6 On/6 Off watchkeeping = fatigue
A small cargo vessel was on a coastal passage and proceeding at full sea speed. At midnight, the Master, one of the two watchkeepers on board, was relieved by the other officer. Soon after taking over the watch the OOW, as was the common practice on this vessel, sent the duty lookout below.
It was later determined that the OOW fell asleep sometime after sending the lookout below. With the Bridge Navigational Watch Alarm System (BNWAS) turned off and other alarms not activated, available bridge resources that could have alerted the crew and/or awoken a sleeping OOW were silenced. As a result the vessel steamed at 11.5 knots with no-one in control on the bridge for over an hour before grounding.
All of the vessel’s crew, with the exception of the OOW, were awoken by the vessel running aground. The Master ran to the bridge, where he found the OOW still asleep. He roused him and simultaneously placed the engine control to neutral. The OOW awoke confused and was shocked to find that the ship was aground.
In the days leading up to the accident, the OOW had maintained the 0000-0600 watch. However, for the 24-hour period preceding the accident this routine was reversed. While the vessel was alongside he was the duty night officer, but was expected to rest from midnight (when he would normally be on watch) and work through from 0700-1200, (when he would normally be asleep). It is likely that this change of routine impacted upon his quality of sleep during the night in port. He did have over four hours rest before taking over the watch from the Master at midnight and appeared to be fit and well at that time. However, within one hour of taking the watch the OOW failed to call the pilot station, despite specific instructions in the Master’s night order
book (which he had signed) and the Master’s verbal reminder to him at the watch handover. This suggests that weariness was already affecting his cognitive ability.
Findings of the report
* The OOW fell asleep on watch as a result of insufficient stimulation and probable fatigue following a change of work and rest pattern.
* There was no lookout on the bridge, as required during the hours of darkness, allowing the OOW to fall asleep unnoticed. It was not unusual for lookouts to be dismissed from the bridge during the hours of darkness.
* By including the AB/cook on the look-out duty roster, there would have been sufficient manpower for a dedicated lookout to be maintained during the hours of darkness, whilst ensuring personnel did not work excessive hours.
* The Master did not exercise his overriding authority for the safety of the vessel to delay sailing until his watchkeepers and lookouts were adequately rested.
* Navigational aids were not used effectively to ensure a vigilant and effective watch was maintained at all times.
* The vessel was equipped with a BNWAS. However, neither the ship’s managers nor the Master required that this equipment be used; it was seldom, if ever used by the bridge watchkeepers.
Editor’s note: Although the change in the OOW’s work routine probably exasperated his fatigue, it has been amply demonstrated that a watchkeeping system using a 6 on/6 off routine does not allow for enough continuous hours of rest to be restorative. The Nautical Institute is of the opinion that this watch system should not be used.
（译文参考：船舶管理部机务培训分析师 傅恒星译）
编者注：尽管值班驾驶员的值班安排改变是导致疲劳的原因，但大量的事实表明，两班倒的工作模式让值班人员无法得到足够的连续休息时间来恢复，Nautical Institute不建议采取这种值班安排方式。
两班倒值班（工作6小时休息6小时）=疲劳
一艘小货轮在海上沿岸全速航行。午夜时分，两个值班驾驶员之一的船长下班，由另一个驾驶员上驾驶台换班，通常按照该轮惯例，驾驶员在交接完成后立即安排值班水手到下层安全巡视。
后来判断，值班驾驶员可能在安排水手下去安全巡视后不久便进入梦乡，此时驾驶台值班报警电源被关闭，其他相关报警也没有被触发，驾驶台可用资源里所有能够警告船员和/或使驾驶员从睡梦中惊醒的报警均归于寂静。就这样，船舶在驾驶台无人照管情况下以11.5节的速度全速航行了超过1个小时，直至最后搁浅。
除了值班驾驶员外所有其他船员均因船舶搁浅动静被惊醒，船长冲上驾驶台时，值班驾驶员依然还在熟睡，船长叫醒驾驶员同时将主机推到停车档，值班驾驶员迷糊醒来，但发现船舶搁浅后立刻被眼前景象所惊呆。
在事故发生前的一段日子，该值班驾驶员一直值0000-0600班，然而在事故发生前24小时，该值班惯例被打断，船舶靠泊期间，该驾驶员值夜间班，被要求其从午夜开始休息（平时的值班时间），从0700-1200值班（通常的睡觉时间），似乎这种改变影响了该驾驶员在港期间的休息质量，午夜驾驶员接船长班前实际仅休息了4个小时，接班时驾驶员的似乎状态还不错，然而接班一小时里忘了呼叫引水站，尽管在船长的夜航命令里已明确写了该特别指令。
调查结果报告
值班驾驶员因为不够兴奋和可能由于工作休息模式发生改变引起疲劳导致在值班期间入睡。
按照常规要求，在夜间值班，驾驶台上应有协助瞭望人员，但是在黑暗条件下瞭望人员缺位十分常见，使得值班驾驶员有机会在无人注意的情况下进入梦乡。
包括水手和大厨均在夜间执勤表上，这意味着有足够的人力资源专门用于夜间警戒，同时可确保个人工作时间不会超过最大工作时间规定。
船长没有出于船舶安全的理由在值班人员和夜间警戒人员得到充分休息前使用其否决权延期开航。
相关助航设备未有效使用来确保驾驶台任何时候都维持安全有效的值班。
驾驶台安装了驾驶台值班报警装置（BNWAS），但无论是公司还是船长本人从没要求该设备必须使用，因此驾驶台值班人员极少使用该设备；
