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                                       Guidelines on Fatigue Module 5

                            FATIGUE AND SHIP DESIGN

Module 5 contains practical information intended for the Naval Architect/Ship Designer for improving the ship design conditions on ships. Module 1 (Fatigue  -  Causes and Consequences) should be read prior to going through this module. 

 1. Why do ship designers need to know about shipboard fatigue? 
    
 Fatigue threatens ship safety and can cause accidents[1]. Evidence that fatigue plays in maritime accidents has been provided by a number of submissions to IMO, e.g. those made by Australia (HTW1/INF. 2 and MSC 69/INF.15); United Kingdom (STW 44/10); Netherlands (STW 40/INF. 2);  Japan (MSC 71/INF.8; MSC 69/INF.16); and Finland (MSC 68/INF.15). 
 
 Whatever the cause, the effect of fatigue on performance is serious, threatening safe operations which rely on alertness and concentration. In addition to the threat to ship safety, fatigue can negatively affect seafarers' physical and psychological health, at a high cost to the individual and the industry. 
 
 Fatigue can result in long term effects on health and clinical illnesses, increasing the risks of pain, stress, obesity, coronary heart disease, gastrointestinal disorders and diabetes. Long term affects also point to mental health problems such as negative mood states and depression. Exhausted seafarers are also more vulnerable to the many hazards on ships, resulting in slips, trips and falls, strikes by falling objects, burns, body strains and other injuries. Injury claims from P&I Club statistics illustrate how much these hazards cost the industry, in addition to lost time and vessel delays.
 
 As highlighted in Module 1, fatigue can arise from a range of factors but is primarily affected by inadequate restorative sleep, excessive wakefulness, work/sleep at inappropriate times of the body clock (circadian cycle) and demanding mental and/or physical work. Even the boredom of watchkeeping in the still of the night can cause fatigue. Inadequate restorative sleep (duration and quality)  is among the main causes of  fatigue. Amongst others, sleep is affected by the living and working environment onboard[2][,3]. 
 

 Reducing shipboard fatigue will require orchestrated action by many groups, including  companies, seafarers and administrations. Naval architects and ship designers make their unique contribution by improving the design of shipboard conditions and incorporating `fatigue proofing' into ship and equipment design to reduce potential to cause fatigue.
 
 
 
 
 
 
 
 
 

 
 
 
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 In controlling and managing the risks of fatigue at sea shipboard ergonomics and the improvement of conditions on board are important considerations in ensuring seafarers are provided with the best opportunity to: 
      (a)gain adequate sleep quality onboard; and 
      (b) maintain safe levels of alertness and performance during duty periods. 
 


 3. What elements of fatigue can be influenced by design? 

 There are various aspects of  fatigue that can potentially be influenced by the design of the living and working environment. Excessive heat or cold, too much or too little humidity, poor air exchange in enclosed spaces where people live and work can cause fatigue.  Fatigue that results from the working and living environment can be alleviated by design improvements. The following aspects should be considered in design:
 
  Sleep area (Design for sleep)
    *          Cabin, cool, ventilated, quiet and dark
    *          Bunk design and layout, add sofa  -  different orientation
    *          Mattress, bedding
    *          Insulate and/or isolate sleeping areas
  
  Ship seakeeping  -  minimise in living and working spaces
                    *      Ship movement 
                    *      Vibration
                    *      Noise
  
  Accommodation spaces and layout (Design for personal needs and comfort)
   Crew accommodation is usually located in a far from ideal location. It is built around the operation of the ship, being placed directly over the engine room. This area does not give the best quality of ride. In addition, it can be noisy.
   

   Acoustic insulation could be used to reduce noise in this area, but it must also be considered in conjunction with measures to increase sleep disturbances that must be heard, i.e. fire alarms. Consideration could be given to ensure that the accommodation area is restful and that it aides in recovery from fatigue, e.g. in terms of decor, easy to clean. The following should be considered:
  
    *          Design for minimal crew flow in sleeping quarters;
    *          Consider laundry, changing, hygiene, privacy;
    *          Insulation or isolation from cargo, engine, other disturbances (noise and vibration);
    *          Lighting/dimmers (design for sleep);
    *          Ventilation/air exchange;
    *          Temperature and humidity (design for sleep);
    *          Design for natural light access;
    *          Galley & mess room/s;
    *          Design of napping stations;
    *          Appropriate medical facilities.

  Workplace design (Design for alertness and performance)
  Workplace design, particularly those that require unnecessary sustained exertion (physical or mental), can be offset by better design of the workplace or by better upkeep of the original condition of the ship. Aspects to consider include: 
  
      * Layout of workspaces for efficient work;
      * Natural light access;
      * Design for workflow;
      * Working position (seated/standing, height, flooring material (shock and balance));
      * Avoid fatigue "inducers";
      * Lighting (design for alertness);
      * Ventilation/ air exchange;
      * Exposure to chemicals;
      * Noise and vibration;
      * Temperature and humidity (design for alertness).

   Additionally, design control centres such as machinery control room layout, cargo control room layout, etc., should consider the integration of people with equipment and systems to reduce mental overload and boredom.

  Recreation and recovery
    *          Privacy and social life ;
    *          Minimal "housekeeping";
    *          Gym/training facilities;
    *          Library, media rooms.
 

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 Ergonomic principles should be used and have been developed to aid designers. These are examined in the next section.

 4.     What does ergonomics have to do with shipboard design?

 The discipline of ergonomics is founded on the belief that good design supports human performance and is not limited to aesthetic qualities. A well-designed work system or piece of equipment, from an ergonomics viewpoint, takes advantage of human capabilities and minimizes the impact of human limitation while ensuring that the equipment or system is fully functional, 
 i.e. designed for human use and meets operational requirements. Ergonomics has been defined as:
 
 
 "The scientific discipline concerned with the application of validated scientific research about people, their abilities, characteristics and limitations to the design of systems they use, environments in which they function and interact, and jobs they perform to improve health,  safety, well-being and overall system performance." 
 
 





 Ergonomically designed work systems enhance safety, effectiveness, and efficiency. They should also support shipboard tasks under all conditions, including situations where people may be fatigued. 
 
 The ergonomics approach to design is human-centred. This means that all designable components (ship, ship's systems, equipment, service, etc) are fitted to the characteristics of the intended users, operators or workers (e.g. seafarers, maintainers, etc.) rather than selecting and/or adapting humans to fit the system and/or product. This should be done by consideration of:

 * the intended target population;
 * the task, goal or intended outcome of the system, product or service; and
 * the environment in which the design is to function.
 
 Ergonomic principles should be employed.
 
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 Those affected by the design (the seafarers) should be involved throughout the whole design process, including evaluation. This will help to optimize solutions (e.g. by providing specific experience and requirements). Their early and continued participation and involvement is regarded as an efficient design strategy within ergonomics.
 
 Task-oriented design also takes into account differences that can be observed between the designed task and the way the task is actually performed. Activities in performing a task are affected by variations and changes in, for example, context, procedures, equipment, products or materials.
 
 The relations between the conditions and demands placed on the seafarer and their response to being exposed to such conditions which are dependent on individual characteristics (e.g. body size, age, capacities, abilities, skills, etc.) and their effects need to be considered in the design of ship systems, services, products and tasks in order to avoid impairing effects on the individual.
 
 Appropriate standards are referenced throughout the following sections. A few standards give guidance on how to incorporate ergonomics into the design process, e.g. ergonomic principles in the design of work systems. The remaining sections also look at specific help that is available to the ship designers  to incorporate `fatigue proofing' strategies into design. This "help" takes the form of tools, guides, standards, regulations and rules.

 5. What tools are available for designing/building fatigue resistant ships? 
    
 

 Ergonomic standards are effective tools for improving the working environment, particularly those that deal with environmental conditions (such as temperature, vibration, ventilation, etc.). 

 Tools that support ergonomic design include the use of computer simulation. These are increasingly being used to assess both the impact of environmental conditions as well as work and living design ergonomics. Examples include virtual reality and three-dimensional computer aided design (JACK; SAMMIE; etc.). Use of such simulation tools is encouraged as they allow early and more cost effective evaluation of various aspects of design.


 Environmental conditions also extend across structural design, propulsion, hull forms and   several other aspects of design. Often, constructive solutions may be employed to improve environmental conditions. For example, the transmission of noise can be dampened by the insertion of acoustic insulation; similarly, resilience techniques can be used to alleviate vibration problems.

 There are a variety of design tools available for this and include recommended guides, prescriptive and evaluation standards. Design software such as Finite Element Analysis (FEA) can assist the ship designer in ensuring that specified limits are not exceeded. These tools can be used for:

    * Calculating noise limits;
    * Calculating vibration limits;
    * Calculating seakeeping qualities/quality of ride;
    * Analysing ventilation flows; and
    * Performing model tests.



 6.     What rules and guidance are available for designing/building a fatigue resistant ship?

 There are a number of rules, regulations, standards and guidelines designed to enhance environmental shipboard conditions, which can be used by the ship designer to reduce fatigue. This is a developing field.

 Accommodation
 	
 Some aspects of crew accommodation, for instance minimum size and acoustic insulation, are subject to regulation such as the International Labour Organization (ILO), Maritime Labour Convention (MLC) 2006.  The MLC, 2006 addresses crew accommodation in Title 3 (Accommodation, Recreational Facilities, Food and Catering).  The purpose is to ensure that seafarers have decent accommodation and recreational facilities on board. Regulation 3.1  -  Accommodation and recreational facilities and Standard A3.1  -  Accommodation and recreational facilities, incorporates prescriptive requirements for accommodation spaces (i.e. crew will have for example fewer or no cabin mates, a larger cabin floor area and more convenient access to showers, water closets, and lavatories).   
 
 The MLC, as it relates to habitability, institutes minimum standards of living through the provision of crew accommodation areas that 
 are:
   * free from hazardous levels of noise and vibration;
   * provide appropriate levels of lighting and indoor climatic qualities; and
   * offers improved crew accommodation design.

 The MLC (2006), Guideline B3.1 (Accommodation and recreational facilities) provides more specific guidelines for ship design, covering the following aspects:
   * Ventilation;
   * Heating;
   * Lighting;
   * Sleeping rooms;
   * Mess rooms;
   * Sanitary accommodation;
   * Hospital accommodation; and
   * Prevention of noise and vibration.


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Crew accommodation is also subject to National Standards.

Environmental conditions in living and working spaces

 Some Classification Societies have rules, most of them being optional rules, for aspects of environmental conditions (i.e. noise and vibration) for certain ship types. 
 
 
 
 
 A number of these Rules include crew-only spaces as well as passenger spaces. Crew-only spaces are defined as follows:
       * accommodation spaces (e.g. cabins, corridors, offices, mess rooms, recreation rooms)
       * work spaces
       * navigation spaces

 These Rules are contained in:

      * Comfort Class: Rules for Classification of Ships. Part 6, Chapter 33. Det Norske Veritas (DNVGL). January 2014
         
      * Rules for Passenger and Crew Accommodation Comfort. Part 7, Chapter 12. July 2014. Lloyd's Register of Shipping

      * Rules for the Evaluation of Noise and Vibration Comfort on Board Passenger Ships. January 1999. Registro Italiano Navale

Noise
      
      IMO developed requirements and Resolutions aimed to protect the seafarer from unacceptable levels of noise:
      
      
       * SOLAS Regulation II-1/3-12 Protection against noise.
       * Res. MSC. 337(91) Code on noise levels onboard ships (This code is mandatory under regulation II-1/3-12 with entry into force on 1 July 2014). 
       * Resolution A.468(XII) (1981), Code on noise levels onboard ship fixes permissible maximum limits of noise depending on the type of space.

Relevant Standards on Noise	

 
 
 ISO 2923:1996 Acoustics - Measurement of noise onboard vessels
 
 
      ISO 1999:2013 Acoustics - Estimation of noise-induced hearing loss
      
      
      ISO 717-1; 717-2: 2013 Acoustics - Rating of sound insulation in buildings and of building elements:
            oo Part 1: Airborne sound insulation.
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            oo Part 2: Impact sound insulation.

      ISO 15186-2:2003 Acoustics - Measurement of sound insulation in buildings and of building elements using sound. 
      Part 2: Field measurements 
      
      ISO 140-5:1998 Acoustics - Measurement of sound insulation in buildings and of building elements. Part 7: 
      Field measurements of airborne impact insulation of floors

      IEC Publication 60651 Sound level meters
      
      IEC Publication 60225 Octave, half-octave and third octave band filters intended for the analysis of sound and vibrations
      
      IEC Publication 60804:Ed. 2.0 Integrating-average in sound level meters
      
      IEC Publication 60942:2003 Electroacoustics Sound calibrators

Other Standards on Vibration:


ISO 2041:2009 Mechanical vibration, shock and condition monitoring 	 -  vocabulary


      ISO 2631 (Series) Mechanical vibration and shock - E	valuation of human exposure to whole-body vibration
      
      ISO 20283 Mechanical vibration - Measurement of vibration on ships.
            oo Part 2 (2008): Measurement of structural vibration
            oo Part 3 (2006): Pre-installation vibration measurement of shipboard equipment
      Part 4 (2012): Measurement and evaluation of vibration of the ship propulsion machinery
      
      ISO 6954:2000 Mechanical vibration - Guidelines for the measurement, reporting and evaluation of vibration with regard to habitability on passenger and in merchant ships
      

	

	

Classification Societies' Guidelines for Noise and Vibration

      In addition to the Comfort Notation described above, Classification Societies have guidelines for noise and vibration limits onboard ship, as listed below:

           NK	Noise and Vibration Guideline, July 2011
           	
           
           ABS	Noise and Vibration control for inhabited spaces, July 2014
           
           ABS	Guidance notes on ship vibration, April 2006

           KR	Guide to control of ship vibration and noise, 2[nd] edition, 1997
           IACS	Unified Interpretation SC82 Protection against noise, 1993
                  BV		Recommendation  designed  to  limit  the  effects  of  vibrations     onboard, Guidance note, NI38 A-RD3, 1979
                  
                  VERITEC  Vibration control in ships, 1985
           
           LR	Guidance notes on acceptable vibration levels and their measurement, 1990

      In addition to the guidelines above, classification societies have guidelines for crew Habitability on ships, offshore installations, workboats and mobile offshore drilling units, developed with the objective of improving the quality of crew member performance and comfort by improving working and living environments in terms of accommodation area design as listed below:

      ABS	Guide for crew habitability on ships, July 2012
      
            ABS	Guide for crew habitability on offshore installations, September 2012
      
      ABS	Guide for crew habitability on workboats
      
            ABS	Guide for crew habitability on mobile offshore drilling units (MODUs), September 2012

Working spaces

 Regulations and standards exist for dealing with improvements to working spaces which may help in reducing fatigue. Some of the standards are still under development. These measures include bridge layout and navigation equipment, engine rooms, and general ergonomics, as follows.

Bridge Layout and Navigation Equipment

           IMO MSC/Circular.982, Guidelines on Ergonomic criteria for bridge equipment and layout
                  
           ISO 8468:2007 Ships and marine technology - Ship's bridge layout and associated equipment - Requirements and Guidelines
           
           	
           
           	








           
                        
                        IACS	Unified N1 requirements for One Man Bridge Operated (OMBO) Ships. International Association of Classification Societies. 1992
                        
                        ABS	Guidance notes on Ergonomic Design of Navigational Bridges, Oct 2003
                        
                        IMO	Resolution A.708(17), Navigation bride visibility and functions, adopted on 6 November 1991
                        
                        SOLAS	Bridge Design, Equipment arrangement and procedures (BDEAP)
                        
          MSC.1/Circ. 1512 Guidelines of software quality assurance and human centred design for e-navigation. 
                        
                        


          Engine Rooms

          IMO MSC/Circular.834, Guidelines for engine room layout, design and arrangement.17

          ISO 8861 Shipbuilding -- Engine-room ventilation in diesel-engine ships -- Design requirements and basis of calculations. 

          General Ergonomics
          
          

ABS Guidance Notes on  the  Application  of  Ergonomics  to  Marine   Systems. 
          American Bureau of Shipping, January 1998

          CEN EN 614-1 (2006) Safety of machinery -- Ergonomic design principles Part 1: Terminology and general principles. 

          CEN EN 563 (1994).Safety of machinery -- Temperatures of touchable surfaces -- Ergonomics data to establish temperature limit values for hot surfaces. 
          
          

           ILO International data on anthropometry. Eds. Jurgens, H., Aune, I. and Pieper, U. Federal Institute for Occupational Safety and Health, Dartmund. Federal Republic of Germany. 92-2-106449-2. Occupational Safety and Health Series: No. 65, (19

          ISO 26800:2011 Ergonomics -- General approach, principles and concepts.
          
          ISO/TS 20646:2014 Ergonomics guidelines for the optimization of musculoskeletal workload.
          
          ISO 6385:2004 	 Ergonomics principles in the design of work systems.
          
          

          ISO 10551:1995 Ergonomics of the thermal environment -- Assessment of the influence of the thermal environment using subjective judgment scales. 
          
          

          ISO 11399:1995 Ergonomics of the thermal environment -- Principles and application of relevant International Standards. 
          
          ISO 9241-110:2006 Ergonomics of human-system interaction  -  Part 110: Dialogue principles 
          
          ISO 9241 Ergonomic requirements for office work with visual display terminals (VDTs):
            oo Part 5 (1998): Workstation layout and postural requirements
            oo Part 6 (1999): Guidance on the work environment
          
          ISO 11064 Ergonomic design of control centres. Part 1 (2000): Principles for the design of control centres
          
          ISO 15535:2012 General requirements for establishing anthropometric databases
                  
                  















References

 
 
 
 
 
 
 

 

   1.     Allen, P., Wadsworth, E. & Smith, A. (2008). Seafarers' fatigue: A review of the recent literature. Internat. Marit. Health, 2008, 59, 1  -  4.
    
   2.     Xhelilaj, E. & Lapa, K. (2010). The Role of Human Fatigue Factor Towards Maritime Casualties. Maritime Transport & Navigation Journal, Vol. 2 (2010), No. 2.

   3.     Calhoun, S. R. (2009), Human factors in ship design: Preventing and reducing shipboard operator fatigue. University of Michigan, Department of Naval Architecture and Marine Engineering. U.S. Coast Guard Research Project.

   4.     Jurgens, H. W., Aune, I. A. & Ursula, P. (1990). International data on anthropometry. Geneva [Switzerland] : International Labour Office, 1990

   5.     ASTM F1166-07(2013), Standard Practice for Human Engineering Design for Marine Systems, Equipment, and Facilities, ASTM International, West Conshohocken, PA, 2013, www.astm.org.




                                  
