A fish finder is a marine electronics device that looks into the water with sound waves and converts the returning signals into a picture you can see and interpret on a display screen.
Referred to by a myriad of other names including depth finder, sounder, sonar, or bottom machine, they all use a transducer to send pulses of sound into the water and listen for their return. Recreational transducers vary significantly in size, power, and price. The Airmar 260 series is an example of a top of the line transducer.
It is important when selecting a fish finder that you choose the right screen size, power output, and features to suit your needs and budget. If you plan to display fishfinder data through a multifunction display you will need to find the right black box sounder for your system.
It also measures the amount of time those pulses take to return and converts that information into distance.
All this data is then converted by the electronics package into pixels on a display screen to be read and interpreted by you.
Fishermen, power boaters, sailors, and cruisers, can all benefit from the information provided by a good quality sounder. These devices are not solely for locating fish.
Obviously, a sounder will tell you the water depth. In the right hands one of these units can reveal much about the bottom composition. This can be valuable information for anyone getting ready to drop the anchor and spend the night.
Fisherman looking for certain species that may prefer a particular type of bottom can use a quality sounder to help determine whether the bottom is muddy or rocky.
Using a fishfinder to locate likely fish-holding structure can improve your fishing success and turn a mediocre day into an outstanding catch.
Generally a bottom machince looks down into the water column and tells you what is below, however today a number of units can also scan forward or out to the side.
A small standalone fish finder with a screen measuring near 4-inches on the diagonal might start as low as $100. Prices go up from there. As you increase display screen size and get more sophisticated electronics coupled to a larger more capable transducer expect to spend more dollars.