Originally Posted by 5 speed
are you sure about that? My understanding all along is that at top race speeds you are completely driving beyond what you can see which is why you have the roadbook/ co driver to begin with
In Baja the competitors prerun the course days ahead of race day (memorizing it), they have very accurate GPS tracks showing very inch of the course, and many have written course notes detailing hazards that they saw while prerunning. So, in Baja the co-driver IS responsible for letting the driver know about hazards including sharp curves, or even small curves if they are in heavy dust. Many drive completely blind in dust, following the GPS.
In Dakar and most other cross-country rally events it's completely different. The course is secret. The competitors don't know where it goes until they are on it racing, and even then it's easy to get lost. There are no course markers, no GPS tracks or maps, no prerunning, and no custom made course notes. Most of the time the only things they have for navigation are the official roadbook, their odometer, and a digital compass.
The roadbook usually indicates moderate and severe hazards, but not curves in the road, unless it's a particularly dangerous curve that might have a cliff or something really bad at the edge. It's not like WRC rally, where EVERY turn and bump is in the roadbook. In this type of rally, the job of the navigator is to tell the driver which way to go at intersections, and basic direction information like that. In a 300 mile Special, there typically might be 10 to 20 hazards marked in the roadbook, and a few hundred "turn left at this intersection" type directions. In those 300 miles, they might go through 5000 "curves" which are not in the roadbook. Think of the roadbook as the MINIMUM information needed to navigate your way through the stage, plus 20 or so SERIOUS marked hazards.