1. Navigational Devices Used At Sea By: Reynaldo Thomas

2. Compass
This is a magnetic needle which is mounted on a pin so it is free to spin around.
The compass point always points north.
Compasses are mounted on gimbals which make the compass always horizontal when the boat moves up and down.

3. Echo Sounders/ Sonar
Fishermen use it to find fish
It sends short pulses of sound
through the water surrounding
a fishing boat.
If the sound waves strike a shoal of fish they are reflected back to the boat.
The sound is detected by an operator in the boat.

4. Radar
This uses electromagnetic waves to detect the range, speed and direction of objects.
A transmitter emits the waves.
The waves then scattered when they contact an object.
A receiver detects the signal
which is reflected back from
the object.

5. The wavelength change slightly in the returned signal when the object is moving.

6. GPS (Global Positioning System)
A global navigation satellite system
Can be use by anybody worldwide
The GPS satellites broadcast signals from space
Any GPS receiver can obtain a three-dimensional location giving the latitude, longitude and altitude at a certain time.