.S.C. resulted in a requirement to set manning levels as the minimum "necessary for safe operation" (46 U.S.C. § 8101(a); emphasis added). As a result of this change, the agency pays more attention to maintenance plans in manning determinations today than it did in the past. (Well maintained equipment is especially vital with smaller crews.) In most cases, the agency requires a strong preventive maintenance program. Owners or operators wishing to reduce manning on existing ships through automation must submit an application, together with required documentation showing how the vessel may be operated safely at the reduced level. Often the Coast Guard grants conceptual approval of such plans before investments in vessel modifications are made. After the modifications are made, the systems must undergo a trial period to prove their reliability and safety. During this period, which may last for 6 months or more, the owner must keep detailed records of the vessel's operating history, crew overtime, equipment casualties, and other information. A Coast Guard inspector sails aboard the vessel, observing routine operations and emergency drills to assess the adequacy of the reduced manning.
62 Deck Department CREW SIZE AND MARITIME SAFETY Manning Reductions to Date Deck department reductions to date have been the simplest crew reductions to evaluate and have generally been processed in the field by the cognizant OCMIs. The most common reduction at present involves the addition of devices such as constant-tension winches, a watch call system, and sanitary and coffee facilities on the bridge. If these additions are approved, up to three ordinary seamen (OSs) may be removed from the vessel's COI. If they are removed, the COI may be further amended to allow two of the required six able-bodied seamen (ABs) to be "specially trained" OSs (with the physical and training qualifications of able seamen, but holding ordinary seaman endorsements). Some day-working maintenance workers may be required in lieu of the removed ordinary seamen. Engine Department Engine department reductions are more complex and are usually re- ferred to Coast Guard Headquarters for approval. Technical standards are set out in 46 CFEt Part 62 (Vital System Automation, § 62.5~Manning). Such reductions are of three types: (1) elimination of the requirement for fire/watertenders on steam-powered vessels; (2) minimally attended engine room operation (with the addition of a central engine room monitoring and control station) to eliminate the need for several or all unlicensed watch standing personnel; and (3) periodically unattended engine room operation, with a variety of labor saving devices and monitoring and control systems so that the engine room can be left unattended for prolonged periods. Maintenance Departments Use of a maintenance department (see Chapter 1) increases oper- ational flexibility and permits reduced manning through reassignment of personnel. Maintenance departments are subject to the approval of Coast Guard Headquarters. Future Manning Reductions In the relatively near future, more complex manning reductions are likely to be requested. For example, the Coast Guard may receive requests to implement the dual-qualified, watch officer concept on the Japanese model. In the long run, the advance of technology will generally tend to erode the departmental distinctions aboard ships.
ESTABLISHING SAFE CREW LEVELS A FUNCTIONAL MODEL FOR ASSESSING CREW LEVlELS 63 The committee developed a functional model for task analysis and evaluated it by applying it to data from two actual ships. The model proved easy to use, comprehensive, and accurate. With further development, it could be used by the U.S. Coast Guard and by ship owners and operators to determine, systematically and reliably, the minimum manning levels for a variety of ship types and operating conditions. Additional work, for example, would make it more robust and flexible and would add risk or hazard analysis information. The thorough assessment of shipboard functions and tasks permitted by the model would be particularly useful to the Coast Guard in setting manning levels. An initial determination of crew requirements could be made using the model with data from expert opinions, and then confirmed during sea trials by entering actual voyage data into the model. Certification for smaller crews, using the model, could be based on actual performance, rather than on judgment alone. Such a process might have two steps. First, the owner or operator would submit for Coast Guard conditional approval a functional analysis of crew activities (with specified crew numbers and structure, skills and training, voyage profile, and operation and maintenance plans). Upon conditional approval, the vessel would be subjected to sea trials of up to six months, with logs of crew activities. The data from the trials would be used to validate the results obtained from the model. Such a procedure would give the Coast Guard a sound basis for decisions, explicitly taking account of the vessel's type, voyage profile, level of technology, and operating conditions. It would replace the current system of reliance on a patchwork of manning statutes, informal policy, and tradition. It would thus permit the U.S. shipping industry to take advantage of new technology without sacrificing the safety of vessels or shipboard personnel. Shipboard Task Analysis Over the last decade, the maritime community has combined concerns about the safety of navigation in an increasingly complex environment with concerns about more efficient operations. One trend toward reducing operational costs and increasing operational safety focuses on applying systems engineering. Systems engineering normally begins with a requirements analysis to determine the mission and functional requirements of present and future systems to help identify the tasks that must be supported (Figure 4-1~. Next, a task analysis identifies the tasks presently performed and those
64 Tasks Requirements Analysis Task Analysis Man-machine tradeoff studies Organizational Analysis Software Analysis l Hardware Analysis CREW SIZE AND MARITIME SAFETY Results System requirements Tasks to be supported l ~ · Present · Future Man-machine tradeoff matrix Organizational constraints Software Breakdown · Information Systems · Decision Support Systems · Expert Systems Hardware Design and Specifications FIGURE 4-1 Systems Engineenng Approaches to Shipboard Manning. to be performed In the future. During the task analysis, a man-machine tradeoff study is performed to determine which tasks will be performed by people and which by machines. The next step is an organizational analysis to determine how the human and machine tasks of the future will be supported in the organization. A software analysis then focuses on the information processing requirements of the tasks allocated to machines to determine, for example, which of the machine tasks can be supported with conventional software, and which are more amenable to decision support systems or expert systems implementa- tion. Finally, a hardware analysis is performed to identify the appropriate hardware. The Committee's Functional Model The committee's model is a task analysis tool applicable to all ship types, classes, and trades. It permits the assessment of manning over an entire voyage and in emergencies such as shipboard fires. Appendix E describes earlier shipboard task analyses.
ESTABLISHING SAFE CREW LEVELS 65 The model uses a taxonomy of 10 general functions, broken down into subfunctions, and sub-subfunctions that describe all aspects of shipboard operations across a broad spectrum of cargo, ship, and voyage types (dibble 4-1~. The general skills and time required to perform these functions are then determined to yield qualitative and quantitative minimum manning requirements. The model was applied to two actual ships. First, the taxonomy of functions was used to code two sets of data from American President Lines (APL): 30 months of actual maintenance data and summary deck operations data developed by a panel of APL ship's officers (described later in this chapter). Later, the taxonomy was used to code engineering and deck operations data developed by a panel of Exxon ship's officers for a specific Exxon ship and voyage profile (also described below). This coding demonstrated the comprehensiveness of the initial taxonomy and resulted in some refinements. Descr~pi~on of the Model Ten major shipboard functions identified in Table 4-1 are: cargo, ballast, navigation, main engine operations, auxiliary equipment operations, long-range radio operations, deck operations, general operations, general administration, and hotel functions. Data were collected from APL and Exxon for each function, subfunction, and sub-subfunction, and for each of three voyage phases- at dock, transiting restricted waters, and at sea. The time it took to perform any specific function was recorded for the range (i.e. the minimum and maximum times) and for the average time required. The maximum number of people required to perform the function at any specific time was recorded, along with the number of persons of any given skill level required. For example, if the average time for a given function (such as loading cargo) was four hours, and one person of a given skill classification (a licensed deck officer, for example) worked on the function full-time, while another of the same skill classification was required for two hours, 1.5 would be entered as the number of people of that skill classification required to perform that function. Five general skill classifications were used: licensed (N1) and unlicensed (N2) deck personnel; licensed (E1) and unlicensed (E2) engineering personnel; and steward's department personnel (G). Any tasks that must be done in conjunction with the specific task were also noted. Where the manning requirements for a specific function under restricted visibility were greater than those in good visibility (for example, while transiting restricted waters), the restricted visibility requirements were recorded. Above the function coding portion of the form, spaces were provided for indicating whether tasks were mandatory or discretionary for
66 CREW SIZE AND MARITIME SAFETY TABLE 4-1 Shipboard Functions Identified in Committee's Functional Model TASKS TO BE EVALUATED 1.0 CARGO 1.1 On-load 1.2 Off-load 1.3 Maintenance of cargo equip~nent/deck stores/wares and ballast tank cleaning and repairs of cargo, desk equipment, stores and wares 1.4 Record keeping (port logs) 1.5 Repair 1.5.1 Reefer-maintenance 1.5.2 Inspection 2.0 BALLAST 2. 1 On-load 2.2 Off-load 3.0 NAVIGATION 3.1 Track keeping 3.1.1 Daygood visibility 3.1.2 Night~ood visibility 3.1.3 Restricted visibility 3.2 Maneuvering 3.2.1 Chart correction 3.3 Collision avoidance 3.4 Voyage/passage planning 3.5 Record/chart keeping and update/bridge logs/charts and navigation information 3.6 Maintenance 3.6. 1 PMS 3.6.2 Unscheduled 3.7 Test vital systems 3.7.1 Prior to leaving port 3.7.2 Prior to entering port 3.8 Bridge housekeeping 3.9 Weather monitoring 3.9.1 Reporting 3.9.2 Planning 3.10 Hull Performance 3.10. 1 Monitoring 3.10.2 Maneuvering 3.10.3 Planning Training (equipment operations, procedure review, standard operations) 4.0 ENGINE OPERATIONS 4.1 Operations routine and watch standing 4.2 Maintenance 4.2. 1 Unscheduled 4.2.2 PMS 4.3 Record keeping 4.3.1 Records and record keeping 4.3.2 Soundings 5.0 AUXILIARY EQUIPMENT OPERATIONS (all non-main engine propulsion equipment) 5.1 Generators 5.1.1 Operations 5.1.2 Unscheduled maintenance 5.1.3 PMS 5.2 Fuel oil systems 5.2.1 Operations 5.2.2 Unscheduled maintenance 5.2.3 PMS 5.3 Boilers 5.3.1 5.3.2 Operations Unscheduled maintenance 5.2.3 PMS Evaporators 5.4. 1 Operations 5.4.2 Unscheduled maintenance 5.4.3 PMS ~ ~ . . . 5.5.1 5.5.2 Refrieerator/air conditioning Operations Unscheduled maintenance 5.5.3 PMS Sewage systems 5.6.1 Operations 5.6.2 Unscheduled maintenance 5.6.3 PMS Inert gas systems 5.7.1 Operations 5.7.2 Unscheduled maintenance 5.7.3 PMS 5.8 Electrical/electrical control systems 5.8. 1 Operations 5.8.2 Unscheduled maintenance 5.8.3 PMS
ESTABLISHING SAFE CREW LEVELS TABLE 4-1, Continued 67 5.9 Tools and test equipment 5.9.1 Operations 5.9.2 Unscheduled maintenance 5.9.3 PMS 5.10 Pumps 5.10.1 Operations 5.10.2 Unscheduled maintenance 5.10.3 PMS 5.11 Fuel transfer 5.12 Record keeping 6.0 LONG RANGE RADIO OPERATIONS 7.0 DECK OPERATIONS 7.1 Dockinglundocking 7.2 Mooring/unmooring (offshore) 8.15 7.3 Anchoring/heaving-in 8.16 7.4 Helicopter operations 7.5 Underwater lighting 7.6 Tugs/crane using 7.7 Preparation for going into yard/drydock 8.0 GENERAL OPERATIONS 8.1 Drills Lifeboat, firefighting, etc.) 9~4 8.2 Maintenance (lifeboats) 9~5 8.3 Safety tours 8.4 Vessel fabric maintenance (paint, chip. grease, coat) Deck equipment maintenance Qights, structure, mooring equipment, anchor, bow transfer, gangway, capstans, windlass) 8.6 Line and wire maintenance 8.7 Stores and supplies 8.7.1 Handling 8.7.2 Storage 8.7.3 Ordering 8.8 Other training 8.9 Medical 8.10 Bunkering 8.11 Safety equipment maintenance, gas test meters, and gauging equipment 8.12 Vessel structure . , . mamtenance/repalr 8.13 Steering gear maintenance 8.14 Cleaning/wash down 8.14.1 Deck 8.14.2 Engine room housekeeping Supervise shore personnel/gangs Stability and cargo planning 9.0 GENERAL ADMINISTRATION 9.1 Financial 9.2 Labor relations 9.3 Meetings 9.3.1 Shipboard management 9.3.2 Safety Payroll Regulatory requirement . . .. . . mon~tonng/lnspecuans/ walkarounds with inspection regulatory authonues 9.6 Special projects 10.0 HOTEL FUNCTIONS 10.1 Catenng 10.2 Accanrnodai~on and space clearing 10.3 Management 10.4 Provisioning 10.5 Maintenance the given time periods, and whether they were intended to be performed by the ship's crew or by a riding crew. To determine the manning requirements, the ship voyage profile and operating conditions were first specified. For each shipboard function, the average time required was recorded, then multiplied by its frequency of occurrence per voyage. This data was then multiplied by the number of persons of a given skill classification needed to perform the function. This gave the total amount of time required by persons of a given skill classification to perform that specific function during the voyage. Dividing this figure by the total number of voyage days yielded the average time per day required for that function; dividing this number by the average number
68 CREW SIZE AND MARITIME SAFETY of true working hours per day per person in that skill classification gave the number of persons required per day. In the validation studies, described below under the heading "Evaluation of the Model," a 10-hour working day was used as a baseline, reflecting experience at the two companies. This procedure was repeated for each function and skill classification. For each skill classification, the total number of persons per day required across all functions yielded the total number of persons of that skill required to operate the vessel safely and to support the requisite shipboard work load. Summing these totals across all five skill classifications (N1, N2, E1, E2, and G) yielded the total manning requirement for that ship, that voyage profile, and that set of given operating conditions. Based on the two validation studies described below, it appears that simply adding the data across all phases provides an accurate estimate of the minimum manning requirements for a particular ship. The data can also be calculated for different phases of the voyage (at dock, transiting restricted waters, at sea) to determine if different voyage phases require different manning levels. Similarly, if some functions are routinely performed by a riding crew, separate calculations can be performed to determine the appropriate manning tradeoffs between the ship's crew and the riding crew. Emergency Conditions The procedures described apply to normal operating conditions only. New state-of-the-art ships may be able to operate under normal operating conditions with crews that are too small to handle emergency conditions. Based on expert opinions of the persons who participated in the develop- ment and two initial validation studies of the model, the ability to fight shipboard fires will require larger crews than normal operations on some highly automated ships. As a result, manning requirements for emergency conditions particularly fighting shipboard fires were analyzed. This anal- ysis required estimating both the manning requirements for operating the ship while the fire is being fought and those for actually fighting the fire. Two types of fire (an engine room fire from a broken high-pressure fuel line and a container fire on deck) were analyzed. Operating Conditions Affecting Manning In developing and validating the model, the committee identified a number of operating conditions bearing on manning: . Operating procedures i.e., will certain maintenance functions be performed by the ship's crew, a riding crew, or a shore gang when the ship is in port? · Maintenance concept employed i.e., is a maintenance department in use?
ESTABWSHING SAFE CREW LEVELS 69 · Crew/role 17e~ability--i.e., to what extent can persons perform both deck and engineering functions, or possess dual certification? · Crew coniinuity--i.e., to what extent do crew members stay together, or train as a crew? Ship familianty--i.e., to what extent do crew members sail on the same ship or same class of ship? · Regulatory and union contract requirements and restnci'ons i.e., interdepartmental flexibility, employment continuity aboard the same ship or class of ship, familiarity with the specific ship. · Personnel selection procedures/cntena i.e., skills, physical condition, personality factors, expectation levels. · Job designe.g., chief mate's responsibilities. · 7?ainingJproficiency i.e., to what extent do crew members receive training/education to upgrade skills, or cross-train to broaden their skills? Evaluation of the Model To test the model's utility, it was used to determine manning re- quirements for two different ships, operated by different companies, with different voyage profiles. Both shipping organizations had already under- taken extensive manning studies and both had high confidence in their manning requirements. The first ship used was an American President Lines C-9 container ship operating between the west coast of the United States and the Far East. The second ship was an Exxon product tanker on a 14-day coastwise run between Houston, Texas, and a variety of southeastern U.S. ports. The committee's first objective was to determine whether the functional model was adequate to accommodate all functions performed on both ships during routine voyages. As noted above, the model was found to be comprehensive and required only minor refinement, mainly the addition of some sub-subfunctions (primarily in Function 5, Auxiliary Equipment Operations). The second objective was to determine whether the model would produce results that accurately reflected manning requirements. This de- termination was made somewhat differently for the two ships, as described below. American President Lines C-9 Container Ship Study American President Lines (APL) had conducted an extensive study of one of its C-9 container ships by carefully collecting actual maintenance data over a Month period, during 25 voyages. In addition, a panel of C-9 ship's officers had classified and developed consensus expert opinions on the functions and manning requirements for all bridge operations. With
70 CREW SIZE AND MARITIME SAFETY assistance from APL personnel who had worked on the computerization and coding of the C-9 data, the data were recoded using the committee's functional model codes. These data were compiled and used to determine manning requirements for the subject C-9 ship. These calculated require- ments matched its actual manning scale, both in number (21 people) and crew organization. They also suggested that under different operating con- ditions (i.e., those that would provide crew continuity or familiarity with the C-9), manning requirements could be reduced. Four major types of fires were identified to be of concern: (1) high- pressure fuel line break in the engine room, (2) generator fire, (3) stores fire, and (4) container fires (from internal combustion or stack exhaust sparks). Of these, the engine room fire from a high-pressure fuel line break was judged to be the most labor-intensive. ~ operate the ship while fighting the fire, two persons the master and a helmsman would be required for machinery operations. To fight the fire, an emergency coordinator and two three-man hose teams, each with a squad leader, would be required. This estimate results in a total of 11 people, well below present manning. Environ Mated Product Tanker Study Through careful observation and study of many of their voyages, the officers of an Exxon mixed product tanker had developed expert opinions about the time and skill requirements for the various ship operating func- tions. Several of the ship's officers and several senior ship captains from other Exxon tankers helped the committee complete the function analysis forms for the model. The data thus gathered were used to determine the vessel's minimum manning requirements. The vessel's present manning is 18 people: 4 N1 (1 master, 3 mates), 6 N2 (6 ABs), 4 E1 (1 chief engineer, 3 assistant engineers), 2 E2 (1 engine unlicensed, 1 pumpman), and 2 G (2 stewards).] The Exxon group believed that two of the ABs were not actually needed, and that with some policy modification it would be possible to operate with only one steward. The vessel's COI authorizes a crew of 14, based on the use of a maintenance department and only 1 steward (the maintenance department having eliminated the need for one AB). The manning requirements determined by the model are 4 N1, 3 N2, 4.5 E1, 2 E2, and 1.5 G. for a total crew of 15. Rounding up to the nearest whole person in each skill classification brings the total number to 16. In summary, the model supported the Exxon team's belief that the number of N2s (ABs) could be reduced by at least two. By requiring the crew to do 1 Shipboard positions were classed as N1 (licensed deck), N2 (unlicensed deck), E1 (licensed engine), E2 (unlicensed engine), and G (stewards).
ESTABLISHING SAFE CREW LEVELS 71 more of their own housekeeping, the number of stewards could be reduced to 1, for a total of 15. After reviewing the model's output, the Exxon team agreed that, with minor changes in task distribution, the ideal minimum crew would be a crew of 15: 4 N1 (1 master, 3 mates), 4 N2 (4 ABs), 4 E1 (chief engineer, 3 assistant engineers), and 2 E2 (1 engine unlicensed, 1 pumpman). By changing maintenance procedures and assigning painting and chip- ping to shore-based personnel, manning could be reduced by an additional N2 (1 AB), for a total of 14. The vessel's manning requirements for an engine room fire resulting from a high-pressure fuel line break were analyzed and found to be the same as the those of the APL C-9, or a total of 11 people, which is below the minimum manning level of 14 for normal operations. The tanker study not only validated the model's utility in determining minimum manning requirements, it also demonstrated how the model could be used as a management tool to make manning adjustments for greater operating efficiency. It should be remembered that the data used in the tanker validation study were based mainly on expert opinion, backed up by some recorded data and considerable deliberate observation by the team of experts and their colleagues aboard the vessel. A next logical step would be to conduct a validation study of the model, based on systematically recorded voyage data for the same vessel. The Model's Utility The validation studies show that the model provides an accurate esti- mate of minimum manning levels. Manning by phase (at dock, transiting restricted waters, or at sea) can be calculated, and tradeoffs (e.g., ship crew tasks versus riding crew tasks) can be analyzed. Once the data for a given voyage profile and set of operating conditions have been collected and analyzed, the model can be used to estimate the effect of new technology (i.e., unattended engine room, decision support systems), alternative voyage profiles, or revised operating conditions. The model can thus be used as a management tool to assess the impact of changes (or proposed changes) on safe manning requirements. The model also would allow the U.S. Coast Guard, ship owners, and operators to identify manning-sensitive tasks, manning-rich areas (can- didates for manning reductions), simultaneous tasks (time-substitutable tasks), tasks performed by similarly skilled personnel (skill-substitutable tasks), and tasks requiring similar time to perform (duration-substitutable tasks). Such tradeoff studies could assess the manning impact of new technology; of new ship designs, layouts, facilities configurations; or new
72 CREW SIZE AND MARITIME SAFETY shipboard procedures, processes, and controls. Safety concerns could be highlighted, or safety issues addressed, by maintaining minimum hourly performance requirements in the data. Limitations of the Model The work to date supports the notion that the functional model devel- oped can be used by the U.S. Coast Guard, ship owners, and operators in determining minimum manning levels for a variety of ship types. However, there are a number of limitations to the model as it exists: · The model has been validated with two sets of shipping data: one from a product tanker in the domestic trade, one from a container ship trading between the U.S. West Coast and the Far East. Before the model is accepted for general use, it needs to be validated against actual voyage data for a wider variety of ship types, trades, designs, and under varying operating conditions. · A more thorough empirical analysis of emergency and restricted visibility conditions needs to be conducted with the model; only anecdotal emergency and restricted visibility information were used during the initial validation studies. The model is not at present tied to risk or hazards analysis data (or a risk or hazards analysis model). If it were, model-recommended manning estimates could be compared with preferred manning structures (from a risk or hazards analysis perspective) to produce qualitative comparisons and rankings between alternative manning structures. · There is no formal mechanism within the model for ranking and comparing alternative manning structures. This decision support capabil- ity could be incorporated into the model, so that ranked recommended manning alternatives, with explanations, would be the model's output. · At present, the model does not accommodate uncertain or incom- plete information. Neither does it accommodate decision making under time pressure. Both capabilities could be incorporated. · The model does not offer a graphical representation of shipboard tasks over time, which would be helpful in visualizing those performed at different times, at the same time, or by similarly skilled personnel. In addition, beneath the graphic representation, a link between the model and cost-benefit analysis data would be helpful, so that recommendations for time- and personnel-substitutable tasks could be linked to cost data for a quantitative and qualitative comparison. These limitations do not suggest that the model as it presently exists is not a useful preliminary tool in arriving at minimum manning estimates. However, additional validation studies need to be conducted before it
ESTABLISHING SAFE CREW LEVELS 73 is adopted for general use. The added enhancements may improve its robustness, decision support capabilities, and ease of use. FINDINGS In establishing safe crew levels, the government and industry need to consider demands on the crew: each vessel's technology, type of service, crew skills, and quality of management and management programs. Systems engineering methods, including functional task analysis, offer an objective basis for such determinations. The model developed Is one approach to implementing systems engineering approaches to determining safe ship manning levels. REFERENCES Connaughton, Sean. 1987. Coast guard merchant vessel manning. Paper presented at 1987 Ship Operations, Management and Economics International Symposium, U.S. Merchant Marine Academy, Kings Point, New York. September 17-18. Denny, M. 1987. Shipboard productivity methods. U.S. Department of Transportation, Maritime Administration, Washington, D.C. Volumes 1-3. February. Liverpool Polytechnic and Collaborating Colleges. 1986. Technology and Manning for Safe Ship Operations, Volumes 1 and 2. Department of Transport. London. November. Schuffel, H., J. P. A. Boer, and L" van Breda, 1989. The ship's wheelhouse of the nineties: The navigation performance and mental workload of the officer of the watch. Journal of Navigation 42~1~:60-72. Williams, V. E. 1983. Crew Rationalization Study: ODS Liner Vessels. U.S. Department of Transportation, Maritime Administration, Office of Research and Development, Washington, D.C. April Yamanaka, K., and M. Gaffney. 1988. Effective manning in the Orient. U.S. Department of Transportation, Maritime Administration, Washington, D.C. Report Number MA- RD-770-87052. March 15.