In its essence, navigation in ocean races is the same as navigation on any other voyage; the processes are the same and the drill is not very different. But it is a specialized thing and there are certain interesting problems which demand special solutions and special ways of doing things. To start with, the vessel is propelled by wind and one cannot, in the ordinary course of events, lay off one's mean course and steer it; the course will be continually varying, and the whole of the navigational problem is coloured by this fact. Again, navigation in ocean racing demands a much higher accuracy than navigation in an ordinary sailing vessel, where a landfall within five or perhaps even more miles in good visibility will be quite enough; the difference between spot-on and five miles away may well be the difference between winning an ocean race and otherwise.