Ships' bridge watchkeeping, although the prime task of the officer of the watch, makes very low task demands in terms of information processing and required speed of response compared to most other vigilance tasks. Consequently, performance of the visual lookout task is difficult to describe and evaluate systematically. Results from an on-board observational study show that lookout lapse periods can be economically described by simple mathematical models, which assist in comparison and evaluation of task performance.

In many aviation and nautical contexts, single manning is common. Some aircraft and some vessels are designed for single manning with no choice. Others can have multiple or single manning, usually depending on such factors as operational requirements, mission objectives, intended human roles, task demands, workload, envisaged mission duration, and environmental conditions.

The safety on board medium-sized fishing vessels in relation to working conditions on the bridge is analysed by means of a problem-solving method developed by the Safety Science Group of the Delft University of Technology. The potential of the method is illustrated by a number of case studies on selected aspects of the bridge design, since a complete application of the method is not yet available.