The pattern of any health problems in seafarers will reflect those of their social group and country of origin. The risks of becoming ill at sea will, to an extent, be influenced by the risks, especially from climatic extremes and from prevalent infections met with during voyages. Access to medical care in the event of an emergency will depend on the level of medical skills available on the vessel, or by telemedicine, the distance to port and the quality of health care available there.

 Variations in disease patterns can be the basis for determining the contents of the fitness assessment, for instance by screening for tuberculosis or for kidney stones in those coming from high prevalence areas, but not in those from places where these conditions are rare. Any such differential requirements need to have a valid evidence base as they are open to challenge as for being discriminatory against certain ethnic groups or nationalities.

 Climatic extremes are often modified now by climate control within a vessel, but extremes can still occur, for instance during mooring operations in the arctic and during engine maintenance in tropical climates. Above all they can arise in the event of vessel emergencies where systems fail or when evacuation of the vessel is required. Risks at low temperatures may arise in some people with peripheral circulatory disorders, while high temperatures require fully functioning thermoregulation and the ability to maintain fluid balance – both potentially at risk in some forms or circulatory and kidney disease.

 Both risk factors for infections and the consequences of those that may either impair individual fitness or, more importantly, be transmissible to other crew members need to be covered . In terms of medical screening risk factors for severe malaria infections and for some other tropical diseases are relevant, with the absence of the spleen seen as one well defined cause of increased risk of a fatal outcome if infection occurs.

 Distance from care and its adequacy are important for anyone who has an increased risk of becoming ill while at sea. If a heart condition recurs at sea, can it be investigated and treated before it becomes life threatening, and will the treatment be one that meets good standards of medical practice? A seafarer with a condition that may recur may be just made fit for coastal work in a country where there are good onshore medical facilities that can be reached before any complications become serious. Thus a small risk of incarceration of a hernia or of dental pain from tooth or gum disease may be compatible with work on a vessel that is never far from a port with good medical facilities.


Positions and functions


The functions of crew members are not uniform. On larger vessels they are differentiated by deck, engineering and catering departments. Passenger vessels may in addition carry a wide range of customer service staff. As the job requirements vary, so do the health related capabilities that are needed to do them. In addition, officers and ratings will have different duties and so the capabilities required will not necessarily be the same.

 Safe navigation of the vessel depends on the perceptual and cognitive skills of the bridge crew. In particular, and despite the increased use of radar and other aids, visual lookout remains important. Hence, there are detailed standards for visual acuity and for colour vision that are specified internationally. The ability to analyse and respond appropriately to external events is essential. This can be compromised by any dementing conditions or by behavioural traits such as aggression. More commonly it is adversely affected by psycho-active substances. These may be medications given for therapeutic purposes, or alcohol or drugs inappropriately taken prior to safety critical duties.

 Unlike passenger aircraft, ships’ bridges are not usually ’dual manned’ in the sense of having two officers on watch both trained to take over command from the other should they become incapacitated or behave erratically. This means that a condition that could lead to a substantially increased risk of sudden incapacitation is likely to make a person unsuitable for bridge watch keeping. Examples include: disabling cardiac arrhythmias, recurrence of vascular events such as stroke or heart attack, seizure risks, or poorly controlled use of insulin to treat diabetes.  On occasions it may be possible to allow the person to do bridge duties, but only when there is a second competent person present. The role of the engineer has changed now that most marine engines operate with little need for continuing oversight and can be controlled from the bridge. Vision and other senses remain important as does the ability to carry out both routine and emergency maintenance – the latter often in hot, cramped and tense conditions.

 Both deck and engineering ratings do a higher proportion of the physically demanding tasks on a vessel and usually need the ability to perform manual handling tasks, to work in extreme conditions of heat and cold and to be free from prior conditions that could predispose them to skin or lung problems from irritants or sensitizers. However with reductions in crew numbers officers also now often perform similar duties.

 Catering staff, like food handlers anywhere, are in a position where they can spread food-borne infection to others on the vessel. Prevention is in the main by good practice, but examination should include the identification of any sources of sepsis, for instance skin lesions or ear discharges that could contaminate food. Where there is a relevant history, or where they come from a place where bacterial or viral diseases spread by faecal-oral contamination are common, examination of a faecal specimen may be indicated.


Safety and security


The risks from sudden collapse on the bridge have already been noted. Collapse elsewhere can also be a major risk, even if it does not directly endanger the vessel. Sudden incapacitation while working at heights has clear risks but there are also many maintenance tasks that take place in confined spaces on a vessel. Collapse here can result in big rescue problems, especially if the seafarer is obese. The situation will be even more complex if the cause of collapse is an oxygen deficient or toxic atmosphere and breathing apparatus is required.  Ships normally carry self-contained breathing apparatus sets. To wear these effectively, a good seal between the face and the mask is needed and vision can be a problem if the face piece is incompatible with a user’s glasses. In addition, anyone who is physically unfit or overweight will make greater demands on the air supply carried and so will only be able to wear the apparatus for a short time as compared with someone who is fit and not overweight. As the sets are worn on the back, an obese person may also find it impossible to get through the entrance to a confined space.


International seafaring


The geographical aspects have been noted above.  Where the crew of a vessel all come from the same area and this is within the ship’s flag state for registration, compliance with national requirements on fitness is all that is required and the examination arrangements in the country will be such that this is easily achieved. This pattern of crewing is now rare on all but the most local vessels. Many ship’s crews now include seafarers from several countries and so there is a need for internationally comprehensible systems of fitness assessment and documentation.  International crewing can also cause problems of communication and a range of manifestations of psychological stress among different nationalities in the crew.  This can be accentuated when different crew members are on different terms of engagement and paid at differing rates. While such issues do not normally directly arise during routine assessments for fitness, they can be a contributory factor to illnesses presenting during periods at sea and so lead to requests for additional assessments and to decisions about fitness to continue working.


Fish catching


The diversity of tasks in fishing is vast, from the locally used open boat with a single crew member to factory ships and catchers working in remote seas distant from any land.  All the navigation and engineering functions of other seafarers are relevant, but there are additional risks. Most come from work on small vessels in hostile conditions as gear is set, hauled in and the catch sorted and processed. The biggest risks are of injury, but heat and cold exposure, skin reactions to marine organisms and venom from spines and nematocysts can also occur(3).  Assessment needs to take account of any past reactions to conditions in the fishery and to the scope for prevention in future.  While acute injury prevention is outside the scope of this section, there is evidence of very high incidences of chronic musculoskeletal pain in fish catchers and the consequences of this for safe work in future and the risk of progression leading to termination of career because of incapacitation needs to be considered. 

 In many countries fishing is outside the regulatory frameworks applied to merchant seafarers and it often operates on a catch share basis where all the crew of a boat share in a joint venture and share the profits once the costs of the voyage have been paid off. This means that the normal framework of employer and employee responsibilities does not exist and assessment of fitness beyond the testing of vision is often not currently a formal requirement, although there are ILO and IMH conventions that make provision for medical assessment of the crews of fishing vessels (4).


The offshore industry


Oil, gas and other mineral exploitation offshore uses a range of vessels and fixed structures, as well as some that spend part of their time as vessels, either being towed or self-powered and part as structures fixed by legs, multiple anchors or dynamic position control. In addition to seafarers, a range of other personnel may be carried, for instance divers, seismic experts and other scientists and surface crews operating remote controlled submarines. Groups such as divers are covered by their own medical assessment regulations which reflect their tasks and risks. In many countries there are also fitness requirements for those working on fixed installations.  Because structures are fixed, often carry paramedical staff and are in regular helicopter communication with the shore, these differ in detail from those applied to seafarers. For other groups of non-seafarers working offshore the task done and its location in terms of climate and distance from care needs to be reviewed in making fitness decisions. 

 The largest group of seafarers in the offshore industry works on supply and safety vessels servicing fixed structures. These are relatively small vessels that have to meet schedules or be on station in all weather conditions. Supply vessels have to transfer cargoes to fixed structures in open waters, while safety vessels may have to launch boats or rescue people from the sea in difficult conditions. A high standard of physical capability is therefore required. Although these vessels can be thought of as coastal, the inflexibility of their schedules and duties means that going off-station because of a medical emergency on board can have major operational and safety implications for a production platform. Hence a significant risk of illness recurrence usually makes a person unfit to work on an offshore support vessel.


Maritime pilots


Pilotage requirements vary from passages of less than an hour to some which can take well over a day. A pilot will have to embark and disembark from a vessel to a pilot launch frequently using a ladder down the side of a ship. This can be a climb of 20 metres on a ladder that can sway away from the side as the vessel rolls. This requires good strength, coordination and limb function and the absence of any risk of sudden incapacitation. On board, the pilot will be advising the master on details of navigation, and on occasions taking over the control of the vessel. The visual and cognitive requirements are similar to those for a deck officer.