The most important things we want to know when using a fish finder is the bottom type and whether there are any fish around.
Let’s start with the bottom. The transducer – typically mounted on the transom of a trailer boat or through the hull on larger vessels – sends a soundwave down through the water at up to 50 times per second. When it makes contact with the bottom, the soundwave is reflected back to the transducer. The time it takes for this signal to return is how the unit works out depth.
A good fish finder can differentiate between hard and soft bottoms and small/large fish by the strength of the returned signal. Hard objects will return a strong signal, while soft or small objects will return a weak signal.
The days of buying a cheap sounder to just show you the depth are gone. If you invest in a high-resolution colour sounder and learn how to read it, your fishing will improve out of sight. There is no point fishing if there are no fish around, so why not find them first, then fish with confidence and accuracy!