Answer:
Actually, captain does not 'locate' specific destination, instead, it is the work of the navigator.
Navigator use a method by means of using objects in the skies as reference with the use of a tool called 'astrolabe' and 'sextant' an angle-measuring instrument. astrolabe is used to measure the altitude of the stars and constellations and sextant is used to measure the angle of the sun above the horizon, in short, astrolabe is used in night and sextant is used in daylight. They also use compass which always points out in north, therefore they could use it also as reference. Of course all navigator uses charts which we called maps, it has a line graph of longitude and latitude which helps them locate almost accurately and without these charts, it's harder to voyage as they need to make a chart while voyaging, for later use.
Source:
trust me bro.
