The magnetic compass was the most important navigational instrument used by the Tudors. It is a device that uses the Earth's magnetic field to determine direction. The compass consists of a magnetized needle that is free to rotate on a pivot. The needle points towards the Earth's magnetic north pole, which is located near the geographic North Pole.
Astrolabe
The astrolabe was a complex instrument used to measure the position of the sun, moon, and stars. It was used to determine latitude, longitude, and time. The astrolabe consisted of a circular disk with a graduated rim. It had a number of sighting devices, including a pinhole, a sight vane, and a cross-staff.
Cross-staff
The cross-staff was a simple instrument used to measure the altitude of the sun, moon, and stars. It consisted of two wooden staffs that were crossed at right angles. The cross-staff was held up to the eye, and the observer sighted the sun, moon, or star through the pinhole at one end of the staff. The other end of the staff was then moved until it lined up with the horizon. The angle between the two staffs could then be measured, and this could be used to calculate the altitude of the celestial body.
Backstaff
The backstaff was a navigational instrument that was used to measure the altitude of the sun. It was similar to the cross-staff, but it had a reflecting mirror instead of a pinhole. The reflecting mirror reflected the light from the sun into the observer's eye, and this made it easier to sight the sun. The backstaff was invented in the 16th century, and it quickly became the most popular navigational instrument for measuring the altitude of the sun.
Log and line
The log and line was a simple instrument used to measure the speed of a ship. It consisted of a piece of rope with a wooden float at one end. The float was thrown overboard, and the rope was paid out. The number of knots that passed over the ship's side in a certain amount of time was used to calculate the ship's speed.