Regulation 10(1) A shipowner shall not permit a seafarer to work on board a ship unless that seafarer holds a valid medical certificate issued by a medical practitioner recognised by the Authority.(2) A seafarer who has been issued a medical certificate shall carry that certificate on board during that seafarer's employment on the ship.(3) The Authority may permit a seafarer to be examined by a medical referee, where(a) a medical practitioner issues a medical certificate with restrictions imposed on the seafarer's ability to work; or(b) a medical practitioner refuses to issue a medical certificate to the seafarer.(4) A medical certificate issued under sub regulation (1) shall—(a) be in accordance with the STCW Convention and where a seafarer is not covered by the STCW Convention, the medical certificate shall have similar requirements;(b) state that the seafarer's hearing, sight and colour vision, where colour vision is a requirement for the work to be performed, are satisfactory; and(c) state that the seafarer is not suffering from any medical condition that may(i) be aggravated by sea service;(ii) render the seafarer unfit for sea service; or(iii) endanger the health of persons on board the ship.(5) The Authority may, in urgent cases, permit a seafarer to work without a valid medical certificate until the next port of call, where the seafarer may obtain a medical certificate from a medical practitioner recognised by the administration in that port of call if(a) the seafarer holds a medical certificate that expired within the preceding six-month period; and (b) the period of the permission does not exceed three months.(6) Where the medical certificate of a seafarer expires during the course of a voyage, the medical certificate shall, despite the expiration, continue in force until the next port of call where the seafarer may obtain a medical certificate from a qualified medical practitioner except that the period that an expired medical certificate continues to be in force shall not exceed three months.(7) Except where a shorter period is required by the seafarer’s duties or is required under the STCW Convention, a medical certificate is valid(a) for a period of two years except where the seafarer is under the age of eighteen years in which case the certificate is valid for one year; and(b) in the case of a certificate in respect of colour vision, for a period of six years.(8) A medical certificate for a seafarer working on a ship ordinarily engaged on international voyages shall be in English.