4 Fitness for duty

4.1 All persons who are assigned duty as officer in charge of a watch or as a rating forming part of a watch must be provided a minimum of 10 hours of rest in any 24‑hour period.

4.2 The hours of rest may be divided into no more than two periods, one of which must be at least 6 hours in length.

4.3 The requirements for rest periods laid down in 4.1 and 4.2 need not be maintained in the case of an emergency or drill or in other overriding operational conditions.

Note: “Overriding operational conditions” means essential shipboard work that cannot be delayed for safety or environmental reasons or which could not reasonably have been anticipated at the commencement of the voyage.

4.4 Notwithstanding 4.1 and 4.2, the minimum period of ten hours may be reduced to not less than 6 consecutive hours provided that any such reduction must not extend beyond two days and not less than 70 hours of rest are provided each seven day period.

4.5 Watch schedules must be posted where they are easily accessible.

4.6 Companies must arrange for records to be maintained of hours of work and rest.

Note: Although there is no universally accepted technical definition of fatigue, everyone involved in ship operations should be alert to the factors that can contribute to fatigue, including, but not limited to, those identified in IMO Resolution A.772(18).

In applying Provision 4, the following should be taken into account:

 Provisions made to prevent fatigue should ensure that excessive or unreasonable overall working hours are not undertaken. In particular, the minimum rest periods should not be interpreted as implying that all other hours may be devoted to watchkeeping or other duties.

 The frequency and length of leave periods, and the granting of compensatory leave, are material factors in preventing fatigue from building up over a period of time.

 The provisions may be varied for ships on short sea voyages, provided special safety arrangements are put in place.