Day or night, Northern or Southern hemisphere, the compass always points more or less north. Mariners found them beneficial when used for finding headings. The magnets are used to measure where the north, south, east, and west poles are. (Isil)

Detailed drawings of the earth's oceans and land. They helped sailors know where everything was on the globe. They weren't very accurate because no one knew that much about our earth at the time. 

Used for determining the angle between the horizon and a celestial body such as the Sun, the Moon, or a star, used in celestial navigation to determine latitude and longitude. The device consists of an arc of a circle, marked off in degrees, and a movable radial arm pivoted at the center of the circle. (Richey)

Used to determine latitude by measuring the angle between the horizon and Polaris, also called the North Star, the Pole Star, or Stella Maris. (Isil)

Shaped like a pizza, it is another hand-held instrument of wood or brass. The user measured the altitude of Polaris by sighting through a tiny hole and taking a reading where a short line intersected the scale on the outer edge of it. (Isil)

The timepiece most used in navigation. The most common were the four-hour and half-hour hourglasses. Sailors used it to measure how long they've been out and how far they've gone, also known as "miles per hour".