Fish finders are installed on fishing boats and other watercrafts. They consist of an electrical supply and digital display that are located at the top of the boat, as well as transducer sensors mounted on the bottom of the hull. The transducers serve a dual purpose as they emit sound waves, directing them towards the floor of the water body, and also they receive the sound waves that bounce back. They are connected to components called transmitters, located at the top of the boat with the power supply. The transmitters are then connected to electrical receivers that are connected to the displays which fishermen use to interact with the fish finder system. Once turned on, fish finders do all the work, leaving fishermen to just read the display and catch the fish. The fish finding process begins when a transmitter sends an electrical impulse to the transducer, instructing it to create a sound wave in the water. This sound wave travels downward while expanding as it moves farther away. When the sound wave hits an object, it sends the sound wave bouncing back up. The transducer recognizes this signal and relays it to the transmitter. The transmitter then puts the echo data in the form of an electrical signal and sends it to the receiver, which in turn translates it into digital data that can be displayed. By looking at the display screen, a fisherman can tell what is beneath the watercraft in real time. There are many different manufacturers that all produce multiple models of fish finders, so there are lots of different display configurations. Some have sensitive transducers that their displays indicate what is and is not a fish. They can actually detect the contours of fish and distinguish them from other underwater objects and also report them to the fishermen in the boat by displaying little fish-shaped cursors on the screen. Less-sensitive fish finders normally have displays that look like sideways-scrolling line graphs. The uneven but usually horizontal line represents the floor of the body of water, and then fish or other objects are represented by spikes in the line or floating dots above the line. Using these systems, fishermen must note other information to determine whether the objects being detected by the fish finder are fish or something else.