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2. National laws or regulations shall determine when vessels are to be regarded as seagoing. 3. This Convention does not apply to — (a) Vessels of less than 200 tons gross register tonnage; (b) Wooden vessels of primitive build such as dhows and junks; (c) Fishing vessels; (d) Estuarial craft. Article 2 Without prejudice to the steps which should be taken to ensure that the persons mentioned below are in good health and not likely to endanger the health of other persons on board, this Convention applies to every person who is engaged in any capacity on board a vessel except — (a) A pilot (not a member of the crew); (b) Persons employed on board by an employer other than the shipowner, except radio officers or operators in the service of a wireless telegraphy company ; (c) Travelling dockers (longshoremen) not members of the crew; (d) Persons employed in ports who are not ordinarily employed at sea. Article 3 1. No person to whom this Convention applies shall be engaged for employment in a vessel to which this Convention applies unless he produces a certificate attesting to his fitness for the work for which he is to be employed at sea signed by a medical practitioner or, in the case of a certificate solely concerning his sight, by a person authorized by the competent authority to issue such a certificate. 2. Provided that, for a period of two years from the date of the entry into force of this Convention for the territory concerned, a person may be so engaged if he produces evidence that he has been employed in a seagoing vessel to which this Convention applies for a substantial period during the previous two years. Article 4 1. The competent authority shall, after consultation with the shipowners' and seafarers' organizations concerned, prescribe the nature of the medical examination to be made and the particulars to be included in the medical certificate. 2. When prescribing the nature of the examination, due regard shall be had to the age of the person to be examined and the nature of the duties to be performed. 3. In particular, the medical certificate shall attest — (a) That the hearing and sight of the person and in the case of a person to be employed in the deck department (except for certain specialist personnel, whose fitness for the work which they are to perform is not liable to be affected by defective colour vision) his colour vision, are all satisfactory; and (b) That he is not suffering from any disease likely to be aggravated by, or to render him unfit for, service at sea or likely to endanger the health of other persons on board. Article 5 1. The medical certificate shall remain in force for a period not exceeding two years from the date on which it was granted. 2. In so far as a medical certificate relates to colour vision it shall remain in force for a period not exceeding six years from the date on which it was granted. 3. If the period of validity of a certificate expires in the course of a voyage the certificate shall continue in force until the end of that voyage.

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