Depth Finders - How They Work
You may have used a fishfinder or depth finder before, but you may not know exactly how it works.
Fishfinders use Sonar to give a picture of what cannot be seen.
Sonar stands for Sound and Navigation Ranging.
It is used to show the contours and structures under the water.
It also can give depth readings.
Sonar works by sending out a sound wave and measuring the time it take for the sound wave to return.
It then converts this information to a picture that shows up on a screen.
This happens very fast.
A sound wave can travel 240 feet and back within one quarter of a second.
The picture shows up and is scrolled across the screen as new images come into the sonar range.
Using this technology, a person looking at the screen can see structures and fish and even see what size they are in relation to one another.
These sound waves are transmitted at various frequencies.
The higher the frequency the more detailed the results will be.
However the depth capabilities are less.
Lower frequencies allow for more depth but less detail.
Most fishfinders operate from 200 kHz to 83 kHz.
Some are dual or triple frequency units.
Higher end models will use the "side imaging" feature that allows a view of a large precise area of water around the unit.
This feature uses frequencies in the range of 455 kHz to 800 kHz.
Some depth finders also use two or more beams of sound.
The dual beam can give a 20 degree narrow view or the second, wider, 60 degree view under the unit.
Most fish finders are mounted on the boat in a convenient location to the viewer.
A power cable is used on stationary units.
This is connected to a 12 volt battery system, normally the battery system powering the boat.
Portable units use portable batteries, such as regular double A or rechargeable batteries made for that particular model.
Fishfinders come in many sizes and types with various bells and whistles.
Many come with a combination GPS integrated alongside the sonar.
Prices range from $80 to several thousand dollars.
There are also many different brands to choose from.
When shopping, make sure you do your research and get one that will satisfy all your needs.
Fishfinders use Sonar to give a picture of what cannot be seen.
Sonar stands for Sound and Navigation Ranging.
It is used to show the contours and structures under the water.
It also can give depth readings.
Sonar works by sending out a sound wave and measuring the time it take for the sound wave to return.
It then converts this information to a picture that shows up on a screen.
This happens very fast.
A sound wave can travel 240 feet and back within one quarter of a second.
The picture shows up and is scrolled across the screen as new images come into the sonar range.
Using this technology, a person looking at the screen can see structures and fish and even see what size they are in relation to one another.
These sound waves are transmitted at various frequencies.
The higher the frequency the more detailed the results will be.
However the depth capabilities are less.
Lower frequencies allow for more depth but less detail.
Most fishfinders operate from 200 kHz to 83 kHz.
Some are dual or triple frequency units.
Higher end models will use the "side imaging" feature that allows a view of a large precise area of water around the unit.
This feature uses frequencies in the range of 455 kHz to 800 kHz.
Some depth finders also use two or more beams of sound.
The dual beam can give a 20 degree narrow view or the second, wider, 60 degree view under the unit.
Most fish finders are mounted on the boat in a convenient location to the viewer.
A power cable is used on stationary units.
This is connected to a 12 volt battery system, normally the battery system powering the boat.
Portable units use portable batteries, such as regular double A or rechargeable batteries made for that particular model.
Fishfinders come in many sizes and types with various bells and whistles.
Many come with a combination GPS integrated alongside the sonar.
Prices range from $80 to several thousand dollars.
There are also many different brands to choose from.
When shopping, make sure you do your research and get one that will satisfy all your needs.
