A ship's doctor describes a doctor who guarantees medical and dental care on board ships in the civil and military sectors and is responsible for compliance with health and safety regulations. Whether there must be a ship's doctor on board is regulated by national regulations. The United Nations International Labour Organization recommends that a ship's doctor should travel on ships with more than 100 persons on board and on journeys longer than 3 days (Health Protection and Medical Care Convention 1987 (No. 164, § 8).
Ships with over 800 people should have two ship's doctors. Staffing ships with medical personnel is regulated by national regulations. The regulations of the flag of the country under which the ship sails are valid. In § 8 of the International Labour Organization (ILO) Convention Number 164 of 1987 concerning Health Protection and Medical Care for Seafarers, the ILO recommends that a ship's doctor travels on ships with more than 100 persons on board and on journeys longer than 3 days.
However, national regulations may deviate from this. Thus the British Merchant Shipping (Ships' Doctors) Regulations of 1995 states that is also the duty of British ship owners to have a qualified doctor on board ships with more than 100 people on board which are more than 1.5 days away from the nearest port with adequate medical provisions.