Im currently based in the UK and work at sea serving as the the ships medic have had some recent AMA training but was originally a Radiology Technoloist hopefull im looking to move over to the US and complete my EMT training up to Paramedic level.
Working on Ships at sea can take on many roles dependant on your qualifications and the type of ship.
For instance i currently work on Emergency Response and Rescue Vessels we work primarily on contract to the oil companies round the world and provide response in case of emergencies on the oil platforms we are covering hence we undertake the industry standard Advanced Medical Aid (AMA) course wich gives us training upto EMT-Intermediate in the US and Technician status in the UK but only on these ships.
Im a Navigating Officer on the ships and also qualified as an AMA so cover both duties in emergencies (we usually have at least two AMA's on one ship).
On other ships its the duty of the second officer to undertake the ships medical officers duties which can at times range from a simple injury (like a engineer hitting thumb with a hammer) to major medical problems (heart attack / loss of limbs) it does happen but fortunatly not so often.
thats reall a basic of what we do. (hope it helps)