Grounding and collision are, next to fire, threats to a safe journey. The navigator needs to know exactly where the ship is and that the ship is on the expected route, which means that there is no risk for grounding, and finally that interference with surrounding traffic is avoided.
Navigators may suffer from loss of important information, for instance in situations where visibility is reduced and in darkness. In addition to watching the surroundings, the navigator needs to monitor the radar screen and, more frequently, an electronic chart display (ECDIS). These displays provide information but the monitoring and managing of the displays may reduce the navigator's attention on the surrounding world. A recent accident report (Investigation report C4/1998) pointed out that adjustment of sea clutter required the navigator to go through five separate steps on the radar equipment. Accidents have also happened where the navigator in the course of events have been preoccupied with e.g. adjustment of radar screen clutter (MS Sleipner, 2000).
The solution suggested here integrates information from a number of sources and presents safety-critical navigational information on the windscreen in front of the navigator. Such information can consist of markings for navigable channel, contours and waypoints of a pre-defined route, contours of shorelines and rocks, wrecks etc., and possibly heading and speed of surrounding vessels as well as information regarding the potential threat from an oncoming vessel. It is important that the projected objects are subtle and do not interfere with the navigator's focus on the real world.
The different pieces of information presented in the navigator's visual field will be picked up from DGPS/GPS, transponders, radar, ARPA and electronic chart systems (ECDIS). In the experiment reported here a Plexiglas display covered with holographic film was used as the windscreen that safety critical information was projected on. Tracking equipment was used to let the navigator move freely and continuously have the enhanced information in the correct position, as an overlay on the real world.
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