Survival. Knowledge of navigator's tools helps you avoid becoming lost and also grants you insight into the most likely location for roads and settlements.
Sighting. By taking careful measurements, you can determine your position on a nautical chart and the time of day.
Additional uses. You can use your navigator's tools to do a variety of things, as your DM if you may use the tools for a specific task. Examples of such tasks are as follows; Plot a course, discover your position on a nautical chart.