As perhaps the biggest innovation in fishing, having a sounder suited to you, and that you know how to use is very important!
Choosing a fish finder, or chart plotter, can be a daunting exercise in a day and age with so many options, sizes and features available. Nonetheless we are here to help you make the choice that best suits you!
The first and easiest way to narrow this down is screen size. This is most likely where you will be limited, unless you have plenty of room for 10", 12" and larger units. Once you have decided what screen size you require, a good next step is whether you'd like touch screen or a button operated unit - touch screen often provides more screen space to display information.
It is also pertinent to decide whether you simply require a high frequency for shallower water, and inshore applications. Or you may need a lower frequency for deeper water, for offshore fishing. Heck, you may even need both - as some sounders can chop and change between high and low chirp. This is for the fishermen who has a snapper fish on his way home from catching Puka' and Bluenose.
"Higher frequency sounders have a larger cone to cover more of the oceans bottom, while lower frequencies have a narrower cone to make sure the detail you require to spot the fish is accurate at deeper depths."
If you have decided you usually fish inshore for coastal species such as snapper, kingfish, gurnard and kahawai, the next step is deciding if you are happy with simple sonar functions. Alternatively, if you often lure fish in shallow water with Softbaits, kaburas, and jigs - side scan is a very helpful tool. This allows you to use two beams to cover a lot more of the seafloor. Spotting fish and structure with ease.
If you simply fish with bait and just need to find a bit of sign on the bottom then simple sonar functions will likely fulfil your requirements.
For the game fishermen and deep water fishos' a low frequency sounder, or 1KW (potentially with a module), will greatly improve the accuracy of your fishfinding, albeit narrowing your cone angle. A multi function display where you can change between high and low frequency or chirp, will make for easy usage in shallow or deep water. Even for finding gamefish in the upper section of the water column.