The direct cause of the collision between the Z60 Blue Angel and the Amadeus Aquamarijn was that the mate of the Z60 Blue Angel failed to see the Amadeus Aquamarijn, and therefore took no action to avoid the Amadeus Aquamarijn. The visual observability of the Amadeus Aquamarijn may be
reduced by a combination of disrupted night vision, the low position of the Amadeus Aquamarijn in the water and both the trim and the masts of the Z60 Blue Angel, which partially disrupted the view, looking forward. Also the alertness of the watchman may be influenced by the effects of fatigue.
It is likely that The Amadeus Aquamarijn was visible on the systems (radar, AIS overlay on the chart plotter) during the hour that the watchman was on duty prior to the collision. The most probable explanation is that the effects of fatigue were combined with a subconscious dependency in the mind of the watchman on the CPA alarm, which was switched off prior to the collision. The second mate on the Amadeus Aquamarijn, convinced that the fishing vessel had changed course following his call, took no further action to monitor the situation because he assumed that the fishing vessel would pass safely.
The Dutch Safety Board calls on ship owners and maritime training institutes to focus attention on awareness that fatigue can result in reduced alertness. It is also important that warning equipment, such as the CPA alarm, is switched back on after being switched off for fishing. The CPA alarm which during certain activities, such as fishing, is regularly triggered. This is experienced by the crew as disruptive and therefore switched off. Also the shipping sector should make non-standard situations part of training.