To navigate, Lindbergh had drawn out a great circle route on a globe and then transposed that course route onto charts. Since the Spirit cruised at about 100 mph, the heading was adjusted each hour for both the route and winds observed from waves on the ocean. The long wings and small tail made the Spirit unstable in the roll axis, which required constant hands-on flying thus helping to keep Charles Lindbergh awake.
There were also distractions from icing, compass problems, and never accurately calculating the strength and direction of any crosswinds. However, the navigation errors luckily averaged out and the Spirit arrived over Dingle Bay, Ireland on the morning of May 21st right on course!!.
The navigation technique of maintaining a course over time is called “dead reckoning”. Lindbergh depended upon the method, but didn’t appreciate the description! From Ireland, navigation was a “piece of cake” cruising over the English countryside and following the Seine River towards Le Bourget Field.
By then, the whole world was watching and waiting along with thousands of cars and headlights creating confusion over The nighttime landing field.
A very exhausted Charles Lindbergh landed the Spirit of St. Louis on the grass field 3000 miles from takeoff and just a quarter century after the first powered flight under control in 1903!!